An Inverse Vibration Method Applied to Bond Evaluation of Space Shuttle Tiles

Abstract

This paper describes an inverse vibration method for determining unknown parameters of the physical system by using partial modal information. The method is based on knowing the complete mass matrix of the system and part of its stiffness matrix. The unknown parameters in the stiffness matrix are related to the physical system. This method is applied to the bond evaluation of the space shuttle tiles. The tiles are excited by audible acoustic energy and the response is measured by a noncontact laser vibrometer. The inverse solution is incorporated into a user-friendly computer program to determine the size and location of disbonded regions in the tile assembly. The program allows for any tile geometry as well as the orthotropic properties of the the material. Both simulated data, provided by finite element analysis, and experimentally acquired data are used to verify the proposed method.