Mechanical behaviour of circular and triangular glass fibres and their composites

Single fibre testing of circular (CircGF) and triangular (TriGF) glass fibres of equivalent cross-section has shown the TriGF to have a 25% higher average tensile strength compared to CircGF. Micro-composite compression testing (using resin bonded tows of 12-15 filaments) has revealed the TriGF to have a compression strength 60% greater than CircGF. Some of the increase can be attributed to an effective increase in second moment of area for the TriGF specimens due to imperfect packing. However, allowing for this effect there still appears to be an underlying significant improvement in compressive strength performance attributable to the inherent fibre shape. Mechanical testing under tensile load has shown that the triangular glass fibre reinforced plastic (TriGFRP) performs marginally better (20%) than that manufactured using circular fibre (CirGFRP) for equivalent fibre volume fractions. Similarly, under compressive loading the TriGFRP outperforms CircGFRP by a significant margin of 40%. Interlaminar shear testing has also indicated that TriGFRP may offer a performance advantage of approximately 5%, although this needs further verification to be conclusive.