  The study is devoted to geometrically non-linear modelling of viscoplastic
structures with residual stresses. We advocate and develop a special approach
to residual stresses based on the transition between reference configurations.
The finite strain kinematics of the viscoplastic material is modelled by the
multiplicative decomposition of the deformation gradient tensor. Numerical
algorithms originally developed for unstressed materials are extended to
materials with pre-stresses. Owing to the weak invariance of constitutive
equations, the incorporation of pre-stresses happens without additional costs.
Thus, the advocated approach is especially efficient. A novel
experimental/theoretical method for assessment of residual stresses in welded
structures is presented; the method combines advantages of purely experimental
and theoretical approaches. To demonstrate the applicability of the proposed
procedure, we simulate plate welding. As an example we show that the procedure
allows to extrapolate the filed of residual stresses away from the measurement
points. As another example, we address the reduction of weldment-related
residual stresses by mechanical treatment.
