| Contact-impact of large-scale complex structural system, such as car crash, is involved with geometric nonlinearity caused by large deformation, material nonlinearity due to elastoplastic constitutive relation, and boundary nonlinearity related to multiple contact surfaces;furthermore it is transient response of a system with large number of DOE For the numerical simulation of such problem, in general, it is required to carry out the response computation of several hundred thousands time steps for a system with several hundred thousands DOF, which raises very high demand for the memory of computer and the computing speed. It was very difficult to obtain the satisfactory results required by the engineering practice without supercomputers. In order to improve such situation, it is dealt with the scalable parallel algorithm for the simulation of such problem on a PC cluster in this dissertation;an improved automatic domain-decomposition algorithm is presented as well. The presented algorithms are applied to the simulation of practical car crash problem, and some satisfactory results have been obtained.The dissertation consists of several parts as follows:At first, it is required to ensure the computational model containing many complex factors fully compatible, in order to carry out the numerical simulation of the impact response of such large-scale complex structural efficiently. Therefore it is started with the derivation of variational equation, full formulations including contact boundary conditions, internal forces of shell element are given, and the algorithms for contact-surfaces searching, contact-force computation, and even time integration for the response computation are listed as well. The computational model formulated is fully compatible, and numerical examples have shown rather high efficiency.Based on domain decomposition method, parallel algorithms for internal force computation, contact searching and contact force determination are developed, in which the domain decomposition approach on element level is adopted for both internal and contact force computation, and in this way the incompatibility of two parts of parallel computation encountered in literature has been avoided. Thenumerical examples have shown that the parallel algorithm presented for contact-impact simulation on a PC cluster exhibits good parallel efficiency and scalability. A new Modified Greedy Algorithm is presented in this paper which can obtain better length to width ratio through considering the information of nodes coordinate. The numerical examples have shown that the algorithm presented gives satisfactory results for several different meshesFinally, the large-scale parallel computation of car crash simulation is carried out on a PC cluster using the presented numerical model and algorithms. Dual dynamic domain decomposition technique is integrated into parallel algorithm, and the domain decomposition both for internal force computation and contact force computation is accomplished on element level, in order to keep the consistency of computational model. The simulation results of practical car case- and car-crash, in comparison with the corresponding experimental results, show that the numerical simulation is reasonable, the variation tendence of response curves and some key values of the numerical and experimental results at some key points have shown good agreement. In comparison with the computation on single PC, the parallel computing on PC cluster can reduce computing time significantly, and has good scalability. On a PC cluster with 8 nodes, the speedup can approximately reach 5.5, and for the whole car crash simulation of 150000 DOFs and 160000 time steps takes the computing time of 7.26 hours. In this way, the parallel computing on PC cluster consisted of 8 nodes can be applied to the numerical simulation of practical car crashworthiness.
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