Accession Number : AD0822678

Title :   A STUDY OF THE THERMODYNAMICS OF ONE-DIMENSIONAL DEFORMATIONS OF NONLINEAR MATERIALS CHARACTERIZED BY QUASILINEAR DIFFERENTIAL CONSTITUTIVE EQUATIONS.

Descriptive Note : Interim technical rept.,

Corporate Author : CALIFORNIA UNIV BERKELEY STRUCTURAL ENGINEERING LAB

Personal Author(s) : Lubliner, J.

Report Date : SEP 1967

Pagination or Media Count : 26

Abstract : The thermodynamics of one-dimensional deformations of materials of first-order quasilinear differential type is studied on the basis of the assumption that the strain is the sum of a 'rate-independent' and a 'rate-dependent' part, and that the material time derivative of the latter, but not of the former, is a kinematical variable of state. This assumption is shown to lead to the most general isothermal constitutive equation of such a material. Furthermore, non-isothermal behavior can be predicted from the isothermal characteristic functions at various temperatures. A distinction is made between viscoelastic and viscoplastic materials on the basis of the continuity (or lack of it) of the rate equation with respect to strain rate. For viscoelastic materials the functional form of the free-energy density is determined completely, and specific examples of such materials are discussed. Viscoplastic materials are discussed with regard to yield condition and relationship to plastic materials. The validity of the development for three-dimensional deformations is remarked upon. (Author)

Descriptors :   (*EQUATIONS OF STATE, NONLINEAR SYSTEMS), (*NONLINEAR SYSTEMS, DEFORMATION), (*DEFORMATION, DIFFERENTIAL EQUATIONS), VISCOELASTICITY, PLASTIC PROPERTIES, THERMODYNAMICS.

Subject Categories : Mechanics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE