<?xml version="1.0" encoding="UTF-8"?><rss version="2.0"><channel><title><![CDATA[Archives of Mechanics]]></title><description><![CDATA[Articles]]></description><link>http://am.ippt.gov.pl/</link><copyright><![CDATA[Copyright Archives of Mechanics]]></copyright><generator>CMS</generator><item><title><![CDATA[Profile reconstruction of a continuously-stratified layer from reflection data on acoustic waves]]></title><description><![CDATA[
  
The paper investigates the reflection-transmission process of acoustic waves, generated by an inhomogeneous fluid layer of finite thickness, which is sandwiched between two semi-infinite homogeneous half-spaces. First a direct problem is solved by determining the reflection and transmission coefficients along with the wave solution in the layer, produced by a known incident wave. Owing to the planar stratification of the layer, the unknown acoustic pressure is looked at as a generalized plane wave. Upon the Fourier transformation, the second-order wave equation is written as a firstorder system of equations for the dependence on the depth of the pressure and the partial derivative. The corresponding Volterra integral equation gives the pressure in the layer as a series of repeated integrals of powers of the pertinent depth-dependent matrix of the system. The reflection and transmission coefficients of the layer are then determined for any incidence angle. Next an inverse problem is investigated. The derivatives of the reflection coefficient, with respect to the frequency, are shown to provide the thickness of the layer, the speed beyond the layer and the moments, of any order, of the refractive index.
  ]]></description><pubDate>Wed, 17 Mar 2010 12:48:04 +0000</pubDate><link>http://am.ippt.gov.pl/volume-62-2010/issue-1/profile-reconstruction-of-a-continuouslystratified-layer-from-reflection-data-on-acoustic-waves/</link><guid>http://am.ippt.gov.pl/volume-62-2010/issue-1/profile-reconstruction-of-a-continuouslystratified-layer-from-reflection-data-on-acoustic-waves/</guid></item><item><title><![CDATA[Some theorems of incremental thermoelectroelasticity]]></title><description><![CDATA[
  
We extend to incremental thermoelectroelasticity with biasing fields certain classical theorems, which have been stated and proved in linear thermopiezoelectricity referred to a natural configuration. A uniqueness theorem for the solutions to the initial boundary value problem, the generalized Hamilton principle and the theorem of reciprocity of work are deduced for incremental fields, superposed on finite biasing fields in a thermoelectroelastic body.
  ]]></description><pubDate>Wed, 17 Mar 2010 12:46:02 +0000</pubDate><link>http://am.ippt.gov.pl/volume-62-2010/issue-1/some-theorems-of-incremental-thermoelectroelasticity/</link><guid>http://am.ippt.gov.pl/volume-62-2010/issue-1/some-theorems-of-incremental-thermoelectroelasticity/</guid></item><item><title><![CDATA[Viscoelasticity and fractal structure in a model of human lungs]]></title><description><![CDATA[
  
This paper provides a model of the human respiratory system by taking into account the fractal structure of the airways and the viscoelastic properties of the tissue. The self-similarity of airway distribution is admitted up to the 24th generation. Due to periodic breathing which results in sinusoidal excitation of the respiratory system, an electrical equivalent model is developed. The periodic current in this electrical network, that preserves the geometry of the human respiratory tree, is equivalent to the oscillatory air-flow. The model is expressed by Navier–Stokes equations under cylindrical symmetry, linked with an equation responsible for the motion of viscoelastic tissue of airway walls. By use of both electro-mechanical analogies, the total impedance of the respiratory system is determined and compared to the measured data in the clinical range of 4–48 Hz, as well as in the low-frequency
range of 0.1–5 Hz. We propose also a lumped model of fractional orders, which is able to capture frequency-dependent variations in both clinical as well as in the low-frequency ranges. The models proposed in this paper can be further used to determine the effects of disease on the lung morphology.
  ]]></description><pubDate>Wed, 17 Mar 2010 12:44:26 +0000</pubDate><link>http://am.ippt.gov.pl/volume-62-2010/issue-1/viscoelasticity-and-fractal-structure-in-a-model-of-human-lungs/</link><guid>http://am.ippt.gov.pl/volume-62-2010/issue-1/viscoelasticity-and-fractal-structure-in-a-model-of-human-lungs/</guid></item><item><title><![CDATA[Deformation of orthotropic porous elastic bars under lateral loading]]></title><description><![CDATA[
  
The present paper is concerned with the linear theory of inhomogeneous and
orthotropic, porous elastic cylinders. The work is motivated by the recent interest in using of orthotropic porous elastic solid as a model for bones and for various engineering materials. A generalization of Saint–Venant’s problem to the case when the cylinder is subjected to body forces and to surface forces on the lateral boundary. The three-dimensional problem is reduced to the study of plane problems. The method is applied to investigate the deformation of a uniformly loaded circular cylinder.
  ]]></description><pubDate>Wed, 17 Mar 2010 12:41:53 +0000</pubDate><link>http://am.ippt.gov.pl/volume-62-2010/issue-1/deformation-of-orthotropic-porous-elastic-bars-under-lateral-loading/</link><guid>http://am.ippt.gov.pl/volume-62-2010/issue-1/deformation-of-orthotropic-porous-elastic-bars-under-lateral-loading/</guid></item><item><title><![CDATA[Bounds and self-consistent estimates of overall properties for random polycrystals described by linear constitutive laws]]></title><description><![CDATA[
  
Analytical solutions for bounds of overall properties are derived for singlephase polycrystalline materials of random texture, composed of grains with arbitrary anisotropy and described by the linear constitutive law. Self-consistent estimates are found for these materials and they are studied in more details when anisotropic grains are volumetrically isotropic. Reduction of the above solutions for incompressible materials or materials with constraint modes of deformation is also derived. Existence and uniqueness of the obtained solutions are discussed. In order to obtain the solutions, simultaneously the spectral and harmonic decomposition of fourth order Hooke’s tensor are used. Utility of the obtained results is demonstrated on the examples of metals and alloys of high specific strength and stiffness.
  ]]></description><pubDate>Tue, 29 Dec 2009 17:28:44 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-6/bounds-and-selfconsistent-estimates-of-overall-properties-for-random-polycrystals-described-by-linear-constitutive-laws/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-6/bounds-and-selfconsistent-estimates-of-overall-properties-for-random-polycrystals-described-by-linear-constitutive-laws/</guid></item><item><title><![CDATA[Improved five-parameter fractional derivative model for elastomers]]></title><description><![CDATA[
  
The dynamic behaviour of elastomers is assumed to follow a constitutive differential equation of non-integral (fractional) order. In order to describe the peculiar frequency response of the loss factor, the constitutive equation has been refined by introducing the fifth parameter to the classical fourth-order equation. The asymmetry of the loss factor in the frequency domain comes from the different time-derivative orders of the stress and strain. Either smooth asymmetry or stabilization by a plateau at high frequency can be modelled by suitable difference between the two orders of the time derivatives. The physical validity of the model is discussed and a parametrical analysis is conducted on diagrams relating the height and the width of the loss factor.
  ]]></description><pubDate>Tue, 29 Dec 2009 17:25:43 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-6/improved-fiveparameter-fractional-derivative-model-for-elastomers/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-6/improved-fiveparameter-fractional-derivative-model-for-elastomers/</guid></item><item><title><![CDATA[Relation between shakedown and shape memory of metallic materials considering their mesoscale and atomic scale substructures]]></title><description><![CDATA[
  
Shakedown (SD) and shape memory (SM) – generally looked upon as two different phenomena – are shown to have close relations from the point of view of their mechanisms, if considering the respective mesoscale processes on the one hand and the atomic scale processes on the other hand. With the use of the general mesomechanical concept of the first author, their constitutive equations are formulated using the same basic formulae, but with different meanings of the symbols. Constitutive equations are based on the description of internal stresses, in the case of SD on the mesoscale, in the case of SM on the atomic scale. Whereas in the case of SD, plastic deformation means shifting of atomic blocks and changing atomic neighbors, in the case of a diffusionless SM the atomic neighbors are maintained, what simplifies the analysis.
  ]]></description><pubDate>Tue, 29 Dec 2009 17:22:20 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-6/relation-between-shakedown-and-shape-memory-of-metallic-materials-considering-their-mesoscale-and-atomic-scale-substructures/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-6/relation-between-shakedown-and-shape-memory-of-metallic-materials-considering-their-mesoscale-and-atomic-scale-substructures/</guid></item><item><title><![CDATA[Description of anisotropic pore space structure of permeable materials based on Minkowski metric space]]></title><description><![CDATA[
  
This paper contains an extended presentation of a new approach to the macroscopic description of anisotropic pore space structure of rigid permeable material, utilizing the concept of Minkowski metric space. The metrics of the Minkowski and Euclidean spaces are used to determine double measures of any line, surface and volume elements, and to define geometrical macro-parameters characterizing anisotropic pore space structure: the volume and surface porosities, and the tortuosity of the pores. It is shown that the metric tensor of the Minkowski space can be interpreted as a tensor of the pore tortuosity, and its inverse as a tensor of the surface porosity. This means that the pore tortuosity has a pure geometrical character and is of fundamental importance for description of anisotropic pore space structure and for all physical processes taking place in the pore space. The approach presented in this paper allows a description of fluid dynamics in the anisotropic pore space in the framework of rational mechanics.
  ]]></description><pubDate>Tue, 29 Dec 2009 17:15:58 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-6/description-of-anisotropic-pore-space-structure-of-permeable-materials-based-on-minkowski-metric-space/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-6/description-of-anisotropic-pore-space-structure-of-permeable-materials-based-on-minkowski-metric-space/</guid></item><item><title><![CDATA[On the deformation of transversely isotropic porous elastic circular cylinder]]></title><description><![CDATA[
  
In this paper we study the deformation of right circular cylinders filled by a linear transversely isotropic porous material. We construct a solution of the relaxed Saint–Venant’s problem using the results established for anisotropic porous cylinders. Firstly, we decompose the relaxed Saint–Venant’s problem into two problems: extension–bending–torsion problem and flexure problem. Then, for each of them we give the exact expressions of the solutions.
  ]]></description><pubDate>Mon, 02 Nov 2009 17:54:57 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-5/on-the-deformation-of-transversely-isotropic-porous-elastic-circular-cylinder/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-5/on-the-deformation-of-transversely-isotropic-porous-elastic-circular-cylinder/</guid></item><item><title><![CDATA[Magnus effect and dynamics of a spinning disc in a rarefied medium]]></title><description><![CDATA[
  
Magnus effect consists in deflection of the trajectory of a rotating body moving in a gas. It is a direct consequence of the interaction between the body surface and the gas particles. In this paper, we study the so-called inverse Magnus effect which can be observed in rarefied gases. We restrict ourselves to the two-dimensional case, namely a spinning disc moving through a sparse zero-temperature medium. We consider general non-elastic interaction between the disc and the particles depending on the incidence angle. We give a classification of auxiliary parameters with respect to possible dynamical response. In the absence of other forces, three kinds of trajectories are possible: (i) a converging spiral, (ii) a curve converging to a straight line and (iii) a circumference, the case intermediate between the two first ones. A specific 2-D parameter space has been introduced to provide respective classification.
  ]]></description><pubDate>Mon, 02 Nov 2009 17:52:06 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-5/magnus-effect-and-dynamics-of-a-spinning-disc-in-a-rarefied-medium/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-5/magnus-effect-and-dynamics-of-a-spinning-disc-in-a-rarefied-medium/</guid></item><item><title><![CDATA[Taxonomy of polar decompositions for singular second-order tensors in R^3]]></title><description><![CDATA[
  
The well-known polar decomposition theorem is analyzed for the case of second-order, singular tensors on R^3. A precise analytical and geometric characterization of the split is provided for tensors of rank two and one.
  ]]></description><pubDate>Mon, 02 Nov 2009 17:48:09 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-5/taxonomy-of-polar-decompositions-for-singular-secondorder-tensors-in-r3/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-5/taxonomy-of-polar-decompositions-for-singular-secondorder-tensors-in-r3/</guid></item><item><title><![CDATA[Uniqueness in thermoelasticity of porous media with microtemperatures]]></title><description><![CDATA[
  
The problem determined by thermoelastic deformations when the internal energy is not positive definite, becomes ill-posed.We recall that this kind of situation happens in the study of prestressed thermoelastic solids. Thus, it will be of interest to obtain qualitative properties of solutions in this case. In this note we prove the uniqueness of solutions for the linear thermo-poro-elasticity with microtemperatures theory, when the internal energy is not to be assumed to be positive definite. We use the energy arguments combined with the Lagrange identities.
  ]]></description><pubDate>Mon, 02 Nov 2009 17:44:38 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-5/uniqueness-in-thermoelasticity-of-porous-media-with-microtemperatures/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-5/uniqueness-in-thermoelasticity-of-porous-media-with-microtemperatures/</guid></item><item><title><![CDATA[Analysis of uncertainties in MEMS and their influence on dynamic properties]]></title><description><![CDATA[
  
