Combined measurement of complex vibrational modes and surface form for noise radiation prediction

This paper presents a combined measurement system based on TV Holography for vibration measurement and structured light for surface form measurement. A common CCD camera is used for both measurements. In both cases phase stepping techniques have been developed for automation of the analysis. The vibration measurements have been achieved using an 8 frame stereoscopic algorithm which can analyze complex vibrational modes. The two data sets are combined in a wireframe representation and animated to provide a direct visual interpretation of the information. It is necessary to measure complex vibration modeshapes and the surface form of a structure in order to predict noise radiation. Noise radiation predictions are of increasing importance in the design and optimization of motor vehicle structures to achieve desired levels of refinement. Noise radiation can be measured directly using the appropriate microphones and analysis equipment. However, such techniques provide no direct information on the source of the noise, or provide an insight for an approach to reduce the noise level.