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本文从子结构的原理出发,推导了子结构法法用于动力分析的基本公式,对在地震作用过程中,已知结构的线性反应部分和非线性反应部分的情况,采用线性子结构与非线性子结构耦合的分析方法,这样不仅节省费用,并且概念明确,有助于将结构分析的重点放在非线性反应部分,在此基础上,借助于结构振动的主模态,提出了采用耦合法进行拟动力试验的方法,并通过一模型的拟动力试验就计算方法和模型结构的若干反应性能进行了探讨和研究。 相似文献
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针对一种半柔性悬挂减振结构提出其简化计算方法。根据这种结构的特点,将柔性悬挂层作为连接子结构,应用子结构模态综合法分析结构动力特性,得到结构的简化运动方程;分析了柔性层与悬挂楼面层间刚度比和综合模态数对结构简化计算精度的影响;提出了确定参与综合模态数的选取方法;基于模态综合法进行了算例的时程分析对比。结果表明:采用合理的子结构模态法减少了参与结构分析的自由度数目;综合模态数对结构计算精度的影响更显著。子结构模态法具有应用方便、计算精度高的特点,完全可以满足工程分析的需要。 相似文献
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本文把最近发展起来的Ritz向量直接叠加方法代替动力子结构法中的子结构模态分析,提出无对接自由度的子结构Ritz向量综合法。 相似文献
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本文提出一种动态子结构综合法与加权残数法相结合的求解结构动力特性的计算方法。这个方法具有动态子结构法与加权残数法的一些共同特点。它可以克服用加权残数法求解复杂形状的结构的动力问题时试函数不易选取的困难。通过一些算例表明该方法是有效的。 相似文献
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《振动与冲击》2019,(3)
为了合理评估设备与结构的抗震性能,开展设备-结构动力相互作用振动台试验方法研究。按照分支子结构方法推导设备-结构动力相互作用运动方程,提出了考虑设备-结构动力相互作用振动台实时子结构试验方法,该方法将设备作为试验子结构由振动台加载同时结构作为数值子结构由仿真软件计算联合进行振动台试验,能够考虑设备-结构相互作用对设备抗震性能的影响。设计了四层的钢框架设备-结构动力相互作用缩尺模型,进行各地震动作用下的振动台实时子结构试验与传统整体振动台试验。通过比较发现两种试验方法得到的结果基本吻合在一起,证明提出的振动台实时子结构方法是可靠有效的。试验分析表明忽略设备-结构动力相互作用将影响结构或设备真实的地震反应,特别是对于设备反应的影响更显著。 相似文献
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本文把Ritz 向量直接迭加法同静力子结构相结合,不形成也不存贮总体刚度、质量矩阵,使动力分析在子结构的层次上进行,降低了对计算机内存容量的要求。本方法在有限元和Ritz向量直接迭加法的基础上,没有引入新的假设,因此,比起传统的求解大型结构固有振动的模态综合法来精度是有保证的。 相似文献
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大跨圆拱屋盖结构的风致响应分析 总被引:10,自引:2,他引:10
大跨屋盖特征值问题的求解是结构动力响应分析中最繁琐的一个环节,而且一些对结构响应贡献较大的高阶模态容易在传统的模态叠加法中被忽略。本文以典型的大跨圆拱屋盖为例,将里兹向量直接叠加法应用于屋盖系统特征值问题计算和风致响应分析,其特点是在误差逼近的基础上自动生成一组正交的里兹向量并用于缩减系统自由度数。与传统模态叠加法算得的结果相比,里兹向量直接叠加法只用很少数目的向量就可以得到较精确的结果,而且高阶模态的贡献不会被忽略。该方法不仅大幅度地减少了机时,而且提供了动力分析的误差估计。 相似文献
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用改进Ritz法计算耗能减震高层建筑结构的地震响应。改进Ritz法采用基于外荷载空间分布的Ritz向量和基于外荷载频率的Ritz向量。其中,基于外荷载空间分布的Ritz向量用Lanczos法形成。基于外荷载频率的Ritz向量则用外荷载主频的平方进行特征值平移后再用Lanczos法形成。文中还给出上述两种Ritz向量的截断标准。之后用改进Ritz法的Ritz向量对结构动力方程进行线性变换。由于耗能减震高层建筑结构的阻尼是非比例阻尼,广义阻尼矩阵是非对角矩阵,所以文中采用拟力实模态法对线性变换后的耦联动力方程进行求解。最后的算例说明该方法用于耗能减震高层建筑结构的地震响应分析是有效可行的。 相似文献
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Gil Ho Yoon 《International journal for numerical methods in engineering》2012,89(11):1451-1470
Computational issues concerning the calculation of acoustic responses of a complex finite element (FE) model for various noise and vibration inputs have become prevalent. Such a model requires a significant amount of computation time because of repeated inversions of dynamic stiffness matrices. Thus, even state‐of‐the‐art computer hardware and software often face limitations where a model order reduction (MOR) scheme can help. The established MOR schemes such as Ritz vector or quasi‐static Ritz vector methods are efficient for general engineering systems, but these MOR methods become inaccurate for frequency response analyses in some acoustic systems with frequency‐dependent mass and stiffness matrices and force vectors (hereinafter frequency‐dependent acoustic systems). To cope with the inaccurate prediction by these methods for frequency‐dependent acoustic systems, this research presents and applies the multifrequency quasi‐static Ritz vector method. Unlike the Ritz vector or quasi‐static Ritz vector methods, the present multifrequency quasi‐static Ritz vector method employs direct Krylov subspace bases without an orthonormal procedure at multiple center frequencies. In comparison with the existing MOR scheme, a significant gain in computational efficiency is achieved, as well as enhanced accuracy. A comparison of these methods based on criteria such as efficiency, accuracy, and reliability was also conducted. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Ahmed K. Noor Sandra L. Whitworth 《International journal for numerical methods in engineering》1987,24(5):913-926
