Element's materials testing laboratories provide ASTM E466, which is the standard practice for conducting force controlled, constant amplitude axial fatigue tests of metallic materials. The specification is typically applied to high cycle fatigue tests of 1,000,000 or more cycles. This methodology is useful when studying materials that are subjected to primarily elastic strain.
High cycle fatigue testing to ASTM E466 is performed on an axial fatigue testing machine with a force-monitoring system. The subject material is first machined and longitudinally polished or ground into cylindrical or flat test specimens with a uniform or hourglass gage section. Alignment of the machined specimen is crucial, and Element's Engaged Experts perform verification prior to beginning a test. Samples are typically tested at frequencies ranging between 20Hz and 100Hz, depending upon material types and environmental conditions.
Testing continues until specimen failure or until a predetermined number of cycles is reached. If an S/N curve is desired, Element tests multiple specimens at varying applied forces to create sufficient data points for the curve.
ASTM E466 also suggests several items to include in high cycle fatigue test reports, including:
- Objective of Testing
- Description of material and specimens
- Test environment and conditions
- Results in tabular format
- Maximum stress (psi)
- Maximum force (lbs)
- Total number of cycles
- Reason for test termination
- S/n graphical depiction