Constitutive Modeling of Ratchetting Effects—Part I: Experimental Facts and Properties of the Classical Models

The constitutive modeling of cyclic plasticity has made great progress during the past twenty years. One of the incompletely solved problems concerns ratchetting, that is the progressive strain accumulation, cycle-by-cycle, induced by the superposition of a cyclic secondary load to a constant primary load. The paper discusses the main experimental facts and identifies the main inadequacies of the classical cyclic constitutive equations when they are used to predict ratchetting effects.