A discussion of mathematical aspects of general stress‐strain problems involving viscoelastic materials is given. Constitutive equations are presented in a general differential form. These equations generalize the Boltzmann constitutive relations and provide a convenient way to solve stress‐strain problems. A stable and efficient finite‐difference scheme is constructed and applied to the calculation of the residual stress distribution in a laminar viscoelastic‐elastic composite plate cooled by convection from both sides. In the appendices general relations among relaxation functions are discussed. The results can be used to determine the shift in average relaxation times depending on geometry of relaxation experiment.