Development of global contact searching method based on octree algorithm

In finite element simulations, contact searching is the most time-consuming part in the problems involving contact-impact, therefore it is significant to develop an efficient contact-pairs searching method.In this paper a new global searching method based on octree algorithm is developed and implemented in PANDA-Impact program.In the proposed method, centroid of the master segment and relevant characteristic length are used to represent its true geometry.Two new concepts, tree-bounding-box and slave-bounding-box, are presented.The cost of the new contact searching method is of the order of O(Nlog₈M), where N is the number of the slave nodes, and M is the number of master segments.In implementation, pre-searching and neighbor-searching are introduced to accelerate the efficiency of contact-searching.The results of typical numerical experiments show that the new contact searching method is very efficient.In dealing with problems involving complex and large amount of contact pairs, the new method has an apparent observable advantage over the bucket sorting method.