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Low
Cycle Fatigue to
ASTM E466, E606 & BS 3518 gives fully flexible recording and display of
hysteresis loop
 
Low cycle fatigue
is associated with high strain fatigue where a fatigue cycle incorporates a
component of cyclic plastic strain.
Fatigue failure
generally occurs in a relatively small number of fatigue cycles, typically
a few thousands of cycles, compared with hundreds or thousands or millions
of cycles in normal fatigue failure.
The fatigue cycle
may be load, extension, stress or strain controlled or a mixture of these
modes. Frequently, dwell periods are incorporated as part of the fatigue
cycle and these may be from some seconds to many hours duration.
Cycle rates for low
cycle fatigue are normally less than 1 Hz. Low cycle fatigue is generally
conducted at elevated temperatures between 200°C to 1100°C.
Sophisticated data
capture techniques are required to minimise the quantity of data collected
whilst retaining the integrity of the test. Critical cycles are analysed to
determine stress and strain components.
The most common
specimens used in LCF testing are:
·
Hour glass
·
Parallel-sided, plain or ridged
·
Common cross-sections including: round or tubula
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