In the undisturbed area of conventional metallic hydraulic cylinder tubes under inner pressure, the mechanical stress distribution is homogeneous but different in longitudinal and tangential direction for physical reasons. Here, the use of carbon fiber reinforced plastics (CFRP) offers the potential to improve the utilization as well as the power-to-mass ratio in such structures. In the case of multi-axial mechanical stresses in loaded structures, the exploitation of their high orientation dependent specific stiffness and strength is associated with challenges in design and dimensioning. Selective hybridization offers numerous advantages for hydraulic cylinder requirements, especially in high-performance applications such as aviation. Hybrid hydraulic cylinder tubes can already be found in technical applications and are also the subject of research. However, there is little literature on the methods used to design them. For this reason, the authors present a basic method for the development of a lightweight hydraulic cylinder tube in metal-fiber composite hybrid design using selected insights from an aviation research example.
The hybrid design concept is developed in a virtual-physical combined procedure. For this, the hydraulic-functional regions of established metallic hydraulic cylinder tubes can be partially kept as an inner substructure. Externally, CFRP reinforcement is designed and dimensioned in such a way that a high utilization of the overall structure is given. Well-known analytical calculation approaches are useful for pre-dimensioning. Simulation studies on simplified models are used to specify the choice of materials and the geometries of the inner substructures. Depending on the requirements, these investigations are supported by physical experiments on the necessary material data, on the feasibility of manufacture and on mechanics on substructures or scaled models. To validate this engineering process, simulations and tests are performed on a full-scale specimen. The presented method offers a rapid approach for design and dimensioning of CFRP-metal hydraulic cylinder tubes.