SimWeld and DynaWeld Software tools to setup simulation models for the analysis of welded structures with LS-DYNA

The analysis of residual stresses or distortion of welded structures requires a welding structure analysis. This kind of analysis incorporates some specifics compared to other FEM-simulations. Apart from the definition of geometry (mesh) and clamps the welding structure analysis requires the definition of heat sources, trajectories and time schedules. The heat source applies the heat input in the model according to the welding process. An equivalent heat source is used which needs to be calibrated for tests or predictively calculated from a welding process analysis. The trajectories describe the path of the moving welding heat source in the simulation model. The most heat sources for welding are not rotational symmetric. Their trajectories require a path to define the local origin of the heat sources and a reference line to define the orientation of the heat source. Welding is a transient process where the time schedule of the actions - welding time, intermediate time - have an impact on the result. The process plan defines the welding time schedule and has to be considered in the simulation model. The setup of simple models with single welds is easy and can be performed by writing the input deck with text editors. More of interest are assemblies with many weld seams. The setup of these models require auxiliary tools for the setup to decrease the work time and to minimize the risk of errors in the input deck. SimWeld, a software for the welding process simulation of gas metal arc welding is developed continuously in research and industry projects since over 25 years. SimWeld is highly specified to its application, thus the simulation time of less than 1 minute is extremely short. The welding engineer can predict the weld pool geometry and its quality according to the process parameters and machine settings. The predictive calculation of the heat input can be calculated with every SimWeld simulation and can be used for the welding structure analysis. An interface exports the parameter of the equivalent heat source either in general format or in LS-DYNA Keyword format. Thus SimWeld resolves the issue of a calibrated heat input for the welding structure analysis. This benefit has a big impact in the design state. Apart form the manufacturing, SimWeld enables the design engineer to calculate realistic conditions for the weld and use these data in numerical analyses. The DynaWeld project was established at the engineering office Tobias Loose in 2015. DynaWeld concentrates software modules for an efficient setup of input decks for the LS-DYNA solver and associated auxiliary tools. DynaWeld is intended for welding and heat treatment processes. The philosophy is to provide a general tool as well as special versions adapted on the customers’ needs. DynaWeld starts with a welding input-writer for LS-DYNA. The input writer reads the welding process plan and generates the LS-DYNA input for the equivalent heat source. Additionally, part, contact and material assignment as well as the time stepping for the solver can be defined with DynaWeld. SimWeld and DynaWeld do not require a change of existing pre- or postprocessor but can be supplemented to any existing software in the simulation or design departments. This paper demonstrates the workflow of an efficient setup of welding structure analysis with LS-DYNA using SimWeld and DynaWeld especially for assemblies with a large number of weld seams.