A polycrystal plasticity model based on the mechanical threshold

Research output: Contribution to journalArticlepeer-review

Abstract

A temperature and rate-dependent viscoplastic polycrystalmodel is presented. It uses a single crystal constitutive response that is based on the isotropic Mechanical Threshold Stress continuum model. This combination gives us theability to relate the constitutive model parameters between the polycrystaland continuum models. The individual crystal response is used to obtain themacroscopic response through the extended Taylor hypothesis. A Newton-Raphsonalgorithm is used to solve the set of fully implicit nonlinear equations for each crystal. The analysis also uses a novel state variable integration method which renders the analysis time step size independent for constant strain rate simulations. Material parameter estimates are obtained through an identification study, where the error between experimental and computed stress response is minimized. The BFGS method, which is used to solve theidentification problem, requires first-order gradients. These gradients arecomputed efficiently via the direct method of design sensitivity analysis. Texture augmentation is performed in a second identification study by changing crystal weights (volume fractions).

Original languageEnglish (US)
Pages (from-to)715-741
Number of pages27
JournalInternational journal of plasticity
Volume18
Issue number5-6
DOIs
StatePublished - 2002

Keywords

  • B. Crystal plasticity
  • B. Viscoplastic material
  • C. Optimization

ASJC Scopus subject areas

  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering

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