MTS Fatigue Template - Manual (Page 47)

6.3.7.0 Ramp to Start Temperature
The Ramp to Start Temperature button prompts you to confirm the ramp to start temperature. Click Yes to
start the ramp or click No to prevent the ramp.
Click Run to start the ramp. After the ramp is started, if you click Stop to end the ramp, another ramp occurs
to cool the specimen.
6.3.8.0 Strain-Controlled Test
A typical low-cycle fatigue (LCF) test sequence includes:
1. Ramp to mean level, if the mean level at the start of the test is not zero. All data recorded during the ramp
is stored in cycle number 0 (zero).
2. Identify a stable cycle for comparison with other test values.
3. Start the test cycle count, start test data collection, and run the test to completion.
4. Ramp the system to the mean load of the last cycle.
Cycle 0 (zero)
The application collects data for each complete cycle. A cycle starts at mean level and ends at mean level.
In most cases, mean level is zero. For cases where mean level is not zero, a ramp initially occurs to mean
level before the test actually starts. The application stores the data collected during this initial ramp in cycle
count 0.
Stable cycle determination
The application identifies the stable cycle based on user-entered parameters.
Application-determined stable cycle
For an application-determined stable cycle, a consecutive number of cycles must remain within the stable-cycle
deviation factor to determine the reference cycle. Typical cycle counts are from 5 to 100 cycles.
Enter the percentage deviation that consecutive cycles must be within, as compared to an initial cycle. If a
cycle deviates beyond this percentage before the stabilizing factor amount is reached, that cycle becomes
the new cycle against which following cycles are compared. Typical stable cycle deviation factors are around
1%.
Test completion
The LCF test runs until it meets one of the termination criteria. Examples of test termination criteria include:
• Non-controlling failure threshold (%)
• Peak-valley deviation
Non-controlling failure threshold (%)
For tests run in strain control, you define a percentage of stable load amplitude to use for failure detection.
When the test reaches the stable cycle, the test compares the peak loads with this cycle to determine if the
test should be terminated due to specimen failure. For tests run in load control, enter the percentage of stable
MTS TestSuite 47
6.0 ASTM Low-Cycle Fatigue (LCF) Elevated Temperature Template