one of the basic premises of statics. According to the solidification principle, the state of equilibrium of a mechanical system undergoing change is not disrupted upon solidification of the system. Systems undergoing change include systems of material particles interconnected by forces of interaction; systems of solids connected by hinges, rods, or threads; and systems of particles of a deformable solid, liquid, or gaseous medium.
The solidification principle establishes that if a system undergoing change is in equilibrium, then this state of equilibrium cannot be disrupted by the addition of more connections between the points and bodies of the system. On the basis of the solidification principle, it can be stated that the necessary (but not sufficient) conditions for equilibrium in a system undergoing change or deformation and acted on by a given set of forces include all conditions of equilibrium for an ideal solid acted upon by the same set of forces. Consequently, in formulating the conditions necessary for the equilibrium of any system undergoing change, the system in question may be considered as an ideal solid. This correspondence is used extensively in engineering studies of equilibrium in systems undergoing change.
S. M. TARG