Design of end terminations for textile tension members involving biological functional principles

• Applicants: Dr.-Ing. Christoph Müller, since 8/2016; Professor Dr. Hartmut Witte
• Subject Area: Engineering Design, Machine Elements, Product Development ; Automation, Mechatronics, Control Systems, Intelligent Technical Systems, Robotics
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 260206766

In modern engineering, ropes are used as load handling devices and tension members to fasten loads or in hoisting and conveying machinery. In most of the applications, steel wire ropes are applied because of their advantage of parallel load bearing elements and the resultant, redundant structure, which does inhibit abrupt failure as this can e.g. happen in chain drives. Tension members made from high-strength polymer fibers do offer an advantage of low density, compared to steel wire ropes with a similar structure. This results in higher breaking lengths and opens up the possibilities of higher hoisting heights. Additionally, the bending stiffness of polymer fiber ropes is significantly lower than at steel wire ropes, what does reduce the power demand for bending around sheaves and also results in the possibility of applying smaller bending radii. Furthermore, fiber ropes are much easier to handle than steel wire ropes are. Focusing safety-related applications, e.g. in conveying engineering, these properties are not utilizable, despite their high economic potentials and their availability for many years, because there are no valid standards and rules for dimensioning available. Further on, fundamental knowledge and experience for integrating fiber ropes in machinery and equipment is missing. Common knowledge on end terminations has mainly been carried over from steel wire rope applications. Due to the high susceptibility of polymer fibers to compressive loads and their propensity to kinking and creeping, these systems of setting up end terminations cannot automatically be applied to textile tension members and traction mechanisms. This being the case, it is important to force research with a hard focus on end terminations and widely spread solutions.With the aid of functional analogies of load bearing structures in organisms, solutions that enable safe transmission of tensile forces under the stipulation of the means of textile technology are to be indentified and tested, based on the mechanical system of non-rigid tension members combined with rigid, load carrying, solid bodies. Within a bionic approach, specific recommendations for a durable end termination can be observed. In organic substrates at multi-cellular organisms, gradual changes in properties can be found as a mechanism of equalization of stress over the whole cross section and attenuation of impact loads, but also as a kind of customized form of end terminations. Beside the known tendon-bone-connection, further biological objects and principles are taken into account. Based on this, appropriate structures for the areas of force transmission are to be ascertained. Parameters of influence, e.g. material composition and textural design, are verified experimentally and metrologically. Mechanically effective structures that are fitting the technical purpose are to be identified and to be turned into model systems for verification of the working hypotheses.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Dr.-Ing. Markus Michael, until 8/2016