摘要
The influence of initial groove angle on strain rate inside and outside groove of Ti6Al4V alloy was investigated.Based on the evolution of strain rate inside and outside groove,the effect of strain rate difference on the evolution of normal stress and effective stress inside and outside groove was also analyzed.The results show that when linear loading path changes from uniaxial tension to equi-biaxial tension,the initial groove angle plays a weaker role in the evolution of strain rate in the M-K model.Due to the constraint of force equilibrium between inside and outside groove,the strain rate difference makes the normal stress inside groove firstly decrease and then increase during calculation,which makes the prediction algorithm of forming limit convergent at elevated temperature.The decrease of normal stress inside groove is mainly caused by high temperature softening effect and the rotation of groove,while the increase of normal stress inside groove is mainly due to strain rate hardening effect.
研究初始凹槽角对Ti6Al4V合金凹槽内、外应变速率的影响。基于凹槽内、外应变速率的变化,分析应变速率差对凹槽内、外正应力和等效应力演变的影响。研究结果表明,在M-K模型中,当线性加载路径由单向拉伸变化到等双拉伸时,初始槽角对应变速率变化的影响减弱。由于凹槽内、外力平衡的约束,在计算过程中应变速率差使凹槽内的正应力先降低后升高,这使得合金高温下成形极限的预测算法收敛。凹槽内正应力的降低主要由高温软化效应和凹槽旋转引起,而凹槽内正应力的升高主要由应变速率硬化效应引起。
基金
Project(51775023)supported by the National Natural Science Foundation of China
Project(YWF-18-BJ-J-75)supported by the Fundamental Research Funds for the Central Universities,China
