混合硬化弹塑性本构关系及其在环件冷辗扩模拟中的应用

ELASTIC-PLASTIC CONSTITUTIVE RELATION WITH HYBRID HARDENING AND APPLICATION IN COLD RING ROLLING SIMULATION

采用数值模拟方法和混合硬化弹塑性本构关系,提出了基于弹性张量的应力补偿更新算法,引入等向强化系数,给出了有限元计算步骤,基于ABAQUS/Explicit平台开发了子程序VUMAT,并在单个单元模型中验证了其可靠性。将其应用于环件冷辗扩过程模拟中,着重研究了等向强化系数对环件冷辗扩成形的影响规律。结果表明,随着等向强化系数的增大,辗扩力、辗扩力矩增大,鱼尾形状系数减小,环件外圈金属受各向异性硬化影响较大,进而从理论上进行了解释。研究结论指出该研究对环件冷辗扩成形工艺具有指导意义。

Numerical simulation method and elasticplastic constitutive relation with hybrid hardening are adopted, the stress compensation updating algorithm based on elastic tensor is brought forward, isotropic hardening coefficient is introduced, the steps for computation of the elastic-plastic constitutive relation in FEM are given, and the subroutine VUAMT is developed on the plat of ABAQUS/Explicit, whose reliability is verified by a single element model. Apply the subroutine in cold ring rolling simulation and pay emphasis on the regularity of the effects that coefficient does on the isotropic hardening process of cold ring rolling. The results show that draught pressure and roll torque increase, fishtail coefficient decreases with the increase of isotropic hardening coefficient; anisotropic hardening does more effects on the metal near the outer of the ring. Theoretic analysis on the regularity above is given further. The conclusion can do instruction to the process of cold ring rolling in factory.