A three-dimensional damage model for composites with non-linear shear behaviour

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Abstract

In this paper an experimental study is carried out to characterise the shear response of carbon fibre reinforced epoxy laminates. While maintaining an essentially linear response in longitudinal and transverse directions, it is shown that this material displays significant non-linear shear stress-strain behaviour to rupture and that it is not possible to model this with existing closed form constitutive models, such as the Hahn-Tsai model. A novel damage model is derived where the non-linear shear behaviour is captured using a cubic spline interpolation method. The model can capture the non-linear stress-strain behaviour, including the damage progression and the rupture response. Hashin"s failure criteria are used to predict damage in the laminates and this is incorporated within the framework of the material model. The model is three-dimensional and is implemented into the ABAQUS finite element code using the UMAT user defined material subroutine. The cubic spline equations are linearised, thus allowing them to be written in incremental form and so easily implemented into UMAT. The material Jacobian matrix is fully defined, thus allowing a full implicit material model to be derived. Hence, the model is suitable for both implicit and explicit codes. It is shown that the model accurately predicts the response of the laminates under longitudinal, transverse and shear loadings. The paper will present both the experimental and numerical findings and give the complete derivation of the damage model.

Original languageEnglish
Title of host publicationProceedings of the 9th International Conference on Computational Structures Technology, CST 2008
PublisherCivil-Comp Press
Volume88
ISBN (Print)9781905088232
Publication statusPublished - 2008
Event9th International Conference on Computational Structures Technology, CST 2008 - Athens, Greece
Duration: 2 Sep 20085 Sep 2008

Conference

Conference9th International Conference on Computational Structures Technology, CST 2008
Country/TerritoryGreece
CityAthens
Period2/09/085/09/08

Keywords

  • Composites
  • Constitutive modelling
  • Finite element analysis
  • Material damage
  • Non-linear shear

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