论文部分内容阅读
重频是多自由度结构中自振频率存在重叠的现象,对应此频率的重频结构的振型是由多个线性无关的特征向量构成的振型子空间。实测振型时若不考虑重频的影响,可能将重频模态看成孤立模态,造成模态的遗漏。针对重频模态识别问题,推导了加速度传递函数矩阵与重频振型之间的关系,提出了对结构进行多次激励识别重频的方法,每次激励针对不同的自由度,并分析了不同激励的选取方式。通过一个三质点模型的有限元算例,验证了多次激励法的有效性。与此同时,推导了重频振型关于质量阵的带权正交化方法,对振型叠加法是一种补充及完善。
Frequency repetition is a phenomenon that natural frequencies overlap in a multi-degree-of-freedom structure. The mode of a repetition frequency structure corresponding to this frequency is a mode shape subspace formed by a plurality of linearly independent eigenvectors. If we do not consider the influence of the repetition frequency in the actual vibration mode, it is possible to regard the repetition mode as an isolated mode, resulting in the omission of modalities. Aiming at the problem of modal recognition of repetition frequency, the relationship between the matrix of acceleration transfer function and the repetition mode is deduced. A method to recognize the repetition frequency of the structure is put forward. Each excitation is aimed at different degrees of freedom and analyzed Selection of different incentives. Through the finite element analysis of a three-mass model, the validity of the multiple excitation method is verified. At the same time, we derive the weighted orthogonalization method of mass modes for the repetition mode, which is a complement and perfect to the modal superposition method.