On the reaction stress in bodies with linear internal constraints

The existence of a material internal constraint in a continuous body generally implies the existence of an indetermination in the reaction stress. One may think that it can be eliminated by the prescriptions of the external contact force and body force: .The precise value of the reaction stress depends on the external body forces and the boundary tractions. The aforementioned indetermination is studied for a linearly elastic, prestressed body B subject to any internal material constraint, with regard to the initial/boundary value-problem; it is pointed out that diflerent external actions can sustain body processes with the same motion and different reaction stresses.