| 摘要 |
PROBLEM TO BE SOLVED: To provide a method by which breaking strain generated in the end part of a flange when forming a stretch flange is specified accurately. SOLUTION: A plate-like test-piece 1 in the end part of which a notch 6 is formed is set to a side bend testing machine and, by making it break by imparting in-plane tension and bending, and strain, a strain gradient and strain concentration in the broken part are measured. Data are collected by using two or more kinds of the plate-like test-pieces 1 which are changed in the strain gradient from the end part of a plate to the inside and the strain concentration along the plate end part, which are generated when applying load are changed and the breaking strain is specified as the function of the strain gradient and the strain concentration, or a map of the strain gradient and the strain concentration. COPYRIGHT: (C)2011,JPO&INPIT
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