Evaluation of viscoelastic-viscoplastic characteristics and finite element analyses for thermoplastics

Haruki Takaoka, Kenichi Sakaue

Research output: Contribution to journalArticle


Thermoplastics are viscoelastic-viscoplastic materials whose mechanical behavior depends on temperature and strain rate. In this study, the viscoelastic-viscoplastic characteristics of polybutylene terephthalate (PBT) are evaluated on the basis of the mechanical model consisting of Schapery nonlinear viscoelasticity and Perzyna viscoplasticity. Also, the viscoelastic-viscoplastic behavior of the PBT is predicted by finite element simulation. The evaluation reveals that the initial yield stress depends on temperature and strain rate; however, viscosity depends on only strain rate. Furthermore, the rate sensitivity is independent of temperature and strain rate. The finite element simulation using identified viscoelastic-viscoplastic characteristics can reproduce the stress–strain relationship in the uniaxial tensile tests under various testing conditions. It is expected that the time-temperature superposition principle can be applied to not only the maximum stress but also the initial yield stress.

Original languageEnglish
JournalAdvanced Composite Materials
Publication statusAccepted/In press - 2019 Jan 1



  • finite element analysis
  • material testing
  • thermoplastics
  • Viscoelasticity
  • viscoplasticity

ASJC Scopus subject areas

  • Ceramics and Composites
  • Mechanics of Materials
  • Mechanical Engineering

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