Investigation of strained states of materials using fiber-optic and acoustic-emission methods

Contemporary systems for technical diagnostic of structural components and units of aircraft and spacecraft are based largely on measurements of characteristics of strained states of materials with the help of traditional physical NDT techniques. Obviously, the reliability of technical diagnostic data can be improved by applying complex testing techniques, in particular, combined acoustic and fiber-optic methods. The paper reports on investigations of strained states and fracture of elements of thin-wall structures using acoustic and fiber-optic methods. A correlation has been found between the parameters of optical and acoustic signals on one side and strength characteristics of tested materials on the other. Combined tests using acoustic-emission and fiber-optic methods yield more reliable information about strained states of structural elements fabricated from various materials. These investigations can be used in developing diagnostic criteria for assessing technical conditions of thin-wall structures with the help of acoustic and fiber-optic methods. (Samples used were aluminum.)