TS2b10 - CONSTITUTIVE FUNDAMENTALS IN SIMPLE-SHEAR-INVOLVED DEFORMATION

Abstract

Simple shear deformation almost always takes place in the modes of complex deformation characterized by unbalanced or varying metal flow. Simple shear strain has so far been defined as totated pure shear strain in isotropic material according to Cauchy's theorem of moment equilibrium in which pure shear stress only is accepted as real existence. The author pointed out some dilemmas of the present understanding of pure and simple shear strains. The re-examination of moment equilibrium theorem has been done from the geometrical, phenomenological and mechanical points of view, to reach a new way of understanding simple shear deformation where a new stress state, a single couple, is named “simple shear stress” and is proposed for the stress corresponding directly to simple shear strain. This paper tries to discuss this new possible approach to understanding of simple-shear-involved deformation. The local loss of moment equilibrium causes the finite local rotation of a deforming element until the induced moment is compensated by the restraint of its neighbors or the stress is only propagated to the next element successively without any rotation as in the torsion of a round bar or tube.