Multi-scale modelling of the effect of a viscoelastic matrix on the strength of a carbon fibre composite

Abstract

A recently developed multi-scale model has proven successful in predicting the tensile strength of a unidirectional fibre composite from fundamental molecular inputs. This technique is now extended to subtle changes in the properties of the matrix. The chemistry of the resin matrix is varied on the functional group level resulting in a series of stress–strain profiles predicted using group interaction modelling. The transfer of strain as the result of a fibre break in the composite is modelled using finite element methods. The resulting characteristic ineffective lengths and strain concentration factors are incorporated into a statistical simulation of the propagation of fibre failure events in a typical composite. This allows the prediction of ultimate tensile strength for a composite containing a yielding and non-yielding matrix phase.

Keywords:

• epoxy resin
• composite material
• modelling
• strength

Acknowledgements

This work was carried out as a part of the Weapons and Platform Effectors Domain of the UK MoD Research Program. EPSRC is thanked for the funding of the Ceramics and Composites Laboratory.