Issue 37

M. Margetin et alii, Frattura ed Integrità Strutturale, 37 (2016) 146-152; DOI: 10.3221/IGF-ESIS.37.20 146 Focussed on Multiaxial Fatigue and Fracture Multiaxial fatigue criterion based on parameters from torsion and axial S-N curve M. Margetin Slovak university of technology, Faculty of mechanical engineering, Slovakia R. Ďurka VAKUUMTECHNIK s.r.o., Slovakia V. Chmelko Slovak university of technology, Faculty of mechanical engineering, Slovakia A BSTRACT . Multiaxial high cycle fatigue is a topic that concerns nearly all industrial domains. In recent years, a great deal of recommendations how to address problems with multiaxial fatigue life time estimation have been made and a huge progress in the field has been achieved. Until now, however, no universal criterion for multiaxial fatigue has been proposed. Addressing this situation, this paper offers a design of a new multiaxial criterion for high cycle fatigue. This criterion is based on critical plane search. Damage parameter consists of a combination of normal and shear stresses on a critical plane (which is a plane with maximal shear stress amplitude). Material parameters used in proposed criterion are obtained from torsion and axial S-N curves. Proposed criterion correctly calculates life time for boundary loading condition (pure torsion and pure axial loading). Application of proposed model is demonstrated on biaxial loading and the results are verified with testing program using specimens made from S355 steel. Fatigue material parameters for proposed criterion and multiple sets of data for different combination of axial and torsional loading have been obtained during the experiment. K EYWORDS . Fatigue; Multiaxial; S355, Criterion, Material properties. I NTRODUCTION atigue life time prediction plays an important part in mechanical equipment design, regarding operating safety as well as equipment's reliability and economical design. The ongoing increase of machines' operating parameters and the pursuit of both effective material use and operating reliability make the analysis of fatigue process significant in the area of constructions' mechanical endurance calculation. The critical point of a construction that determines the life time of the whole equipment is often localized on a component that is exposed to a complex loading of external forces. Whether it's high-pressure piping systems [1] or F