Vibration response analysis on stainless steel thin plate weldments

Dynamic responses of welded thin plates are influenced by welding residual stress, and improving this phenomenon understanding would turn possible to develop a new residual stress detection method. This research investigates natural frequency variations in welded thin plates. Experimental analysis was conducted for eight AISI316LSS plates, 6.30-mm thickness, bead on plate (BOP) and butt welded. Modal variations, comparing natural frequencies before and after welding, are negative, due to longitudinal compressive residual stress predomination. It was detected that higher variations occur for the first torsional mode and the variation for the longitudinal flexural mode is around null. It was observed that BOP welds do not always result in higher modal variations for higher heat inputs, as it occurs with butt welds. Moreover, it shows that, for the same heat inputs, modal variations were higher for butt welds than BOP tests. Numerical analysis was also performed, and theoretical results were compared to experiments.