METHOD FOR PREDICTING PRESS FORMATION CRACKS AND METHOD FOR MANUFACTURING PRESSED PRODUCT

摘要

A first crack prediction is executed, whereby the limit surface strain at which cracks occur in the surface of a metal plate which is to be press-formed is calculated in advance, and a simulation is performed using a finite element method, wherein the metal plate is press-formed into a desired product shape, and when the surface strain of any of the elements is equal to or greater than the limit surface strain of the metal plate, it is predicted that cracks will occur. A second crack prediction is executed, whereby the forming limit diagram of the metal plate which is to be processed is determined in advance, and a simulation is performed using a finite element method, wherein the metal plate is press-formed into a desired product shape, and when the plot of the maximum main strain and the minimum main strain at the plate thickness center of any of the elements is equal to or greater than the forming limit curve of the forming limit diagram, it is predicted that cracks will occur. Then, the occurrence of cracks is predicted on the basis of whichever of the two predictions is stricter with respect to cracking, thereby improving the precision with which the occurrence of cracks during press formation can be predicted.