Whether car wheels or bicycle pedals - many parts are subject to cyclical loads. While the healthy human heart only reaches a billion of these stresses after 60 years, this is already the case with metallic materials after a much shorter time. Cracks and fractures are often the result. The aim of research at the Institute of Materials Engineering is therefore to minimise the non-metallic inclusions that are known to cause fractures and to increase the purity of the metallic material. One experimental method of determining the service life is ultrasonic fatigue.

This allows the one billion load cycles diagnosed up to a fracture to be realised in less than two days. The material is stimulated to vibrate mechanically at a frequency of 20 kilohertz, i.e. above the human hearing frequency range. With a conventional testing system operating at one hertz, it would take several years to achieve one billion load cycles. The researchers can utilise this improved testing technology at two facilities funded by the German Research Foundation (DFG).

The facilities also enable research to be carried out in a temperature range from room temperature to 700 degrees Celsius. Steels, aluminium alloys, composite and high-temperature materials, as well as nickel-based superalloys, are examined. There is interest in practical tests from gas turbine manufacturers, for which a project with Siemens Energy, MTU, MAN Energy Solutions and Ruhr University Bochum has also been launched in autumn 2023.