(1. 中南大学 材料科学与工程学院，长沙 410083；
2. 中南大学 有色金属材料科学与工程教育部重点实验室，长沙 410012)
摘 要: 本文提出了一种结合有限元模拟预测金属板材成形极限曲线(FLC)的失稳准则-最大应变速率失稳准则。该准则考察试样所有单元体的整个变形历史，通过厚向应变及厚向应变速率随时间的变化来判定颈缩时刻和颈缩位置，可以应用于变形过程中存在应变路径变化的情况。对比AA3003板材预测与实验结果发现，本方法所预测的FLC整体上与实测结果符合较好，优于传统M-K理论的计算结果。
关键字: 失稳准则；颈缩；成形极限曲线；有限元模拟
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410012, China）
Abstract:In this work, an instability criterion (maximum strain-rate instability criterion) was proposed to predict forming limit curve (FLC) of sheet metal based on finite element simulation. The criterion analyzed the entire deformation history of all elements in the specimen. The necking time and necking position were identified by tracking the temporal change of thickness strain and thickness strain-rate. The criterion could be applied to deformation processes with possible strain path changes. Application to the AA3003 aluminum sheet shows that the FLC predicted by the present method is in overall good agreement with the experimental results, and it is better than that predicted by the traditional M-K theory.
Key words: instability criterion; necking; forming limit curve; finite element simulation
