Technical & Applied Article

Hybrid assessment of acoustic radiation damping combining in-situ mobility measurements and the boundary element method

¹ Technical University of Munich, TUM School of Engineering and Design, Chair of Vibroacoustics of Vehicles and Machines, Boltzmannstraße 15, 85748 Garching, Germany
² KU Leuven, Laboratory of Acoustics, Soft Matter and Biophysics, Department of Physics and Astronomy, Celestijnenlaan 200D, Leuven 3001, Belgium

^* Corresponding author: suhaib.baydoun@tum.de

Received: 28 April 2022
Accepted: 2 September 2022

Abstract

A hybrid experimental-numerical approach is proposed for assessing acoustic radiation damping – a major energy dissipating mechanism in lightweight structures. The vibrational behavior is characterized by distributed mobility measurements using laser Doppler vibrometry allowing to realistically capture the mechanical behavior of the structure under test. The experimentally obtained matrix of mobilities are coupled to a boundary element model to evaluate the radiated sound power numerically. Thereby, acoustic measurements and associated low frequency limitations are avoided, which results in two salient features of the proposed hybrid approach: modeling of diffuse incident acoustic fields and consideration of acoustic short-circuiting induced by slits and gaps. These features contribute to an accurate and excitation-dependent estimation of acoustic radiation damping in the low frequency range. The proposed hybrid approach is applied to flat and C-shaped aluminum sandwich panels mounted onto a tub-shaped foundation. The results are compared to those obtained by a previously reported numerical method.