考虑接触应力非线性分布的接触力元模式及其验证分析

在作者提出的非连续变形计算力学模型中，采用接触力元模型描述多体接触界面上的接触特性．由于这种模型中假定接触应力沿接触界面为线性分布，从而得到的接触界面应力分布往往出现跳跃等非光滑性特征，该文对此进行了改进，采用具有高阶光滑性的非线性函数建立了能够考虑界面上接触应力非线性分布的接触力元模式，以期合理地揭示多体系统中界面的接触特性．对某一典型算例进行了数值计算，通过与大型通用非线性有限元结构分析软件ABASQUS的计算结果对比，验证了所建议计算模型的合理性与有效性．两种方法计算得到的界面接触对上的接触力基本相同；而由于采用的应力分布模式的假定不同，接触应力有所差别，由于在该文计算模型中接触对上的接触应力是按照未知量直接求得的，因此按照所建议的非线性接触力元模式所得到的接触应力更为合理．

NUMERICAL IMPLEMENTATION AND VERIFICATION OF THE HIGH-ORDER CONTACT-INTERACTION FORCE ELEMENT MODEL CONSIDERING NONLINEAR DISTRIBUTION OF CONTACT STRESSES

In the discontinuous deformation computational mechanics model of multiple bodies developed by the authors,the contact-interaction force element model is proposed to simulate complex contact behavior of interfaces among multiple bodies. However,the non-smooth feature will be manifested and jump of contact stresses frequently occurs since the contact stresses along the contact surface are assumed to vary linearly. In order to properly display the contact behavior of interfaces during loading,an improved contact-interaction force element is given by virtue of a nonlinear function of relative distance with high-order differential continuity. In the modified model,the nonlinear distribution of contact stresses along the contact surface is taken into consideration. For a given benchmark problem,numerical analysis is conducted and verification of rationality and effectiveness of the proposed method is made by comparing the computed results with the solution given by ABAQUS which is an universal finite element software for structural analysis. It is shown that the contact nodal forces at the contact pairs predicted by both methods are in good agreement. However,the difference of contact stresses between two solutions occurs due to the different patterns with respect to the distribution of contact stresses. In fact,in the proposed method,the contact stresses are directly solved as independent unknown variables While the contact stresses is induced from the contact forces at the contact pairs in the analysis based on ABAQUS. The proposed method will offer a more rational solution for the contact stresses than the conventional solutions.