Design and optimisation of composite spatial frame connectors

Demands of the market and current mindset of nowadays engineers are to create vehicles as efficient and eco-friendly as possible. In the automotive industry, one of the ways to achieve that is a reduction of the support structure weight. The solution that was derived from aerospace industry is monocoque support structure. Nevertheless, proper design of such structure is challenging, expensive, especially in unit production and hard to repair or modify in case of new subassemblies. An alternative solution for vehicle lightweight support structure is spatial frame created from carbon fibre reinforced composite tubes. A problem of such structure, in case of laminate composite materials, are the tubes connections. In classical aluminium spatial frame connections are welded, and therefore their strength is close to the material strength. In case of carbon fibre, such connections are usually created using adhesives, connecting carbon fibre reinforced tubes with composite shaped connectors or by precise cutting of the ends of tubes in order to increase area of contact between interfaces, applying adhesive and bounding tubes using composite materials. Another considered solution is carbon fibre tubes reinforced with 3D printed ribbing. Both analysis and optimization were conducted using HyperWorks software. The paper presents a novel approach to composite structures connectors optimization.