Study Of Effects Of Bolt Connection On Aeroengine Case Vibrational Behavior

As an inherent structure of mechanical system, the contact surface is a prerequisite for predicting the properties of mechanical structure and improving capability of mechanical structure. Thus, the study to dynamics of machine joint is of great significance.The stator casing is generally composed of several segments,while each segment is connected using the flange construction, so that there is contact surface between adjacent segments. On the other hand, the existence of these contact surfaces is bound to produce changes in stiffness and damping, resulting in series of changes in the vibration characteristics of the entire system. The study of the contact surface can be divided into two aspects: microscopic study and macroscopic study. Microscopic study is essential to analyzing the physical mechanism of contact surface deformation and the theory of contact surface damping characteristics. Macroscopic study is mainly to simulate the contact surface using springs and damper and to establish the whole model of the contacting system.This paper considers the influence of the contact stiffness and damping characteristics of the bolt-connected structure to the vibration characteristics of the stator casing. Firstly, according to the existing research results of connect stiffness and damping to analyze the reasons of its impact on the dynamic characteristics from the micro-mechanism. Secondly, a method of combining the finite element analysis and experimental modal analysis is adopted based on the study of domestic and international technique. As an example of this method, the L-shaped test piece with a simple bolt-connected structure and the cylinder test piece with a simple bolt-connected structure are used to identify the equivalent kinetic parameters of the typical contact surfaces. Then, the identified parameters are used to study the influence on the vibration characteristics of the stator casing. Finally, summarize the contents by arranging the experimental data and calculating data.To reflect the influence of mechanical stiffness and damping of contact surface on vibration characteristics of the system, the ANSYS analysis software is used. Through a comparative analysis of the structures with interface and without interface, the differences between the natural frequencies and the normal modes of the two models are presented. And the research result has very important significance on studying the vibration problem of the stator casing with a simple bolt-connected structure.