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基于有限元法对裂纹悬臂平板叶片的频率转向和振型转换特性进行了线性和非线性研究。首先使用张开型裂纹模型通过线性模态分析研究了裂纹长度变化引起的频率转向和振型转换问题,使用模态置信因子定量分析了频率转向区内振型的渐变过程。而后考虑裂纹闭合效应,建立了裂纹平板的双线性模型,使用张开型和闭合型模型线性分析结果计算得到双线性频率,其中张开型和闭合型裂纹振型通过模态相关性分析进行匹配。计算了裂纹叶片双线性频率,分析了非线性频率转向特性与线性分析结果的差异。最后使用接触有限元模型瞬态响应扫频计算得到非线性共振频率,对张开型模型和双线性模型在典型弯曲、扭转和面内弯曲模态的共振频率进行了验证。
Based on the finite element method, the frequency and mode transition characteristics of cracked cantilever blade were studied linearly and nonlinearly. Firstly, the open-type crack model was used to study the frequency steering and mode switching problems caused by the change of crack length through the linear modal analysis. The modal confidence factor was used to quantitatively analyze the change of mode shape in the frequency steering region. Then, the bilinear model of the crack plate was established considering the crack closure effect. The bilinear frequency was calculated using the linear analysis results of the open and closed models. The open and closed crack modes were analyzed by modal correlation analysis Match. The bilinear frequency of the cracked blade was calculated and the difference between the nonlinear frequency steering characteristics and the linear analysis results was analyzed. Finally, the nonlinear resonant frequency was calculated by using the transient response sweep of the contact finite element model. The resonance frequencies of the open model and the bilinear model were tested under typical bending, torsion and in-plane bending modes.