Evaluation of the application potential of non-destructive measurement methods for the characterisation of cyclic deformation behaviour in high-frequency fatigue tests

• Applicant: Professor Dr.-Ing. Peter Starke
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 538354247

The weight-optimised component design and the resulting estimation of the fatigue life of metallic materials require a comprehensive understanding of the fatigue processes and the systematic investigation of the cyclic deformation behaviour. For reasons of time and cost alone, many components can neither be built as prototypes nor tested as such under operating conditions. In order to reduce the time and costs within the scope of the provision of S-N curves, various fatigue life prediction methods (LPV) can be used, which have been developed in recent years at the Department of Materials Science and Materials Testing at the University of Applied Sciences Kaiserslautern, among others. The basis of these methods is the process-oriented consideration of the fatigue process by means of predominantly non-destructive testing methods. The information derived from this thus serves on the one hand as input variables for the LPV and also enables the comprehensive characterisation of the fatigue behaviour and the description of the damage development in materials, specimens and components. Within the scope of this research project, the application potential of different measuring methods (thermometry: IR camera, thermistors, thermocouples; resistometry: direct current measurement) during higher-frequency fatigue tests on a resonance pulsator is to be tested and validated using the example of the quenched and tempered steel SAE 4140. In addition to the general applicability, a quantification of which measurement technique can detect the fatigue processes with the best possible resolution and selectivity is to be carried out. In order to be able to consider as wide a range of influencing factors as possible in the project, a total of three important influencing parameters are systematically regarded in the investigations. In addition to the frequency influence demonstrated at three frequencies, the size influence of the specimens and the influence of notches will be taken into account. Due to the planned investigations on different specimen geometries, a possible heating of the specimen and thus an overlap with the fatigue life extension due to an increased measuring frequency will be considered. In particular, the differentiation between notched and unnotched specimens is of great technical importance. The application of non-destructive testing methods on notched specimens enables a transfer of the data obtained here into new fatigue life prediction methods and thus represents an important step towards an accelerated determination of component S-N curves.

• DFG Programme: Research Grants