Simulation of the creep of materials with different strengths

Abstract

It is well known that certain materials, such as cast iron, titanium and aluminum‐magnesium alloys, beryllium copper, carbon plastic, granite, sandstone, coal, etc., behave in different ways under compressive and tensile loads [1‐3]. This difference is due to various internal microprocesses, such as the generation and growth of microcracks and microvoids, disclination distribution, sliding of grain boundaries, etc. This phenomenon is observed in both reversible [4‐6] and irreversible [7‐10] deformation processes and affects the entire spectrum of the mechanical and physical properties of materials. In this study, a creep model for materials with different moduli is constructed using piecewise-linear deformation potentials, and a technique for determining the material constants responsible for its mechanical properties is discussed. The creep model with piecewise-linear potentials for materials with different moduli is constructed on the basis of the assumption that, in the initial creep stage, the total strains of a material remain small, and the stresses are moderate and do not lead to plastic flow. Therefore, the total strain tensor e ij is the sum of the elastic strain tensor and the creep strain tensor :