During discussions on welding simulation with various industrial representatives, it became clear that there are two coupled but distinct areas of concern. The first concerns local effects, that is, physical processes that are local to the weld pool and its solidification, and to evolution of final material properties and local stresses. The second area concerns more global features such as distortion of an entire structure due to the strains induced during welding. Because CaPS is well suited to the study of local effects, it was decided that only weld pool dynamics would be considered in the initial development. A link to global structural concerns and perhaps to other structural computer codes is being left for later development.
Most weld materials are alloys or mixtures of several constituents.
While the constituents are uniformly distributed in the object part and filler wire, they are usually of different compositions. As the filler wire melts and combines with the molten portion of the object part and begins to solidify, the alloying constituents separate due to solubility differences between liquid and solid phases. This macroscopic segregation creates an inhomogeneous distribution of the constituents in the final weld due to variations of mechanical properties that, in turn, affect weld performance. The CaPS modification that allows simulation of the welding process provides detailed information on weld geometry and time histories of all points within and external to the weld pool. Comparison of these results with data to be obtained from detailed experiments at ANL will provide the basis for code validation.