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Material parameter identification using constitutive models of elasticity, viscoelasticity, rateindependent plasticity and viscoplasticity has a long history with regard to homogeneous and inhomogeneous deformations. For example, uniaxial tensile tests, pure shear tests, torsion experiments of thin-walled tubes or biaxial tensile tests are used to obtain the material parameters by solving the inverse problem. Frequently, the parameters are determined by numerical optimization tools. In this paper, we investigate some very basic single- and two-layered examples regarding identifiability, because these tests are the basis for more complex geometrical and physical nonlinear problems. These simple examples are the uniaxial tensile/compression case, biaxial tensile tests of a cruciform specimen, torsion of a thin-walled tube, a thick-walled tube under internal pressure and the indentation test. For the thick-walled tube under internal and external pressure with an axial pre-strain with several layers, an analytical solution is provided directly suitable for programming. The aim is to get an understanding whether some problems lead to non-identifiable parameters. [ABSTRACT FROM AUTHOR]

From the decomposition theorem of elastic beams, two classes of exact stress states are investigated for the equations of three dimensional elasticity governing elastic beams in bending deformations with free faces. One of these is the analogue of the Levy solution for elastic plates and is designated as the interior state. The other complementary class corresponds to a decaying state and is designated as the Papkovich-Fadle state. The appropriate boundary conditions have been established recently for the prescribed data at the end edge of beams to induce only an exponentially decaying elastostatic state. The present paper describes how these conditions may be used to determine the boundary conditions of these two states. The decomposition theorem of beams effectively allows us to split the prescribed edge-data correctly into two parts, one for the interior solution components and the other for the decaying solution components. An analytical solution of the decaying state is formulated to verify the validity of our boundary conditions. The results in turn show that the necessary conditions for the Papkovich-Fadle state are also sufficient conditions. The boundary conditions obtained for the interior state show that the interior solution determined by these conditions is the correct solution in the beam interior up to exponentially small terms. Moreover, with the separate consideration of the interior and decaying solution components, a relatively simple analytical solution is often practical and desirable, and the numerical computation process is essentially simplified. As an illustrative example, the present results are applied to the end-loaded cantilever beam. [ABSTRACT FROM AUTHOR]

The paper is concerned with the determination of edge effect zone in a laminated composite with laminas subject to longitudinal compression. The dependence of the maximum decay length on the ratio between the period of external loading and the structure parameter is studied. The load period depends on the number of unloaded laminas. The decay of the edge effect is analyzed by numerically solving a boundary-value problem of elasticity for piecewise-homogeneous materials and using a quantitative decay criterion for the near-edge normal stresses [ABSTRACT FROM AUTHOR]

In this paper, the simultaneous identification of the Poisson ratio, the shear modulus and a circular cavity embedded in an isotropic linear elastic material from boundary measurements is investigated. The numerical method proposed is based on the least-squares minimisation of the errors between the measured and the calculated tractions on the outer boundary using the boundary element method (BEM). [ABSTRACT FROM AUTHOR]

We consider the problem of determining the stability boundary of an elastic rod clamped at both ends and loaded by a compressive force and a couple. The constitutive equations of the rod are such that both shear of the cross section and compressibility of the rod axis are considered. The stability boundary is given by the bifurcation points of a system of eight nonlinear first-order differential equations, obtained by using the first integrals. Depending on the parameter values the type of bifurcation is determined. The post-critical shape of the rod is obtained by the numerical integration of a system of 12 nonlinear first-order differential equations. [ABSTRACT FROM AUTHOR]

A simple deformation field associated with an exact torsion-like solution of the equilibrium equations of linear elasticity is shown to provide a good approximation of the deformation field in interior elements of a mesh that models pure torsion of a right cylindrical bar with rectangular cross-section. Using this solution, modified torsion coefficients are proposed for a 3-D brick Cosserat point element (CPE) which are shown to improve convergence properties for solutions of pure torsion. [ABSTRACT FROM AUTHOR]

Abstract  In a dynamic experiment to obtain the high-rate stress–strain response of a ductile specimen, it takes a finite amount of time for the strain rate in the specimen to increase from zero to a desired level. The strain in the specimen accumulates during this strain-rate ramping time. If the desired strain rate is high, the specimen may yield before the desired rate is attained. In this case, the strain rates at yielding and early plastic flow are lower than the desired value, leading to inaccurate determination of the yield strength. Through experimentation and analysis, we examined the validity and accuracy of the flow stresses for ductile materials in a split Hopkinson pressure (SHPB) bar experiment. The upper strain-rate limit for determining the dynamic yield strength of ductile materials with a SHPB is identified. [ABSTRACT FROM AUTHOR]

New representations of the stress tensor in the linear theory of elasticity and thermoelasticity are proposed. These representations satisfy the equilibrium equations and the strain compatibility equation. The stress tensor is expressed in terms of a harmonic tensor or a harmonic vector. The second boundary-value problem for an elastic half-space and an elastic layer is solved as an example [ABSTRACT FROM AUTHOR]

Based on the refined plate theory, a refined theory of rectangular beams is derived by using the Papkovich-Neuber solution and Lur’e method without ad hoc assumptions. It is shown that the displacements and stresses of the beam can be represented by the angle of rotation and the deflection of the neutral surface. The solutions based on the new theory are the same as the exact solutions of elasticity theory. In three examples it is shown that the new theory provides as good or better results than Levinson’s beam theory when compared to those obtained from the linear theory of elasticity. [ABSTRACT FROM AUTHOR]

We give a review of works devoted to the application of the acoustic emission method for studying the onset of plastic deformations in crystalline bodies. The mechanisms of generation of acoustic emission signals in the course of plastic deformation of various materials are considered. We also illustrate the application of parameters that are used most often and show the trends of development of investigations in this field. [ABSTRACT FROM AUTHOR]

Based on the general solution of the three-dimensional problem for piezoelectric materials, the problem of a piezoelectric cone subjected to concentrated loads at its apex is solved by trial-and-error method. The displacements and stresses are explicitly given for the cases of compression in the presence of point charge, bending and torsion. These solutions are simple in form and convenient for application. When the apex angle 2α equals π, the solutions for concentrated force, point charge and torsion reduce to solutions of the half-space problem. [ABSTRACT FROM AUTHOR]