Verification of the method of equivalent amplitude determination based on two - parameter fatigue characteristic

UTP University of Science and Technology in Bydgoszcz, Faculty of Mechanical Engineering, al. Prof. S. Kaliskiego 7, 85-796 Bydgoszcz, Poland

^* Corresponding author:karolina.karolewska@utp.edu.pl

Abstract

In the most causes the loads which are affected on structural components are various over time and their character changes is stochastic. The stochastic character of operational loads of construction elements in various machine types is depended on many factors, included : work forces variability, environmental conditions, physical properties of components etc. Fatigue life calculation for this type of loads are conducted on the basis of determined sinusoidal cycles set through to use of the cycles counting method. The cycles which are contained to the sinusoidal cycles set are characterized by extensive range of amplitude Sai variation and mean values Smi. Application of Sa-N curve in fatigue life calculations caused disregard of the cycle mean value. This may affect the accuracy of calculations. Taking into account the cycle mean value Sm in the calculations may be realized by determining a substitute cycle with an average value Sm=0 and a substitute amplitude Saz≠Sa.