EXPERIMENTAL AND THEORETICAL INVESTIGATION OF SCATTERING FROM A DISTRIBUTION OF CRACKS

This paper presents the results of an experimental and theoretical inv estigation that studies the scattering of longitudinal elastic waves b y a distribution of cracks. The experimental portion measures the tran smission coefficients at imperfect interfaces using a high fidelity he terodyne interferometer. Specimens are manufactured with known distrib utions of cracks that vary from 0% (perfect interface) to 24%. Inciden t longitudinal elastic waves are generated with a broadband, contact p iezoelectric transducer and the backscattered wave field is measured w ith the interferometer. The theoretical analysis examines the interact ion of elastic waves with a distribution of cracks using a different s elf-consistent scheme in conjunction with Auld's formula for backscatt ering. In this model the multiple scattering problem from a distributi on of cracks is reduced to finding the crack opening displacement of a single crack. Transmission coefficients are presented as functions of incident wave-number, flaw size and percentage of defects. The experi mentally measured values are compared with the theoretically predicted results and excellent agreement is obtained.