Lightweight distributed vibration absorbers for marine structures

When combined with attached motors and rotating machinery, the lightly damped, thick plating required in maritime applications becomes a broadband noise and vibration control problem. A typical solution is to adhere heavy and dense damping materials for dissipation of the plate vibrational energy. In order to attenuate low frequencies, significant mass must be added to the structure. This paper will review the development of two, passive treatments intended to resolve this issue. HG blankets are constructed using small masses embedded into poroelastic material. Together with the inherent stiffness of the poroelastic material, the masses become embedded mass-spring-dampers and their presence is found to notably increase the low frequency transmission loss of the host material. DVAs are compact vibration absorbers that distribute continuous mass and spring elements over the surface while generating ample reactive damping at low frequencies. This paper will overview the concepts and development of adapting DVAs and HG blankets for use on heavy plate structures, their testing for broadband control performance, as well as their versatility for thinner panels. A comparison with a conventional, marine noise control treatment will be considered.