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Low cycle fatigue (LCF) is low-cycle endurance testing, where components are subject to mechanical cyclic plastic strains that cause fatigue failure within a short number of cycles. ºÃÉ«TV provides testing to several industry specifications including ASTM E606, the standard test method for strain-controlled fatigue testing.

Fatigue testing can predict how a material will wear and react throughout its life, or in a high-stress environment. Low cycle fatigue is useful for simulating specific scenarios and investigating real-world failures.

What is the difference between HCF and LCF fatigue? 

High cycle fatigue (HCF) uses a low force load over a large number of cycles to cause failure. This generates an SN (stress/number of cycles) curve, which predicts how it will wear over time. In contrast, low cycle fatigue (LCF) uses high levels of force over a smaller number of cycles to stimulate a high-stress environment that might cause a more immediate break. This is measures with a strain vs. life curve. 

Low cycle fatigue (LCF) test procedure per ASTM E606

Before testing, 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 a tension-compression endurance testing machine and subject to 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 ranges between 0.25 Hz and 5 Hz, 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 ten samples to gain statistical confidence in strain-life curves.

Fast, accurate LCF testing to a wide range of standards

ºÃÉ«TV offers LCF testing to a range of standards, including: 

ASTM International 

• ASTM E467, ASTM 606

British Standards

• BS 7270

General Motors Specifications 

• GMW16704, GMW16705

International Organization for Standardization 

• ISO 12106