Vibro-acoustic optimisation of composites with multiple parameters

Abstract

Composites, light and stiff, are sensitive to propagate structure borne sound but simultaneously offer a wide range of adjusting the material behaviour. Thereby, stiffness and damping are contradictory material properties related to the fibre orientation. Commonly, the composite design is based on FEA simulations requiring special modelling efforts. In contrast, the multi-dimensional optimisation of a laminate with numerous layers requires very fast numerical solutions for numerous repetitions. Using a complex but efficient vibro-acoustic simulation model is essential in optimising composites. Therefore, the FEA is extended by a strain energy based modal damping approach for the layerwise accumulation of the anisotropic damping. In addition, the radiated sound power is determined by a velocity-based approach directly on steady state structural simulations avoiding a complex multi-physical modelling. Moreover, the frequency dependent radiation is consolidated to a single scalar optimisation objective with analytical formulations of amplification factors of the modal power contributions. This methodology is applied to design a vibro-acoustically optimised composite part. The achieved results emerge the NVH potential of thermoplastic composites compared to a steel reference case.