The Effects of Crack Closure on Ultrasonic Scattering Measurements

Abstract

The ultrasonic scattering from cracks is traditionally modelled by requiring that the stresses vanish on the crack faces. A violation of this assumption is found in real cracks when asperities on opposing faces are forced into contact by closure or applied stresses. Many investigators have reported substantial decreases in ultrasonic reflections, as well as partial transmission through such cracks. This paper describes a model which has been developed to take into account the effects of the contacts on the ultrasonic signals scattered from the crack.