Contribution to the introduction of torsional moments in highly stressed fiber composite drive shafts

• Applicant: Professor Dr.-Ing. Helmut Schürmann
• Subject Area: Lightweight Construction, Textile Technology ; Engineering Design, Machine Elements, Product Development
• Term: from 2014 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 267625657

Shafts are a perfect application for lightweight design using fiber-polymer-composites. The primary challenge is the design of the load introduction at the shaft ends. A number of solutions are known. The lengthwise press fit fulfills both requirements: it is best in weight and suitable for series production. At the institute Konstruktiver Leichtbau und Bauweisen theoretical and experimental investigations have been carried out. The stress distribution during the lengthwise press fit assembly and during torsional load of the shaft were analytically specified, the design parameters can directly be used by the design engineers. However, important details which are crucial for an appropriate layout are still missing. In addition, many approaches to optimize driveshafts have not been worked on.The most important unanswered questions will be addressed in this research project. The micro-toothing of the longitudinal press fit joint has a critical effect on the lightweight grade. Its optimization is the most urgent aim, primarily the most suitable tooth geometry and the number of teeth around the circumference have to be worked out. Monitoring the depth of penetration of the teeth into the laminate is to picture the extent of fiber damage and its influence on the strength of the shaft. If the hub is fitted from the outside onto the driveshaft, a pillar ring must be attached to the inner driveshaft radius. The fibers of this pillar ring will be stressed by longitudinal compression stresses. To avoid stability failure, reliable solutions have to be developed. High torque loads induce high press forces, due to the larger press fitting needed. It is essential that measures are taken to minimize the amount of force needed to join the lengthwise press fit. The superior goal is to develop design guidelines for composite design engineers, providing them with the necessary data to develop lightweight longitudinal joints able to transfer maximum torsional moments.

• DFG Programme: Research Grants