Phenomenology and Experimental Parameters

It has to be expected, and must be recognized, therefore, that three principal mechanisms may contribute to fatigue failure thermal softening, excessive creep or flow, and/or the initiation and propagation of fatigue cracks. 

The experimental parameters of a fatigue test have been aptly defined by Andrews [126]  

More recently the (computer-programmed) random loading has also found growing application in testing structural components [132]. Of course, the above parameters can be combined in different ways and be changed within a test. They partially depend upon each other and on environmental conditions. 

The experimental equipment will not be described here, the reader is referred to the cited review articles or pertinent research papers (e.g. 132—138), In practice five different types of stress-strain control are employed which are classified by Andrews [126] and Manson et al. [127] as  

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