Ultrasonic Technique and Equipment for Residual Stresses Measurement

Different methods exist to measure the residual stresses (RS). One of the advantages of ultrasonic techniques for RS measurement is that they are non-destructive. Using such techniques, one can measure the RS in the same points many times, studying, for instance, the changes of RS under the action of service loading or effectiveness of stress-relieving techniques. An Ultrasonic Computerized Complex (UCC) for non-destructive measurement of residual and applied stresses was developed recently. The UCC includes a measurement unit with transducers and basic supporting software and an advanced database and an Expert System, housed in a laptop, for analysis of the influence of RS on the fatigue life of welded elements. In general, the ultrasonic method allows one to measure the RS in both cases: averaged through thickness or in surface layers. The advanced ultrasonic method, the equipment and some examples of RS measurement in welded elements and structures are discussed in this paper.