Numerical aspects of non-coaxial model implementations

Yunming Yang, Hai Sui Yu

Research output: Journal PublicationArticlepeer-review

23 Citations (Scopus)


This paper ascertains the reasons for the numerical problems when the yield vertex non-coaxial model is implemented in the finite element analysis to predict the behaviour of complicated geotechnical engineering problems. The numerical problem, reflected in the failure of convergence in the non-linear solutions in ABAQUS, is likely to happen when a smaller non-coaxial plastic modulus is used. It is found that a large non-coaxial influence at the start of elastoplastic loading, which causes the predominance of non-coaxial plastic strain rate over the coaxial plastic strain rate in stress-strain responses, is the reason for the numerical problem. The original yield vertex non-coaxial model is modified to overcome the numerical problem. Instead of a constant non-coaxial plastic modulus in the original yield vertex non-coaxial model, the non-coaxial modulus is made a function of cumulative deviatoric plastic strain. It shows that the modified non-coaxial model retains the functions of the original non-coaxial model. Meanwhile, it overcomes the non-convergence problem when a smaller non-coaxial plastic modulus, representing a larger non-coaxial influence, is used.

Original languageEnglish
Pages (from-to)93-102
Number of pages10
JournalComputers and Geotechnics
Issue number1-2
Publication statusPublished - Jan 2010
Externally publishedYes


  • Constitutive models
  • Finite element method
  • Non-coaxial
  • Numerical implementation

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Computer Science Applications


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