Accession Number : AD0718400

Title :   Inelastic Constitutive Relations for Solids: An Internal Variable Theory and Its Application to Metal Plasticity.

Descriptive Note : Technical rept.,

Corporate Author : BROWN UNIV PROVIDENCE R I DIV OF ENGINEERING

Personal Author(s) : Rice,James R.

Report Date : JAN 1971

Pagination or Media Count : 44

Abstract : Constitutive laws at finite strain are studied for a class of inelastic solids. These exhibit inelasticity as a consequence of specific structural rearrangements, on the microscale, of constituent elements of materiel (a case being metal plasticity as a consequence of dislocation motion). The theory of such materials is developed in general terms, with 'internal variables' representing the structural rearrangements. The greatest emphasis is placed on the normality structure which emerges in constitutive laws when the rate of each structural rearrangement is governed by its associated thermodynamic force. A scalar potential function of stress is then shown to exist at each instant during the deformation so that its derivatives are the components of the inelastic portion of the strain rate. The limiting case of a time-independent material and yield surface normality is discussed as well, as are some thermodynamic features of the internal variable model. Constitutive laws for metal plasticity are studied from this viewpoint: Crystalline slip is the presumed mechanism of structural rearrangement, and this characterized through both a continuum and a discrete dislocation slip model. The assumption that associated thermodynamic forces govern rates, which leads to the macroscopic normality structure, is shown to reduce in cases of small elastic distortions to the commonly assumed stress dependence of metallic slip in terms of resolved shear stresses on slip systems or of glide forces per unit length of dislocation line. (Author)

Descriptors :   (*DEFORMATION, THERMODYNAMICS), (*PLASTIC PROPERTIES, METALS), STRESSES, CREEP, VISCOELASTICITY, STRAIN(MECHANICS), PARTIAL DIFFERENTIAL EQUATIONS, GRAIN STRUCTURES(METALLURGY)

Subject Categories : Metallurgy and Metallography
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE