COLONNETTIS MINIMUM PRINCIPLE EXTENSION TO GENERALLY NONLINEAR MATERIALS

In this paper two minimum principles are presented for the continuum p roblem with general non-linear materials (holonomic, non-holonomic, wi th hardening or softening, time-dependent, etc.). The proof of the fir st principle is based on the use of an elastic auxiliary problem assoc iated to the original non-linear one and on the interpretation of the actual inelastic strains as unknown strains imposed on the elastic aux iliary solid. In a dual way the proof of the second principle is given through the imposition of suitable stresses on the elastic auxiliary solid. Classical principles of elasticity and incremental elastoplasti city are then derived from the new principles as particular cases. Thr ee simple illustrative examples are given.