Effect of Loading Sequence on the Fatigue Life of Notched Specimens Made From Steel and Aluminium Alloys

Abstract

A statistical parameter which can be derived from the Markov matrix has been defined in order to characterize the intermixture of random loading fluctuations. By means of this intermixture parameter, load sequences for fatigue tests can be generated closer to reality, and thus more reliable effects as well as effects resulting from loading sequences can be taken into account quantitatively in life calculations. The intermixture parameter has been calculated for 17 test load sequences. The corresponding fatigue test results obtained for notched specimens (Ki = 1.4–3.6) made from steels or aluminium alloys, either under bending or axial loading, led to a general relation between intermixture and fatigue life, being primarily influenced by the stress ratio.