Large-scale non-linear analysis of residual stresses in multi-pass pipe welds by idealized explicit FEM

In this research, idealized explicit FEM (IEFEM), which can analyze residual stress of the practical structures in practical time, was applied to large-scale residual stress problem of X groove multi-pass pipe welding. The analysis model has 3, 376,074 degrees of freedom and 108 welding passes. In the analysis, all the welding passes and welding pass grouping technique were considered to investigate the influence of welding pass grouping on residual stress distribution. As a result, it was found that the residual stress distribution can be different if pass grouping technique is used. In addition, to investigate the influence of the welding pass sequence on residual stress distribution, analyses which consider another in-layer welding sequence and build-up sequence were carried out. As a result, it was found that the influence of the welding sequence on residual stress distribution is small. The computing time was practical even though all the welding passes are modeled in a full pass model.