*Article* **Validation of Multiaxial Fatigue Strength Criteria on Specimens from Structural Steel in the High-Cycle Fatigue Region**

**František Fojtík 1,\*, Jan Papuga 2,3, Martin Fusek <sup>1</sup> and Radim Halama <sup>1</sup>**


**Abstract:** The paper describes results of fatigue strength estimates by selected multiaxial fatigue strength criteria in the region of high-cycle fatigue, and compares them with own experimental results obtained on hollow specimens made from CSN 41 1523 structural steel. The specimens were ˇ loaded by various combinations of load channels comprising push–pull, torsion, bending and inner and outer pressures. The prediction methods were validated on fatigue strengths at seven different numbers of cycles spanning from 100,000 to 10,000,000 cycles. No substantial deviation of results based on the selected lifetime was observed. The PCRN method and the QCP method provide best results compared with other assessed methods. The results of the MMP criterion that allows users to evaluate the multiaxial fatigue loading quickly are also of interest because the method provides results only slightly worse than the two best performing solutions.

**Keywords:** multiaxial fatigue; high-cycle fatigue; multiaxial fatigue experiments; S-N curve approximation
