METAL SHEET BENDING FRACTURE DETERMINATION METHOD AND RECORDING MEDIUM

摘要

A bending fracture limit stress is calculated for each of (bend radius at sheet thickness center of a metal sheet)/(initial sheet thickness of the metal sheet); a fracture limit curve and a fracture limit stress are calculated from work hardening characteristics; a fracture limit curve corresponding to (the metal sheet bend radius at sheet thickness center)/(the initial sheet thickness of the metal sheet) is calculated; a corresponding fracture limit stress is calculated from stress of the element subject to determination and the fracture limit curve; a risk ratio that is a ratio between the stress of the element subject to determination and the fracture limit stress is computed; and performing fracture determination for the element subject to determination based on the risk ratio.

主权项

1. A metal sheet bending fracture determination method comprising:
calculating a bending fracture limit stress for each of (bend radius at sheet thickness center of a metal sheet)/(initial sheet thickness of the metal sheet); calculating a fracture limit curve for a uniform deformation state in space of stresses under the assumption of static strain rate and calculating a fracture limit stress under plane strain deformation, from work hardening characteristics obtained by uniaxial tensile testing of a material configuring the metal sheet; determining a ratio between the bending fracture limit stress corresponding to (the metal sheet bend radius at sheet thickness center)/(the initial sheet thickness of the metal sheet) of an element subject to determination in the metal sheet and the fracture limit stress under plane strain deformation, and calculating a fracture limit curve corresponding to (the metal sheet bend radius at sheet thickness center)/(the initial sheet thickness of the metal sheet) by multiplying a stress component of the fracture limit curve in the uniform deformation state by the ratio between the bending fracture limit stress corresponding to (the metal sheet bend radius at sheet thickness center)/(the initial sheet thickness of the metal sheet) of the element subject to determination in the metal sheet and the fracture limit stress under plane strain deformation; calculating a corresponding fracture limit stress from stress of the element subject to determination and the fracture limit curve corresponding to (the metal sheet bend radius at sheet thickness center)/(the initial sheet thickness of the metal sheet); computing a risk ratio that is a ratio between the stress of the element subject to determination and the fracture limit stress calculated from the stress of the element subject to determination and the fracture limit curve corresponding to (the metal sheet bend radius at sheet thickness center)/(the initial sheet thickness of the metal sheet); and performing fracture determination for the element subject to determination based on the risk ratio.