Use of stress measurements with ultrasonics for nondestructive evaluation of the J integral

Abstract Ultrasonic measurements with longitudinal waves in plane specimens combined with the theory of acoustoelasticity, permit the determination of the planar first stress invariant ( σ xx + σ yy ), and by using an automatic scanning technique such measurements may be made at many points. This paper is concerned with the application of ultrasonic stress analysis to fracture mechanics. A method will be described for nondestructively evaluating the J integral in a plane body containing a crack from knowledge of ( σ xx + σ P yy ) in a region in the vicinity of the crack, by making an assumption about the deformation fields in the region. This technique has been tested experimentally on two specimen configurations, with results that compare favorably with theoretical predictions.