MTS Acumen - Manual (Page 80)

Important: It is best practice to always have the crosshead high enough so that the actuator cannot
contact the table if the actuator were to go to full extension.
Retracting the Actuator
This step accomplishes a couple things. First, it allows you to verify that the actuator moves in the direction
that you expect when you invoke manual command. Second, it allows you to determine the retracted
actuator endpoint. Once you have that point, you can determine where full extension is by adding the full
stroke [70 mm (2.76 in) for most MTS Acumen load frames].
To retract the actuator:
1. Set your displacement limits to their maximum value so that travel is not impeded when you retract the
actuator.
2. Turn on High-Power Prohibit.
3. In the Actuator Power panel, click Low.
4. Use the manual controls to fully retract the actuator. Make sure the actuator moves in the direction you
expect. If not, have the engineer on the project reset the motion polarity.
Positioning the Actuator for the Test
Proper positioning of the actuator for the test is dependent on the test that you are running. General
guidelines are:
• Compression Test: 20% extended
• Through-Zero Test: 50% extended
• Tension Test: 80% extended
Note: These are general guidelines only and may need to be adjusted if more actuator travel is
necessary.
Use the manual controls to extend the actuator. Limits should be set immediately following this step.
When installing the specimen, be sure to use the crosshead controls to bring the crosshead and actuator
into position. Do not use the actuator controls when installing the specimen.
Understanding Nested Limits
Nested Limits
The MTS Acumen test system allows you to set multiple limits to help you protect your fixturing and
specimen. These varying levels of limits are called nested limits. When a limit is exceeded, an action is
invoked. Available actions include Station Power Off, Interlock, C-Stop Interlock, and more. However, MTS
recommends setting the Action to C-Stop Interlock in all cases. Before setting the action to something
other than C-Stop Interlock, contact an MTS service representative.
It is important to understand the concept of nested limits (shown in the following illustration) to help ensure
that your limits do not conflict with one another. An example of improperly set limits might be specimen
limits set lower than your test limits. If this occurred, your test would stop prematurely. By properly setting
your nested limits properly, you can ensure adequate protection for each component while also ensuring
that your tests run smoothly without unexpected interruptions.
80 | MTS Acumen ™
Key Concepts