Design and numerical analysis of shaped connection made of CFRP

Project BloStEr (Block Structures - Mechanical joining innovations to replace conventional fasteners in aerostructures) is being realized within consortium between PZL Mielec and research partner Lublin University of Technology. In the project, a new approach for mechanical assembling of thin - walled structures is being realized by developing geometry of shaped connections for joining different materials. The scope of work cover 3 configurations of joints: metal + metal (aluminum alloys), metal + composite (hybrid) and composite + composite. The main idea is to eliminate or reduce connecting elements like rivets, screws, adhesives, or welding. The design of this approach required these mechanical connections to be analyzed using FEM (Finite Element Method) tools and verified numerical models in laboratory tests. In parallel with the design task the technology limitations have been studied for manufacturing of thin-wall integral elements made of carbon woven composites using autoclave technology, dedicated tooling and appropriate polymerization parameters. A critical element is the achieving the desired shape accuracy to get optimal connection properties.