Research On Vibration Transmission Characteristics Of Marine Floating Raft Vibration Isolation System

The hull is a flexible structure with complex spatial structure, whose vibration mode is relatively complex under the interference forces from power equipments and storm. The performance and life-span of devices themselves can be influenced because of fiery vibration. On account of huge noise, the comfort in boats and personnel health are harmed. With the development of lightening and large-scale ship structures and high-speeding devices, the vibration noise control problems of ship equipments are increasingly serious. At present, floating raft isolation form is widely used in the field of ship which have been gaining widespread attention by researchers both at home and abroad. The vibration transfer characteristics of floating raft isolation system with multi-exciters are researched in this paper. The main contents as follows:(1) The single degree of freedom and two degrees of freedom vibration isolation system theories are introduced briefly, whose vibration characteristics are analyzed. The influence on the vibration characteristics of the system from vibration isolator stiffness and mass in the middle are discussed.(2) The basic theories of FEM for structural vibration analysis are recommended. The finite element model of vibration isolation device was established. The acceleration response of vibration isolator was calculated through ANSYS harmonic response analysis; The test bench of vibration isolation device was constructed, and the differences of the finite element results with the test results were analyzed. According to the analysis results, the correctness of the finite element model was validated.(3) The dynamic model of floating raft isolation system with multi-exciters was presented, using the substructure synthesis method. The influence on displacement response from excitation phase was analyzed from the theoretical perspective, providing certain theoretical guide for the engineering design of vibration isolation and the construction of isolation system test platform.(4) The displacement and power flow of floating raft isolation system with multi-exciters was calculated through writing relevant MATLAB program, and the corresponding FE model is set up at the same time. By comparing the results through the two kinds of methods, the rationality of the theoretical model was approved. On this basis, the relationship between the displacement amplitude and phase was analyzed. The influence on displacement and power flow of isolation system from the excitation parameters (amplitude, phase and direction) and the system structural parameter was discussed. Some matters needing attention and basic principles in the design of floating raft isolation system were summarized.