Udimet 720 Li材料B-P型粘塑性本构建模研究

针对航空发动机用涡轮盘材料Udimet 720 Li,根据高温单轴实验结果,对其在各种载荷条件下的力学行为,开展了采用Bodner-Partom(B-P)统一型弹-粘塑性本构方程进行建模的研究.充分讨论了基于内变量理论的该型本构模型对率相关拉伸、循环硬化及蠕变等力学行为同时进行建模的能力;根据对模型的本构分析,给出了一种分类加整体考虑的模型参数优化策略.通过ABAQUS用户子程序,把该模型结合进了有限元方法,并进行了计算验证.研究表明B-P本构模型可较好地建模高温镍基合金Udimet 720 Li的各种力学行为. 

B-P viscoplastic constitutive modeling of Udimet 720 Li

Udimet 720 Li is a Ni-based superalloy used for aeroengine disc. Based on the uniaxial tensile, cyclic loading and creep experiments results at 650℃, the Bodner-Partom unified viscoplastic constitutive theory was applied to model the mechanical behaviors of the material under three different loading conditions. After detailed analysis of constitutive characteristics of B-P model, a global optimized strategy for model parameters was given in order to simulate tensile, cyclic and creep curves simultaneously. The B-P model was implemented in ABAQUS soft ware through UMAT subroutine using a self-adaptive time stepping strategy. The results shows that B-P model is able to describe such kinds of mechanical behaviors, but it needs to be modified to model fast isotropic softening and ratchetting.