Method for determining bending fracture in metal plate, program, and storage medium

Abstract

A bending fracture limit stress [sigma]cr is calculated for each bending radius R at plate thickness center / initial plate thickness t0 of a metal plate. A fracture limit stress [sigma]1_pl under plane strain deformation is calculated, as is a fracture limit line L1 in a uniform deformation state in a stress space for which a static strain rate is assumed from work hardening characteristics obtained from uniaxial tensile testing of the material constituting the metal plate. A determination is made of the ratio [gamma] between the bending fracture critical stress [sigma]cr and the plane strain fracture limit stress [sigma]1_pl in a uniform deformation state that corresponds to the R / t0 of a determination subject element in the metal plate. The ratio [gamma] is multiplied by the stress component of the fracture limit line L1, whereby a fracture limit line L2 corresponding to R / t0 is calculated. The maximum principal stress [sigma]OBcr of the determination subject element is calculated from the maximum principal stress [sigma]OR of the determination subject element and the fracture limit line L2 corresponding to R / t0 in a stress mode. A risk ratio [sigma]OR / [sigma]OBcr, which is the risk ratio for tensile bending fracture, is calculated from the sizes of the stress [sigma]OR and the fracture limit stress [sigma]OBcr. Fracture is determined for the determination subject element on the basis of the risk ratio [sigma]OR / [sigma]OBcr.

Description

technical field [0001] The invention relates to a bending fracture prediction method, program and storage medium of a metal plate. More specifically, the present invention relates to bending of a metal plate for judging the risk of bending fracture of the metal plate in a forming process of stamping a body part of an automobile or during collision deformation of a body part of an automobile Fracture judging method, program and storage medium. Background technique [0002] In recent years, due to the requirements of crash safety and light weight, the application of high-strength steel plates to automobile bodies has developed rapidly. High-strength steel plates used in automobile bodies can increase energy absorption during collisions and increase buckling strength without increasing plate thickness. However, since the ductility and bendability of the steel sheet decrease with the increase in strength of the steel sheet, the steel sheet may break during press forming or col...

AI Technical Summary

Problems solved by technology

That is, when the strain in the deformation process obtained from the simulation reaches the limit strain specified by the fracture limit line, it is judged to be fractured or the risk of fracture is high

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