Dynamic analysis and design of novel distributed lump-parameters mounting system for marine power devices

Marine power devices (MPD) are one of the dominant vibration and noise sources on board marine vessel. Its vibration can be attenuated effectively through floating raft mounting system. But this becomes unsuitable to implement due to a more stringent light-weighting request. In this paper, a novel distributed lump-parameters mounting system (NDLMS) for MPD is proposed consisting of two-stage mounting subsystem, attitude monitoring and controlling subsystem, and emergency protection subsystem. A theoretical model under multiple excitations is presented to estimate the vibration isolation effectiveness (VIE) using equivalent mobility matrix methods. To improve the VIE of NDLMS, distributed dynamic vibration absorbers (DDVA) are introduced. Compared with the equally weighted rigid mass blocks, DDVA has a qualitative improvement in the attenuation ability of the characteristic spectrum. Replacing part of the mass of mounting system with finely tuned DDVA can greatly reduce the vibration transmitted from vibratory MPD to the foundation. DDVA are validated to compensate for the vibration transmission loss by light-weighting. A scaled and a practical NDLMS prototypes are manufactured and tested. Experimental results validate the effectiveness of theoretical models and show that the performance of NDLMS satisfies the operation requirements of MPD.