Design of acoustic insulation in ships based on predictive vibro acoustic models

The marine industry has used empirical models to predict transfer functions between source locations and noise sensitive cabins extensively in the past. These empirical methods work well for standard construction types, material and small number of cabins. Today’s tendencies are to use complex construction methods, exotic material such as composite and build larger and larger yachts with cabin layouts and numbers not easily represented in an empirical way. This paper presents an approach to build predictive vibro-acoustic models for full frequency analysis (0-10 000 Hz). The approach makes use of several modeling methods and coupling such as FEM (Finite Element Method), FMM-BEM (Fast Multipole Method- Boundary Element), SEA (Statistical Energy Analysis) and “FE/SEA Coupled” to represent the yacht structure, interior cabins, fluid tanks, underwater fluid loading and noise radiation. This approach also permits the representation of the acoustic insulation and the optimization of its content to achieve required targets while reducing mass and insulation cost. This paper also discusses the source models to be used to represent the airborne, structureborne and waterborne contribution of major excitations. This approach is applied on a 70m luxury yacht where these vibro-acoustic concepts are discussed and illustrated.