Radiation efficiency from a vibrating structure is defined as the ratio of the radiated sound power to the sound power emitted from a baffled piston having the same area and average mean square velocity. The standard radiation efficiency measurement consists of a sound intensity scan to find sound power and use of an accelerometer array to determine spatially averaged vibration. Besides being a multiple step process, this method is difficult to apply to lightweight structures and complicated geometries. Over the past two decades, robust combination sound pressure - particle velocity sensors have been developed. Both particle velocity and sound intensity can be measured simultaneously and at the same location. This research describes a potential protocol for measuring radiation efficiency with the combination sensor. The approach is validated with several examples including an aluminum flat plate, an oil pan, and a gasoline tank on a running small engine.
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