Optimization design on floating raft system for advancing vibration isolation charaeteristics

The floating raft system is more and more used in ship powerplant for the purpose of reducing vibration and noise; it is that the multi-equipments are installed on the same vibration isolating system with the double layer isolators and a middle raft frame. The optimization design on float raft system is significant for advancing the design level and enhancing the vibration isolating performance. The finite element model of floating raft system is set up, the system modal is computed, and the vibration feature is determined by the use of the direct finite element method. Then, a optimization model is formulated for enhancing vibration isolating performance, the local thicknesses of middle raft frame are taken as design variables, the weight of middle raft frame is taken as constraints, the response accelerations on base of floating raft system are taken as objection, the optimization problem is solved by the feasible directions method. An example optimization is achieved, the example results show that the vibration isolating performance is greatly enhanced by thickness redistribution of middle raft frame while the weight is not added.