Crack identification in beam structures using mechanical impedance

The influence of a transverse open crack on the mechanical impedance of cracked beams under various boundary conditions is investigated both analytically and experimentally. It is shown that the driving-point impedance changes substantially due to the presence of the crack and the changes depend on the location and the size of the crack and on the force location. Monitoring the change of the first antiresonance as a function of the measuring location along the beam, a jump in the slope of the plot in the vicinity of the crack occurs. The magnitude of the jump depends on the crack size. Experimental results are presented from tests on Plexiglas beams damaged at different locations and different magnitudes and are found to be in good agreement with theoretical predictions. Based on the results of the present work, an efficient prediction scheme for accurate crack localization is proposed. (C) 2002 Elsevier Science Ltd. All rights reserved.