An application of uncertainty analysis of microelectromechanical resonator is presented. A number of different uncertain parameters have been considered, connected both to geometric characteristics and material property. Sensitivity analysis has been carried out in order to study the influence of each input uncertain parameter on the chosen dynamic characteristics. The propagation of given uncertainties into the variation of studied output parameter has been evaluated by means of the Monte Carlo simulation, the vertex method and genetic algorithms. Finite element model of microresonator has been elaborated. It has taken into account the phenomenon of viscous damping coming from the presence of surrounding air as well as the inﬂuence of constant electrostatic field.
  ]]></description><pubDate>Mon, 02 Nov 2009 17:37:46 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-5/analysis-of-uncertainties-in-mems-and-their-influence-on-dynamic-properties/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-5/analysis-of-uncertainties-in-mems-and-their-influence-on-dynamic-properties/</guid></item><item><title><![CDATA[WOJCIECH KRZYSZTOF NOWACKI (1938–2009) OBITUARY]]></title><description><![CDATA[
  

  ]]></description><pubDate>Mon, 02 Nov 2009 17:23:48 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-5/wojciech-krzysztof-nowacki-19382009-obituary/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-5/wojciech-krzysztof-nowacki-19382009-obituary/</guid></item><item><title><![CDATA[Representing a non-associated constitutive law by a bipotential issued from a Fitzpatrick sequence]]></title><description><![CDATA[
  
We analyze the relation between Géry de Saxcé's bipotentials representing non-associated constitutive laws and Fitzpatrick's functions representing maximal monotone multifunctions. We illustrate by two examples (one linear and monotone, the
other non-linear and non-monotone) the fact that Fitzpatrick's representation coming
from convex analysis provides a constructive method to discover the "best" bipotential
modelling of a given Implicit Standard Material.
  ]]></description><pubDate>Sun, 13 Sep 2009 01:04:32 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-34/representing-a-nonassociated-constitutive-law-by-a-bipotential-issued-from-a-fitzpatrick-sequence/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-34/representing-a-nonassociated-constitutive-law-by-a-bipotential-issued-from-a-fitzpatrick-sequence/</guid></item><item><title><![CDATA[On the thermoelastic problem of uniform heat flow disturbed by a circular rigid lamellate inclusion]]></title><description><![CDATA[
  
A complete solution in elementary functions is given for the three-dimensional
thermoelastic ﬁeld in an elastic space, containing an absolutely rigid circular inclusion
(anticrack) under a normally incident uniform heat ﬂow. The inclusion is assumed
to be slightly conducting, with a certain thermal resistance. The analysis is based
on the potential theory method. The resulting boundary-value problems are reduced
to classical mixed problems of the potential theory. The temperature, ﬂuxes, thermal stresses and displacements in the inclusion plane are given in closed forms and
interpreted from the point of view of the failure theory.
  ]]></description><pubDate>Sun, 13 Sep 2009 01:02:19 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-34/on-the-thermoelastic-problem-of-uniform-heat-flow-disturbed-by-a-circular-rigid-lamellate-inclusion/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-34/on-the-thermoelastic-problem-of-uniform-heat-flow-disturbed-by-a-circular-rigid-lamellate-inclusion/</guid></item><item><title><![CDATA[Notched concrete beams under bending -- calculations of size effects within stochastic elasto-plasticity with non-local softening]]></title><description><![CDATA[
  
Numerical FE investigations of a deterministic and statistical size effect in
notched concrete beams of a similar geometry under three-point bending were performed. The FE analyses were carried out with four different beam sizes. Deterministic calculations were performed assuming constant values of tensile strength. In turn,
in statistical calculations, the tensile strength took the form of random spatial fields
described by a truncated Gaussian random distribution. In order to reduce the number of stochastic realizations without loosing the accuracy of the calculations, Latin
hypercube sampling was applied. The numerical results were compared with the corresponding laboratory tests. The numerical outcomes show that the bearing capacity
of beams and their ductility increase with decreasing specimen size. If the distribution
of the tensile strength is stochastically distributed, the mean beam strength is always
smaller than the deterministic value.
  ]]></description><pubDate>Sun, 13 Sep 2009 00:59:50 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-34/notched-concrete-beams-under-bending-calculations-of-size-effects-within-stochastic-elastoplasticity-with-nonlocal-softening/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-34/notched-concrete-beams-under-bending-calculations-of-size-effects-within-stochastic-elastoplasticity-with-nonlocal-softening/</guid></item><item><title><![CDATA[A multi-grain model for migration recrystallization in polar ice]]></title><description><![CDATA[
  
In the paper a multi-grain model for a migration recrystallization phenomenon
in polar ice is presented. A single crystal of ice is treated as a transversely isotropic
and incompressible medium which deforms by viscous creep. The anisotropic viscous
behaviour of the ice crystal is described by a constitutive law that includes three microscopic viscosity parameters, and the macroscopic behaviour of the polycrystal is
derived by adopting the Taylor–Voigt approximation of the velocity gradient homogeneity in the material. It is assumed that recrystallize, that is gradually disappear,
these crystals which are most stressed, and at their expense new crystals are nucleated with the orientations that enhance the deformation of the polycrystal. The
model predictions are illustrated by results of numerical simulations of simple ﬂows,
showing the evolution of the oriented structure of ice and the variation of macroscopic
viscosities with increasing strains.
  ]]></description><pubDate>Sun, 13 Sep 2009 00:52:55 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-34/a-multigrain-model-for-migration-recrystallization-in-polar-ice/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-34/a-multigrain-model-for-migration-recrystallization-in-polar-ice/</guid></item><item><title><![CDATA[Torsional deformation and rotary driving characteristics of SMA thin strip]]></title><description><![CDATA[
  
The torsional deformation properties of a TiNi shape-memory alloy thin strip
were investigated. The results obtained are summarized as follows. (1) The martensitic transformation starts at the edge of the thin strip. (2) The torsional deformation
properties change slightly under thermomechanical cycling. (3) The fatigue life in pulsating torsion is longer than that in alternating torsion. (4) A simple rotary driving
element can be developed by using the SMA thin strip.
  ]]></description><pubDate>Sun, 13 Sep 2009 00:50:26 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-34/torsional-deformation-and-rotary-driving-characteristics-of-sma-thin-strip/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-34/torsional-deformation-and-rotary-driving-characteristics-of-sma-thin-strip/</guid></item><item><title><![CDATA[Inelastic behavior and numerical analysis in twin-roll casting process of AZ31 alloy]]></title><description><![CDATA[
  
In this paper, Anand’s model, a uniﬁed visco-plasticity constitutive model, was
employed to simulate the highly nonlinear behavior in the twin-roll casting process.
Anand model’s parameters were regressed based on compression tests at various temperatures and strain rates for magnesium alloy AZ31. To calculate the thermal mechanical stresses, the thermal ﬂow of twin-roll casting process was simulated ﬁrstly;
then the stresses were calculated by the imposed thermal ﬂow as the body load, and
a small displacement load along roller’s tangential direction was imposed simultaneously in order to simulate the rolling action. The stresses and deformation results were
compared with experimental data. Based on the stresses analysis and experimental
tests, it reveals that separating force should be strictly controlled in the twin roll
casting process in order to avoid cracks caused by thermal and deformation stresses.
  ]]></description><pubDate>Sun, 13 Sep 2009 00:47:56 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-34/inelastic-behavior-and-numerical-analysis-in-twinroll-casting-process-of-az31-alloy/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-34/inelastic-behavior-and-numerical-analysis-in-twinroll-casting-process-of-az31-alloy/</guid></item><item><title><![CDATA[On the problems of Almansi and Michell for anisotropic Cosserat elastic shells]]></title><description><![CDATA[
  
This paper investigates the equilibrium of cylindrical elastic shells under the action of prescribed body loads, external loads on the lateral edges, and resultant forces
and moments on the end edges. We consider anisotropic and inhomogeneous cylindrical shells with arbitrary (open or closed) cross-sections, and we employ the linear
theory of Cosserat surfaces. We present a method to construct the solutions to the
problems of Almansi and Michell. Then, we apply these results to study the deformation of orthotropic and homogeneous circular cylindrical tubes and Cosserat plates.
  ]]></description><pubDate>Sun, 13 Sep 2009 00:45:01 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-34/on-the-problems-of-almansi-and-michell-for-anisotropic-cosserat-elastic-shells/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-34/on-the-problems-of-almansi-and-michell-for-anisotropic-cosserat-elastic-shells/</guid></item><item><title><![CDATA[Numerical modelling of the opening process of the three-coating aortic valve]]></title><description><![CDATA[
  
Numerical modelling of the three-coating human aortic valve is the objective of
the paper. The proposed approach is used to select the material properties and the
thickness of outer coating of the valve, which are required to obtain the proper work of
the valve, which in the present paper is considered as the opening process. Following
the previously developed model of the monocoating leaﬂet of the natural human aortic
valve, the model of three-coating valve is prepared. Finite element method (FEM)
and sensitivity analysis are used to solve the formulated and selected problems. Two
methods of estimation of the valve opening process in numerical models are elaborated
on the basis of experimental studies.
  ]]></description><pubDate>Sun, 13 Sep 2009 00:40:36 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-34/numerical-modelling-of-the-opening-process-of-the-threecoating-aortic-valve/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-34/numerical-modelling-of-the-opening-process-of-the-threecoating-aortic-valve/</guid></item><item><title><![CDATA[Preface]]></title><description><![CDATA[
  

  ]]></description><pubDate>Sun, 13 Sep 2009 00:35:51 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-34/preface/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-34/preface/</guid></item><item><title><![CDATA[Preface]]></title><description><![CDATA[
  

  ]]></description><pubDate>Sun, 13 Sep 2009 00:26:18 +0000</pubDate><link>http://am.ippt.gov.pl/uncategorized/preface/</link><guid>http://am.ippt.gov.pl/uncategorized/preface/</guid></item><item><title><![CDATA[Basic solution for three parallel non-symmetric permeable mode-III cracks in a functionally graded piezoelectric material plate]]></title><description><![CDATA[
  
The behavior of three parallel permeable cracks with different lengths in a functionally graded piezoelectric material plane subjected to anti-plane shear stress loading
was studied by the Schmidt method. The problem was formulated through the Fourier
transform into three pairs of dual integral equations. To solve the dual integral equations, the jumps of displacements across the crack surfaces were directly expanded
in a series of Jacobi polynomials. The results show that the stress and the electric
displacement intensity factors at the crack tips depend on the lengths, spacing of the
cracks and the material parameters. It is also revealed that the crack shielding effect
is present in functionally graded piezoelectric materials.
  ]]></description><pubDate>Fri, 08 May 2009 01:52:12 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-2/basic-solution-for-three-parallel-nonsymmetric-permeable-modeiii-cracks-in-a-functionally-graded-piezoelectric-material-plate/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-2/basic-solution-for-three-parallel-nonsymmetric-permeable-modeiii-cracks-in-a-functionally-graded-piezoelectric-material-plate/</guid></item><item><title><![CDATA[Influences of magnetic field on wave propagation in generalized thermoelastic solid with diffusion]]></title><description><![CDATA[
  
This paper is devoted to estimation of the influence of magnetic field in an elastic
solid half-space under thermoelastic diffusion. The governing equations in xz-plane
are solved taking into consideration the GL model. The reflection of dilatational (P)
wave and shear vertical (SV) wave splits into four waves, namely: P wave, thermal
wave, mass diffusion wave and SV wave. The reflection phenomena of P and SV
waves from the free surface of an elastic solid with thermoelastic diffusion, under the
influence of magnetic field is considered. The expressions for the reflection coefficients
for the four reflected waves are obtained. These reflection coefficients are found to
depend upon the angle of incidence θ of P and SV waves, thermoelastic diffusion,
magnetic field and other material parameters. The numerical values for the reflection
coefficients are calculated analytically and presented graphically for various values of
these parameters. Relevant results of previous investigations are deduced as special
cases from this study.
  ]]></description><pubDate>Fri, 08 May 2009 01:49:19 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-2/influences-of-magnetic-field-on-wave-propagation-in-generalized-thermoelastic-solid-with-diffusion/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-2/influences-of-magnetic-field-on-wave-propagation-in-generalized-thermoelastic-solid-with-diffusion/</guid></item><item><title><![CDATA[Large Eddy Simulation of transitional flows in rotor/stator cavity]]></title><description><![CDATA[
  
