Internal constraints in mechanics

We study the internal constraints on the state quantities and on their velocities. We show that they can be taken into account by the free energy and the pseudopotential of dissipation. Applications to collisions of rigid and deformable solids, to damage, to adhesion, to phase changes with and without discontinuities of temperature, to shape-memory alloys, and finally to collisions of solids and liquids, show how flexible and productive is the method.