The first second Generation models define a distributed heat source function. The best known example of such a function is the double ellipsoid model, see Figure 2-9. Another example is a conical model for deep penetration electron or laser beam welds, see Figure 2-11. These were the first weld heat source model capable of simulating welds with deep penetration. Linear combinations of such ellipsoidal, conical or other shapes can be used. If one knows the ’’exact” temperature solution, then one can substitute it in the energy equation to determine the “exact” distributed heat source function directly. Thus the distributed heat source function exists whenever the temperature solution in the weld pool region exists. However for weld pools with complex shapes, it can be very difficult to determine the distributed heat source function if the temperature distribution in the weld pool is not known.

Because of the discrete FEM mesh, one should constrain the net heat input of the weld heat source model to equal the net heat input of the weld. This is easily done by scaling the load vector for the heat source model.

The FEM mesh can conform to the weld pool boundary but it need not conform.