模态密集能够反映模态的快速甚至剧烈变化的现象,同时也反映了动力系统对某个设计参数是非常敏感的,因此模态密集与跳跃的重要性应予以足够的关注。首先根据实模态的一阶灵敏度理论,分析了影响实模态一阶灵敏度的变化的重要因素,排除了实频率的弯转与实模态一阶灵敏度的关系。其次通过一个实频率密集结构和一个实频率重复结构,展示了实模态跳跃现象的发生,揭示了实模态跳跃现象产生的原因,提出了实模态不可导的概念及判定方法。最后在这两个结构中分别施加了简谐激励,通过计算稳态响应研究了实模态跳跃及重、密频现象对结构振动分析的影响。
Abstract
Mode localization can reflect rapid and even violent changes in dynamic modes. It also reflects that the dynamic system is fairly sensitive at a certain parameter. Therefore, the significance of mode localization and mode jumping was paid attention in this work. Firstly, according to the real mode Firstorder Sensitivity Theory, the factors affecting the real mode firstorder sensitivity were analyzed, and the relation between the real frequency curve veering and the real mode firstorder sensitivity was removed. Secondly, through the analysis of the structure of closed frequencies and the structure of multiple frequencies, the mode jumping phenomenon was illustrated and the reasons for mode jumping were explored. Then the concept and determination method of the modewhich is not differentiable at a certain point of design parameterwere proposed. Finally, through computing the steadystate responses of the two structures under simple harmonic excitation, the effects of mode jumping and closely & multiple frequencies on vibration analysis were studied.
关键词
振动分析 /
密集频率 /
模态跳跃 /
动力响应 /
灵敏度
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Key words
vibration analysis /
closely frequency /
mode jumping /
dynamic response /
sensitivity
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参考文献
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脚注
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