Low Cycle Fatigue
Low Cycle Fatigue (LCF) describes the service environment of many critical (and
primarily metal) components: low frequency, large loads/strains. The LCF environment
is typical of turbine blades (heat-up/cool down cycling) and other power generation
equipment subject to thermal and/or mechanical cycling (ie. pressure vessels, piping,
etc.) LCF typically involves large deformations, thereby accumulating damage on
the specimen. LCF research is essential for the understanding of failure (in metals),
for design and engineering purposes.
High Cycle Fatigue
High Cycle Fatigue (HCF) results from vibratory stress cycles at frequencies which
can reach thousands of cycles per second and can be induced from various mechanical
sources. It is typical in aircraft gas turbine engines and has led to the premature
failure of major engine components (fans, compressors, turbines). While LCF involves
bulk plasticity where stress levels are usually above the yield strength of the
material, HCF is predominantly elastic, and stress levels are below the yield strength
of the material.