Paper number 237

A STUDY OF 0°-FIBRE MICROBUCKLING IN MULTIDIRECTIONAL COMPOSITE LAMINATES

P. Berbinau and C. Soutis

Department of Aeronautics, Imperial College of Science, Technology & Medicine
Prince Consort Rd, London SW7 2BY, UK

Summary

The aim of this work is to study the compression failure mechanisms in multi-directional CFRP composite laminates with internal 0°-plies. In such laminates, as in uni-directional 0° laminates, catastrophic failure initiates by kinking of 0°-plies at the free-edges or manufacturing defects. T800/924C carbon fibre-epoxy laminates with a [+-theta/02)2]s lay-up with theta equal to 30°,45°,60° or 75° are used here to study the effect of the supporting ply angle theta on the stress initiation of 0°-fibre microbuckling. Experimental compressive strengths are compared to theoretical predictions obtained from a fibre kinking model that incorporates interlaminar shear stresses developed at the free edges at (0/?) interfaces. Initial misalignment of the fibres and non-linear shear behaviour of the matrix are also included in the analysis. Interlaminar stresses do not appear to have a significant influence on fibre microbuckling initiation and on the static compressive strength of the laminates.

Keywords

composite laminates, compression, microbuckling, kink bands, interlaminar edge stresses, compressive strength.