SIMPLIFIED FINITE-ELEMENT MODELING OF ACOUSTICALLY TREATED STRUCTURES

The application of non-optimized damping and phono-absorbent materials to automotive systems has not proved fully satisfactory in abating no ise and vibration. The objective of this work was to develop a simple finite element modelling procedure that would allow optimizing structu res such as a car body-in-white in terms of vibroacoustic behavior fro m the design stage. A procedure was developed to determine the modific ations to be made in the mass, stiffness and damping characteristics i n the finite element (FE) modelling of a metal structure meshed with s hell elements so that the model would describe the behavior of the aco ustically treated structure. To validate the modifications, a numerica l-experimental comparison of the velocities on the vibrating surface w as carried out, followed by a numerical-experimental comparison of the sound pressures generated by the vibrating plate. In the comparison a simple monopole model was used, in which each area of vibrating surfa ce could be likened to a point source. The simulation and experimental procedures, previously validated for the metal structure, were then a pplied to multi-layered panels. Good agreement between the experimenta l and simulated velocities and sound pressures resulted for all the mu lti-layered panel configurations examined. (C) 1997 Academic Press Lim ited.