Force Analysis Technique: Reconstruction of Force Distribution on Plates

This paper deals with the identification of stationary force distributions exciting plates from the knowledge of measured flexural displacements. The method, Force Analysis Technique (F.A.T.), is based on the computation of the force distribution from equation of motion which is sampled by a finite difference scheme. The main difficulty associated with this problem comes from uncertainties in the data that produce a high noise level in the results. To overcome this instability problem, a regularization technique must be used. Two methods are proposed. The first approach, based on Singular Value Decomposition (S.V.D.), consists of eliminating the singular values of the operator applied to the displacements. The second approach is based on high wavenumber filtering. Applications of both regularization methods on numerical simulations are presented, in order to validate the approach and check the influence of different parameters. Finally, results on a real experiment are reported demonstrating the ability of the method to identify force distribution acting on plates. The advantage of the proposed method compared to previous techniques based on the spatial Fourier transforms of the equation of motion, is the possibility of applying it locally to part of the structure instead of the whole structure.