查询词典 boundary element method

Incurrent research, aiming at the rupture problem engendered in the shooting process of acertain 5.56mm automatic rifle, the strain and stress distributions on the cartridge caseunder the action of axial pull have been analyzed. Based on the theories of elastic-plasticmechanics and contact mechanics, a mathematic and physical model of the cartridge-caseand chamber system has been set up; and based on the platform of the general softwarepackage APDL of ANSYS for finite element analysis, a parameterized model of thecartridge-case and chamber system has also been established. The method for nonlinearFEA has been adopted to analyze the stress distribution on the entire cartridge-case andchamber system, and the method of contact element has been employed to investigate thecontact stress between the cartridge case and chamber, and then the influences of frictioncoefficient and locking space on the static and dynamic stress and strain response of thecartridge case and chamber to the action of power gas have also been discussed. On thebasis of a lot of numerical tests, a kind of element Plane13, which is concentrated incoupled computation of heat and construction, has been used finally to simulate thetransient response of the cartridge-case and chamber system to the power gas. Throughloading the temporary thermal characteristics of explosive gas in the procedure of emulate, the corresponding transient thermal stress distributed on the entire system under thecombined load of transient thermal stress and transient pressure has been obtained. Owingto these comprehensive considerations, the numerical results obtained in this paperrepresent the actual situations comparatively exactly.

本文针对某5.56mm自动步枪在工作中出现断壳的问题，分析了弹壳在轴向拉力作用下的应力应变；基于弹塑性力学及接触理论，建立了弹壳弹膛系统的数学、物理学模型，在通用有限元ANSYS软件的参数化建模工具APDL平台上，建立了弹壳弹膛系统的参数化模型；采用非线性有限元法计算了弹壳弹膛系统的整体应力，引入接触单元法分析弹壳和弹膛的接触压力，探讨了在不同的摩擦系数和不同的闭锁间隙对弹壳弹膛静、动态响应的影响；本文进行了大量的尝试，最后确定采用热、结构耦合单元Plane13，在计算中加载了火药气体的温度历程，成功的获得了弹壳弹膛系统在瞬态的热载荷和瞬态的压力载荷同时作用下弹壳弹膛系统的热应力数值解，考虑因素全面，比较真实的反映了弹壳弹膛系统在火药气体压力和热载荷下作用的情况。

Compared with the research of the geometric nonlinear finite element method home and aboard in the components such as bar, plate, beam and shell element, the present problems is analyzed and the future research direction is described for the theoretical research and program design of geometric nonlinear finite element method.

综合比较了几何非线性有限元法在杆、梁、板、壳等方面的国内外研究成果，指出目前仍存在的问题，提出今后的发展方向，为几何非线性有限元的理论研究与程序设计提供参考。

For some shortcomings of unknown quantity numbers in finite element method, QR-method establishes a transformed relationship between a unit node displacement vector and the entire framework of spline node displacement vector,making the structure of the total stiffness matrix, damping matrix, mass matrix directly superimposed in no need of finite element method in the first expansion after the superposition process. So the method greatly simplifies the calculation process and improves computing speed.

针对有限单元法中未知量数目很多的缺点，QR法建立起单元结点位移向量与整个框架样条结点位移向量的转化关系，使得结构总刚度矩阵、阻尼矩阵、质量矩阵可以直接叠加，不需要有限单元法中先扩张后叠加的手续，大大简化了计算过程，提高计算速度。

And their improved methods were also researched, for example the force density method with the triangle element transformed the three links, surface stress density method, surface stress density method of sub-structure and nonlinear finite element method of little youngs modulus.

并且对它们的改进方法，比如三角形单元转化成三杆单元的力密度法、面力密度法、考虑子结构的面力密度法和小杨氏模量的非线性有限元法进行了深入的探讨。

Three moment method,the transition matrix method and finite element method in shipping shaft system alignment are used ,the application of finite element method in shipping shaft system alignment is proved to be more reasonable through an example .

并以某实船为例，利用三弯距法、迁移矩阵法和有限元法对船舶轴系进行校中计算，说明有限元法更先进合理。

In this paper, arrangement scheme of a novel multi-star phase shifted pole changing coil was given and the methods to determine coil split ratio were analyzed. According to electromagnetic theory, 2D electromagnetic mathematical model in which stator windings were spitted coil was developed, and magnetic field distribution of the novel motor at starting was solved by finite element method, starting performance of motor was calculated. Based on energy method, rotor slot leakage reactance under different poles and different loads were calculated, and the variation of rotor slot leakage reactance with loads was gotten. Based on time-step finite element method, distribution of branch current in stator windings and operating performance were calculated and analyzed when branch was unbalance, the method to calculate circulating loss in stator windings of novel multi-star phase shifted pole changing motor was given, and the effects of the loads variation and degree of unequilibrium on circulating loss in stator windings were calculated and analyzed.

