EXPERIMENTAL ANALYSIS OF CROSSING WARP EFFECT ON IN-PLANE AND OUT-OF-PLANE TENSILE BEHAVIOUR OF 3D WOVEN COMPOSITE T-JOINTS
Topic(s) : Material science
Co-authors :
Ziyue WEI (UNITED KINGDOM)Abstract :
Composite T-joints have overtaken the role of conventional T-joints in the manufacture of marine shells, aircraft wings and wind turbine blades to take responsibility for transitioning of in-plane and out-of-plane load and improvement of structural strength. A long-standing issue for composite T-joints is that the junction is susceptible to delamination failure. From the structural viewpoint, the junction of the T is the region of the highest stress concentration because this area witnesses the transfer of tensile and flexural loads. If circumstances arise in which composite T-joints are reinforced by 2D laminates or 3D reinforcements with simple weave structures, it is inevitable to create an empty void at the T junction. This void occurs because of reinforcements bending to the 3D T shape, which is usually filled with resin during the composite manufacturing process. Therefore, in the absence of reinforcing fibres in the stress concentration area, the junction of composite T-joints is seriously prone to delamination.
To address this problem, 3D woven reinforcements become interested in the manufacture of composite T-joints as their advantages of the continuous fibres aligned in the through-the-thickness direction. In this research, 10 types of crossing warp architectures based on the use of 3D woven orthogonal structures were designed and engineered into the 3D woven composite T-joint to understand the effect of weave architectures on mechanical performance and optimising the 3D woven architectures. The assessment of the mechanical behaviour was carried out by tensile testing in the in-plane and out-of-plane directions under quasi-static conditions. The increase in tensile behaviour of composite T-joints was found in the testing due to the introduction of the crossing warp architectures. Resistance to the delamination of the composite T-joints witnessed an increase as more warp yarns from the web were arranged to cross into the flanges. To further understand the influence of the 3D weave architectures on the mechanical performance of the composite T-joint at the micro level, the internal and external crossing warp were characterised and their effects were compared. It was found that regardless of the crossing warp proportions, the external crossing warp led to a higher in-plane performance for the composite T-joint than the internal crossing warp. By contrast, the internal crossing configurations resulted in better out-of-plane behaviour for the composite T-joint than its external crossing counterpart.
To address this problem, 3D woven reinforcements become interested in the manufacture of composite T-joints as their advantages of the continuous fibres aligned in the through-the-thickness direction. In this research, 10 types of crossing warp architectures based on the use of 3D woven orthogonal structures were designed and engineered into the 3D woven composite T-joint to understand the effect of weave architectures on mechanical performance and optimising the 3D woven architectures. The assessment of the mechanical behaviour was carried out by tensile testing in the in-plane and out-of-plane directions under quasi-static conditions. The increase in tensile behaviour of composite T-joints was found in the testing due to the introduction of the crossing warp architectures. Resistance to the delamination of the composite T-joints witnessed an increase as more warp yarns from the web were arranged to cross into the flanges. To further understand the influence of the 3D weave architectures on the mechanical performance of the composite T-joint at the micro level, the internal and external crossing warp were characterised and their effects were compared. It was found that regardless of the crossing warp proportions, the external crossing warp led to a higher in-plane performance for the composite T-joint than the internal crossing warp. By contrast, the internal crossing configurations resulted in better out-of-plane behaviour for the composite T-joint than its external crossing counterpart.