Fatigue Events
The software handles two different types of fatigue events: constant
amplitude and variable amplitude. You can define multiple fatigue events
for a study but they have to be of the same type. The software uses the
Miner's
Rule and the ASME Boiler and Pressure Vessel Code to evaluate
the alternating stresses and the corresponding numbers of cycles based
on a number of fatigue events.
Constant Amplitude Events
All cycles of a constant amplitude event have the same alternating and
mean stresses. A constant amplitude fatigue event is fully defined by
an alternating stress, mean stress (or stress ratio), and the number of
cycles. A fatigue event can refer to one or more static studies, or to
a particular solution step from nonlinear or modal time history dynamic
studies. The software calculates the worst alternating stress levels for
each event.
Example
Evaluation of
Alternating Stresses from Constant Amplitude Events
Variable Amplitude Events
A variable amplitude fatigue event
is a load history record that defines the fluctuation history of a load.
The time values do not play any role for fatigue studies with a single
variable amplitude event. In this case, it is adequate to define the amplitude
sequence. For studies with more than one variable amplitude fatigue events,
time values are needed for each record to correlate to other loading events.
Example
Related Topics
Fatigue
Analysis
Performing
Fatigue Analysis