Investigation of the Effect of Welding Residual Stress on Natural Frequencies, Experimental and Numerical Study

This paper investigates the effect of residual stresses resulting from welding on the values of natural frequencies of welded structures. First, two aluminum sheets constructed of the 6061-T6 alloy were argon welded together, and the residual stresses were measured via the hole-drilling method. Welding is carried out in two passes. Before starting the longitudinal weld, the beginning, the middle, and the end of the weld line are connected by spot welding to prevent the sheets from moving. The plate's natural frequency values without and with residual stress were retrieved using experimental modal analysis. The two aluminum plates are three-dimensional simulated in Abaqus finite element software, and residual stresses are extracted to validate the experimental results of the welding process. All the conditions in finite element analysis are similar to the welding conditions in the experimental specimen. The results demonstrate high accuracy in modeling the finite elements of the welding process. Then frequency analysis is performed numerically considering the residual stresses. Ultimately, the influence of residual stresses on natural frequency values was examined. The results illustrate that residual stress in the aluminum plate changes the natural frequency. This approach can be used as a non-destructive test to investigate the presence of residual stress in structures.