The finite element model WeldsimS has been developed that quantifies residual stresses in welded steel structures. Input to the model is the structure geometry, material properties, and welding procedure; the output includes the development of temperature, stress, and strain fields during the welding operation. The residual stress field is then made available for a failure assessment analysis.

All main mechanisms causing residual stresses in steel are included in WeldsimS:

• Transformations between different solid phases (austenite, ferrite, bainite,…) and their dependence on thermal history.
• Phase dependent densities and thermal expansions.
• Transformation plasticity.
• Flow stress that depends on temperature and viscoplastic strain rate and deformation.

Some WeldsimS features:

• Differences in properties between weld metal and base metal are taken into accounted.
• Weld metal elements are “activated” when they are approached by weld heat source.
• The build-up of fillet regions in multi-pass welding is simulated by pre-defining weld metal elements that are activated during each pass.
• Weld joint bonding is obtained by changing the interface boundary conditions after reaching a threshold surface temperature.
• Adaptive mesh refinement for numerical accuracy and spatial resolution of the stress field.
• Export of stress field to failure assessment analyses in 3D domains or 2D cross sections.

Temperature field during deposition of weld metal in the groove.

Residual hoop stress for 2 different levels of local mesh refinement.