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蔡永昌, 朱合华. 基于局部搜索算法的自然邻接点方法[J]. 力学学报, 2004, 36(5): 623-628. DOI: 10.6052/0459-1879-2004-5-2003-517
引用本文: 蔡永昌, 朱合华. 基于局部搜索算法的自然邻接点方法[J]. 力学学报, 2004, 36(5): 623-628. DOI: 10.6052/0459-1879-2004-5-2003-517
Natural neighbour method based on the algorithm of local search[J]. Chinese Journal of Theoretical and Applied Mechanics, 2004, 36(5): 623-628. DOI: 10.6052/0459-1879-2004-5-2003-517
Citation: Natural neighbour method based on the algorithm of local search[J]. Chinese Journal of Theoretical and Applied Mechanics, 2004, 36(5): 623-628. DOI: 10.6052/0459-1879-2004-5-2003-517

基于局部搜索算法的自然邻接点方法

Natural neighbour method based on the algorithm of local search

  • 摘要: 自然邻接点方法(NNM)采用自然邻接点形函数进行插值,其插值形函数具有严格定义,且与有限元形函数一样形式简洁、性能优良,因而避免了EFG法里难以准确施加位移边界条件和材料不连续条件等诸多主要困难. 但是从形式上看自然邻接点方法仍然属于有网格的方法,其研究和应用受到了较大的限制. 为了克服这个缺点,对于任意给定的数值积分点,提出了一种基于局部搜索自然邻接点的寻找算法对NNM进行改进. 改进后的NNM与无单元伽辽金法(EFG)的插值和求解过程类似,兼具有EFG的真正无网格特性及NNM的便于处理边界和材料不连续条件等优点. 所得计算结果表明,改进后的NNM的计算精度和计算时间与NNM相当,是一种比较理想的数值求解方法.

     

    Abstract: The natural neighbour method (or natural element method),which is based on the natural neighbour interpolation, is a method betweenmeshless and mesh. The discrete model of the domain \it\Omega in naturalneighbourmethod(NNM) consists of a set of distinct nodes, and a polygonal descriptionof the boundary. The whole displacement interpolations are constructed withrespect to the nature neighbour nodes and Voronoi tessellation of the givedpoint. The natural neighbours of the gived point have been definitelydefined. The properties of the natural neigbour interpolation are excellent.For instance, the conditions of linear consistency, partition of unitity,positivity, and delta properties are all satisfied in natural neigbourinterpolation. The disadvantages in element-free Galerkin method(EFG), suchas, the difficulties of imposition of essential boundary and treatment ofmaterial discontinuity, the complex algorithm of matrix inverse in thecomputation of Moving Least Squares(MLS) shape function, the uncertainchoice of the weight functions can be avoided in NNM. But, NNM is usuallyregarded as a mesh-based method beacause the delaunay triangulations fromthe whole solution domain are still needed for neighbour-search. In stead ofsearching for the natural neighbors from delauny triangulation of the wholedomain, an algorithm quantifies the natural neighbour nodes of the givenpoint based on the locally delaunay triangles is proposed for theimprovement of the NNM. Similar to the EFG method, the procedure ofinterpolation and construction in the improved NNM is meshless. As a result,the improved NNM can possesses both the excellent properties of the naturalneigbour interpolation and advantages of the EFG method. Numerical resultsshow that the excellent agreement with exact solution is obtained in thismethod. Convergence studies in the numerical examples also show that thepresent method possesses an excellent rate of convergence for both thedisplacement and strain energy.

     

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