THE EQUIVALENT STRESS CONCEPT IN MULTIAXIAL FATIGUE
DUMITRU ION 1, KUN LORAND 1, DREUCEAN MIRCEA 2, MENYHARDT KAROLY 3 1. Strength of Materials Department, Mechanical Engineering Faculty, “Politehnica” University of Timisoara, Mihai Viteazul Blvd. 1, 300222 Timisoara, Romania
2. Mechatronics Department, Mechanical Engineering Faculty,“Politehnica” University of Timisoara, Mihai Viteazul Blvd. 1, 300222 Timisoara, Romania
3. Mechanics and Vibrations Department, Mechanical Engineering Faculty,“Politehnica” University of Timisoara, Mihai Viteazul Blvd. 1, 300222 Timisoara, Romania
Some equivalent stress methods, applicable for life prediction in case of multiaxial loading, are presented in this paper, such as empirical equivalent stresses, frequency and “signed von Mises” stress. To apply the latter method, a calculation program that allows the transformation of a fluctuating load cycle into a fully reversed cycle is developed. The authors extend the equivalent stress concept towards critical plane models. This is illustrated by a calculated equivalent shear stress based on the Yokobori criterion. Both the „signed von Mises” and Yokobori approaches have the advantage of allowing multiaxial fatigue calculations for limited durability, as opposed to classical methods which are applicable only for unlimited durability.
