Structural-Acoustic Simulations of Naval Vehicles Using an Energy Finite Element Method

Simulation methods can be used for meeting both the new stealth initiatives for surface ship silencing, and the stringent limits on acceptable hull vibration. Additionally, interior noise concerns must be considered due to habitability and operational readiness. The pursuit of innovative ship designs, utilization of new materials, and the increasingly demanding performance requirements, dictate a more broadly focused thrust for addressing noise and vibration issues due to multiple sources of excitation during the design process. This expanded technical view also requires that the types of tools utilized for these assessments also improve and that they can provide results within a short enough time that can affect the design cycle. An Energy Finite Element Analysis (EFEA) formulation has been developed for computing efficiently the vibration of complex vehicles and the associated radiated noise at frequencies beyond the limits of conventional finite element methods. In this paper, the main theoretical aspects of the EFEA will be presented first. Results are presented for two 1/8th scale structures representing an advanced double hull design and a conventional hull design of a surface ship. Results for the structural vibration induced on the outer bottom part of the structures are compared to available test data.