Ultra-light drive shaft

Owing to its efficiency enhancing effects, lightweight construction plays an increasingly important role in the design of high performance machines and traffic technology systems. One example of this is the use of ultralight drive shafts in combined fibre composite and metal construction. Fibre composites, as well as being light in weight, demonstrate advantageous mechanical characteristics regarding strength and rigidity in comparison to conventional materials such as steel. This results in a greater degree of freedom when designing components. In order to support constructors in the selection and design of lightweight drive shafts, an innovative design guideline for shaft-hub connections "GWeN" was developed in this project. GWeN is based on comprehensive numerical and experimental investigations. The guideline presents the primary design parameters and the application limits of selected connection types.

Motivation

The lightweight construction of drive shafts made from carbon fibre reinforced plastics (CFK) is a promising field in order to increase the efficiency of high performance machines and mobility systems. These drive shafts are mostly constructed in a combined fibre composite and metal construction and are only half the weight of conventional steel shafts. This method of construction is characterised by cylindrical wavebands made of CFK and load applications made with aluminium or steel materials. The project set itself the goal of developing the design guidelines for these ultralight drive shafts.

Methodology

The starting point of the investigation was the numerical analysis of different form fit dominated connection types. These included parameter studies about pin, bolt and profile connections for different geometric boundary conditions. Static load tests on a newly developed test facility formed the focus of the experimental work. On the basis of simulations and test results, the design statements were derived and the design methodology "GWeN" developed. GWeN shows the primary design parameters for each of the three connection types as well as their application limits, for example, regarding wall strengths or the maximum number of connecting elements.

Result

With the new design guidelines "GWeN", a rulebook is made available for the simple configuration of ultralight drive shafts. It considers the connecting types bolt, pin and profile and can ascertain the effect of different parameter combinations on the load-bearing behaviour of connections. It shows that the connection design of both bolt and profile has little influence on the load-bearing effect. As long as an adequate cross-section of connecting elements is present, a complete load introduction in the fibre-composite pipe is possible. In contrast, there should be as small a cross-section as possible with pins, elements enclosed by fibres. The economic potential of the connecting types is an additional selection criterion. Here, GWeN offers a qualitative statement about suitable connecting technologies with respect to different quantities and application areas.

Documentation

Ultra-lightweight Drive Shafts | High performance drive shafts, ultralight composite construction: New practical design guidelines for highly stressed shaft-hub connections | Project No. 1069 | AiF Funding ID 17085 BR

Themis