Metal sheet forming limit determination method and forming limit determination system, and computer program

Abstract

A metal sheet includes a forming test step that forms a test specimen with an arbitrary lattice or a pattern for strain analysis while capturing an image of the surface, analyzing images obtained during the forming to measure the strain, and storing the strain in time series from the start of the forming to the occurrence of fracture to construct a strain database; and a forming limit analysis step includes setting, an evaluation point sequence for acquiring a strain distribution in the vicinity of a portion where fracture has occurred, extracting strain corresponding to the position of the evaluation point sequence in an arbitrary forming step from the strain database, calculating an approximation strain curve corresponding to the position of the point sequence, determining, the difference between the strain based on the approximation strain curve and analyzing the images, and determining a forming limit based on the obtained approximation error.