Modeling of welding residual stresses

An analytical model for predicting the through-thickness distribution of residual stresses in multi-pass welding of thick plate was developed. This model can be used for the evaluation of temperature and stress history throughout the welding process. A two-dimensional thermal model was developed for analysis of the temperatures in the plate. A ramp heat input function was used in the thermal model to apply the heat flux gradually to the plate. The mechanical model was developed to predict the thermal and residual stresses using thermal history obtained by the thermal model. Two types of lumped pass models were developed to reduce the total computation time and cost. The first lumped pass model assumed that each layer of weld bead was one lumped pass. The heat input for every pass in that layer was added and applied on the top surface of the weld layer. The second lumped pass model assumed two layers of weld bead corresponded to one lumped pass. This model was used for the 2 inch (50.8mm) thick plate only. The results obtained for the two different lumped pass models showed good agreement with experiment as well as with the results by another model which analyzed every weld pass separately.