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71.
72.
重庆“朝天扬帆”钢结构工程风振研究 总被引:1,自引:0,他引:1
“朝天扬帆”是位于重庆朝天间广场的钢结构雕塑工程,该工程建筑型体复杂、结构布局不规则,通过该雕塑工程缩尺模型的几洞试验,确定其风载计算的体型系数;用时程法计算结构的风振响应,且在模拟作用于结构上的脉动风时程曲线时考虑结构的高度相关性,应用ALGOR93软件对结构进行风振时程分析,并自编程序加以前、后处理。通过对比该结构在脉动风和平均风作用下的杆件内力、节点位移响应,约定结构风振系数,为该雕塑工程抗风设计参数的确定提供理论依据。 相似文献
73.
74.
水轮发电机转子偏心引起的非线性电磁振动 总被引:5,自引:0,他引:5
由于机械和电磁相互耦合,水轮发电机的电磁振动具有强非线性特征。根据不平衡磁拉力与转子偏心的非线性函数关系,通过简化的各向同性的单圆盘转子系统,建立了水轮发电机转子电磁振动的非线性系统。利用非线性振动理论的多尺度方法,从理论上分析了该系统强迫振动的稳态响应,进而研究了水轮发电机转子偏心引起的电磁振动。研究发现不平衡磁拉力使系统的涡动频率下降,使运动的中心发生变化;并且会引起两倍转频的振动。最后用模型转子仿真试验的结果验证了这些理论分析的结论。 相似文献
75.
Feng Ruoqiang Wu Yue Shen Shizhao 《Acta Mechanica Solida Sinica》2006,19(3):248-254
The cable net supported glass curtain wallas the most advanced technique in dot point supported glass curtain wall, is widely used in China. Because of its large deflection and high nonlinearity under wind load, the dynamic performance of the cable net is greatly different from that of the conventional linear structures. The continuous membrane theory is used to construct the nonlinear vibration differential equation of the cable net, and the harmonic balance method is used to solve the analytic formula of the nonlinear frequency. In order to verify the accuracy of the above analytic formula, the results of the formula and the nonlinear FEM time-history method are compared and found to be in good agreement. Furthermore, the nonlinear vibration differential equation and the nonlinear frequency obtained in this paper are the basis for the wind-induced response analysis of a cable net under fluctuating wind load. 相似文献
76.
According to the differential equation for transverse displacement function of anisotropic rectangular thin plates in free vibration, a general analytical solution is established. This general solution, composed of the composite solutions of trigonometric function and hyperbolic function, can satisfy the problem of arbitrary boundary conditions along four edges. The algebraic polynomial with double sine series solutions can also satisfy the problem of boundary conditions at four corners. Consequently, this general solution can be used to solve the vibration problem of anisotropic rectangular plates with arbitrary boundaries accurately. The integral constants can be determined by boundary conditions of four edges and four corners. Each natural frequency and vibration mode can be solved by the determinate of coefficient matrix from the homogeneous linear algebraic equations equal to zero. For example, a composite symmetric angle ply laminated plate with four edges clamped has been calculated and discussed. 相似文献
77.
Xiaoling He 《International Journal of Non》2006,41(1):43-56
Non-linear dynamics behavior of a thin isotropic laminate in a simply supported boundary condition is studied for its response with both mechanical and thermal loads in effect. The thermal effects of both the in-plane and transverse non-uniform temperature variations in steady-state are considered. The equation of motion for the laminate deflection is reduced to the Duffing equation in a decoupled modal form by means of a generalized Galerkin's method. The stress field as a function of deflection and temperature variation is also obtained in a plane stress condition for its non-linear elastic behavior with von Karman strain field.For an exemplary laminated microstructure used as a printed wiring board, it is found that a high rise of the in-plane temperature increases the resonance frequency and could significantly increase the stresses of the lamina. The through thickness temperature variation has no significant effect on the deflection. Failure analysis is also made based on the composite failure criteria for a laminate to identify the critical mechanical and thermal loads. 相似文献
78.
非高斯随机激励下工程结构可靠性估计的一种方法 总被引:1,自引:0,他引:1
本文将工程结构考虑为振动系统,把随机载荷及在结构上的载荷效应作为随机过程,分析状态函数的高阶矩,进行最大熵概率分析,得到结构在随机载荷作用下失效的概率。此法为随机环境下工作的结构、构件或设备的安全设计、可靠性检验提供了一个可行的方法。 相似文献
79.
车-桥系统耦合振动响应的简便计算 总被引:13,自引:1,他引:13
依据振动理论推导出了二自由度模型车辆与桥梁系统竖向耦合振动微分方程,采用模态分析的离散化方法,将复杂的偏微分方程问题转化为变系数常微分方程问题,并将微分方程数值积分的Runge-Kutta方法引入到该时变系统的振动响应计算中,使复杂的耦合响应问题得到简便的解决。通过算例验证了该方法的有效性和简便性。该方法只需要直接数值积分,具有公式简单,编程方便,计算速度快等优点,特别适合于工程实际问题的计算,并且不仅适用于匀速运动车辆,也适用于变速运动车辆。 相似文献
80.
Here, the large amplitude free flexural vibration behaviors of thin laminated composite skew plates are investigated using finite element approach. The formulation includes the effects of shear deformation, in-plane and rotary inertia. The geometric non-linearity based on von Karman's assumptions is introduced. The non-linear governing equations obtained employing Lagrange's equations of motion are solved using the direct iteration technique. The variation of non-linear frequency ratios with amplitudes is brought out considering different parameters such as skew angle, number of layers, fiber orientation, boundary condition and aspect ratio. The influence of higher vibration modes on the non-linear dynamic behavior of laminated skew plates is also highlighted. The present study reveals the redistribution of vibrating mode shape at certain amplitude of vibration depending on geometric and lamination parameters of the plate. Also, the degree of hardening behavior increases with the skew angle and its rate of change depends on the level of amplitude of vibration. 相似文献