采用Bodner-Partom本构模型的粘塑性有限元应力分析方法研究

通过用户子程序将Bodner Partom统一弹粘塑性本构模型引入通用有限元程序中 ,该子程序包括初始化数组、单元应力计算、弹性矩阵计算和计算结果输出等 4个部分。对于一个从时间t到t+Δt的载荷 (时间 )步 ,主程序将经过平衡迭代求解出来的总应变增量分成若干个子增量 ,并且对每一个子增量步都调用一次该用户子程序 ,以便更新每一个子增量步的应力和其它与历史相关的变量 ,一旦算出本载荷 (时间 )步的最后应力便输出最终结算结果。算例分析表明 :本文的计算方法可靠 ,计算结果正确 ,能够模拟应变率敏感性、热恢复效应、循环软化和循环硬化。

Visco-Plastic Finite Element Method for Stress Analysis with Bodner-Partom Constitutive Equations

This paper introduced Bodner-Partom unified ela st ic-vicsoplastic constitutive equations into a finite element program by user de fined subroutine. This subroutine has four functions: initializing the arrays, c alculating element stresses, calculating elastic stiffness matrix and outputting the results. During a load incremental step from t to t +Δ t, the ma in program calculates the total strain increments by equilibrium iteration metho d, divides them into several sub-increments, and calls the user defined subrout ine at each sub-step. At each sub-step the subroutine calculates the stresses and other variables dependent on load history and updates them. The above-menti oned calculation does not stop utill the final stresses of this load incremental step are obtained. Finally, using the program developed, some stress-analysis problems are solved , the results show that the method is correct, and the progr am can simulate the characteristics of strain rate sensitivity, thermal recovery , cyclic softening and cyclic hardening.