Finite Element Analysis of Underwater Wet Welding: The Implementation of Bubble Configuration

To reasonably characterize the features of underwater wet welding, especially the bubble effect engendered from a high concentration of heat, a three-dimensional (3D) numerical model considering the interaction of bubble dynamics with the boundary layer was developed. A semi-empirical method assessing the bubble growth process was incorporated into the model as boundary conditions to account for the heat loss mechanism. It was proven that consideration of the bubble configuration can improve prediction accuracy, and the predicted weld profile was in good agreement with the experimental results. To reveal the contribution of the bubble configuration while maintaining processing variables consistency, the influences of the equivalent contact radius of the bubble and its floating frequency on the temperature field evolution were evaluated. The results showed that low floating frequency and/ or a high equivalent contact radius tend to depress the heat losses to a water environment, prolong the t8/5 time, and enhance the weld width and joint penetration, which render the role of optimized bubble dynamics beneficial. Under otherwise identical conditions, the equivalent contact radius of the bubble plays a much better role than the bubble floating frequency in promoting weld pool dimensions. Based on the quantified data, suggestions concerning the matching strategy of bubble configuration and heat input for underwater wet welding may be provided.