Dept. of General Eng., Univ. of Illinois, 117 Transportation Bldg., 104 S. Mathews, Urbana, IL 61801
A review of the nature and the underlying rationale of the acousto-ultrasonic methodology is presented. The term acousto-ultrasonics denotes a nondestructive evaluation technique that combines some aspects of acoustic emission methodology with ultrasonic simulation of stress waves. Unlike most nondestructive evaluation techniques, acousto-ultrasonics is less concerned with flaw detection than with the assessment of the collective effects of the various flaws and materials anomalies. Acousto-ultrasonics is primarily concerned with material properties variations, such as the significant reduction in strength and toughness caused by combinations of minor flaws and diffuse flaws populations. Porosity content, and fatigue and impact damage are typical examples of factors that affect material properties variations. Applications of the acousto-ultrasonic approach to the nondestructive evaluation of wire rope, porosity in laminated composites, fatigue damage in ceramic matrix composites, and adhesive bond strength in finger joint connections of structural lumber and in other structural systems are presented and discussed.