A simple computational procedure is presented for reducing the size of the analysis model for a symmetric structure with asymmetric boundary conditions to that of the corresponding structure with symmetric boundary conditions. The procedure is based on approximating the asymmetric response of the structure by a linear combination of symmetric and antisymmetric global approximation vectors (or modes). The key elements of the procedure are (a) restructuring the governing finite element equations to delineate the contributions to the symmetric and antisymmetric components of the asymmetric response, (b) successive application of the finite element method and the classical Rayleigh–Ritz technique. The finite element method is first used to generate a few global approximation vectors (or modes). Then the amplitudes of these modes are computed by using the Rayleigh–Ritz technique. A tracing parameter is introduced which identifies all the contributions to the antisymmetric response. The global approximation vectors are selected to be the solution corresponding to a zero value of the tracing parameter and the various-order derivatives of the solution with respect to this parameter, evaluated at zero value of the parameter. The size of the analysis model used in generating the global approximation vectors is identical to that of the corresponding structure with symmetric boundary conditions. The effectiveness of the computational procedure is demonstrated by means of numerical examples of linear static problems of shells, and its potential for solving non-linear problems is discussed. 相似文献
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根据复合材料具有可重复单胞的特征,提出一种基于重复子结构的缝合式夹芯板动力学建模方法。利用复合材料精细化单胞有限元模型构造初始子结构和残余结构,通过空间位置关系映射得到重复子结构,将所有子结构组装到残余结构上,实现复合材料重复子结构动力学建模及分析。以缝合式夹芯板为例,对其进行重复子结构建模及动态特性分析,并与精细化实体有限元模型进行对比,验证方法的计算精度和效率。研究了初始子结构外部节点选取、残余结构位置选取、初始子结构尺寸选取对重复子结构建模及分析结果的影响。结果表明:针对具有重复性单胞的缝合式夹芯板结构,利用重复子结构进行动力学建模,残余结构的选取具有不唯一性,且初始子结构外部节点数量越多,重复映射过程越少,计算精度和计算效率越高;当初始子结构外部节点选取比例为50%时,相比较复合材料结构的精细化建模方法,可以提高结构动态分析效率。 相似文献
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Paul E. Barbone Dan Givoli Igor Patlashenko 《International journal for numerical methods in engineering》2003,57(3):341-369
A structure which consists of a main part and a number of attached substructures is considered. A ‘model reduction’ scheme is developed and applied to each of the discrete substructures. Linear undamped transient vibrational motion of the structure is assumed, with general external forcing and initial conditions. The goal is to replace each discrete substructure by another substructure with a much smaller number of degrees of freedom, while minimizing the effect this reduction has on the dynamic behaviour of the main structure. The approach taken here involves Ritz reduction and the Dirichlet‐to‐Neumann map as analysis tools. The resulting scheme is based on a special form of modal reduction, and is shown to be optimal in a certain sense, for long simulation times. The performance of the scheme is demonstrated via numerical examples, and is compared to that of standard modal reduction. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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This paper demonstrates the possibility of incorporating load-dependent Ritz vectors as an alternative to modal parameters into a Bayesian probabilistic framework for detecting damages in a structure. Recent research has shown that it is possible to extract load-dependent Ritz vectors from vibration tests. This paper shows that load-dependent Ritz vectors have the following potential advantages for damage detection over modal vectors: (1) in general, load-dependent Ritz vectors are more sensitive to damage than the corresponding modal vectors; and (2) substructures of interest can be made more observable using the load-dependent Ritz vectors generated from particular load patterns. An eight-bay truss example and a five-story frame example, explicitly considering both modeling error and measurement noise, are presented to illustrate the applicability of the proposed approach. 相似文献
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M. V. Belyi 《International journal for numerical methods in engineering》1993,36(13):2263-2286
A superelement algorithm for the transient dynamic analysis of structural systems is presented. The method represents a generalization of existing static and dynamic superelement (substructure) algorithms. Natural frequencies and modal shapes of a fixed boundary substructure are used to obtain equations of motion of a superelement. An implicit time-stepping algorithm is presented for the numerical solution of a resulting superelement system of equations of motion. Numerical examples are given to illustrate the presented approach. The method is believed to be effective for large-scale problems of structural analysis. 相似文献