Stretch flange crack prediction method, stretch flange crack prediction apparatus, computer program, and recording medium

摘要

A stretch flange crack prediction method of predicting initiation of stretch flange cracks that occurs in a flange end section during stretch flange forming of a deformable sheet, includes: a measurement value acquisition process of acquiring, for each of a plurality of sheet-shaped test pieces, a fracture strain measurement value, a normal strain gradient measurement value, and a circumferential strain gradient measurement value; a CAE analysis process of acquiring a maximum major strain maximum element having a highest maximum major strain, a normal strain gradient of the maximum major strain maximum element, and a circumferential strain gradient of the maximum major strain maximum element; a fracture determination threshold acquisition process of acquiring a fracture determination threshold by converting the fracture strain measurement value; and a prediction process of predicting that stretch flange cracks will be initiated, when the maximum major strain is equal to or higher than the fracture determination threshold.