Development of Acoustic Sensitivity Analysis Based on Experimental Data and its Applications

The experimental modal analysis is widely utilized in dynamic design of machines to meet the requirement for less vibration and noise, and further the sensitivity analysis is newly adopted to find the appropriate points to reduce the vibration due to structural modification for better dynamics. On the contrary, concerning about the noise induced by the vibration, the present analysis consists of two steps: after the vibrational sensitivity analysis, the noise may be predicted through coefficient of sound radiation, for instance, which yields rather time consuming and inaccuracy. This paper describes the development of a new acoustic sensitivity analysis, which is directly based on the result of acoustic modal analysis when measuring the sound with a microphone against the excitation force. This analysis can provide very useful informations on which parts of the structure should be modified in order to reduce the noise with easy-use and enough accuracy. A simple plate structure and a complex automobile engine are used to confirm the effectiveness of the acoustic sensitivity analysis developed.