Study on diesel engine block dynamic response based on mode contribution factors

Mode contribution factors were analyzed to research dynamic response for two kinds of diesel engine blocks, in-line four cylinder and V-type six cylinder engine blocks, under multi-support sine excitation. Contribution factors of structural dynamic response in each order mode and the modal vibration type of greatest contribution to the structural dynamic response were found. Vibration characteristics of the two kinds of structures were improved by changing dominant mode parameters. The feasibility and superiority of dominant mode analysis method in designing and improving the structure like solid boxes is proved by contrasting the vibration intensities before and after structural improvement using two finite element calculation examples. After structural improvement, mass and vibration intensity of solid box structure for in-line four cylinder engine is reduced by 1.5% and 8.5%, and for V-type six cylinder engine by 3.1% and 13.6% separatly. The workload is diminished for not needing to analyze each order mode parameters.