An algorithm for the Large Eddy Simulation, with subgrid modelling based on
the spectral Chebyshev–Fourier approximation, is developed for the investigation of
3D turbulent and transitional non-isothermal flows within a rotor/stator cavity. In
LES we use a version of the dynamic Smagorinsky eddy viscosity model in which the
Smagorinsky coefficient at a given position x depends on the history of the flow along
the fluid particle pathline. Computations are based on the efficient pseudo-spectral
Chebyshev–Fourier method (S. Hugues, A. Randriamampianina,   An improved projection
scheme applied to pseudospectral methods for the incompressible Navier–Stokes
equations  , Int. J. Numer. Methods Fluids, 28, 501, 1998). To demonstrate the effectiveness of the proposed algorithm, computations were performed for the cavity of
aspect ratio L=5 and results were compared favorably with the experimental data
taken from literature.
  ]]></description><pubDate>Fri, 08 May 2009 01:45:50 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-2/large-eddy-simulation-of-transitional-flows-in-rotorstator-cavity/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-2/large-eddy-simulation-of-transitional-flows-in-rotorstator-cavity/</guid></item><item><title><![CDATA[Modeling of articular cartilage replacement materials]]></title><description><![CDATA[
  
The development of replacement material for human articular cartilage exhibiting
similar mechanical properties as the native tissue is a problem of high actuality in
biomedicine. In the present work a new condensed collagen material is investigated.
The study aims at developing a mechanical model especially adapted to this particular
collagen material. For this purpose, a viscoelastic-diffusion (VED) model is proposed,
accounting for two different diffusion evolutions assumed. Moreover, the need for
a gradient material description is discussed in order to cover fabrication influences
leading to a variable Young’s modulus for the material. On this background, a phe-nomenological law is presented to predict deformation-dependent diffusion behavior
and internal reaction forces. Furthermore, the present approach allows a practible
identification of diffusion parameters. The theoretical model is implemented into a fi-nite element code and parameters are identified by tension tests. The simulation
results are validated experimentally.
  ]]></description><pubDate>Wed, 11 Mar 2009 10:48:26 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-1/modeling-of-articular-cartilage-replacement-materials/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-1/modeling-of-articular-cartilage-replacement-materials/</guid></item><item><title><![CDATA[Phase transitions in thermoelastic and thermoviscoelastic shells]]></title><description><![CDATA[
  
Applying the general non-linear theory of shells undergoing phase transitions,
we derive the balance equations along the singular surface curve modelling the phase
interface in the shell. From the integral forms of balance laws of linear momentum,
angular momentum, and energy as well as the entropy inequality, we obtain the local
static balance equations along the curvilinear phase interface. We discuss general
forms of the constitutive equations for thermoelastic and thermoviscoelastic shells,
as well as propose their simple cases for the linear isotropic shell behaviour. We
also derive the thermodynamic condition allowing one to determine the interface
position on the deformed shell midsurface. The theoretical model is illustrated by
the example of thin circular cylindrical shell made of a two-phase elastic material
subjected to tensile forces at the shell boundary. The solution reveals the existence
of the hysteresis loop whose size depends upon values of several loading parameters.
  ]]></description><pubDate>Wed, 11 Mar 2009 10:45:12 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-1/phase-transitions-in-thermoelastic-and-thermoviscoelastic-shells/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-1/phase-transitions-in-thermoelastic-and-thermoviscoelastic-shells/</guid></item><item><title><![CDATA[Velocity and gas-void fraction in two-phase liquid-gas flow in narrow mini-channels]]></title><description><![CDATA[
  
In the study, the values of velocity and gas void fraction in two-phase gas-liquid
flow in narrow vertical mini-channels were experimentally determined. The influence
of the physicochemical properties of liquid, the channel gap width and the superficial
velocity of gas and liquid, on gas void fraction and gas bubble flow velocities in the
flowing two-phase mixture in narrow, vertical mini-channels was investigated. The
value of gas phase velocity was defined by means of a drift model, determining the
values of distribution parameter C0. The relation describing the value of gas void
fraction depended on the Bankoff coefficient and gas input volume fraction.
  ]]></description><pubDate>Wed, 11 Mar 2009 10:42:17 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-1/velocity-and-gasvoid-fraction-in-twophase-liquidgas-flow-in-narrow-minichannels/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-1/velocity-and-gasvoid-fraction-in-twophase-liquidgas-flow-in-narrow-minichannels/</guid></item><item><title><![CDATA[Fluid-structure interaction for large scale complex geometry and non-linear properties of structure]]></title><description><![CDATA[
  
In this paper fluid-structure interaction, taking into account the nonlinearity of
structural models, is concerned. This phenomenon has important influence in many
aeronautical applications. The method and developed system is demonstrated on
NACA-0012 wing mounting, made of non-linear springs and include structures with
non-linear materials, modelled by Neo–Hooke and Mooney–Rivlin models, like flexible
delta wing. For the first flow the comparison with experiment made in Institute of
Aviation Warsaw is presented. For both mentioned above models, the linear and non-linear analysis are presented and the critical flutter speeds are determined. Finally,
aeroelastic simulation of full I23 aircraft configuration presents the capability of used
numerical codes to analyze large-scale complex geometries. All computations were
carried out in parallel environment for CFD mesh of order of millions tetrahedral
elements.
  ]]></description><pubDate>Wed, 11 Mar 2009 10:38:24 +0000</pubDate><link>http://am.ippt.gov.pl/volume-61-2009/issue-1/fluidstructure-interaction-for-large-scale-complex-geometry-and-nonlinear-properties-of-structure/</link><guid>http://am.ippt.gov.pl/volume-61-2009/issue-1/fluidstructure-interaction-for-large-scale-complex-geometry-and-nonlinear-properties-of-structure/</guid></item><item><title><![CDATA[Preface]]></title><description><![CDATA[
  
This issue of the   Archives of Mechanics   contains papers presented at the   XVIII Polish Fluid Mechanics Conference   (KKMP), 21–25 September, 2008.
  ]]></description><pubDate>Sun, 18 Jan 2009 22:46:33 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-6/preface/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-6/preface/</guid></item><item><title><![CDATA[Reduced order modelling of a flow around an airfoil with a changing angle of attack]]></title><description><![CDATA[
  
Model reduction based on Galerkin projection is a key technique used in feedback
flow control. It significantly accelerates the flow computations, and thus it can be
suitable for the aeroelastic simulations or, generally, in the flow analysis of changing
configurations and boundaries. The present paper concerns the reduced-order
Galerkin modelling of 2D flow around NACA-0012 airfoil, with angle of attack
changing from α=30◦ to α=45◦ . It emphasizes the requirements of simplicity
and accuracy of reduced order models (ROMs) used in control applications and
discusses possible mode bases. Finally, it describes the constructed model, based on
the modes resulting from Proper Orthogonal Decomposition (POD) and the novel
technique of continuous mode interpolation. This method allows smooth transition
between different operating and boundary conditions and allows the design of
least-dimensional Galerkin model for control purposes.
  ]]></description><pubDate>Sun, 18 Jan 2009 21:11:20 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-6/reduced-order-modelling-of-a-flow-around-an-airfoil-with-a-changing-angle-of-attack/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-6/reduced-order-modelling-of-a-flow-around-an-airfoil-with-a-changing-angle-of-attack/</guid></item><item><title><![CDATA[Third-order method for simulation of compressible flows]]></title><description><![CDATA[
  
The paper discusses finite volume WENO reconstruction applied to simulation of
compressible 3D Euler flows. The main objective of this work is presentation of the
new reconstruction procedure (third-order of accuracy in space), together with the
procedure for integration of numerical fluxes applied to simulations of compressible
3D Euler flows, using unstructured meshes.
  ]]></description><pubDate>Sun, 18 Jan 2009 21:08:15 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-6/thirdorder-method-for-simulation-of-compressible-flows/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-6/thirdorder-method-for-simulation-of-compressible-flows/</guid></item><item><title><![CDATA[Aerodynamic characteristics of two-dimensional sharp-edged objects in tandem arrangement]]></title><description><![CDATA[
  
The present analysis addresses the problem of the aerodynamic loads of two prismatic
bodies in tandem arrangement. Two identical square cross-section prismatic
bodies arranged in tandem are considered and represent a two-dimensional configuration.
The program of the study consists of parallel wind-tunnel experiments and
numerical simulation performed with the use of a phase-averaged form of k−ε turbulence
model in RNG version. The simulations revealed a strong dependence between
the interference of the wake flow around the system of sharp-edged bluff-bodies, the
vorticity structure of the separation region, mean position of the reattachment point,
phase-averaged velocity field and skin friction variability. The general aim was to
establish a direct link between the flow around bluff bodies, local time-resolved quantities
like skin friction and surface pressure, and near-wake behaviour behind the square
cylinders in tandem array. In particular, it was found that periodical flow disturbances
bring about a rapid growth of surface pressure and wall shear stress fluctuations.
  ]]></description><pubDate>Sun, 18 Jan 2009 21:06:08 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-6/aerodynamic-characteristics-of-twodimensional-sharpedged-objects-in-tandem-arrangement/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-6/aerodynamic-characteristics-of-twodimensional-sharpedged-objects-in-tandem-arrangement/</guid></item><item><title><![CDATA[The wake behind the sphere; analysis of vortices during transition from steadiness to unsteadiness]]></title><description><![CDATA[
  
This paper reports about an experimental investigation of the wake behind a solid
sphere on a low velocity hydrodynamical channel for the Reynolds number in the
range 250–310. The aim of the work is to analyze the size and shape of the vortices’
cores and its change as a function of the Reynolds number. Special attention is paid to
the transition from stationary flow, characterized by two counter-rotating longitudinal
vortices, to instationary flow. The two-coloured visualization of the wake in steady
and unsteady regimes is also presented.
  ]]></description><pubDate>Sun, 18 Jan 2009 21:03:54 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-6/the-wake-behind-the-sphere-analysis-of-vortices-during-transition-from-steadiness-to-unsteadiness/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-6/the-wake-behind-the-sphere-analysis-of-vortices-during-transition-from-steadiness-to-unsteadiness/</guid></item><item><title><![CDATA[Experimental analysis of turbulent boundary layer under the influence of adverse pressure gradient]]></title><description><![CDATA[
  
The paper deals with the experimental analysis of turbulent boundary layer at the
flat plate for large value of Reynolds number equal Reθ≈3000. The adverse pressure
gradient is generated by curvature of the upper wall and corresponds to the case of
pressure variation in axial compressor. The analysis is concentrated on the problem
of scaling of turbulent boundary layer and on the physical background behind scaling
laws being compared. The results obtained suggest, that boundary layer at APG conditions
requires two velocity scales, i.e. inner (imposed by inner boundary condition)
and outer (imposed by outer layer) velocity scales.
  ]]></description><pubDate>Sun, 18 Jan 2009 20:58:55 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-6/experimental-analysis-of-turbulent-boundary-layer-under-the-influence-of-adverse-pressure-gradient/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-6/experimental-analysis-of-turbulent-boundary-layer-under-the-influence-of-adverse-pressure-gradient/</guid></item><item><title><![CDATA[Effect of rotation on Rayleigh waves in an isotropic generalized thermoelastic diffusive half-space]]></title><description><![CDATA[
  
The present investigation is a study of the effect of rotation on the characteristics of Rayleigh waves propagation in a homogeneous, isotropic, thermoelastic
diffusive half-space in the framework of different theories of thermoelastic diffusion,
including the Coriolis and Centrifugal forces. The medium is subjected to stress-free,
thermally insulated/isothermal and chemical potential boundary conditions and is
rotating about an axis perpendicular to its plane. Secular equations of surface wave
propagation in the considered media are derived. The phase velocities and attenuation coefficients of surface wave propagation have been computed by using the
irreducible case of Cardano's method, with the help of DeMoivre's theorem known
from the secular equations. The amplitudes of surface displacements, temperature
change, concentration and the specific loss of energy are computed numerically. Rotation effect on the phase velocity, attenuation coefficient, amplitudes of surface wave
propagation and specific loss of energy are presented graphically in order to illustrate and compare the analytically obtained results. Some special cases of frequency
equation are also deduced from the present investigation.
  ]]></description><pubDate>Mon, 03 Nov 2008 14:26:27 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-5/effect-of-rotation-on-rayleigh-waves-in-an-isotropic-generalized-thermoelastic-diffusive-halfspace/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-5/effect-of-rotation-on-rayleigh-waves-in-an-isotropic-generalized-thermoelastic-diffusive-halfspace/</guid></item><item><title><![CDATA[Thermal convection of micropolar fluid in the presence of suspended particles in rotation]]></title><description><![CDATA[
  
