材料の加工硬化特性を考慮した変形抵抗曲線取得方法

―第2報　実験データへの適用と提案手法の改良―

抄録

We performed an upsettability test on two steels and converted the obtained results into flow curves by two methods. One is a conventional method using Osakada’s calibration curves, and the other is a Swift-type proposed method based on new formulated calibration curves and an optimization method. The obtained flow curves were applied to the finite element method (FEM) analysis of compression test. The load prediction error of the Swift-type proposed method was reduced by approximately 4 % compared with that of the conventional method. However, the Swift-type proposed method is not very accurate in a very small or large strain region. Then, the converted curves obtained by the Swift-type proposed method were regressed with other four work hardening equations. As a result, we found that the modified Voce equation has the highest regression accuracy. The calibration curves were generated by assuming various material constants of the modified Voce equation, and the modified Voce-type flow curve determination method was proposed. When the flow curves obtained by the proposed modified Voce-type method were applied to the FEM analysis, the load prediction error was further improved by 2 % compared with that in the case of using the flow curves obtained by the Swift-type proposed method.