Directional distortional hardening in metal plasticity within thermodynamics

Heidi P. Feigenbaum, Yannis F. Dafalias

Research output: Contribution to journalArticlepeer-review

137 Scopus citations


This paper presents a complete theory for metal plasticity that includes isotropic, kinematic, and directional distortional hardening, within the framework of thermodynamics. Directional distortion is defined here as the formation of a region of high curvature on the yield surface, approximately in the direction of loading, and a region of flattening approximately in the opposite direction, as observed in experiments on various types of metals. The distinguishing features of this theory are the introduction of a fourth order tensor-valued internal variable, whose evolution in conjunction with a directional scalar multiplier describes the evolving directional distortion, and the fact that the hardening laws for all internal variables are derived on the basis of sufficient conditions to satisfy the thermodynamic requirement of positive dissipation. The applicability of the theory is illustrated by fitting experimental data on distorted yield surfaces in the course of plastic deformation.

Original languageEnglish (US)
Pages (from-to)7526-7542
Number of pages17
JournalInternational Journal of Solids and Structures
Issue number22-23
StatePublished - Nov 2007


  • Distortional hardening
  • Plasticity
  • Thermodynamics

ASJC Scopus subject areas

  • Modeling and Simulation
  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Applied Mathematics


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