Tufting of carbon fibre epoxy composites for improved damage tolerance

Abstract

Laminated composite structures are susceptible to delamination and debonding during their service life due to their poor out-of-plane interlamellar properties. Such damage can occur either during manufacturing or during service due to foreign body impact. One way to improve the interlamellar properties is to develop these structures by introducing fibre/reinforcements in the Z direction, which can arrest the delamination growth to a large extent. Tufting is one such technique, which is carried out on dry preforms followed by liquid composite moulding for manufacturing of aircraft structural part. Research shows that tufting increases the fracture toughness of about 10 times and also reduces the damage propagation to a large extent. However, tufting reduces the in-plane properties due to damage of fabric yarn during the tufting process. Both in-plane and out-of-plane properties depend on tuft density. The out-of-plane properties increase with the increase in tuft density but in-plane properties decrease with increase in tuft density. In order to have a minimum impact on in-plane properties, tufting parameters were optimized. With optimized parameters, composite laminates were characterized for in-plane and out-of-plane mechanical properties. In-plane mechanical characterization was carried out in room temperature dry (RTD) condition and in elevated temperature wet (ETW) test condition. Specimens for ETW test were conditioned at 71and#8304;C and 85%RH and after saturation, testing of specimens was carried out in the same environmental condition... newline