Modelling of high cycle fatigue strength and cyclic crack propagation behaviour of steelsIEHK
Within the RFCS project “Freqtigue” a material database of different steel grades for the automotive industry with fatigue parameters and crack growth data is generated for testing frequencies ranging from 25 to 20 000 Hz. The use of ultrasonic testing equipment allows the determination of fatigue parameters in the ultra-high cycle fatigue regime with several billions of cycles leading to information in a reasonable time for the component assessment of a lifetime of not less than a century. One focus here is the modeling of the service life under cyclic loading with commercial calculation software. For this purpose, a bridging approach is used. With the use of several representative volume elements of the microstructure and a crystal plasticity constitutive model, local plasticity and thus material damage can be calculated depending on the microstructure. The approach takes the statistical spread of these indicators into account. With this approach fatigue parameters can be calculated as well as the lifetime predicted.