Inverse Boundary Element Method Compared to Laser Doppler Vibrometry 2005-26-054

Identification of noise sources that relate to the actual physical geometry of a structure such as an engine, a gearbox, etc. has seen an increasing interest during recent years. New techniques such as the Inverse Boundary Element Method (IBEM) has emerged with capability of displaying surface velocity estimates on the conformal shape of the object using non-contact acoustic measurements around the structure. This paper compares IBEM with the more traditional Laser Doppler Vibrometry (LDV) method. LDV provides a point-by-point sampling of the surface of a structure, thereby producing a vibration map where the IBEM method makes use of acoustic measurements around the structure. These measurement data are fed into an IBEM allowing for reconstruction of the structural surface vibration. The quality of the IBEM surface vibration reconstruction is assessed and discussed for an experiment using a vibrating panel on a closed box and compared to the results from the laser measurements.