MTS Fracture Template - Manual (Page 29)

Delta K Control Mode Parameters
Delta K Control Mode Parameters
Description Parameter
Specify the ratio of the minimum to maximum
K applied to the specimen. The minimum K FCG Load Ratio
is determined by this value and the maximum
K is specified by you.
Specify the initial maximum stress intensity
(K) value used in Delta-K control. FCG Initial - K Max
Specify the rate of change to stress intensity
as the crack site changes. Negative values Normalized K Gradient (C)
cause the alternating stress intensity to
decrease.
Specify the cycle frequency of the command
signal. FCG Frequency
Specify the wave shape of the command
signal. FCG Wave Shape
The choices are True Sine or True Ramp.
Typically, you use a True Ramp wave shape
where uniform strain-rate sensitivity is
important, and a True Sine wave shape
where a continually varying strain rate is
acceptable because of the higher frequencies
of some tests.
This MTS template does not support hold
times or creep-fatigue crack growth testing.
Specify the percent of maximum load level
at which the voltage is measured. All voltage FCG Measure Load Level
Percent
data below this load will not be used to
calculate crack length. This parameter is
used only for FCG DCPD tests.
MTS TestSuite | 29
Fatigue Crack Growth (FCG) Template