Influence of fibre weight fraction on failure mechanisms of poly(ethylene terephthalate) reinforced by short-glass-fibres
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Failure mechanisms of short-glass-fibre reinforced poly(ethylene terephthalate) were investigated with particular attention to the effects of fibre weight fraction (Wf=1 wt%, 30 wt% and 60 wt%). A fracture morphology study was carried out for the surface and for the interior of uniaxial tensile specimens. On the surface, tensile cracks occurring mostly at the fibre ends seemed to be more influential in catastrophic fracture initiation with decreasing Wf. However, the failure mechanisms in the interior were different from those on the surface. For specimens of low Wf (1 wt%), shear bands grew around the fibre ends. A “specific layer” was formed in the matrix along the fibre-matrix interface and shear cracks propagated near the interface in the fibre length direction. The fibre pull-out from the matrix as well as the voiding at the fibre ends, induced by the shear cracks, had strong effect on the fracture initiation. For intermediate and higher Wf (30 wt% and 60 wt%), the shear-band induced cracking near the interface caused matrix shear cracking which was the most influential factor in the fracture initiation. The shear failure in the interior almost dominated the fracture processes throughout the specimens.
KeywordsShear Band Shear Crack Failure Process Fracture Initiation Ethylene Terephthalate
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