The design. and management of the objects about the numerical manifold method are studied by abstracting the finite cover system of numerical manifold method as independent data classes and the theoretical basis for the researching and expanding of numerical manifold method is also put forward. The Hammer integration of triangular area coordinates is used in the integration of the element. The calculation result shows that the program is accuracy and effective.

A local basis algorithm for searching natural neighbours in Natural Element Method (NEM) is presented for solving the elasticity problems in this paper. Comparison with the global sweep algorithm used in natural element method or Natural Neighbour Method (NNM) for searching natural neighbours, the proposed algorithm is more expedient and convenient in the constructions and computation of natural neighbour interpolations. In the proposed NEM based on local search, the Laplace (non-sibson) interpolations are constructed with respect to the natural neighbour nodes of the given point which have been locally defined. The shape functions from the Laplace approximations have the delta function property and the Laplace interpolants are strictly linear between adjacent nodes, which facilitate imposition of essential boundary conditions and treatment of material discontinuity with ease as it is in the conventional finite element method. The Laplace interpolants derived from the local algorithm and the global algorithm in NEM are identical because of the uniqueness of the Voronoi diagram. Numerical results and convergence studies also show that the present NEM based on local search algorithm possesses the same accuracy and rate of convergence as they are in previous NEM.

本文在平面连续体的数值计算中使用数值流形方法的各阶覆盖位移函数和统一的三节点三角形流形单元，能够得到高精度的数值结果，且具有编程和前后处理简单等优点，克服了有限元法复杂理论的不足。文中还引入了三角形单元Hammer 数值积分，使流形方法的程序编制通用化。

讨论了数值流形方法使用高阶覆盖位移函数时权函数、位移函数的选择和位移边界条件的处理。对该方法得到的高精度位移解，利用滑动最小二乘法在全域上构造位移近似函数，得到了与位移解一样连续的应力解。算例结果表明，理论和方法是正确、有效的。

基于自然邻结点近似位移函数提出了一种用于求解弹性力学平面问题的无网格局部Petrov-Galerkin 方法。这种方法在结构的求解域Ω内任意布置离散的结点，并且利用需求解点的自然邻结点和Voronoi 结构来构造整体求解的近似位移函数。对于构造好的近似位移函数，在局部的Delaunay 三角形子域上采用局部Petrov-Galerkin 方法建立整体求解的平衡控制方程，这样平衡方程的积分可在背景三角形积分网格的形心上解析计算得到，而采用标准Galerkin 方法的自然单元法需要三个数值积分点。该方法能够准确地施加边界条件，得到的系统矩阵是带状稀疏矩阵，对软件用户来说，它还是一种完全的、真正的无网格方法。所得计算结果表明，本文方法的计算精度与有限元法四边形单元相当，但计算和形成系统平衡方程的时间比有限元法四边形单元提高了将近一倍，是一种理想的数值求解方法。