Papers by Keyword: Material Constant

Abstract: This paper deals with evaluation of n strain hardening exponent and C material constant at various velocities of the strain rate according to EN 10002-1. Dependence of tensile stress on elongation is carried out at INSTRON shredder in digital form and it is directly introduced into MATLAB working environment. To determine these material parameters suitable material models (Krupkowsky model) and MATLAB programming pack, mainly its Curve Fitting toolbox, which provides the library of standard linear, nonlinear and nonparametric models (e.g. polynomial, rational, etc.), are used. At automobile crash tests kinetic energy conversion into energy of deformation (where it is necessary to know n, C) is theoretically calculated at certain velocities so that the solid parts of the car body would be protected from damage. It would be the best to compare correctness of those calculations to the test carried out at a real model or by simulation created on the computer with necessary software equipment.

Abstract: The material constants calculation models for hyperbolic-sine creep model were proposed. The material constants used in hyperbolic-sine creep model for 316 stainless steel were calculated due to the models proposed and experimental data in the temperature range from 873K to 1023K. The relationships between material constants of 316 stainless steel creep model and temperature were obtained by curve fitting. The creep rate predict model of 316 stainless steel with only stress and temperature was also developed, the creep rates predicted were in good agreement with experimental data.

Abstract: The material modeling of hyper-elastic properties in rubber is generally characterized by the strain energy function. The strain energy functions have been represented either in term of the strain in variants that are functions of the stretch ratios, or directly in terms of the principal stretch. Successful modeling and design of rubber components relies on both the selection of an appropriate strain energy function and an accurate determination of material constants in the function. Material constants in the strain energy functions can be determined from the curve fitting of experimental stress-strain data. The uniaxial tension, equi-biaxial tension and pure shear test were performed to acquire the constants of the strain energy functions which were Mooney-Rivlin and Ogden model. Nonlinear finite element analysis was executed to evaluate the behavior of deformation and strain distribute by using the commercial finite element code. Also, the fatigue tests were carried out to obtain the fatigue failure. Fatigue failure was initiated at the critical location was observed during the fatigue test of rubber component, which was the same result predicted by the finite element analysis.

Abstract: Plasticity Induced Crack Closure (PICC) is an important fatigue phenomenon affecting crack growth under cyclic loading, which makes important to consider it in the design of components. In this paper a parametric study that correlates elastic-plastic material parameters with plasticity induced crack closure (PICC) is presented. Yield stress and hardening coefficient were selected as the material parameters of interest and a sensitivity analysis was developed. The influence of the different parameters on PICC is explained based on the analysis of crack tip micromechanisms for plastic deformation.

Abstract: This paper offers some new calculating equations on the small crack growth rate for describing the elastic-plastic behavior of materials under symmetric or un-symmetric cyclic loading. And it yet suggests the estimating formulas of the life relative to varied small crack size aoi at each loading history. The method is to adopt the ratio e p e e D D / by plastic strain range to elastic strain range as a stress-strain parameter, using some staple material parameters as the material constants in damage calculating expression. And it gives out a new concept of the composite material constant, that it is functional relation with each staple material constants, average stress，average strain and critical loading time. The calculated results are accordant with the Landgraf’s equation, so could avoid unnecessary fatigue tests and will be of practical significance to stint times, manpower and capitals, the convenience for engineering applications.