A study has been made of the convection of micropolar fluids heated from below
in the presence of suspended particles (fine dust) and uniform vertical rotation   Omega   ­(0; 0;­   Omega  ). The effect of Coriolis forces on the stability is chosen along the direction of
the gravitational field. It is found that the presence of coupling between thermal and
micropolar effects, rotation parameter and suspended particles may introduce overstability in the system. Using the Boussinesq approximation, the linearized stability
theory and normal mode analysis, the exact solutions are obtained for the case of two
free boundaries. Graphs have been plotted by giving numerical values to the parameters accounting for rotation   Omega  ­ (0; 0;­   Omega  ­) and the dynamic microrotation viscosity   kappa   and coefficient of angular viscosity   gamma  ' to depict the stability characteristics, for both the cases of stationary convection and overstability. It is found that Rayleigh number for the case of overstability and stationary convection increases with increase in rotation parameters and decreases with increase in micropolar coefficients, for a fixed wave number, showing thereby the stabilizing effect of rotation parameters and destabilizing effect of micropolar coefficients on the thermal convection of micropolar fluids.
Thus there is a competition between the stabilizing effect of rotation parameters and destabilizing effect of micropolar coeffcients and the suspended particles. It is also found from the graphs that the Rayleigh number for the case of overstability is always smaller than the Rayleigh number for the case of stationary convection, for a fixed wave number.
  ]]></description><pubDate>Mon, 03 Nov 2008 14:22:03 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-5/thermal-convection-of-micropolar-fluid-in-the-presence-of-suspended-particles-in-rotation/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-5/thermal-convection-of-micropolar-fluid-in-the-presence-of-suspended-particles-in-rotation/</guid></item><item><title><![CDATA[Some exact solutions for the rotational flow of a generalized second-grade fluid between two circular cylinders]]></title><description><![CDATA[
  
The velocity field and the associated tangential stress corresponding to the flow
of a generalized second-grade fluid between two infinite coaxial circular cylinders, are
determined by means of the Laplace and Hankel transforms. At time t=0, the fluid
is at rest and at t=0+ the cylinders suddenly begin to rotate about their common
axis with a constant angular acceleration. The solutions that have been obtained
satisfy the governing differential equations and all the imposed initial and boundary
conditions. The similar solutions for a second-grade fluid and Newtonian fluid are
recovered from our general solutions. The influence of the fractional coefficient on the
velocity of the fluid is also analyzed by graphical illustrations.
  ]]></description><pubDate>Mon, 03 Nov 2008 14:12:24 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-5/some-exact-solutions-for-the-rotational-flow-of-a-generalized-secondgrade-fluid-between-two-circular-cylinders/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-5/some-exact-solutions-for-the-rotational-flow-of-a-generalized-secondgrade-fluid-between-two-circular-cylinders/</guid></item><item><title><![CDATA[Biaxial extension of a plane single crystal]]></title><description><![CDATA[
  
This paper concerns the rigid-plastic modelisation of a f.c.c. single crystal, deforming
by crystallographic slip, under large strain. Adopting the plane single crystal model,
which corresponds to a true two-dimensional evolution of a real three-dimensional
crystal, the activity of slip systems and the plastic indetermination, due to multiplicity
of solutions, are studied according to the rate-independent Schmid law or the rate-dependent Bingham law. To promote a more general situation of potential multiple
slip and therefore of potential indeterminacy, the biaxial loading is investigated. Based
on this model and the Bingham slip law, the indeterminacy problem is surmounted,
by adopting the geometrical analysis in the strain rate space and it is proved that the
linear viscoplastic analysis is a new way of solving the indeterminacy problem.
  ]]></description><pubDate>Mon, 03 Nov 2008 14:05:35 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-5/biaxial-extension-of-a-plane-single-crystal/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-5/biaxial-extension-of-a-plane-single-crystal/</guid></item><item><title><![CDATA[Kinetic boundary layers for the Boltzmann equation on discrete velocity lattices]]></title><description><![CDATA[
  
We consider families of discrete velocity models with physical collision invariants, and develop algebraic criteria for well-posedness of the linearized kinetic boundary layer problem. Using the obtained criteria we discuss various hierarchies of symmetric discrete velocity models, and calculate analytical and numerical slip coefficients for the representants of the hierarchies.
  ]]></description><pubDate>Mon, 01 Sep 2008 17:16:22 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-1/kinetic-boundary-layers-for-the-boltzmann-equation-on-discrete-velocity-lattices/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-1/kinetic-boundary-layers-for-the-boltzmann-equation-on-discrete-velocity-lattices/</guid></item><item><title><![CDATA[Thermomechanical response of a viscoelastic beam under cyclic bending; self-heating and thermal failure]]></title><description><![CDATA[
  
The thermomechanical response of beams made up of thermoplastic polymer
is analysed in the case of cyclic bending. The material behavior is modelled by a viscoelastic law depending on temperature and frequency. Inertia effects are neglected. The stress, strain and temperature distributions are expressed as functions of the beam geometry, the loading parameters and the material characteristics. The stability of the steady-state solutions is analysed with use of a linear perturbation approach. The conditions for thermal runaway (thermo-mechanical instability) are explored.
  ]]></description><pubDate>Mon, 01 Sep 2008 17:14:07 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-1/thermomechanical-response-of-a-viscoelastic-beam-under-cyclic-bending-selfheating-and-thermal-failure/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-1/thermomechanical-response-of-a-viscoelastic-beam-under-cyclic-bending-selfheating-and-thermal-failure/</guid></item><item><title><![CDATA[Non-local Korteweg stresses from kinetic theory point of view]]></title><description><![CDATA[
  
The aim of the paper is to elaborate a kinetic theory having the non-local Korteweg equations for non-isothermal liquid-vapour systems as the hydrodynamic limit. This is the topic of the second part of the paper. The first part of our paper is devoted to presentation of the Korteweg equations. We write the non-local Korteweg equations in a conservative form and we discuss the relations between them and the local ones.
  ]]></description><pubDate>Mon, 01 Sep 2008 17:11:25 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-1/nonlocal-korteweg-stresses-from-kinetic-theory-point-of-view/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-1/nonlocal-korteweg-stresses-from-kinetic-theory-point-of-view/</guid></item><item><title><![CDATA[Mechano-chemical calcium waves in systems with immobile buffers]]></title><description><![CDATA[
  
We study the existence of travelling waves of the free cytosolic calcium concentration in the presence of immobile buffers. We also take into account the mechanochemical interaction. In the proof we use the   a priori   estimates for solutions of systems with diffusing buffers and pass to zero with their diffusion coefficients.
  ]]></description><pubDate>Mon, 01 Sep 2008 17:10:02 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-1/mechanochemical-calcium-waves-in-systems-with-immobile-buffers/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-1/mechanochemical-calcium-waves-in-systems-with-immobile-buffers/</guid></item><item><title><![CDATA[Spatial estimates concerning the harmonic vibrations in rectangular plates with voids]]></title><description><![CDATA[
  
This paper studies the spatial behaviour of the amplitude of a harmonic vibration in a rectangular plate of Mindlin type, made of a homogeneous and isotropic elastic material with voids. Provided the frequency of vibration is lower than the critical value, some appropriate measures are introduced relating the amplitude of resulting harmonic vibration, and the corresponding first-order differential inequalities are established under mild conditions on the elastic coefficients. The case of a semi-infinite plate is also studied and some Phragmén–Lindelöf alternatives are established.
  ]]></description><pubDate>Mon, 01 Sep 2008 13:19:54 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-3/spatial-estimates-concerning-the-harmonic-vibrations-in-rectangular-plates-with-voids/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-3/spatial-estimates-concerning-the-harmonic-vibrations-in-rectangular-plates-with-voids/</guid></item><item><title><![CDATA[Reflection and transmission of transient acoustic waves with oblique incidence]]></title><description><![CDATA[
  
The aim of the paper is to determine, within the time domain, the waves produced by an oblique incident wave at the interface between two homogeneous half-spaces. By following the acoustic approximation, the wave solutions for the Fourier transform of the displacement field in a viscous fluid are established in a form which generalizes the concept of plane wave. Next the reflection-transmission problem, associated with the interface between an inviscid fluid and a viscous one, is investigated. The incident wave is supposed to propagate in the inviscid fluid. The reflected and transmitted waves, in the time domain, are eventually determined in two particular cases, namely that of normal incidence on a viscous half-space and that of oblique incidence, beyond the critical angle, on an inviscid half-space. In the first case it follows that, provided an approximation of band-limited data holds for the incident wave, the reflected and the transmitted waves are given by linear combinations of the values of the incident wave and of its time derivative. In the second case, the reflected (transmitted) wave is shown to be the sum of a term proportional to the incident wave and another one, proportional to the Hilbert transform of (a convolution of) the incident wave.
  ]]></description><pubDate>Mon, 01 Sep 2008 13:17:16 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-3/reflection-and-transmission-of-transient-acoustic-waves-with-oblique-incidence/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-3/reflection-and-transmission-of-transient-acoustic-waves-with-oblique-incidence/</guid></item><item><title><![CDATA[Constitutive modelling of PMMA-based bone cement: a functional model of viscoelasticity and its approximation for time domain investigations]]></title><description><![CDATA[
  
To represent the mechanical behaviour of polyethylmethacrylate-based bone
cement, a constitutive approach of finite linear viscoelasticity is formulated and identified. Motivated by the experimental data of storage and loss modulus, the model is based on a three-dimensional functional in integral representation. In the investigated frequency range, the master curve of the loss modulus is constant and that of the storage modulus increases linearly with the logarithm of the frequency. This behaviour corresponds to a viscoelastic fluid, and can be described by a continuous relaxation spectrum. For numerical simulations which are planned in future, the constitutive functional is approximated by a discrete spectrum. To this end, an earlier-developed method to approximate continuous relaxation spectra in limited time or frequency ranges by discrete ones is applied.
  ]]></description><pubDate>Mon, 01 Sep 2008 13:15:24 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-3/constitutive-modelling-of-pmmabased-bone-cement-a-functional-model-of-viscoelasticity-and-its-approximation-for-time-domain-investigations/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-3/constitutive-modelling-of-pmmabased-bone-cement-a-functional-model-of-viscoelasticity-and-its-approximation-for-time-domain-investigations/</guid></item><item><title><![CDATA[Slow motion of a rotating circular cylinder through a micropolar fluid]]></title><description><![CDATA[
  
Presented is an analytical solution to creeping flow of a micropolar fluid past a rotating circular cylinder of infinite length in spanwise direction. The solution is decomposed into two parts; first, the flow past a stationary circular cylinder is solved by the use of matched asymptotic expansions method. Afterwards, the rotation of a circular cylinder in a stationary ocean of a micropolar fluid is investigated. Due to linearity of the governing equations, the principle of superposition is then recalled to construct the desired flow field. Ultimately, several kinematic and kinetic quantities of the flow are studied by the use of the obtained closed-form analytical solution.
  ]]></description><pubDate>Mon, 01 Sep 2008 13:12:06 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-3/slow-motion-of-a-rotating-circular-cylinder-through-a-micropolar-fluid/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-3/slow-motion-of-a-rotating-circular-cylinder-through-a-micropolar-fluid/</guid></item><item><title><![CDATA[Qualitative aspects of solutions in resonators]]></title><description><![CDATA[
  
We consider the system of micro-beam resonators in the thermoelastic theory of
Lord and Shulmann. First, we prove the uniqueness and instability of solutions when
the sign of a parameter is not prescribed. Existence of solutions and uniform bounds
for the real part of the spectrum have been found. We finish the paper by proving
the impossibility of the time localization of solutions.
  ]]></description><pubDate>Tue, 26 Aug 2008 14:12:30 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-4/qualitative-aspects-of-solutions-in-resonators/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-4/qualitative-aspects-of-solutions-in-resonators/</guid></item><item><title><![CDATA[Dynamic fragmentation of melted metals upon intense shock wave loading. Some modelling issues applied to a tin target]]></title><description><![CDATA[
  
