Element's materials testing laboratories provide testing to ASTM E606, the standard test method for strain-controlled fatigue testing. This specification is typically used for low-cycle endurance testing, where components are subjected to mechanical cyclic plastic strains that cause fatigue failure within a short number of cycles.
Low cycle fatigue testing is performed using a tension-compression endurance testing machine. The subject material is first machined and longitudinally polished or ground into cylindrical or flat test specimens with a uniform-gage section. The samples are then loaded into the test frame and subjected to a repeated stress under a constant strain rate in accordance with ASTM E606. Extensometers are used to control strain range by measuring deformation in the gage section of the specimen.
Typical low cycle fatigue tests are targeted to run no more than 100,000 cycles. Test frequency typically ranges between 1Hz and 5Hz, depending on material and requirements. By testing multiple specimens at varying strain levels, S/N or strain-life curves can be developed for the material. ASTM E606 recommends testing at least 10 samples to gain statistical confidence in strain-life curves.
ASTM E606 also outlines reporting requirements for strain-controlled fatigue testing, which includes:
- Objective of Testing
- Description of material and specimens
- Test environment and conditions
- Initial, stabilized, or half-life values
- Cyclic strain range
- Number of cycles to failure
- Mode of failure
Element has the unique capabilities required to provide a comprehensive low cycle fatigue testing solution, from raw material blanking and specimen machining to precision data acquisition and reliable, comprehensive test reports.