SUS304鋼を用いたスモールパンチ試験における破壊様式の速度依存性の有限要素解析による検討

抄録

In past studies, the small punch (SP) test using SUS304 is investigated at various deformation rate both experimentally and computationally. The negative rate sensitivity of maximum force and deflection is reported. According to observing fracture surfaces of the specimens by SEM, the failure changes from tensile to shear mode with the increase in deflection rate, and the fracture initiates the outside of the specimens at any deformation rate. However, according to the computational result, the initiation of fracture changes from inside to outside with the increase in deflection rate. To solve the contradiction, it is necessary to get back the boundary conditions, which is precisely same as experiments, in simulation and discuss the damage evolution during the deformation process. In this study, the finite element simulation, in which the constitutive equation and fracture criterion is introduced, is performed for SP tests at various deflection rate. For comparisons, the same deflection rate with experiment is imposed as boundary conditions. From the force-deflection curves obtained by these two methods SUS304 shows negative rate sensitivity in maximum force and deflection as well as positive rate sensitivity in work hardening rate·