We are interested in the dynamic fragmentation event produced in shock-melted
metals called micro-spalling. Global energetic approach is briefly reviewed. It provides
a general modelling framework that leads to realistic fragment-size predictions.
But the actual physical mechanisms involved remain poorly understood. We attempt
to explore the conditions under which cavitation, i.e. nucleation and growth of microvoids,
may be responsible for fragmentation. This cavitation process is described
by means of a hollow sphere model whose matrix is made of liquid tin.
  ]]></description><pubDate>Tue, 26 Aug 2008 14:10:05 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-4/dynamic-fragmentation-of-melted-metals-upon-intense-shock-wave-loading-some-modelling-issues-applied-to-a-tin-target/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-4/dynamic-fragmentation-of-melted-metals-upon-intense-shock-wave-loading-some-modelling-issues-applied-to-a-tin-target/</guid></item><item><title><![CDATA[Post-stagnation-point boundary layer flow and mixed convection heat transfer over a vertical, linearly stretching sheet]]></title><description><![CDATA[
  
A theoretical analysis is made for the steady two-dimensional post-stagnationpoint
flow of an incompressible viscous fluid over a stretching vertical sheet in its own
plane. The stretching velocity, the free stream velocity and the surface temperature
are assumed to vary linearly with the distance from the stagnation point. The governing
partial differential equations are transformed into a coupled system of ordinary
differential equations, which is then solved numerically by a finite-difference method.
Results are presented in terms of the skin friction coefficient and local Nusselt number,
along with a selection of velocity and temperature profiles. It was shown that for
both cases of a fixed surface (ε = 0) and a stretching surface (ε != 0), dual solutions
exist for the assisting flow (positive values of the buoyancy parameter λ), besides that
usually reported in the literature for the opposing flow (λ  < 0). It was also found
that for the assisting flow, a solution exists for all values of λ (>  0), while for the
opposing flow, a solution exists only if the magnitude of the buoyancy parameter is
small.
  ]]></description><pubDate>Tue, 26 Aug 2008 14:04:27 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-4/poststagnationpoint-boundary-layer-flow-and-mixed-convection-heat-transfer-over-a-vertical-linearly-stretching-sheet/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-4/poststagnationpoint-boundary-layer-flow-and-mixed-convection-heat-transfer-over-a-vertical-linearly-stretching-sheet/</guid></item><item><title><![CDATA[Anisotropic damage evolution in shock wave-loaded viscoplastic plates]]></title><description><![CDATA[
  
In the design of structural elements, which are used for protection against explosions,
the damage evolution until failure has to be predicted in numerical simulations.
However, in the literature a wide variety of damage models is available based on different
approaches, e.g. phenomenological and micromechanical theories. Furthermore,
the consequences of connections between new damage models and the constitutive
equations accounting for elastic-viscoplasticity are unclear. The same problem occurs
if structural theories, involving hypotheses, are combined with damage laws. In order
to verify the calculated results, experiments with structures subjected to pressure
waves are necessary. For this reason, an experimental validation method by means of
shock tubes is used in the present study to verify the isotropic and anisotropic damage
models. The measured deformations and experimentally observed failure modes
can then be compared to the simulated results.
  ]]></description><pubDate>Tue, 26 Aug 2008 14:02:24 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-4/anisotropic-damage-evolution-in-shock-waveloaded-viscoplastic-plates/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-4/anisotropic-damage-evolution-in-shock-waveloaded-viscoplastic-plates/</guid></item><item><title><![CDATA[On effects of internal friction in the revised Goodman–Cowin theory with an independent kinematic internal length]]></title><description><![CDATA[
  
In the present study, the revised Goodman–Cowin theory with an independent
kinematic internal length proposed by Fang et al. for rapid dry granular flows is extended
to account for the effects of internal friction. A thermodynamic analysis, based
on the M¨uller–Liu entropy principle, is performed to deduce the ultimate equilibrium
expressions of the constitutive equations. Results show that while internal friction
contributes significantly to the equilibrium expressions of the constitutive variables,
the dependence on internal friction of the Helmholtz free energy becomes a critical
point for the present formulation in practical applications. In comparison with other
constitutive formulations based on the revised Goodman–Cowin theory, the present
formulation is the most general one and shows an ability to take into account the
microstructural effects of volume fraction variation, internal friction and evolution of
internal length of dry granular flows simultaneously.
  ]]></description><pubDate>Tue, 26 Aug 2008 12:53:56 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-2/on-effects-of-internal-friction-in-the-revised-goodmancowin-theory-with-an-independent-kinematic-internal-length/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-2/on-effects-of-internal-friction-in-the-revised-goodmancowin-theory-with-an-independent-kinematic-internal-length/</guid></item><item><title><![CDATA[Flow of Herschel–Bulkley fluid through an inclined tube of non-uniform cross-section with multiple stenoses]]></title><description><![CDATA[
  
The steady flow of Herschel–Bulkley fluid through an inclined tube of non-uniform
cross-section with multiple stenoses has been investigated. Assuming the stenoses to
be mild, the flow equations have been linearised and the expressions for resistance to
the flow and wall shear stress have been derived. The effects of various parameters on
these flow variables have been studied. It is found that the flow resistance increases
with the heights of the stenoses, yield stress, power law index, but decreases with
inclination. Further, the shear stress increases with plug core region radius.
  ]]></description><pubDate>Tue, 26 Aug 2008 12:51:56 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-2/flow-of-herschelbulkley-fluid-through-an-inclined-tube-of-nonuniform-crosssection-with-multiple-stenoses/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-2/flow-of-herschelbulkley-fluid-through-an-inclined-tube-of-nonuniform-crosssection-with-multiple-stenoses/</guid></item><item><title><![CDATA[Distributed loads in an elastic solid with generalized thermodiffusion]]></title><description><![CDATA[
  
The linear theory of generalized thermoelastic diffusion with one relaxation time
is employed to study the interactions in a homogeneous, isotropic elastic solid, when
a distributed instantaneous source is acting on the free surface of the body. The
eigenvalue approach is adopted for the solution of a two-dimensional problem. The
Laplace–Fourier transform technique is used. The expansions of the stresses, displacement
components, temperature, concentration and chemical potential are obtained
analytically. Numerical results are given and illustrated graphically, employing numerical
methods for the inversion for transforms. Comparisons are made with the
results predicted by the theory of generalized thermoelasticity and elasticity.
  ]]></description><pubDate>Tue, 26 Aug 2008 12:47:30 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-2/distributed-loads-in-an-elastic-solid-with-generalized-thermodiffusion/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-2/distributed-loads-in-an-elastic-solid-with-generalized-thermodiffusion/</guid></item><item><title><![CDATA[Space of SO (3)-orbits of elasticity tensors]]></title><description><![CDATA[
  
We construct an eighteen-dimensional orbifold that is in a one-to-one correspondence
with the space of SO (3)-orbits of elasticity tensors. This allows us to obtain
a local parametrization of SO (3)-orbits of elasticity tensors by six SO (6)-invariant
and twelve SO (3)-invariant parameters. This process unravels the structure of the
space of the orbits of the elasticity tensors.
  ]]></description><pubDate>Tue, 26 Aug 2008 12:43:06 +0000</pubDate><link>http://am.ippt.gov.pl/volume-60-2008/issue-2/space-of-so-3orbits-of-elasticity-tensors/</link><guid>http://am.ippt.gov.pl/volume-60-2008/issue-2/space-of-so-3orbits-of-elasticity-tensors/</guid></item><item><title><![CDATA[On the order of singularity at V-shaped notches in anisotropic bodies]]></title><description><![CDATA[
  The self-similar problem of stress singularity at the notch in infinite two-dimensional elastic orthotropic body was considered. The considerations were restricted to the notches symmetrically oriented with respect to the axes of orthotropy. Both, the extension and shear modes were studied. It was confirmed that in the limiting case of zero opening angle (semi-infinite crack), the order of singularity is the same as in the case of isotropic material - r  -1/2  . This is not true in the case of finite opening angles. If the orientation of the notch axis is parallel to the axis of maximal stiffness, the order of singularity is lower than that for the case of perpendicular orientation. In the last case, if the ratio E  T  /E  L   is small enough, then the order of singularity in tension does not practically decrease with growing opening angle 2α up to α ~= π/4.  ]]></description><pubDate>Mon, 25 Aug 2008 13:23:54 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-6/on-the-order-of-singularity-at-vshaped-notches-in-anisotropic-bodies/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-6/on-the-order-of-singularity-at-vshaped-notches-in-anisotropic-bodies/</guid></item><item><title><![CDATA[On material and geometrical instabilities in infinite elasticity and elastoplasticity]]></title><description><![CDATA[
  Material instability phenomena arise in homogeneous stress states if nonlinear stress-strain relations are considered. The stability behaviour is investigated by looking at the Gateaux derivative of the first Piola-Kirchhoff stress tensor in the direction of the deformation gradient. This requires to solve a nine-dimensional matrix eigenvalue problem. In the present contribution, it is shown that material instabilities can be clearly differentiated from instabilities of geometrical character. The latter aspect is especially important for the design of new materials, since unstable solution paths under common loading conditions are not desirable. Geometrical instabilities, however, can usually be avoided by choosing appropriate boundary conditions. The derivation in this work leads to a simple stability criterion which allows to describe the stability behaviour of many materials in a very general context.  ]]></description><pubDate>Mon, 25 Aug 2008 13:18:42 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-6/on-material-and-geometrical-instabilities-in-infinite-elasticity-and-elastoplasticity/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-6/on-material-and-geometrical-instabilities-in-infinite-elasticity-and-elastoplasticity/</guid></item><item><title><![CDATA[Prediction of mechanical behaviour of inhomogeneous and anisotropic materials using an incremental scheme]]></title><description><![CDATA[
  A new multisite homogenisation technique is proposed, suitable for the description of the effective properties of composite materials. After a short presentation of the multisite approach, the traditional self-consistent approximation is developed. The limitations of such an approach are emphasised and a new alternative technique, based on the differential scheme idea, is proposed. The great versatility of this method in predicting the global elastic properties of various inhomogeneous materials is demonstrated. The present examples correspond to extreme situations of composites with voids and that of quasi-rigid (compared to the matrix) reinforcements. Very good agreement between the predicted and measured (or calculated by FEM) equivalent properties are found.  ]]></description><pubDate>Mon, 25 Aug 2008 13:16:40 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-6/prediction-of-mechanical-behaviour-of-inhomogeneous-and-anisotropic-materials-using-an-incremental-scheme/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-6/prediction-of-mechanical-behaviour-of-inhomogeneous-and-anisotropic-materials-using-an-incremental-scheme/</guid></item><item><title><![CDATA[A cracked piezoelectric material under generalized plane electromechanical impact]]></title><description><![CDATA[
  Solution of the generalized plane deformation problem of a piezoelectric material strip with a crack is proposed. Laplace and Fourier transforms are used to reduce the problem to the solution of singular integral equations in the Laplace transform plane. Laplace inversion yields the results in the time domain. This analysis yields six independent stress and three electric displacement components. The model is general enough to account for arbitrary polarization direction, under transient or steady state load, for any mechanical or electrical mode of cracking. Numerical solutions for a piezoelectric material strip under electromechanical impact are illustrated. The influences of strip thickness and crack position on time-dependent crack tip fields are investigated. The results show that the transient electric displacement loads can increase or reduce the stress intensity factors at different time, dependent on the applied electric displacement load direction.  ]]></description><pubDate>Mon, 25 Aug 2008 13:15:17 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-6/a-cracked-piezoelectric-material-under-generalized-plane-electromechanical-impact/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-6/a-cracked-piezoelectric-material-under-generalized-plane-electromechanical-impact/</guid></item><item><title><![CDATA[Thermoelastic plane problem for material with circular inclusions]]></title><description><![CDATA[
  We consider two-dimensional thermoelastic composite materials in the case when the temperature is constant. Using complex potentials and applying a method of functional equations, we construct a simple algorithm to solve the corresponding boundary value problem. The stress tensor is written with the accuracy of up to the term O(R  2  ), where R = max  k,m   r  k   d  km    -1  , rk is the radius of the k-th inclusion, dkm is the distance between centers of the k-th and m-th inclusion (k =/= m). The effective elastic constants and the coefficient of thermal expansion are written in analytic form up to O(R  4  ).  ]]></description><pubDate>Mon, 25 Aug 2008 13:14:06 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-6/thermoelastic-plane-problem-for-material-with-circular-inclusions/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-6/thermoelastic-plane-problem-for-material-with-circular-inclusions/</guid></item><item><title><![CDATA[An attempt to describe heart attacks via continuum damage mechanics]]></title><description><![CDATA[
  In an earlier paper the author expressed evolution equations of classical continuum damage mechanics in terms of unit dissipated power and proposed an extension to biological materials in vivo, adding a term describing recovery. In the present paper an analogy with evolution of coronary artery disease is established. If we denote by S (relative stenosis) one minus the ratio of current luminal area to the initial area, then the condition S = 1 at a certain point of the artery means complete blockage at this point resulting in a heart attack (myocardial infarction). This corresponds to the condition of critical state D = 1 in damage mechanics, where D denotes a scalar measure of damage. Making use of this analogy, an evolution equation for S is proposed with unit dissipated power replaced by unit power of flow in individual cross-sections of coronary arteries and, subsequently, by the heart power. Further, another evolution equation describes the required heart power in terms of external loadings acting on the organism as a whole. Numerical integration of the evolution equations proposed makes it possible to distinguish loadings leading to a myocardial infarction from those subject to recovery. Also, the description of stable and unstable angina pectoris is discussed and illustrated by numerical examples.  ]]></description><pubDate>Mon, 25 Aug 2008 12:56:54 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/an-attempt-to-describe-heart-attacks-via-continuum-damage-mechanics/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/an-attempt-to-describe-heart-attacks-via-continuum-damage-mechanics/</guid></item><item><title><![CDATA[The characteristic-based-split (CBS) algorithm, stability and boundary conditions]]></title><description><![CDATA[
  Recently several papers were published on the subject of the CBS algorithm. This paper presents a brief summary of the theory of the algorithm and some recent findings on stabilization procedures and some appropriate boundary conditions. Several solved examples are also presented in this paper.  ]]></description><pubDate>Mon, 25 Aug 2008 12:56:01 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/the-characteristicbasedsplit-cbs-algorithm-stability-and-boundary-conditions/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/the-characteristicbasedsplit-cbs-algorithm-stability-and-boundary-conditions/</guid></item><item><title><![CDATA[Material instability in the tensile response of short-fibre-reinforced quasi-brittle composites]]></title><description><![CDATA[
  This paper gives the conditions for the onset of instability in the tensile response of short-fibre-reinforced quasi-brittle composites whose deformation is characterised by multiple cracking and localisation. First, the tensile stress-strain relation is established analytically for a body containing multiple bridged microcracks. The material instability is examined using the classical bifurcation criterion, with an emphasis on the role played by fibre bridging in the macroscopic instability. It is found that while the microscopic instability in the bridging traction plays a major role in the macroscopic instability of the composite, it is the level of damage in the matrix that determines when the macroscopic instability is induced by the bridging instability. The satisfaction of the classical bifurcation criterion is identified with several failure modes, depending on the degree of damage in the matrix.  ]]></description><pubDate>Mon, 25 Aug 2008 12:54:38 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/material-instability-in-the-tensile-response-of-shortfibrereinforced-quasibrittle-composites/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/material-instability-in-the-tensile-response-of-shortfibrereinforced-quasibrittle-composites/</guid></item><item><title><![CDATA[Gradient field theory of material instabilities]]></title><description><![CDATA[
  Previously, we developed a gradient thermodynamic theory of internal fields (migratory motions). The theory predicts the observed periodic deformation structures, in material domains under unifirm tractions. More recently we showed, in a uniform stress field, that the theory has the proper mathematical framework for the prediction of Portevin-Le Chatelier (PLC for short) instabilities.  

