A SYSTEM IDENTIFICATION TECHNICAL IS PROPOSED FOR NON-DESTRUCTIVE TEST TO DETECT UNBOUNDS IN LARGE BONDED COMPONENTS.

A SYSTEM IDENTIFICATION TECHNICAL IS PROPOSED FOR NON-DESTRUCTIVE TEST TO DETECT UNBOUNDS IN LARGE BONDED COMPONENTS. THE TECHNIQUE USES THE SYSTEM'S TIME RESPONSE DATA DUE TO RANDOM INPUT EXCITATION. SYSTEM'S EIGENVALUES AND EIGENVECTORS ARE RETRIEVED FROM THE TIME RESPONSES AND USED FOR THE CONSTRUCTION OF ACCURATE SYSTEM MATHEMATICAL MODELS. SYSTEM'S CHANGE DUE TO CRACKS, VOIDS, UNBONDS BETWEEN MATERIALS CAN BE DETECTED BY MONITORING THE PARAMETERS APPEARING IN THE MATHEMATICAL MODEL. TO ACCURATELY IDENTIFY SYSTEM'S PARAMETERS, ADVANCED SIGNAL PROCESSING TECHNIQUES WILL BE EMPLOYED. THESE INCLUDE THE RANDOM DECREMENT PROCESS TO OBTAIN THE FREE DECAY RESPONSE, THE TIME DOMAIN AND FREQUENCY DOMAIN CURVE FITTING PROCESS FOR THE DETERMINATION OF SYSTEM'S EIVENVALUES AND EIVENVECTORS. COMPUTER ALGORITHMS WILL BE DEVELOPED TO ACCOMMODATE ALL THESE PROCESSING TECHNIQUES. TO EVALUATE THE ACCURACY AND EFFECTIVENESS OF THE SYSTEM IDENTIFICATION TECHNIQUE, EXPERIMENTS WILL BE PERFORMED ON A BONDED CANTILEVER BEAM. THREE TYPES OF DAMAGES WILL BE INDUCED IN THE TESTS: DELAMINATION BETWEEN THE DIFFERENT LAYERS OF THE COMPOSITE MATERIAL, CRACKS ON ONE LAYER OF THE COMPOSITE MATERIAL, AND DEBONDING BETWEEN THE BEAM AND THE METAL SUPPORT.