Fatigue Testing at 1000 Hz Testing Frequency

Abstract

In 2014 RUMUL could present a new resonant fatigue testing machine, with a testing frequency of 1000 Hz. The dynamic load of maximum 50 kN peak-peak is produced with an electromagnetic system. Similar to established resonant systems which run on testing frequencies from about 40 up to 250 H. The static portion of the load is provided by a mechanical spindle, the maximum load of the system is ±50 kN. Any load ratio can be selected. Flat and round specimen types that are normally used in fatigue testing can be used. The new testing machine offers new possibilities for investigations of material properties in the very high cycle fatigue (VHCF) regime. Compared to other systems used in the field of VHCF testing the RUMUL GIGAFORTE provides several advantages. The size of the machine is smaller and energy consumption less compared to a servo hydraulic system. The actually tested material volume is larger than the material volume that is tested on ultrasonic systems. The testing frequency of 1000 Hz allows normally continuous testing, without stopping for cooling down the specimen. In the past three years the new testing machine was intensively used for example at the laboratory of the Fraunhofer institute IWS Dresden in Germany. Effects of the 1000 Hz testing frequency on the fatigue behaviour of the material were observed. This talk shows some example of heating up of the specimen related to the 1000 Hz testing frequency and highlights some of the found frequency related effects on fatigue strength.