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Plane stress deformation near a crack tip in a hardening material of stress state dependent propertiesтезисы доклада
- Авторы: Lomakin E.V., Ovchinnikov I.V.
- Сборник: 21st European Conference on Fracture. Programme. Abstracts
- Тезисы
- Год издания: 2016
- Место издания: www.ecf21.eu Catania Italy
- Первая страница: 39
- Последняя страница: 40
- Аннотация: Keywords: stress state dependent properties; micro-heterogeneous materials; effective deformation properties; dilatation; constitutive relations, solution of crack problem, crack growth conditions. Abstract: The behavior of the structural microdefects in damaged media and other heterogeneous materials changes depending on the loading conditions. Therefore, materials with micro-cracks, inclusions or pores are characterized by the dependence of the deformation and strength properties on the stress state type. This complicates the description of the deformation process. The analysis of the experimental data shows the absence of a “single curve” for the dependence of between von Mises equivalent stress and equivalent strain. Instead of the single curve, there is a fan of curves and the interdependence between the shear and volume strains, the appearance of irreversible volume strains and other specific features are observed, too. Such properties are characteristic for cast-iron, structural graphite materials, concrete, rocks some ceramic and composite materials. The influence of these specific features on asymptotic solutions near macro-cracks in a hardening material is studied. The corresponding constitutive relations are used that describe different types of physical nonlinearities and the observed in experiments phenomena. The case of plane stress state is considered. The calculations are performed with the use of experimental data obtained for cast-iron and structural graphite. An approximation for material functions is suggested. This approximation allows one to describe the experimental strain diagrams with a reasonable degree of accuracy. For specific material functions, the distributions of stresses, strains, and displacements near the crack tip are obtained. These distributions are compared with those following from the solution of a similar problem for a plastically incompressible medium. The conditions of the crack growth initiation are determined with the use of the invariant integral. It is shown that the amplitude of singularity for the material with stress-state dependent properties is substantially lower than the corresponding value obtained for the incompressible material. Hence, the account for the plastic compressibility of a material and the stress state susceptibility of its mechanical properties result in significant correction of the stress, strain, and displacement distributions, as compared with the corresponding solution for the incompressible medium with the same hardening exponent.
- Добавил в систему: Овчинников Иван Валерьевич