Study on Simulation of Cyclic Plastic Behavior of Ship Structural Pollycrystalline Metallic Materials under Cyclic Loading Conditions : 4th Report : Development of Iterative Calculation Method

Abstract

The amount of accumulated shear strain and non-reversible slip can be used as the parameters which represent a process of crack initiation. If we can investigate the relationship between macroscopic loading conditions and the development of such microscopic parameters, it can be possible to improve the prediction method of crack initiation life. Such investigation can be performed by crystalline FEM analysis. In the previous papers, the authors has developed a crystalline FEM code which can analyze cyclic plastic deformation behavior of f.c.c. crystals, and showed that the avobe microscopic parameters can be calculated. It is considered that the material instability called 'strain burst' affect the process of crack initiation. So, we have to investigate the deformation behavior on the occurrence of such material instability. However, because the time integration is performed by tangent modulus method in the code, we often cannot continue calculation because the residual force does not disappear. In this report, we modify the FEM code by iteration method, and make it capable of calculating the deformation behavior on the occurrence of 'strain burst'.