Benefits of Vac Damps over adhesive bonded damping pads for impact noise control

Vac Damps, vacuum applied structural damping pads, were developed almost 10 years ago. They were designed to fit the aviation manufacturing industry standards, and were meant to reduce the riveting impact noise on the assembly lines. To this day, few extensive researches have characterized their performance. In this work, the performance differences between Vac Damps and traditional, adhesive bonded damping pads are investigated. Experimental data was obtained from a simple structure, impacted by a rivet gun simulating device. A 64 microphone grid allowed pressure contours to be calculated, on a plane parallel to the structure. The increased efficiency of the Vac Damps over traditional surface treatment is confirmed, on both the acceleration and ringing noises. Additional knowledge is gained concerning the effects of the pads on both the air and flexural wave components of the acceleration noise, their effects on the contact duration, and their influence on the shape of the impact noise field.