Fracture Behaviours and Notch Effects of 2D Carbon/Carbon Composites Performing by Bending and Tensile Tests
摘要
The fracture behaviours and notch effects of single-edge-notched (SEN) and double-edge-notched (DEN) 2D carbon fibre reinforced carbon matrix composites (C/Cs) were discussed and compared. The fracture behaviours of DEN and SEN were performed by tensile and bending load-displacement relationships, and the effects of notch depth on notch sensitivity were determined by DEN specimens. The results from mechanical tests indicated that the SEN exhibited a brittle behaviour with linear elasticity, while the DEN exhibited a ductile behaviour with nonlinearity. It was also found that increasing notch depth and decreasing ligament width can lead to a higher ultimate tensile strength of DEN. On the other hand, the digital image correlation (DIC) method and acoustic emission (AE) system were also applied during the mechanical tests to study the local mechanical characteristics of shear damage, strain concentration and fracture behaviour of 2D C/Cs. The results revealed the mechanisms of notch insensitivity and explained the differences in fracture behaviours between SEN and DEN.