TABLE OF CONTENTS The objective of this chapter is to present the key fatigue testing methods that are developed either to compare materials and fabrication processes or to obtain necessary data to predict fatigue life. Strict application of these methods allows us to accurately take into account the effects of the numerous parameters, which influence the behavior of materials and mechanical components.
If the amplitude and number of periodical loads are sufficient, they lead to progressive cracking and eventually to failure by fatigue. Generally, failure occurs suddenly, without precursory elongation, and the fracture surface presents a smooth zone, the fatigue fracture itself, and a fibrous or brittle fracture zone, which corresponds to the final instant rupture. Failure can occur for applied stresses lower than the tensile strength and even the proof strength. Generally, the term fatigue is used to denote the cause of this failure in service, and the term endurance for the capacity to resist fatigue. General recommendations concerning the terms used and the presentation of the results of the tests are given in standards [NFA 400].
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The objective of fatigue tests is to determine the behavior of test pieces, parts or mechanical structures, under periodical loadings, simulating those which, in practice, are experienced in service. Tests on parts or mechanical structures generally correspond to one of the following three objectives [RAB 00]:
to check the conformity of a product to a standard or specification;
to validate or optimize a...
