Study Of Impact Detection On Global Simulation Of Flexible Multi-Body Dynamics

In this paper, impact detection method on flexible multi-body dynamics and simulation of flexible multi-body impact dynamics were investigated. The Natural Science Foundation of China (Grant No.'s 10772113) funded the research. According to the unique needs of flexible multi-body impact dynamics, the existing some real-time collision detection algorithm was improved, one impact detection method adapted to the flexible multi-body impact dynamics was proposed. Based on additional contact constraint method, automatic adjustment of contact constraint equations according to the result of impact detection was realized. The whole process simulation of flexible multi-body impact dynamics was completed. The main contents are described as follows:In chapter 1, the engineering application background and significance of the research are introduced. The research development of flexible multi-body impact dynamics is summarized. Because of flexible body deformation in the impact process, system topological model is changed. Any impact dynamics solution method combined with impact detection can be used to realize impact dynamics simulation. Finally, research task in this paper is proposed.In chapter 2, based on variable topological thought, the flexible multi-body system global simulation is divided into non-impact stage and impact stage. According to this characteristic, impact detection can also be divided into macro contact detection and micro contact detection. In the macro contact detection, the bounding box method is used. In micro contact detection, based on the contact point tracing thought, the contact point dynamic tracking detection method is proposed. In this chapter, the macro contact detection methods and the micro contact detection methods are expounded. Through numerical examples, the impact detection methods in planar problem and space problem are validated. Finally, from the point of calculation efficiency, the combination mode of the macro contact detection and micro contact detection and traditional single method detection mode are contrasted. The high efficiency of contact point dynamic tracking detection methods is reflected.In chapter 3, impact detection and additional contact constraint method are combined to realize the simulation of planar flexible multi-body impact dynamics. In this chapter, the flexible multi-body dynamics global simulation process is indicated. The dynamic equations in non-impact stage and in impact stage are discussed. Some problems when system topological model switches between different stages are pointed out. Finally, through to the simulation with two planar flexible rods lateral impact problem, from the point of accuracy and efficiency, the additional contact constraint method and LS-DYNA penalty function method are contrasted. The advantages of additional contact constraint method combined with impact detection are reflected.In chapter 4, additional contact constraint method combined with impact detection is extended to triaxial simulation. According to the particularity of triaxial problem, how to establish the contact constraint equations is expounded. Through to the simulation with two triaxial flexible rods lateral impact problem, additional contact constraint method combined with impact detection in solving triaxial problem is proved. The flexible multi-body impact without friction simulation is realized.In chapter 5, the contribution and innovation of this paper are summarized and the prospect of the research is proposed.