  Here we review our previous work and address the more difficult problem of a non-uniform stress field. Specifically, we predict the points of instability of a solid cylinder under torsion, with the experiments of Dillon as backdrop. Again, we find close agreement between theory and experiment.  ]]></description><pubDate>Mon, 25 Aug 2008 12:53:38 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/gradient-field-theory-of-material-instabilities/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/gradient-field-theory-of-material-instabilities/</guid></item><item><title><![CDATA[Fatigue crack evolution in a metal reinforced by short fibres]]></title><description><![CDATA[
  In numerical analyses of fatigue damage evolution in metal matrix composites, the development of final failure and the subsequent crack growth in the material are accounted for. Cell model analyses are used for aluminium reinforced by short SiC fibres, with the matrix material represented by a cyclic plasticity model, in which continuum damage mechanics is incorporated to model fatigue damage. The Bauschinger effect, ratchetting, mean stress relaxation, and cyclic hardening or softening can be accounted for by the material model, as is important in studies of low cycle fatigue. Different fibre aspect ratios and spacings are studied for different loading cases.  ]]></description><pubDate>Mon, 25 Aug 2008 12:52:33 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/fatigue-crack-evolution-in-a-metal-reinforced-by-short-fibres/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/fatigue-crack-evolution-in-a-metal-reinforced-by-short-fibres/</guid></item><item><title><![CDATA[On elastic impact and dynamic hardness]]></title><description><![CDATA[
  Colinear impact and dynamic hardness is analyzed at spherical contact and moderate strains. A consistent three-dimensional contact theory based on viscoplastic material behaviour is laid down involving elements of self-similarity, stationary boundary conditions and cumulative superposition. Universal relations between impact velocity and the resulting contact region, impression depth and duration of impact are derived. Deformed surface shapes are shown to be self-similar for power law material behaviour and their relation to piling-up and sinking-in is explained in detail. The coefficient of restitution at rebound is estimated to first order. The concept of dynamic hardness is not unequivocally defined in general and various definitions in literature are discussed in relation to true material rate sensitivity. Theoretical and numerical predictions of the present model are compared with pertinent experimental findings for different metals. Particular features such as lip formation, plastic zone size and maximum penetration depth are elucidated.  ]]></description><pubDate>Mon, 25 Aug 2008 12:51:16 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/on-elastic-impact-and-dynamic-hardness/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/on-elastic-impact-and-dynamic-hardness/</guid></item><item><title><![CDATA[Probabilistic micromechanical description of fatigue crack initiation]]></title><description><![CDATA[
  In this paper the Mura-Nakasone model for fatigue crack initiation is extended to the situation where randomness in material microstructure (e.g. in grain size) and in the applied stress are important factors. The analysis and formulae presented provide a quantitative characterization of the effect of statistical scatter in grain size of the metals on the crack initiation time. Also, crack initiation time is analyzed for the situation where the applied stress is a narrow-band stationary stochastic process. The mean value, variance and probability distribution of the time to crack initiation are derived, and the results are illustrated graphically for real empirical data.  ]]></description><pubDate>Mon, 25 Aug 2008 12:49:52 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/probabilistic-micromechanical-description-of-fatigue-crack-initiation/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/probabilistic-micromechanical-description-of-fatigue-crack-initiation/</guid></item><item><title><![CDATA[A qualitative approach to Hooke&#039;s tensors. Part I]]></title><description><![CDATA[
  The main qualitative properties of Hooke's tensors can be found in their invariant decompositions, both linear and nonlinear. The invariant nonlinear spectral decompositions are presented in the review [8] and the papers quoted therein. This paper deals with linear invariant decompositions initiated in [12-20]. A straightforward and complete description of all such possible decompositions is presented here in Part I. The main results are given in formulae (7.1), (7.3). The next part (to appear), Part II, will contain derivations, conclusions and unexpected applications.  ]]></description><pubDate>Mon, 25 Aug 2008 12:48:56 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/a-qualitative-approach-to-hookes-tensors-part-i/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/a-qualitative-approach-to-hookes-tensors-part-i/</guid></item><item><title><![CDATA[An approach to elastic shakedown based on the maximum plastic dissipation theorem]]></title><description><![CDATA[
  Elastic-perfectly solid structures are considered subjected to combined loads, superposition of permanent (mechanical) loads and cyclically variable loads, the latter being specified to within a scalar multiplier. The classical maximum dissipation theorem is used to derive known results of the shakedown theory, as well as a few apparently novel concepts: the shakedown limit load associated with a given (noninstantaneous) collapse mode, the mixed upper bound to the shakedown safety factor, and the mixed static-kinematic formulation of the shakedown safety factor problem. The shakedown load boundary surface is also investigated and a number of notable features of it are pointed out. A simple illustrative example is presented.  ]]></description><pubDate>Mon, 25 Aug 2008 12:47:50 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/an-approach-to-elastic-shakedown-based-on-the-maximum-plastic-dissipation-theorem/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/an-approach-to-elastic-shakedown-based-on-the-maximum-plastic-dissipation-theorem/</guid></item><item><title><![CDATA[Iterative methods for solution of contact optimization problems]]></title><description><![CDATA[
  Numerical treatment of frictionless contact optimization problems is presented on the basis of linear elasticity. The minimum of the pressure maximum or other mechanical values (torque, frictional power loss) is sought by controlling the pressure distribution. Smooth contact pressure distribution can be achieved by using an appropriate controlling function on the controlling subdomain. The contact problems are investigated by means of the principle of minimum complementary energy and using the augmented Lagrangian technique. Axially symmetric problems are discretized by p-version finite elements. The optimal shape of a roller bearing is determined by the application of a new controlling function, which takes the rigid body translation and rotation of the roller into consideration. Effectiveness of the proposed algorithms is demonstrated by numerical examples.  ]]></description><pubDate>Mon, 25 Aug 2008 12:46:42 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/iterative-methods-for-solution-of-contact-optimization-problems/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/iterative-methods-for-solution-of-contact-optimization-problems/</guid></item><item><title><![CDATA[3D equilibrium shapes of periodically arranged anisotropic precipitates with elastic misfit]]></title><description><![CDATA[
  A numerical procedure for simulating the equilibrium shapes of precipitates in two phase materials, such as Ni-base alloys is presented. Assuming a periodic arrangement of precipitates a unit cell is analyzed to take particle interaction in 3D into account. Using the concept of generalized driving forces as the source of morphological evolution, a necessary condition for an equilibrium shape is derived. In the derivation of the driving force, elastic strain energy arising from the elastic misfit of the two phases and interface energy is considered. Both phases are assumed to be linear elastic but anisotropic and different from each other. The periodic cell problem is numerically solved with a Boundary Element Method. Numerical simulation for material parameters which mimic Ni-base alloys show the influence of particle size, stiffness ratio of the two phases, volume fraction and external load on the resulting equilibrium shapes.  ]]></description><pubDate>Mon, 25 Aug 2008 12:45:50 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/3d-equilibrium-shapes-of-periodically-arranged-anisotropic-precipitates-with-elastic-misfit/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/3d-equilibrium-shapes-of-periodically-arranged-anisotropic-precipitates-with-elastic-misfit/</guid></item><item><title><![CDATA[Brake squeal: a problem of flutter instability of the steady sliding solution?]]></title><description><![CDATA[
  Brake squeal results from friction-induced vibrations. This phenomenon is considered here and interpreted as a flutter instability of the steady sliding solution of an elastic solid in unilateral contact with friction with a moving obstacle. A mechanical analysis of the governing equations is given, in particular to obtain the steady sliding solution. The stability analysis of this solution is discussed. A numerical analysis by the finite element method is performed in order to compute the steady sliding solution and to discuss its stability for an automotive disk brake. The validation of the numerical procedure is examined in relation with some analytical results of the literature.  ]]></description><pubDate>Mon, 25 Aug 2008 12:44:38 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/brake-squeal-a-problem-of-flutter-instability-of-the-steady-sliding-solution/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/brake-squeal-a-problem-of-flutter-instability-of-the-steady-sliding-solution/</guid></item><item><title><![CDATA[On the limit analysis of defective pipelines under complex loadings]]></title><description><![CDATA[
  The integrity assessment of defective pipelines represents a practically important task of structural analysis and design in various technological areas, such as oil and gas industry, power plant engineering and chemical factories. It is very essential to evaluate the load-carrying capacities of defective pipelines in order to judge safely their working life. In this paper, an iterative algorithm is presented for the kinematic limit analysis of 3-D rigid-perfectly plastic bodies. A numerical path scheme for radial loading is adopted to deal with complex multi-loading systems. The numerical procedure has been applied to carry out the plastic collapse analysis of pipelines with part-through slots under internal pressure, bending moment and axial force. The effects of various shapes and sizes of part-through slots on the collapse loads of pipelines are systematically investigated and evaluated. Some typical failure modes corresponding to different configurations of slots and loading forms are studied.  ]]></description><pubDate>Mon, 25 Aug 2008 12:43:32 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/on-the-limit-analysis-of-defective-pipelines-under-complex-loadings/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/on-the-limit-analysis-of-defective-pipelines-under-complex-loadings/</guid></item><item><title><![CDATA[Time-dependent elastoplastic constitutive equation]]></title><description><![CDATA[
  Various existing constitutive equations aiming at the description of the time-dependent deformation behavior for a wide range of stress below and over the elastic limit, i.e. the yield stress are reviewed in detail. It is suggested that the plastic stretching and the creep stretching have to be treated as independent quantities since they have substantially different physical properties and that a stress goes out from the yield surface at a high rate of deformation since a plastic deformation is suppressed by a high viscous resistance and then the yield surface is kept unchanged. The subloading surface model [1-3] would satisfy these requirements since it does not premise that a stress is on the yield surface even in the plastic loading process. In this article, based on the extended subloading surface model [4] which is capable of describing not only monotonic but also cyclic loading behavior, the generalized time-dependent elastoplastic constitutive equation is formulated allowing the stress go out from the yield surface by letting the plastic deformation be suppressed at a high rate of deformation and introducing the creep stretching which proceeds with time in addition to the elastic and the plastic stretching.  ]]></description><pubDate>Mon, 25 Aug 2008 12:41:25 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/timedependent-elastoplastic-constitutive-equation/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/timedependent-elastoplastic-constitutive-equation/</guid></item><item><title><![CDATA[Elastic-plastic stress-strain analysis of notches under non-proportional loading paths]]></title><description><![CDATA[
  An analytical method for calculating notch tip stresses and strains in elastic-plastic bodies subjected to non-proportional loading sequences is discussed in the paper. The method is based on the incremental formulation relating the hypothetical linear elastic and elastic-plastic strain energy densities at the notch tip, and the material stress-strain behavior simulated according to the Mróz-Garud cyclic plasticity model. Two formulations involving the strain energy density and the complimentary strain density are discussed in the paper, and they appear to give the lower and the upper bound estimations for the elastic-plastic notch tip strains. Each formulation consists of a set of incremental algebraic equations that can easily be solved for elastic-plastic stress and strain increments, knowing the increments of the hypothetical elastic notch tip stress history and the material stress-strain curve. The validation of the proposed model against finite element data obtained for non-proportional loading is also presented. The method is particularly suitable for fatigue life analysis of notched bodies subjected to multiaxial cyclic loading paths.  ]]></description><pubDate>Mon, 25 Aug 2008 12:40:22 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/elasticplastic-stressstrain-analysis-of-notches-under-nonproportional-loading-paths/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/elasticplastic-stressstrain-analysis-of-notches-under-nonproportional-loading-paths/</guid></item><item><title><![CDATA[The role of backstress in phase transforming steels]]></title><description><![CDATA[
  Transformation Induced Plasticity (TRIP) is demonstrated by an experimental programme for a Fe-9Ni-12Cr steel for various loading paths with partial or full unloading. The martensitic transformation is considered. A thermodynamical interpretation as well as micromechanical modelling of TRIP are presented. The selection of distinct variants is explained. Finally a modified constitutive equation for the TRIP strain rate is suggested by introducing a transformation surface including a transformation backstress. The backflow after unloading, which cannot be explained by the currently used TRIP strain rate term, can be represented by the proposed formulation. Aspects of future research are discussed.  ]]></description><pubDate>Mon, 25 Aug 2008 12:39:10 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/the-role-of-backstress-in-phase-transforming-steels/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/the-role-of-backstress-in-phase-transforming-steels/</guid></item><item><title><![CDATA[On Prandltl&#039;s lifting equation arising in wear mechanics]]></title><description><![CDATA[
  A sliding wear contact between a rigid punch and an elastic half plane in presence of a thin aggregate film composed of solid debris and a lubricant fluid is studied. The model is based on any wear criterion and constitutive law of the film suggested by micromechanics approximation. The mechanical system is governed by the evolution of the volume fraction of debris, considered as the internal state variable. The key step of iterative computations for solving the nonlinear system of equations is based on the solution of the fundamental linear integro-differential equation for the compressive normal stress (the W-equation). The uniqueness of the solution of the integro-differential equation is then proved. It is shown that there is a profound relationship between the latter equation and the Prandtl's lifting equation in Aerodynamics: both equations can be solved numerically by Chebyshev's series, and experimentally by similar electrical setups. Mathematically, it is found that both equations are related to real and imaginary components of some complex potential respectively and to weakly adjoint integro-differential operators.  ]]></description><pubDate>Mon, 25 Aug 2008 12:37:55 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/on-prandltls-lifting-equation-arising-in-wear-mechanics/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/on-prandltls-lifting-equation-arising-in-wear-mechanics/</guid></item><item><title><![CDATA[Extremum and saddle-point theorems for elastic solids with dissipative displacement discontinuities]]></title><description><![CDATA[
  In a number of engineering situations concerning structures made of quasi-brittle, concrete-like materials, all nonlinearities can be reasonably confined to a locus of possible displacement discontinuities. This locus has a lesser dimensionality (by one) with respect to the problem domain; it encompasses joints, cracks, fracture process zones (described by cohesive crack models) and their possible propagation paths. Linear elasticity is assumed everywhere else for overall analysis purposes. With reference to a very broad class of interface models, i.e. of (holonomic or nonholonomic, inviscid or time-dependent) relationships between displacement jumps and tractions across that locus, the (possibly multiple, if any) solutions of the initial-boundary-value problem of structural analysis are shown herein to be characterized by duality pairs of extremum and min-max properties.  ]]></description><pubDate>Mon, 25 Aug 2008 12:36:55 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/extremum-and-saddlepoint-theorems-for-elastic-solids-with-dissipative-displacement-discontinuities/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/extremum-and-saddlepoint-theorems-for-elastic-solids-with-dissipative-displacement-discontinuities/</guid></item><item><title><![CDATA[Spatial localization of the error of constitutive law for the identification of defects in elastic bodies]]></title><description><![CDATA[
  The error on constitutive law (ECL) is a cost functional currently used in inverse problems for identifying interior distribution of coefficients of partial differential equations from overspecified boundary conditions. In previous works, different authors have shown that the ECL permits a good spatial localization of the perturbations of the coefficients.  

