THEORETICAL AND EXPERIMENTAL INVESTIGATION OF FAILURE AND DAMAGE PROGRESSION OF GRAPHITE-EPOXY COMPOSITES IN FLEXURAL BENDING TEST

Predicting failure stress and failure modes in composite laminates is very difficult. The choice between failure criteria is complex and the re is a lack of experimental study to validate the results obtained. I n this paper, a theoretical and experimental study of damage progressi on and failure modes of graphite-epoxy laminates in three points bendi ng tests is presented. A quasi-isotropic [(+/-45/90/0)(3)](s) graphite -epoxy composite is investigated. C-scan method and microscopic sectio ning permit to monitor damage progression and failure modes during the experiment. Specimens at different failure levels are used to determi ne damage progression and the effect of geometrical parameters on the successive failures and on failure modes is studied. The progression o f damage has been followed experimentally and identified in detail. Th e theoretical study is based on the classical laminate theory in the c ase of in-plane loads. A software program has been elaborated for post -failure treatment and experimental results are compared with numerica l predictions.