Predicting the natural frequency of submerged structures using coupled solid-acoustic finite element simulations

This study concerns fluid-structure interaction analysis by using a solid-acoustic finite element model, letting an acoustic medium represent the fluid. This is a promising methodology to obtain computationally affordable advanced models of fluid structure interaction problems were the deformations can be assumed relatively small and the added mass effects dominate the dynamic characteristics. The work presents an extensive study of 19 plate specimens with material properties corresponding to carbon-fibre reinforced plastics, glass-fibre reinforced plastics, as well as steel and aluminium, and a range of different panel aspect ratios. In particular the effects of added mass on fibre-reinforced plastic materials are highlighted in comparison to how these typically are treated in the industry today. Based on a systematic isolation of the added mass effects, this paper enables a precise evaluation of the solid-acoustic FSI modelling approach. The modelling technique is also compared with previously published experiments. The results show good agreement (less than ∼±3% difference) between numerical and experimental results for the first natural frequency. The results indicate that this is a very promising modelling technique that can serve as a refined analysis method for design work performed within the maritime industry.