  The purpose of this paper is to justify this spatial localization property. The result is obtained for the elliptic equations of elasticity using boundary integral representations of the solutions and comparing the linear and the perturbed solution of the problem.  ]]></description><pubDate>Mon, 25 Aug 2008 12:35:49 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/spatial-localization-of-the-error-of-constitutive-law-for-the-identification-of-defects-in-elastic-bodies/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/spatial-localization-of-the-error-of-constitutive-law-for-the-identification-of-defects-in-elastic-bodies/</guid></item><item><title><![CDATA[Henky&#039;s elasticity model with the logarithmic strain measure: a study on Poynting effect and stress response in torsion of tubes and rods]]></title><description><![CDATA[
  Hencky's elasticity model is a finite strain elastic constitutive equation derived by replacing the infinitesimal strain measure in the classical strain-energy function of infinitesimal isotropic elasticity with Hencky's logarithmic strain measure. Anand [1,2] has demonstrated that, with only the two classical Lamé elastic constants measurable at infinitesimal strains, predictions of the just-mentioned simple model for a wide class of materials for moderately large deformations may be in better agreement with experimental data than other known finite elasticity models. The deformation modes considered in Anand's work are simple tension and compression, simple shear, and simple torsion and combined extension-torsion of solid cylinders, etc. Here, we indicate some remarkable properties of this Hencky model and, mainly, we investigate the large deformation responses of this model in torsion of cylindrical tubes and rods with free ends. It is pointed out that if in inelastic modeling, especially in modeling of metal plasticity, the widely-used hypoelastic formulation for the elastic rate of deformation is required to be exactly integrable to an elastic relation, as it should be, then the resulting elastic relation is just the Hencky model, and, further, this model is hyperelastic and the only possible one. In the main aspect, i.e. for the torsion of cylindrical tubes and rods with free ends, we derive explicit analytical solutions for the case of compressible small deformations and for the case of incompressible large deformations. The results derived show, in a clear and direct manner, second order effects, including the well-known Poynting effect regarding the length change in the axial direction. It is noticeable that, with only the material properties measurable at infinitesimal strains, the Hencky model can predict the just-mentioned second order effects, in particular the Poynting effect, and its predictions are in good accord with experiments reported in the literature.  ]]></description><pubDate>Mon, 25 Aug 2008 12:34:24 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/henkys-elasticity-model-with-the-logarithmic-strain-measure-a-study-on-poynting-effect-and-stress-response-in-torsion-of-tubes-and-rods/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/henkys-elasticity-model-with-the-logarithmic-strain-measure-a-study-on-poynting-effect-and-stress-response-in-torsion-of-tubes-and-rods/</guid></item><item><title><![CDATA[Preface]]></title><description><![CDATA[
  This special issue of   Archives of Mechanics   is dedicated to Professor Zenon Mróz on the occasion of his 70th borthday.  ]]></description><pubDate>Mon, 25 Aug 2008 12:30:18 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-45/preface/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-45/preface/</guid></item><item><title><![CDATA[Application of a constitutive equation for softening, yield and permanent deformation to finite plane simple shear]]></title><description><![CDATA[
  The finite homogenous simple shear deformation of an incompressible material is considered. The response is modeled with a constitutive equation that reflects a continuous process of microstructural transformation as the deformation increases beyond a threshold value. The original and transformed portions of the material are both taken to respond as incompressible elastic solids. It is shown that the transformation can lead to softening of the response with increasing deformation and to a local maximum in the shear stress-shear strain curve. The existence of permanent deformation after release of the shearing traction is demonstrated. It is confirmed that a process of increasing deformation followed by decreasing deformation to the point of zero shear traction is a dissipative cycle. A special case is then considered in which both the original and transformed materials are assumed to respond as neo-Hookean solids. The critical volume fraction of transforming material at which the shear stress-shear strain curve loses monotonicity is found analytically. Representations are obtained for the dependence of the residual shear deformation on the fraction of transforming material; on the ratio of moduli of the original and transformed materials; and on the maximum shear reached before unloading.  ]]></description><pubDate>Mon, 25 Aug 2008 12:24:08 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-3/application-of-a-constitutive-equation-for-softening-yield-and-permanent-deformation-to-finite-plane-simple-shear/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-3/application-of-a-constitutive-equation-for-softening-yield-and-permanent-deformation-to-finite-plane-simple-shear/</guid></item><item><title><![CDATA[Effect of fiber treatment on bending strength of aramid short fiber reinforced polyester]]></title><description><![CDATA[
  Effect of fiber treatment on the bending strength of the aramid short fiber composite is studied in this paper. Interfacial shear strength and fiber strength are determined for different fiber treatments by performing single-fiber pull-out test. Effect of the fiber treatments on the property of the composite depends both on the interfacial shear strength and the fiber strength, simultaneously. Thus, to evaluate quantitatively the effect of the treatments on the strength of the composite a parameter "critical embedded length" is introduced that covers both the interfacial shear strength and the fiber strength. It is a parameter that defines the maximum embedded length during pull-out test, above which the shear force in the fiber/matrix interface exceeds the value of fracturing force of the fiber. The result shows that decrease of the critical embedded length causes increase in the bending strength of the composite, for the cases of the treatments employed in this research. Finally, an empirical equation is developed to calculate the bending strength of the aramid short fiber composite for the fiber treatments employed in this research.  ]]></description><pubDate>Mon, 25 Aug 2008 12:22:25 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-3/effect-of-fiber-treatment-on-bending-strength-of-aramid-short-fiber-reinforced-polyester/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-3/effect-of-fiber-treatment-on-bending-strength-of-aramid-short-fiber-reinforced-polyester/</guid></item><item><title><![CDATA[Thermomechanics of viscoplastic large strains of solid polymers]]></title><description><![CDATA[
  Experimental results concerning cyclic tension tests performed on polyamid based -   braiding samples   and on   usual samples   machined of the same PA66 polyamid are presented. The measurements are   thermomechanical  : the temperature of the surface of the sample is recorded, resulting in the estimation of the intrinsic internal heat supply. The materials are exhibiting not only the classical viscoelastoplastic behaviour, but also thermomechanical effects of the Kelvin and Taylor-Farreen-Quinney type. Modelling based on a previously proposed constitutive formulation of cyclic viscoplastic isotropic behaviour is implemented.  ]]></description><pubDate>Mon, 25 Aug 2008 12:21:01 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-3/thermomechanics-of-viscoplastic-large-strains-of-solid-polymers/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-3/thermomechanics-of-viscoplastic-large-strains-of-solid-polymers/</guid></item><item><title><![CDATA[Irreducible representations for constitutive equations of anisotropic solids III: crystal and quasicrystal classes D_2m+1h and D_2md]]></title><description><![CDATA[
  A simple unified procedure is applied to derive irreducible nonpolynomial representations for scalar-, vector-, skewsymmetric and symmetric second order tensor-valued anisotropic constitutive equations involving any finite number of vector variables and second order tensor variables. In this part, our concern is for the crystal classes and quasicrystal classes D  2m+1h   and D  2md   for all integers m> =1.  ]]></description><pubDate>Mon, 25 Aug 2008 12:19:12 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-3/irreducible-representations-for-constitutive-equations-of-anisotropic-solids-iii-crystal-and-quasicrystal-classes-d2m1h-and-d2md/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-3/irreducible-representations-for-constitutive-equations-of-anisotropic-solids-iii-crystal-and-quasicrystal-classes-d2m1h-and-d2md/</guid></item><item><title><![CDATA[On interactions of frictional cracks]]></title><description><![CDATA[
  
