FATIGUE PROCESS STAGESoFrom the design applications point of view the main engineering interest in the fatig!e properties lies in the "high#c$cle" region% o&owever there are man$ instances where the so#called 'load c$cle" is ver$ slow( which ma)es the emplo$ment of fatig!e properties in the low c$cle region feasi*le to achieve the desired design e+cienc$% o,hen onl$ a short service life is re-!ired the low#c$cle fatig!e data can advantageo!sl$ *e emplo$ed U.IA/IA0 FATIGUE STRE.GT& U.1ER A0TER.ATI.G STRESSThe fail!re of the railwa$ a2les initiated the 3rst orderl$ approach to the nat!re of s!ch fatig!e fail!res with alternating stress form%Seeing the inade-!anc$ of the classical approaches, ,4hler designed the 3rst 5rotating *ending6 fatig!e tester to determine the fatig!e strength of the a2les of the railwa$ cars%There are di7erent t$pes of fatig!e testing methods8machines regarding the anal$sis of the fatig!e properties of materials9% rotating *ending is the most widel$ !sed method of testing:% alternating *ending is another t$pe of testing method;% a2ial loading