BENDING FAILURE OF ARAMID FIBER-REINFORCED COMPOSITE

Flexural failure of a unidirectional aramid SVM/epoxy composite was st udied using two-point loading of half-ring specimens. Failure originat ed near the compressive side of the specimen where several intersectin g shear yield bands, similar to slip bands in metals, were observed. T he angle between the yield bands and the loading direction was 45 +/- 2 degrees. The thickness of the yield bands grew proportionally to the shear displacement of their opposite sides. The yield stress of the S VM fibres in bending was equal to 500 MPa, which is close to the fibre strength in pure axial compression of 400-450 MPa. The maximum failur e stress of the composite in bending, 530 MPa, was approximately twice as high as the strength of the composite under pure axial compression (260-280 MPa). In bending the composite is elastic in the tensile par t of the beam whilst the other, compressed, part is elastic-plastic.