FEA-based methods for optimising structure-borne sound radiation

Lightweight components are typically stiff and thin-walled and thus tend to have significant sound radiation. Moreover using fibre reinforced plastics offers a wide range of adjusting the material properties such as stiffness and even damping by manipulating layup, fibre and matrix material or fibre volume content. With numerous free parameters within the composites, there is a need of efficient simulation methods in design and optimisation. In contrast, acoustic measures require complex multi-physical models with fluid-structure interaction and are commonly not implemented in standard FEA software. Different approaches based on the surface velocity of the component fill the gap. Namely, there is the equivalent radiated power, assuming a unit radiation efficiency all over the surface and neglecting local effects as an upper bound of structure-borne noise. In addition, the volume velocity provides good results for the lower frequency range with the frequency-dependent radiation efficiency as well as the lumped parameter model predictions being exact for dipole modes, too. Last, the kinetic energy is implicitly given in steady state FEA solutions and thus provides information about the dynamic behaviour without any additional efforts. Possibilities and limits of estimating the radiated sound power by these methods will be shown by numerical studies on a composite component. Moreover, the total power as an integral over frequency is used to demonstrate the feasibility and accuracy of such optimisation objectives. (C) 2016 Elsevier Ltd. All rights reserved.