基于多晶体塑性与唯象学本构模型的纯铝与单晶铝的有限变形分析与对比

Analysis and comparison of finite deformation of pure anluminium and single crystal aluminium based on polycrystal plasticity and phenomenological constitutive models

摘要:

多晶体塑性模型能够反映材料的微观结构和各种力学响应,但是模型复杂,计算量大,而唯象学弹塑性本构模型相对简单,但是基于变形率张量弹塑性加法分解的唯象学弹塑性本构模型在大变形时会产生误差。本文分别采用以上两种本构模型对纯铝与单晶铝的有限变形单向拉伸过程进行了计算分析,比较了两种模型在不同变形量下计算结果的差别。研究了变形量对唯象学弹塑性本构模型计算误差的影响规律,结果表明,纯铝唯象学弹塑性本构模型在真应变超过25.5%时,应力应变曲线开始出现误差,且随应变的增加而增大。多晶体塑性模型能够从变形、织构和残余应力等方面反映纯铝和单晶铝大变形产生的各向异性。

Abstract:

Polycrystal plasticity model can reflect the material’s microstructure and various mechanical response, but it is too complecate for great computation. The phenomenological elasto-plastic constitutive model is relatively simple, as yet based on the additive decomposition of deformation rate tensor of phenomenological elasto-plastic constitutive model under the condition of large deformation will bring error. In this paper, the uniaxial tensile test process of pure aluminium and single crystal aluminium have carried on the calculation based on the polycrystal plasticity finite deformation elasto-plastic finite element method(CPFEM) and phenomenological elasto-plastic constitutive model, and compared the results of two models. It is researched that effect of calculation error about the deformation amount to the phenomenological elasto-plastic constitutive model. The results show that the stress-strain curve of pure aluminium calculated by phenomenological elasto-plastic constitutive model began to cause error when true strain exceeds 25.5%, and increases with increasing of strain. Polycrystal plasticity model reflect the anisotropy of deformation, texture and residual stress during large drformation of pure aluminium and single crystal aluminium.