Advances in Engineering Methods for Non-Destructive Measurement and Beneficial Redistribution of Residual Stresses

Engineering properties of structures and materials, such as fatigue life, distortions, dimensional stability and corrosion resistance can be considerably affected by presence of residual stresses (RS) [1]. The knowledge of RS and ability to control their distribution is critical in welded structures when evaluating their fatigue life and preventing catastrophic failures. To address the major aspects of residual stresses and their behavior in structural elements, an engineering concept of residual stress management (RSM) has been developed [2] that takes into account all major stages of stress interaction with materials and structures, i.e. RS determination, RS analysis and RS redistribution. Using this approach, stresses in structures can be evaluated in each specific case either theoretically or experimentally and their performance optimized. 

This presentation is built as an overview of the application of new RSM tools in the fields of non-destructive measurement of residual and applied stresses and in treatment of structures with residual stresses to achieve better performance and longer fatigue life. It will review and update the audience on arelatively new technique for non-destructive measurements of residual stresses in bulk, surface and subsurface layers of materials using an ultrasonic computerized complex for residual stress measurement. The theoretical background and a number of selected examples of measurements will be discussed. In the follow up sections an update and review of applications of the ultrasonic peening is presented with some theoretical background and examples of application in air and under water that allowed improving the quality of the welds and increasing their fatigue life. The beneficial effects of UP are discussed in terms of relieving of harmful tensile residual stresses and introducing of compressive residual stresses into surface layers of materials, and through decreasing of stress concentration in weld toe zones and enhancement of mechanical properties of the surface layers of the materials.