Definitions
Endurance Limit
As the alternating stress gets smaller, the material can take more stress
cycles before it fails due to fatigue. The endurance limit is the highest
alternating stress that does not result in fatigue failure. In other words,
if the alternating stress is equal to or lower than the endurance limit,
the number of stress cycles to cause failure becomes very large (practically
infinite). The endurance limit is usually defined for zero-mean alternating
stresses. The endurance limit is also called the fatigue limit. Some metals
do not have a measurable endurance limit.
Alternating Stress
The alternating stress is defined as (smax - smin)/2 where smax and smin are the maximum
and minimum stresses respectively.
Stress Range
Stress = (smax - smin)
Mean Stress
Mean stress = Sm = (smax + smin)/2
Mean
stress correction
Stress Ratio
Stress ratio = smin/smax
Fatigue Life
Fatigue life, at a given alternating stress level and mean, is the number
of cycles required to cause failure due to fatigue.
Fatigue Strength
The stress at which fatigue failure occurs after a given number of loading
cycles.
Related Topics
Fatigue
Analysis
Fatigue
Events
Performing
Fatigue Analysis
Fatigue
Plots