为简化复杂结构模态分析计算的复杂程度,有效区分复杂结构发生全局振动和局部振动变化的模态阶数,提出一种基于熵值法的目标模态数目确定新方法.分析结构的目标模态并提取目标振型;计算基于目标振型的Fisher信息矩阵;根据Fisher信息矩阵计算提取不同阶模态时的信息熵,计算信息熵的突变特征函数从而确定突变点;由信息熵的变化来表征对应Fisher信息矩阵信息量的变化从而得到结构全局振动和局部振动对应的模态阶数.CRH3型动车组转向架构架仿真结果表明,基于熵值法确定的目标模态数目能够准确计算出构架全局振动的模态数目.%In order to simplify the calculation process of complex structural model analysis and distinguish the mode number of the complex structure when it changes between the global and local vibrations, an entropy-based approach for determining the optimal number of target modes was proposed. The target modes were analyzed and the information about their vibration modes was generated. The Fisher information matrix was calculated based on the calculated vibration modes. The entropy in various stages was computed according to the Fisher in formation matrix, and the sudden change characteristic function of the entropy was computed to determine the sudden change point. The change of the quantity of Fisher in formation matrix was represented by the change of entropy, and then the mode numbers of global and local vibrations can be calculated. Simulation results of CRH3 bogie frame show that this new approach could determine the number of the global vibration on the frame precisely.
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