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61.
A SINGULAR VALUE DECOMPOSITION BASED TRUNCATION ALGORITHM IN SOLVING THE STRUCTURAL DAMAGE EQUATIONS 总被引:1,自引:0,他引:1
RenWei-Xin 《Acta Mechanica Solida Sinica》2005,18(2):181-188
The structural damage identification through modal data often leads to solving a set of linear equations. Special numerical treatment is sometimes required for an accurate and stable solution owing to the ill conditioning of the equations. Based on the singular value decomposition (SVD) of the coefficient matrix, an error based truncation algorithm is proposed in this paper. By rejection of selected small singular values, the influence of noise can be reduced. A simply-supported beam is used as a simulation example to compare the results to other methods.Illustrative numerical examples demonstrate the good efficiency and stability of the algorithm in the nondestructive identification of structural damage through modal data. 相似文献
62.
The local and global nonlinear dynamics of a two-degrees-of-freedom model system conveying fluid is studied. The undeflected model consistsof an inverted T formed by three rigid rods, with the tips of the twohorizontal rods resting on the viscous foundation. The foundationexhibits a visco-elasto-plastic response, including the Bauschingereffect. The vertical rigid rod of an annular cross-section is subjectedto a conservative (dead) force. Also, it conveys fluid having bothstatic and pulsation components. First, the method of multiple scales isused for the analysis of the local dynamics of the system withvisco-elastic response. Attention is focused on modal interactionphenomena in weak excitation at primary resonance and on hardsub-harmonic excitation. Two different asymptotic expansions areutilised to get a structural response for typical ranges of excitationparameters. Numerical integration of the governing equations is thenperformed to validate the results of asymptotic analysis in each case. Afull global nonlinear dynamics analysis of the visco-elasto-plasticsystem is performed. The role of plastic deformations in thedestabilisation of the system is discussed. Large-amplitude nonlinearoscillations of the visco-elasto-plastic system are studied, includingthe influence of material hardening and of static and periodiccomponents of pulsating fluid. Chaotic regimes of motion with andwithout plastic effects are considered. The results of the analysis maybe used in devices composed of a rather short tube connected to a notcompletely fixed foundation resting on the soil exhibitingelasto-plastic behaviour. 相似文献
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本文运用理论分析、实验与计算的结果对引进的美国SMS公司的结构动力修正软件SDM3.0作了比较详细的探讨,指出了SDM3.0的优点、局限性与使用范围.提出了改进这一软件的方法,研制了相应的软件.结果表明:改进后的方法及相应的软件是有效和成功的. 相似文献
67.
When using H ∞ techniques to design decentralized controllers for large systems,the whole system is divided into subsystems, which are analysed using H∞ control theory before being recombined. An analogy was established with substructural analysis in structural mechanics, in which H ∞ decentralized control theory corresponds to substructural modal synthesis theory so that the optimal H ∞ norm of the whole system corresponds to the fundamental vibration frequency of the whole structure. Hence, modal synthesis methodology and the extended Wittrick-Williams algorithm were transplanted from structural mechanics to compute the optimal H∞ norm of the control system. The orthogonality and the expansion theorem of eigenfunctions of the subsystems H∞ control are presented in part (Ⅰ)of the paper. The modal synthesis method for computation of the optimal H ∞ norm of decentralized control systems and numerical examples are presented in part (Ⅱ). 相似文献
68.
用模态试验结果修改力学模型初探 总被引:1,自引:0,他引:1
利用试验模态分析结果,对有限元力学模型本身或其中某些参数进行修改是必要的和有工程意义的。这一“修改”既是数学上的优化问题又是工程设计问题。本文介绍自研制的“结构动力修改程序”,述及一般原理及框图,并给出一个悬臂梁实例。 相似文献
69.
本文应用投影云纹法研究受压加劲板的大挠度非线性问题。用投影云纹法测量加劲板后屈曲平衡路径,记录了随着载荷的增加,加劲板后屈曲模态变化的全过程。将云纹图输入微型计算机处理,获得了加劲板的全场位移和全场应力的分布情况。用投影云纹法所测得的结果同理论计算值基本吻合。 相似文献
70.
局部裂纹损伤简支梁的曲率模态特性 总被引:1,自引:0,他引:1
将裂缝损伤简化成矩形凹槽,采用delta函数表示简支梁的裂纹损伤位置,得到了全梁范围内截面转动惯量和单位长度质量的表达式,建立了局部裂缝损伤简支梁的横向自由振动方程.利用摄动方法给出了裂纹摄动项的一般表达式,根据摄动项和完整梁都同时满足边界条件的特点,将一阶和二阶摄动项都表示成完整梁模态的线性组合,结合delta函数的性质,最终获得了受损简支梁的特征值和模态振型的解析表达式.最后,通过数值计算得到结构模态参数,对比了一阶摄动和二阶摄动对计算结果的影响,分析了不同阶固有频率和模态曲率的变动量,为简支梁的损伤监控和检测提供了理论依据. 相似文献