Integral formulations for the vibroacoustic characterization of a cello

摘要

An isoparametric element formulation is used for implementing the Helmholtz integral formulation associated with arbitrary shaped three-dimensional bodies [M. Bonnet, Eyrolles editions, 1997]. The inverse problem is solved, i.e., the normal velocity distribution is determined on the surface of the instrument. In this way, the direct problem can be solved: the acoustic field can be calculated anywhere (near field, far field). Because of difficulties in solving the inverse problem (ill-posed problem, i.e., of which the solution is very sensitive to the errors of measurements), a regularization method is used to find the nearest solution of the real one [C. Langrenne and A. Garcia, Inter-Noise 97 Proc., Hungary, August 25–27 (1997)]. Experimental vibroacoustic characterization is done from holography measurements, without any contact with the stucture of the instrument, with the help of a robot describing a cylindrical surface.