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

Abstract

This stretch-flange crack prediction method for predicting occurrence of stretch-flange cracking at a flange end part when stretch-flange forming is performed on a plastic plate, wherein the method is provided with: a measured value acquisition step (S1) for acquiring a breaking strain measurement, vertical strain gradient measurement, and a circumferential strain gradient measurement for each of a plurality of plate-shape specimens; a CAE analysis step (S2) for acquiring a largest maximum principal strain element in which the maximum strain is the largest, the vertical strain gradient of the largest maximum principal strain element, and the circumferential strain gradient of the largest maximum principal strain element; a breakage determination threshold value acquisition step (S3) for converting the breaking strain measurement to acquire a breakage determination threshold value; and a prediction step (S4) for predicting the occurrence of a stretch-flange cracking when the maximum principal strain is equal to or greater than the breakage determination threshold value.

Description

technical field [0001] The present invention relates to a stretch flanging crack prediction method, a stretch flanging crack prediction device, and a computer capable of accurately predicting the occurrence of stretch flanging cracks occurring at the end of a flange when stretch flanging forming is performed on a plastic plate. programs and recording media. [0002] This application claims priority based on Japanese Patent Application No. 2014-137185 for which it applied in Japan on July 2, 2014, and uses the content here. Background technique [0003] Conventionally, plastic plates (for example, high-strength steel plates of 270 to 1470 MPa) are press-formed to manufacture automobile parts and other parts. However, depending on the material of the plastic sheet, the shape of the part, or the molding conditions, cracks may occur at the end of the molded part during press molding. [0004] For drawing or forming, it is possible to evaluate the cracks generated in the plane ...

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Problems solved by technology

[0008] However, in Patent Documents 4 and 5, it is not disclosed that the threshold value for judging the occurrence of fracture with high accuracy is not disclosed. In the stretch flanging of plastic sheets, for example, fractures may occur in parts that are not predicted to be fractured. , or the fact that no fracture occurs at the site predicted to be fractured

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