AN INVERSE VIBRATION METHOD APPLIED TO BOND EVALUATION OF SPACE-SHUTTLE TILES

This paper describes an inverse vibration method for determining unkno wn parameters of the physical system by using partial modal informatio n. The method is based on knowing the complete mass matrix of the syst em and part of its stiffness matrix. The unknown parameters in the sti ffness matrix are related to the physical system. This method is appli ed to the bond evaluation of the space shuttle tiles. The tiles are ex cited by audible acoustic energy and the response is measured by a non contact laser vibrometer. The inverse solution is incorporated into a user-friendly computer program to determine the size and location of d isbonded regions in the tile assembly. The program allows for any tile geometry as well as the orthotropic properties of the tile material. Both simulated data, provided by finite element analysis, and experime ntally acquired data are used to verify the proposed method.