论文系统的给出了采用分裂线圈法新型多星形移相变极绕组的排列方案，进一步分析线圈分裂比的确定方法；根据电磁场理论，建立了定子为分裂线圈绕组的电机二维电磁场数学模型，并采用场路耦合法求解了新型多星形移相变极电机起动时的磁场分布，计算了电机起动性能和基于能量法计算了不同极数下起动时转子槽漏抗和不同负载时转子槽漏抗，得出转子槽漏抗随负载变化的规律；采用时步有限元法计算分析了定子绕组支路不平衡时支路电流的分布情况及运行性能，给出了新型多星形移相变极电机定子绕组环流损耗的计算方法，分析比较了负载的变化和支路不平衡度大小对定子绕组环流损耗的影响。

However,authors still do not find the relevant references on convergence and symmetric problems of the semi-analytical solution.Based on the semi-analytical solution for Hamilton canonical equation theory,the formulations of the clamp and simply supported and symmetric boundary conditions on the Hamiltonian element are derived by the variational principle.Several numerical examples show that with increase of meshes,the convergence rate of the semi-analytical solution is faster than the convergent rate of traditional finite element method based on displacement.

①在厚度上没有任何位移和应力模式的假设，由于传递矩阵方法的引入，从理论上讲，不受板壳厚度或层合板壳层数的限制；②采用弹性力学的Hamilton正则方程半解析法，可以克服边界的局部化效应[8]；③由于在平面内或圆柱壳的曲面内采用了有限元法，所以一般的板壳问题不受结构侧面边界条件的限制，在复杂工程板壳问题上具有广泛的应用领域。

Firstly, according to electromagnetic field theory, the 2-dimensional (2-D) mathematical model of a three phase squirrel-cage Y802-2 induction motor is developed. Then general equations can be deduced from finite element discrete and functional analysis. The motor's 2D solving region of electromagnetic field is given based on the boundary conditions and assumption conditions of the squirrel-cage induction motor. Through finite element mothod and inner–outer convergence method, magnetic field distributions and magnetic forces of bars can be calculated in following rotor conditions: health rotor, one single broken bar, two adjacent broken bars, two broken bars with one good interval, two broken bars with two good interval and four adjacent broken bars.

本文首先根据电磁场理论建立Y802-2型三相笼型感应电动机二维电磁场的数学模型，并对其进行了有限元离散以及泛函分析，推导出总体方程；在基本假设和边界条件基础上，给出笼型感应电动机二维电磁场的求解区域，然后应用有限元并结合内外双收敛方法，对样机稳态运行进行数值计算，得出电机在转子完好、一根导条断裂、连续两根导条断裂、间隔一根两根导条断裂、间隔两根两根导条断裂及连续四根导条断裂六种情况下的磁场分布和导条所受电磁力的变化情况。

Different kinds of integrations have to be evaluated in boundary element methods. The nearly singular integral is the most difficult one of them. A self-adaptive Gauss integral method is proposed to divide the element into finer meshes under the specified conditions.

边界元法通常需要采用数值方法解决单元内的各种积分问题，而准奇异积分是各种积分中数值处理最为困难的部分。

Firstly, the three-dimension boundary question and its corresponding variation question concerning the point-source electrical field on a 3-D structure are presented. Secondly, the finite element method is used to solve the variational equation. The study area is divided into many tetrahedral elements. Then, we interpolate with a tri-linear function in each element. So, the variational equation is converted into a linear equation system. Finally, taking into account saving of time, we make use of symmetric successive overrelaxation preconditioned conjugate gradient algorithm to solve large linear system, and obtain the potential value of each node, resulting in the calculation of the apparent resistivity values on the ground surface.

首先给出了三维构造中点源电场的边值问题以及相应的变分问题；然后利用有限单元法求解变分问题，采用四面体单元对研究区域进行剖分，在单元中进行三线性函数插值，将变分方程化为线性代数方程组；最后，考虑到节约计算时间，利用对称超松弛预条件共轭梯度迭代算法求解大型线性方程组，得到了各节点的电位值，进而计算出地表的视电阻率。

The statistical analysis of this large set of mutations has led us to propose a diagnostic strategy that should help with the molecular work-up of optic neuropathies.

这一大系列基因突变的统计学分析引导我们提出一个诊断策略，可以帮助我们对视神经病变进行分子学的诊断检查。

The results show that the pipe grouting changes the mechanical parameters of surrounding rocks to achieve the security of engineering objectives by reinforcing surrounding rocks and bolcking the water.

研究表明：小导管注浆一方面改变了围岩的力学参数，另一方面利用浆液的固结特性可以实现堵水和加固围岩的工程目标，使隧道在开挖过程中的安全得到保障。