Numerical Model of a Multi-layer Shock and Vibration Isolator

Isolators are used on-board marine platforms to reduce the underwater radiated noise, protect the equipment mounted on them from underwater explosions, and to increase the habitability. Much of the underwater radiated noise is at low frequencies and there is increasing interest in reducing this for both merchant and naval vessels. The JSS 55555 specifications and acceptance tests are also to be considered in the design. They include vibration endurance tests in the 5 to 33 Hz band. As one isolator should serve several purposes while supporting heavy machinery, the optimum isolator is to be defined. In this paper, a multi-layer isolator with resonance frequencies in the 5 to 33 Hz band is analyzed. It attenuates radiated noise above a low cut-off frequency but this affects its ability to attenuate certain shock loads due to explosions.