循环硬化材料本构模型的隐式应力积分和有限元实现

针对新发展的、能够描述循环硬化行为应变幅值依赖性的粘塑性本构模型，讨论了它的数值实现方法。首先，为了能够对材料的循环棘轮行为（Ratcheting）和循环应力松弛现象进行描述，对已有的本构模型进行了改进；然后，在改进模型的基础上，建立了一个新的、全隐式应力积分算法，进而推导了相应的一致切线刚度（Consistent Tangent Modulus）矩阵的表达式；最后，通过ABAQUS用户材料子程序UMAT将上述本构模型进行了有限元实现，并通过一些算例对一些构件的循环变形行为进行了有限元数值模拟，讨论了该类本构模型有限元实现的必要性和合理性。

Implicit stress integration and finite element implementation of constitutive model for cyclic hardening materials

A new visco-plastic constitutive model with strainrange-dependent cyclic hardening was formulated and then implemented into a finite element method.The existing constitutive model was first extended to simulate the ratcheting and cyclic stress relaxation by introducing a combined kinematic hardening model.And then,a new implicit stress integration algorithm was proposed;simultaneously,a new expression of consistent tangent modulus was also derived for the proposed constitutive model.Finally,the proposed model was implemented into a finite element code,ABAQUS,in terms of user material subroutine UMAT.Some numerical examples are given to verify the advantage of the implementation and the capability of the model in simulating the ratcheting,cyclic stress relaxation,and strain cyclic behavior of the materials and structures.