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在采用UH模型的用户材料子程序(UMAT)进行有限元计算过程中时常会出现局部单元破坏的情况,主要包括拉裂和剪坏,这种破坏应力状态的存在不仅会使得计算结果不合理,也会降低有限元计算的稳定性。针对采用UH模型UMAT进行有限元计算时遇到的局部单元破坏问题,根据一定的假设条件,并结合不同坐标系下的应力变换关系,推导得到适用于UH模型的三维问题单元破坏修正公式;采用FORTRAN语言编写出相应的子程序,将其嵌入UH模型UMAT中,以消除采用UH模型进行有限元计算时出现的不合理的破坏应力状态,提高UH模型UMAT有限元计算的稳定性,并通过有限元模拟基坑开挖的例子验证本文所提的单元破坏修正方法的有效性和合理性。
In the process of finite element calculation of user material subroutine (UMAT) using UH model, local unit failure often occurs, including fracture and shear failure. The existence of such failure stress state not only makes the calculation result unreasonable, It also reduces the stability of the finite element calculation. Aiming at the problem of local element failure encountered in the finite element calculation using UMAT UHAT, the formula for the failure correction of three-dimensional problem elements suitable for UH model is deduced according to certain assumptions and stress transformation relations in different coordinate systems. FORTRAN language to compile the corresponding subroutine and embed it into the UH model UMAT to eliminate the unreasonable failure state of the UH model and to improve the stability of the UMAT FEM calculation by using the UH model. Metamorphic excavation example to verify the effectiveness of the proposed unit damage correction method is valid and reasonable.