A prediction equation "R0/t ≥ (2R/t + (2R/t + 1)εf)/2(1 - (1 + 2R/t)εf)" is derived which predicts that bendability-dominated fracture will not occur when the critical surface strain εcritical is not exceeded by a strain on the metal sheet surface causing the occurrence of ductility-dominated fracture that is obtained from the minimum curvature radius R0 of a press-forming mold and the critical strain εf in a plane strain region in a forming limit diagram. The minimum curvature radius R0 of a mold required to prevent the occurrence of bendability-dominated fracture is estimated, and the mold is designed with a curvature radius that is not less than the curvature radius R0.
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机译：推导了预测方程“ R0 / t≥（2R / t +（2R / t +1）εf）/ 2（1-（1 + 2R / t）εf）”，该方程预测在以下情况下不会发生可弯曲性主导的断裂金属板表面的应变不会超过临界表面应变εcritical，从而导致发生延展性断裂，这是由压制成型模具的最小曲率半径R0和平面应变区域中的临界应变εf获得的。成形极限图。估计防止发生可弯曲性占主导的断裂所需的模具的最小曲率半径R0，并且将模具设计为具有不小于曲率半径R0的曲率半径。
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