Optimal Design of a Floating Raft Vibration Isolation System with Multiple Constraints

Abstract

This paper presents an optimal design strategy for a floating raft vibration isolation system which is extensively deployed for mounting engines in ships and underwater vehicles. Multiple design variables of the floating raft including total mass, static stress, resonance frequencies, and vibration isolation effects within a prescribed frequency range are taken into account so as to determine the optimization objective, which are the critical concerns in early design stage, i.e., vibration attenuation and the comfort of the crews. In addition to the conventional constraints like geometric sizes and mass, the static stress and vibration level of the floating raft vibration isolation system under specific load cases are also considered. According to the above requirements and principles, an optimal model is developed. Through comprehensive optimization analysis, an optimized design of a floating raft system is provided, which can ensure lower vibration level of the foundation in a prescribed frequency range without at expenses of unnecessary weight and excessive equipment motions. This design strategy would lend itself to bridge structural and acoustic design in a unified way during early design stage.