边界元法解二维弹性力学问题体积分的处理

二维力学问题中，当有如ａｉ（ｙ）ｘｉ或ｂｉ（ｘ）ｙｉ型的复杂荷载时，给出了如何将体积分近似转换为边界积分的方法．     

一种非线性奇异积分方程的数值解法

讨论用配位法求一种非线性奇异积分方程的数值解。针对不同的可解条件,分别用Lagrange插值和有理插值将原方程离散为代数方程,通过求解此代数方程得到数值解和逼近解。最后将所得结果与已有的解析解的表达式进行比较。     

平面区域边界方程的求解策略

随着新教材中平面区域的引进,平面区域边界方程近几年在各类考试或竞赛中频繁出现.这块内容集新颖性、综合性、探究性于一体,是训练学生思维、提高学生能力、培养学生创新意识的好素材.本文着重介绍有界平面区域的边界方程的一些求解策略,供参考.     

弹性力学平面问题的双调和方程的格林函数解法

讨论了弹性力学双调和方程Δ4U＝0的格林（Green)函数解法。     

有限元求解弹性力学方程的数值实践

考虑二维弹性力学方程,研究有限元法的有效求解,分别基于线性元和二次元基函数,对应形成稀疏程度不同的代数方程组。数值实践充分表明,有限元解有效逼近了原方程的真解,并不断减少各范数度量下的误差,其中二次元格式具有精度更好、收敛更快的对比结果。     

用矩阵近似分解方法求解第二类积分方程

基于区域分解和多项式插值，对积分算子进行离散，得到高精确度的近似离散矩阵．这一方法适应于核函数为光滑、振动较小、只有有限弱奇点的情形．如果采用ｎ个离散点，近似矩阵可以经过Ｏ（ｎ）次计算得到，存储也只要Ｏ（ｎ）．矩阵－向量相乘的计算量为Ｏ（ｎｌｏｇｎ）．所以，此方法特别适合共轭梯度类型算法     

奇异积分方程的插值样条解法

通过对一类奇异积分的插值样条逼近而得出此类积分方程的一种数值解。     

弹性力学反平面剪切问题的半逆解法

半逆解法是求解弹性力学问题的重要解析方法,它通过假设部分或全部应力分量的函数形式,推导出满足相容方程的应力函数,再求出满足边界条件的应力分量,进而利用位移边界条件求出位移分量。弹性力学教学中一般只介绍半逆解法在弹性力学平面问题中的运用,文章通过实例介绍了弹性力学反平面剪切问题及其应力函数法,给出了半逆解法求解弹性力学反平面剪切问题的过程,发展了半逆解法在弹性力学问题中的应用。     

曲面单元上超奇性与近超奇性边界积分数值计算的几何变换法

With the aid of the properties of the hypersingular kernels,a geometric conversion approach was presented in this paper.The conversion leads to a general approach for the accurate and reliable numerical evaluation of the hypersingular surface boundary integrals encountered in a variety of applications with boundary element method.Based on the conversion,the hypersingularity in the boundary integrals could be lowered by one order,resulting in the simplification of the computer code.Moreover,an integral transformation was introduced to damp out the nearly singular behavior of the kernels by the distance function defined in the local polar coordinate system for the nearly hypersingular case.The approach is simple to use,which can be inserted readily to computer code,thus getting rid of the dull routine deduction of formulae before the numerical implementatins,as the expressions of these kernels are in general complicated.The numerical examples were gien in three-dimensional elasticity,verifying the effectiveness of the proposed approach,which makes it possible to observe numerically the behavior of the boundary integral values with hypersingular kernels across the boundary.     

Riemann-Liouville分数阶积分方程的数值解法

通过分部积分公式及r函数的一些性质推得了向左Riemann-Liouville分数阶积分的级数表达形式.数值算例表明,用这种级数表达式做数值逼近是有效的.最后,用这种逼近方式求解一类分数阶积分微分方程.     

