作者: Wen Jun Pan, Xian Guo Ye, Lei Chang

摘要: With the generalized displacement parameters of spline knots chosen as basic unknowns, the node displacement functions of spatial mega frames were built up, then element node displacements could be expressed by these parameters. New stiffness equation of spatial mega frame was deduced according to energy variational principle. The nodal displacement and nodal forces were worked out by the displacement parameters of spline knots. Process of block assembling for spline-discretization matrix was introduced briefly. One spatial mega frame was calculated by QR method and different finite element softwares. Comparation among the results and those of references proves that QR method is exactly an economical, effective and reliable method for computation of spatial mega frames. It provides a new approach for simplified calculation to spatial mega structures, so has good theoretical and practical value.

6049

作者: Zhen Nan Cao, Bo Shen

摘要: In this paper, a multi-body system dynamics problem is considered as a complex system modeling and computation problem. A parallel programming model and its execution environment are designed to reduce model complexity and to improve computational speed. In this architecture, the problem is divided into two levels: 1. Find a parallel mathematical algorithm to describe the behavior of this multi-body system. 2. Build a unified programming language that could leverage many different pieces of computational resources, such as symbolic computing, and numerical libraries. To tackle the first level, Space-Time Finite Element Method (FEM) is applied. The Space-Time FEM formats of Newton-Euler formula is given, as well as its constraint formula. This algorithm has avoided the loop operation during the time field solving. To tackle the second level, a network-based functional programming language - Object Computing Network (OCN) is designed. OCN is inspired by Object-Process Methodology (OPM). In OCN, every computation behavior is treated as a function, which is constructed by a three element set: {Var, Rule. Condition}. Three basic patterns - Branching, Synchronizing, Merging are given in OCN to prove the flexibility of OCN. An communication interface is designed in OCN to connect different programming languages together. Two multi-body system dynamics computing models - Semi-discretization method and Space-Time discretization method - are constructed with OCN, and a significant contrast in task parallelization is shown by different OCN models.

374

作者: Xiao Yu Sun, Zhen Qing Wang

摘要: A non-linear finite element model of inclined cables, cables with non-leveled supports, in the large displacement and deformation fields is proposed for computing the dynamic response to wind loads which blow in arbitrary direction. The temperature-dependent elastoplastic behaviors of cables were taken into account in the nonlinear finite element model. This model was used for an extensive looping factor parameter study.A parametric super element model for cable passing through multiple pulleys is presented in this study for the static analysis of structures. The proposed formulation,which accounts for longitudinal inertia forces, allows to spot the circumstances when the simplified approach, adopting longitudinal mode condensation, becomes too crude.

1498

作者: Xiao Yue Zhang, Jun Yan

摘要: The occurrence of underground piping is a pluralistic and complex problem. Due to the great difficulty of the 3D dynamic simulation of piping both by theoretical and numerical analysis, currently there is no satisfactory mathematical model and numerical analysis software for it. In order to simulate the piping development process of sluice or dike foundation, in this paper, the 3D steady-unsteady saturated-unsaturated FEM seepage simulation method is used, and the concepts of destroyed element and variable grid method are introduced. The destroyed elements are removed from the original grid during the iterative calculation process, and the corresponding procedure for the 3D steady-unsteady piping process of sluice foundation is designed. Using appropriate post-processing program, the whole piping development of a sluice foundation can be displayed. A piping test of a sluice foundation model is simulated by the method provided in this paper. For the comparison of the experimental result and the simulation result, they showed very good agreement, which can verify the correctness of the piping simulation and programming methods given in this paper.

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