On the mechanical performance of noncrimp fabric H-shaped adhesively bonded joints

Adhesive bonding is contemplated as an alternative method to mechanical fastening for joining composite aerostructures. Ongoing research in this area is focused on the development of new bonding techniques and joining elements. In this article, the mechanical performance of the novel noncrimp fabric (NCF) H-shaped adhesively bonded joints subjected to tension, shear and four-point bending loading conditions was investigated by both experimental tests and numerical modeling. The H profiles were manufactured by employing the preforming and injection molding methods, while bonding of the assembled parts was carried out using a novel stepwise procedure which leads to a high bonding quality. Investigation was conducted by means of mechanical testing and a mesomechanical model based on the FE method and the progressive damage modeling approach. In the model, both adhesive failure (debonding) and failure of the NCF material is considered. In the tension and shear load cases, the joint failed due to extensive debonding attributed to adhesive shearing, while in the four-point bending load case, due to failure of the H element. In all three load cases, the experimental and numerical results compare well thus, providing establishment of the numerical model in simulating the performance of textile structural parts. Finally, the effort presented herein is rated as successful since new adhesive bonded joints of high mechanical performance are proposed.