Solution of stress intensity factors of multiple cracks in plane elasticity with eigen COD formulation of boundary integral equation

The concept of eigen crack opening displacement (COD) can be defined as the COD of a crack in infinite plate under the tractions acting on the crack surface. By introducing this concept, the eigen COD formulation of boundary integral equation is proposed in this paper, together with the solution procedures for multiple crack problems in plane elasticity. With the proposed approach, the multiple crack problems can be solved with the conventional displacement discontinuity boundary integral equations in an it...     

一类具有积分边界条件的非线性分数阶微分方程的正解

利用Guo/Krasnoselskii不动点定理研究一类具有积分边界条件的非线性分数阶微分方程边值问题正解的存在性。     

再论几类一阶常微分方程的可积判据

提出几类一阶常微分方程 ,通过变量替换法化为齐次微分方程 ,再借助交换变量位置法 ,论证它们的可积判据 ,给出它们通积分的表达式 ,所得结果是相应文献结果的推广 .     

非Nagumo条件的三阶微分方程的三点边值问题

研究满足一个简单条件,但可能不满足Nagumo条件的三阶微分方程三点边值问题的微分不等式的解的存在性及其唯一性．     

CPV边界积分的对称数值求积法

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｔｈｅｂｏｕｎｄａｒｙｉｎｔｅｇｒａｌｅｑｕａｔｉｏｎｓａｒｉｓｅｉｎｍａｎｙｐｒｏｂｌｅｍｓｏｆｐｈｙｓｉｃｓａｎｄｅｎｇｉｎｅｅｒｉｎｇ .Ｏｎｅｏｆｔｈｅｐｒｉ ｍａｒｙｍａｔｈｅｍａｔｉｃａｌａｎｄｎｕｍｅｒｉｃａｌｄｉｆｆｉｃｕｌｔｉｅｓｏｆｂｏｕｎｄａｒｙｉｎｔｅｇｒａｌｅｑｕａｔｉｏｎａｐｐｅａｒｓｔｏｂｅｔｈｅｔｒｅａｔ ｍｅｎｔｏｆｔｈｅｓｉｎｇｕｌａｒｋｅｒｎｅｌｓ.Ｔｈｅｒｅａｒｅｔｈｒｅｅｄｉｆｆｅｒ ｅｎｔｔｙｐｅｓｏｆｓｉｎｇｕｌａｒｉｔｉｅｓ…     

Numerical approach for a system of second kind Volterra integral equations in magneto-electro-elastic dynamic problems

INTRODUCTION In scientific and engineering problems, Volterra integral equations are always encountered and have attracted much attention (Christopher and Baker, 1977; Delves and Mohamed, 1985; Brunner and van der Houwen, 1986; Kress, 1989; Oja and Saveljeva, 2002; Maleknejad and Shahrezaee, 2004; Maleknejad and Aghazadeh, 2005; Zerarka and Soukeur, 2005). Generally, exact solutions are very difficult to find and solutions have been obtained for only some few special cases (Yan and …     

牛顿-莱布尼茨公式在平面曲线积分和空间曲线积分中的应用

将牛顿-莱布尼茨公式应用到平面曲线积分和空间曲线积分中,使这两类积分的计算大为简化.     

Existence of positive solutions for fourth order singular differential equations with Sturm-Liouville boundary conditions

By using the upper and lower solutions method and fixed point theory, we investigate a class of fourth - order singular differential equations with the Sturm - Liouville Boundary conditions. Some sufficient conditions are obtained for the existence of C^2 [ 0, 1 ] positive solutions and C^3 [ 0, 1 ] positive solutions.     

Existence of positive solutions for fourth order singular differential equations with Sturm-Liouville boundary conditions

By using the upper and lower solutions method and fixed point theory, we investigate a class of fourth - order singular differential equations with the Sturm - Liouville Boundary conditions. Some sufficient conditions are obtained for the existence of C2 [ 0, 1 ] positive solutions and C3 [ 0, 1 ] positive solutions.