Experimental studies of noise/vibration damping for undersea warfare applications

Abstract

Maintaining silence underwater is an important issue with undersea warfare. One technique to reduce noise radiation is to use a passive noise/vibration material. The objective of this research was to investigate the vibration properties of an aluminum foam with various types of damping treatment. The importance of the determination of the damping properties of the aluminum foam and various damping treatments was for the future development of materials that would reduce the radiated noise of undersea weapons and onboard machinery. The frequency response was determined using three tests; swept sine, impact hammer, and random noise. The natural frequencies were determined by examining the Nyquist plot of the frequency response. The damping ratios were determined by using the halfpower point method.