预紧力对螺栓联接机匣模态频率的影响研究

Study on the Influence of Preload Force on the Modal Frequency of the Bolted Joint Aero-engine Casing

为研究预紧力对螺栓联接机匣模态频率的影响,首先,从理论上建立预紧力作用下螺栓联接结构模态方程;其次,以螺栓联接板试件为例,基于有限元分析和试验相结合的方法,验证螺栓联接接触面处理方法的准确性;然后,建立较为精细的机匣有限元模型,进行不同预紧力作用下的机匣模态分析;最后,分析刚性机匣和预紧力作用条件下的实体机匣各阶固有频率相对差异,重点研究预紧力变化对各阶模态频率影响程度。研究表明,随着预紧力增大,机匣各阶固有频率总体上有所增大,并且预紧力对各阶固有频率的影响程度各不相同,结合振型图发现,对于连接面处相对变形较大的振型,其模态频率受预紧力影响较大;而对于连接面处相对变形较小的振型,其模态频率受预紧力影响较小。

The influence of the preload force on the modal frequency of the bolted joint casing is studied.Firstly,the modal equation of the bolted joint structure under the action of the preload force was established.Secondly,with the bolted joint plate as an example,the accuracy of the contact surface treatment method of bolted joint structure was verified by means of the finite element analysis and test.Then,a refined finite element model of the casing was established.The modal analysis of the casing under different preload force was carried out.Finally,the relative differences of natural frequencies of rigid casing and elastic casing under preload force were analyzed.The influence of the preload force on each order modal frequency was studied.The research shows that the natural frequencies of the casing are generally increased with the increase of the preload,and the influence of preload force on each order natural frequency is different.According to the figure of modal shapes,it is found that the modal frequency is greatly affected by the preload force for the modal shapes with large relative deformation in the connection surface.However,the modal frequency is less affected by the preload force for the modal shapes with small relative deformation in the connection surface.