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Zheng Zhaochang Ren Gexue Department of Engineering Mechanics Tsinghua University Beijing 《Acta Mechanica Solida Sinica》1996,9(2):95-103
Based on Arnoldi's method, a version of generalized Arnoldi algorithm has been devel-oped for the reduction of gyroscopic eigenvalue problems. By utilizing the skew symmetry of systemmatrix, a very simple recurrence scheme, named gyroscopic Arnoldi reduction algorithm has been ob-tained, which is even simpler than the Lanczos algorithm for symmetric eigenvalue problems. Thecomplex number computation is completely avoided. A restart technique is used to enable the reductionalgorithm to have iterative characteristics. It has been found that the restart technique is not only ef-fective for the convergence of multiple eigenvalues but it also furnishes the reduction algorithm with atechnique to check and compute missed eigenvalues. By combining it with the restart technique, the al-gorithm is made practical for large-scale gyroscopic eigenvalue problems. Numerical examples are giv-en to demonstrate the effectiveness of the method proposed. 相似文献
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基于陀螺模态综合法,从总装阵的块式结构出发,构造性地证明了具有n片桨叶的旋翼型结构陀螺特征值问题存在一系列的(n-3)重特征根,得到了对应的(n-3)个完备的振型.结论进而推广到有阻尼的旋翼型结构.继续研究证明过程表明:结论适用于更广泛的一类具有重复子结构的结构系统,结果表明这类结构几何上的重复性或对称性导致的重根不会引入退化性.不同类型的算例验证了所得到的解析结果.本文还试图说明动力子结构法的定性性质保持特性是值得继续探讨的课题 相似文献
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This paper proposes a singularity-free beam element with Euler–Bernoulli assumption, i.e., the cross section remains rigid
and perpendicular to the tangent of the centerline during deformation. Each node of this two-nodal beam element has eight
nodal coordinates, including three global positions and one normal strain to describe the rigid translation and flexible deformation
of the centerline, respectively, four Euler parameters or quaternion to represent the attitude of cross section. Adopting
quaternion instead of Eulerian angles as nodal variables avoids the traditionally encountered singularity problem. The rigid
cross section assumption is automatically satisfied. To guarantee the perpendicularity of cross section to the deformed neutral
axes, the position and orientation coordinates are coupled interpolated by a special method developed here. The proposed beam
element allows arbitrary spatial rigid motion, and large bending, extension, and torsion deformation. The resulting governing
equations include normalization constraint equations for each quaternion of the beam nodes, and can be directly solved by
the available differential algebraic equation (DAE) solvers. Finally, several numerical examples are presented to verify the
large deformation, natural frequencies and dynamic behavior of the proposed beam element. 相似文献
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直升机旋翼/机身耦合系统的气弹响应分析(二)方程的求解 总被引:1,自引:0,他引:1
在文(一)得到的直升机旋翼系统运动方程的基础上,运用动态子结构的方法对旋翼系统和机身作为相对独立的部分进行分析,通过界布的力平衡和几何协调将子系统耦合系统整体系统,用分割-迭代法求解直至旋翼系统和机身的响应同时收敛到精度要求,并研制相应的计算程序,给出了工程算例。 相似文献
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大型非经典阻尼系统的动态解耦方法 总被引:1,自引:0,他引:1
提出了大型非经典阻尼系统动力分析的动态解耦方法,同时在特征值问题的求解和动力响应的计算中完全避免复数运算.方法适用于无阻尼陀螺系统、非经典阻尼系统(包括阻尼陀螺系统),且不论系统亏损与否.得到了揭示阻尼作用的有趣的理论结果和实用的数值方法 相似文献
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链轮驱动系统的多刚体建模及分析 总被引:2,自引:1,他引:1
采用多刚体方法对链条链轮系统的驱动过程进行了建模和动力学分析.链节看作刚体,链轮看作等边刚性多边形,辊子看作两个链节之间的旋转副.啮合约束当作可变约束处理,当啮合力为正时,链节和链轮之间是固定约束,当力变负时,链节脱离链轮.利用龙格库塔法求解系统的拉格朗日方程.最后计算并分析了不同工况下的驱动过程,解释了系统的锁死现象,并进一步分析了两种避免锁死的处理方法. 相似文献
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Nonlinear Dynamics - In this paper, a short summary of the formulation of absolute nodal coordinates elements, including beam, plate, and large deformation solid elements, is given and two aspects... 相似文献