水工结构接触问题的多体有限元法
Multi-body finite element method for contact problems in hydraulic structure
-
摘要: 针对水工结构中的局部接触问题,提出了一种新的数值分析方法—多体有限元法。基于DDA方法的分析思路,以结构面切割而成的块体作为分析单元,每一块体均可允许自身有独立的位移和变形,通过块体间的接触和几何关系形成一个完整的块体系统。块体内部采用有限元法求解,块体之间通过接触力相互联系,且在接触界面上引入变形协调条件,保证了多个块体互相接触作用时块体位移和应力状态的连续性,从而使得计算更加符合实际情况。该方法接触求解过程中无需指定法向刚度及切向刚度等参数,避免了DDA方法因引入刚性弹簧而出现的嵌入问题,同时提高了块体内部变形的求解精度。推导了多体有限元法求解接触问题的支配方程,并给出了其增量形式的定解条件和判定条件。最后通过3个数值算例验证了本文方法的正确性和有效性。Abstract: Multi-body finite element method (MFEM) is proposed for analysis of local contact problems in hydraulic structure. Based on the block theory of discontinuous deformation analysis (DDA) method, each block can move and deform independently, and blocks contact with each other on their boundary. Each single block is analyzed using the finite element method (FEM) in the corresponding local coordinate system, and all contacting blocks need to satisfy the displacement compatibility requirements between two blocks. In this way, MFEM assures the continuity of the displacement and stress state between blocks. The calculated results of this method are in fairly good agreement with the actual situations. Normal and tangential stiffnesses are not required in algorithm, and thus the overlap problem is successfully avoided. Moreover, the accuracy of the block internal deformation is effectively improved. The theoretical basis and finite element coordinate equations for the proposed method are obtained. Finally, the validity and accuracy of the proposed procedure are demonstrated through three numerical examples.