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Keywords: composite materials, numerical homogenisation, micromechanical analysis, representative volume element, periodic boundary conditions.

Summary

Effective homogenisation procedures can be used to predict the overall response of a composite structure based on the response of a representative volume element (RVE) of the material [1]. In this work, a general homogenisation procedure for unidirectional composite materials is presented. The finite element analysis (FEA) code ABAQUS [2] is used to model a hexagonal RVE of a carbon fibre-epoxy composite material, HTA/6376. Two-dimensional and three-dimensional RVEs of the material are created. The anisotropy of the carbon fibre material is discussed. Periodic boundary conditions are developed and applied to the two- and three-dimensional RVEs. Effective elastic moduli are calculated by examining the relevant stress-strain response of the RVE in a series of tensile and shear loading states. The homogenisation procedure is validated by comparison with previously published experimental data [3]. It is shown that the proposed homogenisation procedure is an accurate method for predicting the overall properties of the composite material. The largest discrepancy between the numerical results and previously published data is 7% for the transverse shear modulus. This disagreement is attributed to the assumption of an ideal periodic fibre array in the microstructure.

The second part of this work concerns predicting the highly non-linear behaviour of the composite in shear by including plasticity in the matrix material definition. The non-linear (plastic) behaviour for the matrix material is extracted from previously published tensile test data by tuning the response of the RVE to match the non-linear response obtained experimentally. The effects of matrix plasticity on the shear and tensile behaviour of the composite are analysed. The effect of the matrix plasticity is shown to be significant in predicting the highly non-linear in-plane shear response and also slightly improves the prediction of more linear material stiffness in transverse tension.

References

1: C.T. Sun, R.S. Vaidya, "Prediction of composite properties from a representative volume element", Composites Science and Technology, (56), 171-179. doi:10.1016/0266-3538(95)00141-7
2: ABAQUS, Version 6.6 HKS, Inc., 2000
3: T. Ireman, "Three dimensional stress analysis of bolted single-lap composite joints", Composite Structures, 43: p. 195-516, 1998. doi:10.1016/S0263-8223(98)00103-2

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 88 PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping and M. Papadrakakis Paper 312 The Effect of Matrix Non-linearity on the Properties of Unidirectional Composite Materials for Multi-Scale Analysis A. Keane, C.T. McCarthy and N.P. O'Dowd Composites Research Centre, Materials and Surface Science Institute, Department of Mechanical and Aeronautical Engineering, University of Limerick, Ireland doi:10.4203/ccp.88.312 purchase the full-text of this paper Full Bibliographic Reference for this paper A. Keane, C.T. McCarthy, N.P. O'Dowd, "The Effect of Matrix Non-linearity on the Properties of Unidirectional Composite Materials for Multi-Scale Analysis", in B.H.V. Topping, M. Papadrakakis, (Editors), "Proceedings of the Ninth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 312, 2008. doi:10.4203/ccp.88.312 Keywords: composite materials, numerical homogenisation, micromechanical analysis, representative volume element, periodic boundary conditions. Summary Effective homogenisation procedures can be used to predict the overall response of a composite structure based on the response of a representative volume element (RVE) of the material [1]. In this work, a general homogenisation procedure for unidirectional composite materials is presented. The finite element analysis (FEA) code ABAQUS [2] is used to model a hexagonal RVE of a carbon fibre-epoxy composite material, HTA/6376. Two-dimensional and three-dimensional RVEs of the material are created. The anisotropy of the carbon fibre material is discussed. Periodic boundary conditions are developed and applied to the two- and three-dimensional RVEs. Effective elastic moduli are calculated by examining the relevant stress-strain response of the RVE in a series of tensile and shear loading states. The homogenisation procedure is validated by comparison with previously published experimental data [3]. It is shown that the proposed homogenisation procedure is an accurate method for predicting the overall properties of the composite material. The largest discrepancy between the numerical results and previously published data is 7% for the transverse shear modulus. This disagreement is attributed to the assumption of an ideal periodic fibre array in the microstructure. The second part of this work concerns predicting the highly non-linear behaviour of the composite in shear by including plasticity in the matrix material definition. The non-linear (plastic) behaviour for the matrix material is extracted from previously published tensile test data by tuning the response of the RVE to match the non-linear response obtained experimentally. The effects of matrix plasticity on the shear and tensile behaviour of the composite are analysed. The effect of the matrix plasticity is shown to be significant in predicting the highly non-linear in-plane shear response and also slightly improves the prediction of more linear material stiffness in transverse tension. References 1 C.T. Sun, R.S. Vaidya, "Prediction of composite properties from a representative volume element", Composites Science and Technology, (56), 171-179. doi:10.1016/0266-3538(95)00141-7 2 ABAQUS, Version 6.6 HKS, Inc., 2000 3 T. Ireman, "Three dimensional stress analysis of bolted single-lap composite joints", Composite Structures, 43: p. 195-516, 1998. doi:10.1016/S0263-8223(98)00103-2 purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £145 +P&P)
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