Stress concentrations in hybrid unidirectional fibre-reinforced composites

A fundamental issue in modelling the strength of hybrid composites composed of two fibre types is the stress redistribution after a single fibre breakage. All existing models use severe assumptions for the fibre packings, both for the placement of the fibre centres as the assignment of the fibre type. In the present work, we have used a random packing for the fibre centres, combined with a random assignment of the fibre types. The stress redistribution after a single carbon fibre break in a unidirectional glass/carbon hybrid composites was studied using the 3D finite element models. The glass fibres carry a very high stress concentration, of up to 34% if they are very close to the broken carbon fibre. The stress concentration on the carbon fibre is much lower, with a maximal value of 14%. It was found that the stress concentration factor and ineffective length are independent of the relative amount of both fibres. This means the stress on the carbon fibres is almost unaffected by the presence of the glass fibres.

Publication year:2012

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