EFFECT OF VOIDS ON FAILURE MECHANISMS IN RTM LAMINATES

Most studies on the effects of voids aim for determination of the rela tionship between void content and the fracture property of interest. T he effect of voids on the mechanisms of transverse failure was therefo re investigated for predominantly unidirectional resin transfer moulde d laminates of glass-fibre-fabric/vinyl-ester. Laminates with the high est average content of voids had a transverse strain to failure as hig h as 2% whereas low void content laminates failed at 0.3%. Only a few large and well-defined transverse cracks formed in low void content la minates before final failure. Multiple transverse cracks with irregula r shape as well as numerous smaller cracks formed in the high void con tent laminates. The irregularity of these cracks resulted in lower str ess concentration and stress level in the small amount of weft bundles orientated in the loading direction. A simple model was developed in order to demonstrate this and explain the high strain to failure of hi gh void content laminates.