Strain gradient plasticity: theory and experiment. Acta Metallurgica et Materialia 42

Abstract--Dislocation theory is used to invoke a strain gradient theory of rate independent plasticity. Hardening is assumed to result from the accumulation of both randomly stored and geometrically necessary dislocations. The density of the geometrically necessary dislocations scales with the gradient of plastic strain. A deformation theory of plasticity isintroduced to represent ina phenomenological m nner the relative roles of strain hardening and strain gradient hardening. The theory is a non-linear generalization f Cosserat couple stress theory. Tension and torsion experiments on thin copper wires confirm the presence ofstrain gradient hardening. The experiments are interpreted in the light of the new theory. 1