Finite element modal analysis and vibration reduction optimization of a diesel engine

LIN Zhi-qiang1, LU Xiang-lin2, CHEN Zhen-lei1
(1.Faculty of Maritime and Transportation, University of Ningbo, Ningbo 315000, China;
2.Guangxi Yuchai Machinery Co. Ltd., Yulin 537003, China)

Abstract: Aiming at the issues of excessive vibration of a diesel engine under working conditions, the vibration reduction optimization of the diesel engine was carried out by the combination of test detection and finite element analysis. Firstly, the modal test of the whole diesel engine and the finite element modal analysis considering the assembly load were completed. The natural frequency and mode shape from the numerical simulation were consistent with that of the experimental. The similarity of the secondorder natural frequency and fourthorder excitation of the diesel engine was confirmed as the main cause of the excessive vibration. Secondly, the calibrated finite element modal analysis process was applied to optimize the vibration reduction, and an optimization scheme was presented by adding ribs to increase the stiffness of the cylinder head cover. The results show that the optimized natural frequency of the whole engine can effectively avoid the first six exciting frequencies of the diesel engine, which provides a numerical basis for design modification of vibration reduction optimization of diesel engine and an effective approach for the vibration reduction optimization of mechanical systems such as the engine.

Key words: diesel engine; finite element analysis; modal analysis; modal testing