【摘要】 模态密集能够反映模态的快速甚至剧烈变化的现象。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。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;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;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。更多还原

【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 First-order Sensitivity Theory,the factors affecting the real mode first-order sensitivity were analyzed,and the relation between the real frequency curve veering and the real mode first-order 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 mode-which is not differentiable at a certain point of design parameter-were proposed. Finally,through computing the steady-state responses of the two structures under simple harmonic excitation,the effects of mode jumping and closely & multiple frequencies on vibration analysis were studied.更多还原