Study On The Influence Of Bolt Connection On The Dynamic Characteristic Of Aircraft Engine Case

Aeroengine have been developing with high thrust-weight ratio, large load, high speed and high performance. In the process of the aeroengine development, dynamic characteristic study has always been an important subject, including case and rotor dynamic characteristic research. There are many factors that affect the dynamic characteristics of the case. This paper mainly studies the influence of the bolted-connection on it.At present, in the analysis of the whole engine dynamic characteristics, we usually do not consider the influence of bolt pre-tightening force on vibration modal, but make each component of the bolt connection to be mergered as a whole structure. This kind of analysis model can’t correctly reflect the rigid connection , damping connection and bolt pre-tightening force of the bolt connection structure on the dynamic characteristics of the structure and the calculating results and the actual are greatly different, especially we can not use this method in actual application when there are so many bolts. In this paper, based on the finite element software MSC. / Patran, a cell element is added in the connect surface between the bolt connection structure, and then the multi-point constraint technology is used to joint the bolt connection structure together, then the finite element model is established, and then the corresponding program is written for the optimization design of the layer material, finally, through the definiting reasonable layer material properies to achieve the purpose of accurately simulating the joint stiffness between the surface of the bolt connection structure. The aeroengine case model is chosen as the research object, then this method is used to calculate the modal. Compared the analysis results of the rigid connection of completely simplified model with the analysis results of experimental modal. It was shown that using the method in this paper has better results and the calculating is simpler. Provids an accurate and reliable method to calculate the structure under a preloaded force, especially in finite element modeling and vibration modal analysis of the complex bolt connection of engineering structure.