In contemporary society, weight-reducing and durable components made of lightweight materials and composites are of great importance. Non-engaging, flexible shaft couplings are used if misalignments can occur between two shafts. The flexibility of the shaft coupling is often allowed by several individual compensating elements. There are great opportunities for shaft couplings made of fiber reinforced polymers (FRP).
This paper deals with the experimental investigation of the design concept for a non-engaging bellows coupling made of prepreg-based carbon fiber reinforced polymers (CFRP). The main task of this shaft coupling is the torsionally stiff transmission of torque and rotational energy as well as the compensation of axial and angular misalignment of the connecting shafts. The presented design concept combines the fulfillment of the compensation and connection functionality. On the one hand a high torsional stiffness and on the other hand a certain flexibility of the entire shaft coupling geometry are required due to the connection of two torsion-loaded structures. Different lay-up strategies based on a woven fabric prepreg were developed in order to achieve a composite-appropriate drapability of the bellows-shaped compensation structure. Draping experiments were performed over on a double-curved mold. Fabrication parameters such as cutting sizes, local shear angle deviations and wall thicknesses were recorded and analyzed. Cylindrical test specimens were defined for a separate examination of the CFRP metal interface. In order to check the design concept for fulfilling the connection functionality, the slipping torque of the shaft-hub joint was determined via a static torsion test rig. With a new and reusable core system a demonstrator of the CFRP bellows coupling was produced. Due to an adapted production and process technology, the geometry of the compensation structure can be reproduced more precisely than with the existing core system.