The initial conditions include initial stress, i. e., the residual stress and initial effective plastic strain for each part in the structure if it is known. If the residual stress in parts before welding starts is not known, it would usually be set to zero. If the manufacturing process for the part is simulated, the residual stress in the part could be computed. The stress analysis can be done as a quasi-static analysis, i. e., inertial forces can be neglected. Both rate independent plasticity and rate dependent plasticity are included. The stress solver chooses its time steps automatically.

The properties required by the stress solver include the elasticity tensor, Young’s modulus, Poisson’s ratio, yield stress, density or specific volume, viscosity, hardening modulus for rate independent plasticity and softening modulus (a coefficient that defines the rate at which work hardened material softens, i. e., the yield stress decays as a function of temperature). Ideally, these properties should be functions of temperature, time and microstructure. If values of some properties are not available, we suggest using the best available estimates, based on the literature if direct experimental data is not available.