BS ISO 12110-1:2013 - Page 2

Metallic materials. Fatigue testing. Variable amplitude fatigue testing. General principles, test method and reporting requirements | Status: Current, Confirmed

1 Scope This part of ISO 12110 establishes general principles for fatigue testing of laboratory specimens under a sequence of cycles the amplitude of which varies from cycle to cycle. 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 this part of ISO 12110. 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 this part of ISO 12110 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 part of ISO 12110 to loading modes other than force-controlled loading mode. This part of ISO 12110 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 of this part of ISO 12110. This part of ISO 12110 applies to the single actuator loading mode which corresponds to uniaxial loading in many cases. The variable amplitude loading time histories referred in this part of ISO 12110 are deterministic; that is why this part of ISO 12110 deals with variable amplitude loading instead of random loading. The following issues are not within the scope of this part of ISO 12110 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.