Residual stress distribution and relaxation in U-rib full penetration welds by ultrasonic impact treatment

Abstract

Ultrasonic impact treatment (UIT) as an effective method for alleviating welding residual stresses (WRS) is used to improve the fatigue performance of welded structures. However, its application to single- and double-sided U-rib welds in orthotropic decks has been limited. To address this, an experimental and numerical investigation on WRS and UIT was carried out for different deck thicknesses. A 3D thermo-elastic-plastic approach was employed to model the temperature and stress fields by the ABAQUS software. Additionally, a dynamic explicit calculation method was developed to simulate the UIT process, and its accuracy was verified by comparing the actual and numerical grooves and WRS after UIT. Ultrasonic stress measurement was employed to determine the distribution and magnitude of WRS before and after UIT. The results demonstrate that most relative errors of residual stress numerical and test results under different stress paths after UIT are within 10 %, confirming the reliability and effectiveness of this method. For single-sided U-rib welds after UIT, the reduction in WRS at the weld seam ranges from approximately 25.6 % to 87.4 %, while for double-sided U-rib welds, the reduction varies from about 22.2 % to 65.5 %. The impact of UIT on longitudinal residual stresses is more significant compared to its effect on transverse residual stresses. However, UIT results in a relatively smaller reduction in WRS away from the weld seam. Furthermore, it is observed that altering the deck thickness results in different disparities in WRS outcomes after UIT.