Suppression of compression induced delamination in tapered laminated composites using a ply scarfing method

Thickness tapering of composite laminates is a common strategy for efficient and lightweight composite structures. The termination of specific plies necessary to achieve such tapering is well known to introduce sites for delamination initiation in laminates. This propensity for delamination is highly dependent on the thickness of the terminated ply, which presents a significant challenge in using thicker materials to improve the production rate of large-scale composite structures. In this work, the effectiveness of ply scarfing in improving the compressive failure stress of tapered laminates made using thick, unidirectional non-crimp fabrics (NCF) was experimentally investigated for the first time. Unidirectional tapered laminates were manufactured using two different NCFs with fibre areal weights of 620 and 1070 g/m(2) via resin infusion. Specimens made of the 1070 g/m(2) material which incorporated a ply terminated using the ply scarfing method were compared with those including plies terminated using the con-ventional ply-drop method. which incorporated a ply terminated using the ply scarfing method. The compression failure behaviour of the specimens was analysed using a high-speed camera. The results showed that ply scarfing suppressed delamination of the belt plies under compression and increased the failure stress by similar to 60%. Furthermore, the tapered geometry of the terminated ply's end was effective in preventing the void entrapment at the ply drop and significantly reducing the manufacturing variability.

Automated summary

Thickness tapering is a common strategy for efficient and lightweight composite structures, but it can introduce delamination sites. This study investigated the use of ply scarfing method to improve the compressive failure stress of tapered laminates made from thick unidirectional non-crimp fabrics. The results showed that ply scarfing suppressed delamination and increased the failure stress by 60%.