Wrinkle generation determination index acquisition method, wrinkle generation determination method, wrinkle generation determination device, and wrinkle generation determination program for press formed part

Abstract

A wrinkle generation determination method for a press formed part includes acquiring, for each load ratio in in-plane biaxial directions, a relationship between an in-plane biaxial strain generated in a process of inducing out-of-plane buckling in a measurement part and a load, acquiring an in-plane biaxial strain at a point where a primary differential coefficient of an in-plane uniaxial strain on which a compressive load acts becomes local maximum as a stable behavior limit strain, and acquiring a stable behavior limit line that will be an index for wrinkle generation under a biaxial stress condition by plotting, on two-dimensional coordinates, the stable behavior limit strain acquired for each load ratio in a biaxial stress test in which a load in the in-plane biaxial directions is applied to a cruciform test piece for biaxial test so as to induce out-of-plane buckling in the measurement part.