This paper describes an approach to predict the dynamic behaviour and the radiating noise of the diesel engine structure.
Nowadays, all diesel engine designers have to pay their prime attentions to engine specifications so as to meet more stringent future governmental control standards both in exhaust emissions and noise.
For this purpose, it is absolutely necessary to establish criteria that can predict in the early stage of design the vibration modes and their noise levels inherent in individual engine structures so that the most cost-effective engine designs from the noise point of view can be screened out.
Some basic experimental results obtained by using a simple structure model to develop such design criteria are described in this paper.
Natural frequencies and the vibration modes of the structure are calculated by finite element method and the results are ascertained both by accelerometers and holography. It was found that the latter was more effective for accurate measurements of vibration modes and phase than the former. A very good agreement was observed between the calculated results and the actual measurements.
Some results obtained by the application of holography to a real engine structure as a means to make its vibration characteristics clear are also mentioned.