This sequence of cycles is called loading time history (see 3.7) and is usually derived from loading measurements performed on components or structures submitted to true service loadings.
Detailed description of service loads recording is relevant to each laboratory or industrial sector and is therefore outside the scope of ISO 12110-1:2013.
The aim of the two parts of ISO 12110 is to set requirements and give some guidance on how to perform a variable amplitude fatigue test in order to produce consistent results for comparison purposes taking into account the typical scatter of fatigue data. Achieving this should help designers to correlate models and experimental data obtained from various sources.
Since ISO 12110-1:2013 involves mainly loading time histories and control signal generation, one expects it might be applied to strain or fatigue crack growth rate controlled loading conditions as well as to force-controlled loading conditions. This is theoretically true but precautions may be taken when applying this document to loading modes other than force-controlled loading mode.
ISO 12110-1:2013 relates to variable amplitude loading under force control mode which corresponds to most of the variable amplitude fatigue tests performed worldwide at the date of publication.
ISO 12110-1:2013 applies to the single actuator loading mode which corresponds to uniaxial loading in many cases.
The variable amplitude loading time histories referred in this document are deterministic; that is why ISO 12110-1:2013 deals with variable amplitude loading instead of random loading.
The following issues are not within the scope of ISO 12110-1:2013 and therefore will not be addressed: constant amplitude tests with isolated overloads or underloads; tests on large components or structures;environmental effects like corrosion, creep linked to temperature/time interactions leading to frequency and waveform effects; multiaxial loading.