基于振型节径谱的失谐叶盘结构动态特性评价

Dynamic characteristics assessment of mistuned bladed disk using nodal diameter spectrum of mode shapes

基于叶盘结构振型的离散傅里叶变换,给出振型节径谱的定义。对于一个简化的叶盘结构,利用节径谱的概念对失谐叶盘的动态特性进行了评价和分析。在固有特性方面,基于节径谱改进了模态局部化因子的定义,得到了随机失谐叶盘的模态特性的统计特征;在响应特性方面,基于振型和激励节径谱的相似程度定义了模态激励因子,很好地解释了随机失谐程度的"阈值"效应和最优人为失谐的存在性。算例表明,节径谱是衡量的振型空间分布的重要指标,在失谐叶盘结构动态特性分析和评价中有着重要的应用。

The nodal diameter spectrum is defined based on the discrete Fourier transform of mode shapes.The dynamic characteristics assessment and analysis for a simplified bladed disk is performed using the concept of nodal diameter spectrum（NDS）.For the free vibration,the definition of mode localization factor is improved based on the NDS,and the probability statistics of modal properties are obtained for the random mistuned bladed disk.For the forced vibration,the modal excitation factor（MEF） is defined based on similarity between the NDS of the mode shapes and the traveling excitation.The ＂threshold phenomenon＂ of random mistuning strength and the existence of optimal intentional mistuning are well explained through the combined effects of MEF and the corresponding mode localization level on the response amplitude magnification.The numerical results indicate that NDS is an important parameter describing the spatial distributions of the mistuned modal shapes and could be widely applied in the analysis of the dynamic characteristics of mistuned bladed disks.