Impedance Measurements of Loctite Silicone Rubber and Structural Damping Results of Mold-Ex Silicone MX-111

On 5 December 1995, the Naval Undersea Warfare Center (NUWC) Detachment in New London, Connecticut, and the Loctite Corporation in Rocky Hill, Connecticut, signed a Cooperative Research and Development Agreement (CRADA). The CRADA required that the NUWC detachment perform a number of acoustic impedance tests in their New London calibrated air tube facility. Loctite provided specimens of standard silicone rubber and silicone rubber embedded with iron powder and glass microbeads, both of which were especially prepared for the air tube facility. A number of tests were run at several different thicknesses to determine acoustic impedance properties. From these measurements, it was concluded that both specimens respond identically to a plane acoustic air wave. Furthermore, each specimen almost totally reflects this wave and its corresponding acoustic impedance is nearly infinite. In a second set of tests (not sponsored by the CRADA), structural strength and damping data were obtained from analyses conducted on the Mold-Ex silicone MX-111 material with the Metravib-Viscoanalyzer.