This paper deals with the estimation of the stress intensity factors for interacting Mode-II cracks undergoing frictional sliding under overall compressive stresses. Crack interaction effects are examined via the Kachanov method that is extended here to account for frictional and cohesive resistance on crack faces. The accuracy of the obtained results is verified through comparison with the "exact" numerical solutions obtained using a boundary element method.  ]]></description><pubDate>Mon, 25 Aug 2008 11:48:52 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-2/on-interactions-of-frictional-cracks/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-2/on-interactions-of-frictional-cracks/</guid></item><item><title><![CDATA[Quasifractional approximants for effective conductivity of regular arrays of spheres]]></title><description><![CDATA[
  
We study the effective heat conductivity of regular arrays of perfectly conducting spheres embedded in a matrix with the unit conductivity. Quasifractional approximants allow us to derive an approximate analytical solution, valid for all values of the spheres volume fraction φin[0; φ  max  ] (φ  max   is the maximum limiting volume of a sphere). As the bases we use a perturbation approach for φ-> 0 and an asymptotic solution for φ-> φ  max  . Three different types of the spheres space arrangement (simple, body and face-centred cubic arrays) are considered. The obtained results give a good agreement with numerical data.  ]]></description><pubDate>Mon, 25 Aug 2008 11:47:31 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-2/quasifractional-approximants-for-effective-conductivity-of-regular-arrays-of-spheres/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-2/quasifractional-approximants-for-effective-conductivity-of-regular-arrays-of-spheres/</guid></item><item><title><![CDATA[Magnetohydrodynamic convective flow in a rotating channel]]></title><description><![CDATA[
  Combined free and forced convective flow of an electrically conducting viscous incompressible fluid in a rotating parallel plate channel with perfectly conducting walls is investigated. Exact solutions of the governing equations for the fully developed flow are obtained in closed form. It is found that the resultant shear stresses at the walls decrease with the increase in both the rotation parameter K  2   and the magnetic parameter M  2  . The rate of heat transfer at both walls decreases with the increase in the Grashof number G.  ]]></description><pubDate>Mon, 25 Aug 2008 11:34:01 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-2/magnetohydrodynamic-convective-flow-in-a-rotating-channel/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-2/magnetohydrodynamic-convective-flow-in-a-rotating-channel/</guid></item><item><title><![CDATA[Laminar dispersed two-phase flows at low concentration II. Disturbance Equations]]></title><description><![CDATA[
  In a preceding paper (Part I), a generalised system of equations was proposed to represent multi-D flows of particle-fluid mixtures. It was based on a coupling of two sets of equations, one for each phase: the Lundgren hierarchy for the continuous phase and an adaptation of the well-known B.B.G.K.Y. hierarchy for the dispersed phase. It happens that at any order, many of the equations obtained remain intricate: several important terms are difficult either to interpret or to compute effectively such as the averaged extra-deformation tensors, the interfacial force density and finally the pseudo-turbulent tensors in the momentum equations for both phases, arising from inclusion motions alone. That can be remedied by introducing the concept of an "averaged disturbance field" based on differences between two successive conditionally averaged variables. All the equations of both hierarchies are transformed in terms of these fields, which play a central role in our theory, except for the first-order equations of both hierarchies; these correspond to conservation equations of standard two-fluid models.  ]]></description><pubDate>Mon, 25 Aug 2008 11:32:17 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-2/laminar-dispersed-twophase-flows-at-low-concentration-ii-disturbance-equations/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-2/laminar-dispersed-twophase-flows-at-low-concentration-ii-disturbance-equations/</guid></item><item><title><![CDATA[On the singular integral equations approach to the interface crack problem for piezoelectric materials]]></title><description><![CDATA[
  A plane strain problem for an interface crack with poling axis orthogonal to the crack plane is considered. The contact zone model with an artificial contact zone is considered for electrically permeable crack. By means of the method of singular integral equations, the quasi-invariance of the energy release rate with respect to the contact zone length is demonstrated. The appearance of a singularity of real power type instead of an oscillating singularity for insulated crack faces for most combinations of ceramics is shown. In a numerical way, the comparison of stresses and electrical displacements corresponding to the different interface crack models is employed.  ]]></description><pubDate>Mon, 25 Aug 2008 11:30:42 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-2/on-the-singular-integral-equations-approach-to-the-interface-crack-problem-for-piezoelectric-materials/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-2/on-the-singular-integral-equations-approach-to-the-interface-crack-problem-for-piezoelectric-materials/</guid></item><item><title><![CDATA[Asymptotic analysis of heat propagation models]]></title><description><![CDATA[
  The subject of this paper is the analysis of different models of heat propagation. As is well known, one of essential disadvantages of the classical model proposed by Fourier is the infinite velocity at which heat propagates. To avoid that unphysical phenomenon, Cattaneo has proposed a hyperbolic model. An essential feature of that model is the introduction of a relaxation time for thermal processes. In recent years several new models have been proposed which retain the relaxation time phenomenon but are parabolic in their character. When the relaxation time is small, all these models lead to singularly perturbed equations. We analyze some of these models and prove that the solution of the classical heat equation (Fourier model) is a bulk approximation to exact solutions of these models. We show also that the behaviour of the Fourier model depends on the way in which it is applied. Finally, we present numerical comparison of exact solutions with the bulk solution for the test problem of heat propagation in thin metal films heated by a laser beam.  ]]></description><pubDate>Mon, 25 Aug 2008 11:27:36 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-2/asymptotic-analysis-of-heat-propagation-models/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-2/asymptotic-analysis-of-heat-propagation-models/</guid></item><item><title><![CDATA[Modelling of nonstationary heat conduction problems in micro-periodic composites using homogenisation theory with corrective terms]]></title><description><![CDATA[
  Homogenisation based on the asymptotic series expansion is used to model a nonstationary behaviour of a rigid heat conductor with micro-periodic structure. A usual first-order approximation (which cannot be assumed as a satisfactory solution for time-dependent problems) is treated as a suitable starting point for further corrections that make it admissible. An initial correction takes into account some fast processes acting on the level of the microstructure and guarantees that the initial condition is satisfied. Some higher-order correctors are intended to improve the first-order approximation far from the onset of the process, for composites with strongly different properties of components or for the case of a rough microstructure. A numerical example shows that the role of the initial corrector is prevailing in the model.  ]]></description><pubDate>Mon, 25 Aug 2008 11:26:31 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-2/modelling-of-nonstationary-heat-conduction-problems-in-microperiodic-composites-using-homogenisation-theory-with-corrective-terms/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-2/modelling-of-nonstationary-heat-conduction-problems-in-microperiodic-composites-using-homogenisation-theory-with-corrective-terms/</guid></item><item><title><![CDATA[Nanomaterial clusters as macroscopically small size-effects bodies. Part II]]></title><description><![CDATA[ 
  An isotropic elastic spherical size-effect solid body is proposed as a phenomenological model for the description of thermomechanical properties of macroscopically small nanomaterial spherical clusters subjected to a uniform pressure. Nanomaterial clusters being mechanically stable as well as those being mechanically stable of lower order are investigated. It is shown, among others, that the isothermal bulk modulus reveals the size effect due to the influence of surface tension of the cluster boundary solid surface.  ]]></description><pubDate>Mon, 25 Aug 2008 11:07:47 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-1/nanomaterial-clusters-as-macroscopically-small-sizeeffects-bodies-part-ii/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-1/nanomaterial-clusters-as-macroscopically-small-sizeeffects-bodies-part-ii/</guid></item><item><title><![CDATA[Nanomaterial clusters as macroscopically small size-effects bodies. Part I]]></title><description><![CDATA[ 
  One of unusual features of macroscopically small three-dimensional nanocrystalline clusters is the dependence of their properties on the grain size as well as on the cluster size. Consequently, such clusters are ensembles of atoms or particles where the size effect becomes apparent. A phenomenological model of the description of thermomechanical properties of macroscopically small nanomaterial clusters is proposed. The model is based on the concept of size-effect bodies, the thermomechanical properties, dynamics and thermodynamics of which are referred to one whole body, not an infinite system of subbodies. It is pointed out that the proposed model of the size effect leads to an analogy with the theory of capillarity. A class of size-effect bodies generalizing this analogy is introduced and discussed. Particularly, it is stated that the heat capacity reveals not only the size effect but, contrary to the elastic properties, should depend also on the topological invariant of the compact and connected cluster.  ]]></description><pubDate>Mon, 25 Aug 2008 11:06:55 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-1/nanomaterial-clusters-as-macroscopically-small-sizeeffects-bodies-part-i/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-1/nanomaterial-clusters-as-macroscopically-small-sizeeffects-bodies-part-i/</guid></item><item><title><![CDATA[Deflection relationships between the homogeneous Kirchhoff plate theory and different functionally graded plate theories]]></title><description><![CDATA[ 
  We derive field equations for a functionally graded plate whose deformations are governed by either the first-order shear deformation theory or the third-order shear deformation theory. These equations are further simplified for a simply supported polygonal plate. An exact relationship is established between the deflection of the functionally graded plate and that of an equivalent homogeneous Kirchhoff plate. This relationship is used to esplicitly express the displacements of a plate particle according to the first-order shear deformation theory in terms of the deflection of a homogeneous Kirchhoff plate. These relationships can readily be used to obtain similar correspondences between the deflections of a transversely laminated plate and a homogeneous Kirchhoff plate.  ]]></description><pubDate>Mon, 25 Aug 2008 11:05:38 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-1/deflection-relationships-between-the-homogeneous-kirchhoff-plate-theory-and-different-functionally-graded-plate-theories/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-1/deflection-relationships-between-the-homogeneous-kirchhoff-plate-theory-and-different-functionally-graded-plate-theories/</guid></item><item><title><![CDATA[Nonlinearity and memory effects in low temperature heat propagation]]></title><description><![CDATA[ 
  In order to account for low temperature heat propagation phenomena in crystals of sodium fluoride and bismuth, we employ a thermodynamic model for rigid materials involving a vector-field internal state variable. The model is either wavelike or diffusive, depending on the temperature regime considered.  ]]></description><pubDate>Mon, 25 Aug 2008 11:04:17 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-1/nonlinearity-and-memory-effects-in-low-temperature-heat-propagation/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-1/nonlinearity-and-memory-effects-in-low-temperature-heat-propagation/</guid></item><item><title><![CDATA[A new approach to the analysis of polycrystal plasticity]]></title><description><![CDATA[ 
  When a polycrystal is subjected to inelastic deformation, there inevitably exist residual microstress fields in a   polycrystalline material   due to its nonhomogeneous morphology. The energy stored in these microstress fields may partly be released and influence the material behavior during subsequent inelastic deformation. Correspondingly, a simple mechanical model is introduced to formulate the constitutive equation for a slip system and the hardening law for single crystal. The corresponding approach for the analysis of polycrystalline materials is obtained based on KBW's self consistent theory. The proposed approach employs no yield criterion and the corresponding numerical analysis is greatly simplified because it involves no additional process for determination of the activation of slip systems and slip direction. A mixed averaging approach is used in polycrystalline plasticity analysis. The response of 316 stainless steel subjected to typical biaxial nonproportional plastic strain cycling is described and the validity of the proposed approach is demonstrated by the satisfactory agreement between the calculated result and experimental observation.  ]]></description><pubDate>Mon, 25 Aug 2008 11:02:57 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-1/a-new-approach-to-the-analysis-of-polycrystal-plasticity/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-1/a-new-approach-to-the-analysis-of-polycrystal-plasticity/</guid></item><item><title><![CDATA[Stress distribution in the muscles of the diaphragm]]></title><description><![CDATA[ 
  The diaphragm is treated as a membrane subject to a uniform pressure. The muscle action is modeled as a uniaxial active stress in the direction of muscle bundles. In the present paper we look for the generalized stress distribution in the membrane. The shape of the active diaphragm is approximated by a surface know as a cyclide. For this simplified shape, a closed form solution of the equilibrium equations is obtained.  ]]></description><pubDate>Mon, 25 Aug 2008 11:00:35 +0000</pubDate><link>http://am.ippt.gov.pl/volume-52-2000/issue-1/stress-distribution-in-the-muscles-of-the-diaphragm/</link><guid>http://am.ippt.gov.pl/volume-52-2000/issue-1/stress-distribution-in-the-muscles-of-the-diaphragm/</guid></item></channel></rss>