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针对GTN模型不能模拟剪切破坏这一缺陷,基于Nahshon和Hutchinson的修正,在隐式有限元过程中开发了同时适用于拉伸和剪切断裂模式的细观损伤材料本构.首先,推导了适用于修正后损伤本构的全隐式数值积分公式和一致性切线模量,给出了UMAT子程序的计算流程;然后,采用一个单元分别施加拉伸和剪切边界条件,验证了细观损伤材料本构的有效性;最后,分析了薄壁结构在扭转载荷下的弹塑性响应.与试验结果的对比研究表明:修正的细观损伤模型能够较好地预测出延性材料的剪切损伤演化过程.
Aiming at the defect that GTN model can not simulate shear failure, based on Nahshon and Hutchinson’s amendment, the mesoscopic damage material constitutive model which is suitable for tensile and shear fracture modes is developed in the process of implicit finite element method.Firstly, The full implicit numerical integration formula and the consistent tangent modulus which are applied to the modified damage constitutive model are given, and the calculation procedure of the UMAT subroutine is given. Then, the tensile and shear boundary conditions are applied by one element respectively, Finally, the elastic-plastic response of thin-walled structures under torsional loading is analyzed.Comparison with the experimental results shows that the modified mesoscopic damage model can better predict the ductile shear damage of ductile materials Evolutionary process.