Automatic Meshing Method for Optimisation of the Fusion Zone Dimensions in Finite Element Models of Welds

A new method has been designed to automatically adapt the geometry of the fusion zone of a weld according to the temperature calculations when the thermal welding heat source parameters are known. In the material definition in a Finite Element code for welding stress calculations, the fusion zone material has different properties than the base material since, among others, the temperature at which the material is stress free is the melting temperature instead of room temperature. In this work, the fusion zone has been determined by postprocessing the thermal model results. The calculated dimensions of the fusion zone have been used as an input for a user subroutine which automatically creates a Finite Element mesh that separates fusion zone elements and base material elements according to the physical reality. It has been shown that the method allows a more accurate stress prediction in the fusion zone and the heat affected zone close to the fusion line, where residual stresses can be important. Neutron diffraction measurements have been used as a validation of the model.