Accession Number:

ADA222353

Title:

A Continuum Model for Phase Transformation in Thermoelastic Solids

Descriptive Note:

Technical rept.

Corporate Author:

CALIFORNIA INST OF TECH PASADENA DIV OF ENGINEERING AND APPLIED SCIENCE

Personal Author(s):

Report Date:

1989-07-01

Pagination or Media Count:

76.0

Abstract:

Under suitable programs of mechanical or thermal loading, many solid materials are capable of undergoing phase transformations from one crystal structure to another. The austenite-martensite transformation that occurs in a variety of metallic alloys, including the so-called shape memory materials, provides an example. The present paper represents an effort to model coupled thermomechanical effects in the macroscopic response of solids that arise from the occurrence of phase transformations. A Helmholtz free energy potential is constructed to describe the thermo mechanical response of the hypothetical material to be considered here. As a function of shear strain, the potential is non-convex in a certain range of temperature this feature is essential for the modeling of phase transformations. Apart from some general preliminary considerations pertaining to finite thermoelasticity, the analysis is carried out in the context of a simple problem, idealized from an experiment, in which an annular cylinder is deformed to a state of radically symmetric, finite anti- plane shear in the presence of differing inner and outer surface temperatures. After constructing all radially symmetric weak solutions involving at most a single surface of discontinuity of strain or temperature gradient, we determine the implications for quasi-static motions of the second law of thermodynamics. The thermomechanical phase transformation-induced hysteresis, residual deformation and stress relaxation effects exhibited by this model are discussed.

Subject Categories:

  • Mechanics
  • Thermodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE