共查询到16条相似文献,搜索用时 156 毫秒
1.
2.
3.
4.
在辛几何空间中将临界载荷和屈曲模态归结为辛本征值和本征解问题,从而形成一种辛方法.研究和讨论了轴对称屈曲和非轴对称屈曲问题,它们分别属于零本征值问题和非零本征值问题.以弹性圆板屈曲问题作为研究对象,借助于系统的能量构造出哈密顿体系,得到了该体系下的所有的本征解.数值结果给出了圆板和圆环板问题的临界载荷和屈曲模态.数值结果表明:对应低阶屈曲模态的临界载荷相对较小且屈曲模态在周向的波纹数也较少,说明在屈曲过程中低阶屈曲模态容易出现,特别是轴对称屈曲更容易发生;对应较大分支数的临界载荷,其值相对较大且屈曲模态在径向的波纹更加复杂;同时物理常数和几何参数也会直接影响临界载荷的大小. 相似文献
5.
对在热环境中功能梯度材料(FGM)输流管道流固耦合热横向振动问题,基于哈密顿原理和Euler-Bernoulli梁理论,建立了端部不可移简支FGM输流管道的力学模型和运动微分方程。引入量纲为一的量,把运动微分方程离散为以量纲归一化广义坐标表达的常微分方程组。应用哈密顿对偶体系理论,得到了哈密顿正则方程,通过分离变量法得到了哈密顿体系下系统的热本征值和本征解的表达式。算例表明,端部不可移简支FGM输流管道的量纲为一的复频率虚部随着梯度指标的增大而增大,随着量纲为一的温度轴力的增大而减小。 相似文献
6.
7.
8.
基于二维弹性理论, 利用Hellinger-Reissner变分原理, 通过引入对偶变量, 推导
了双参数地基上正交各向异性梁平面应力问题的辛对偶方程组; 采用分离变量法和本征展
开方法, 将原问题归结为求解零本征值本征解和非零本征值本征解, 得到了适用于任意横纵
比的梁的解析解. 由于在求解过程中不需要事先人为地选取试函数, 而是从梁的基本方程出
发, 直接利用数学方法求出问题的解, 使得问题的求解更加合理化. 其中, 地基对梁的力学
行为的影响看作是侧边边界条件, 类似于外载, 可通过零本征解的线性展开来评价, 非零本
征值本征解对应圣维南原理覆盖的部分. 还利用哈密顿变分原理, 给出了两端固支梁的
一种新的改进边界条件. 编程计算了细梁和深梁等算例, 研究了地基上梁的变形沿着厚度方
向的变化特性, 验证了辛方法的有效性. 相似文献
9.
10.
11.
In this paper,a new analytical method of symplectic system.Hamiltonian system,is introduced for solving the problem of the Stokes flow in a two-dimensional rectangular domain.In the system,the fundamental problem is reduced to all eigenvalue and eigensolution problem.The solution and boundary conditions call be expanded by eigensolutions using ad.ioint relationships of the symplectic ortho-normalization between the eigensolutions.A closed method of the symplectic eigensolution is presented based on completeness of the symplectic eigensolution space.The results show that fundamental flows can be described by zero eigenvalue eigensolutions,and local effects by nonzero eigenvalue eigensolutions.Numerical examples give various flows in a rectangular domain and show effectivenees of the method for solving a variety of problems.Meanwhile.the method can be used in solving other problems. 相似文献
12.
In this paper, a new analytical method of symplectic system, Hamiltonian system, is introduced for solving the problem of the Stokes flow in a two-dimensional rectangular domain. In the system, the fundamental problem is reduced to an eigenvalue and eigensolution problem. The solution and boundary conditions can be expanded by eigensolutions using adjoint relationships of the symplectic ortho-normalization between the eigensolutions. A closed method of the symplectic eigensolution is presented based on completeness of the symplectic eigensolution space. The results show that fundamental flows can be described by zero eigenvalue eigensolutions, and local effects by nonzero eigenvalue eigensolutions. Numerical examples give various flows in a rectangular domain and show effectiveness of the method for solving a variety of problems. Meanwhile, the method can be used in solving other problems. 相似文献
13.
14.
SYMPLECTIC SOLUTION SYSTEM FOR REISSNER PLATE BENDING 总被引:3,自引:0,他引:3
Based on the Hellinger-Reissner variatonal principle for Reissner plate bendingand introducing dual variables, Hamiltonian dual equations for Reissner plate bending werepresented. Therefore Hamiltonian solution system can also be applied to Reissner platebending problem, and the transformation from Euclidian space to symplectic space and fromLagrangian system to Hamiltonian system was realized. So in the symplectic space whichconsists of the original variables and their dual variables, the problem can be solved viaeffective mathematical physics methods such as the method of separation of variables andeigenfunction-vector expansion. All the eigensolutions and Jordan canonical formeigensolutions for zero eigenvalue of the Hamiltonian operator matrix are solved in detail, and their physical meanings are showed clearly. The adjoint symplectic orthonormal relation of the eigenfunction vectors for zero eigenvalue are formed. It is showed that the alleigensolutions for zero eigenvalue are basic solutions of the Saint-Venant problem and theyform a perfect symplectic subspace for zero eigenvalue. And the eigensolutions for nonzeroeigenvalue are covered by the Saint-Venant theorem. The symplectic solution method is notthe same as the classical semi-inverse method and breaks through the limit of the traditional semi-inverse solution. The symplectic solution method will have vast application. 相似文献
15.
16.
基于裂纹处范德华力效应,采用非局部弹性理论构造纳米板模型,并通过导入哈密顿体系建立含裂纹纳米板振动问题的对偶正则控制方程组。在全状态向量表示的哈密顿体系下,将含裂纹纳米板的固有频率和振型问题归结为广义辛本征值和本征解问题。利用哈密顿体系具有的辛共轭正交关系,得到问题解的级数解析表达式。结合边界条件,得到固有频率与辛本征值的代数方程关系式,进而直接给出固有频率的表达式。数值结果表明,非局部尺寸参数和裂纹长度对纳米板振动的各阶固有频率有直接的影响。对比表明,辛方法是准确且可靠的,可为工程应用提供依据。 相似文献