MTS TW Elite - Manual (Page 76)

Data Acquisition for Test-Run Displays
In the Test-Run Display Toolbox, the Cycle View category pertains only to data that is divided into blocks.
This is an important consideration, because if you attempt to use one of these display devices to view data
that is not blocked, the view will appear blank, because the device is waiting for the first block boundary.
For example, if you want to view hysteresis by examining load versus displacement in a test that does not
use blocking, you can use:
• The signal Scope (Signal Views category)
• The Array-Variable Chart (Variable Views category) if you map data to variables when configuring data
acquisition
If you use either the Custom Waveform + DAQ or Cycle + DAQ activities (which provide automatic
blocking), or configure the generic Data Acquisition activity for blocking, then you can also use the
Hysteresis Chart (Cycle Views).
Polarity Considerations for MTS Criterion Series 40 Systems
When designing tests, it is important to be aware of the various settings that affect the polarity of your
system. The combined effect of these settings control:
• The direction that the crosshead will move when command activities (such as Go To or Cycle) are run.
• Whether the values in meters, scopes, and data acquisitions either increase (become more positive)
or decrease (become more negative).
For example, you can customize a tension test so that when the crosshead applies tension (that is, pulls
the specimen apart) the measurements in meters, scopes, and data acquisitions become either more
positive or more negative.
Important:
When adjusting the polarity settings of your system, always use a disposable specimen that you
are comfortable with destroying. Modifying the polarity settings of a test may cause unexpected
crosshead movement.
For example, consider the following analogy in which you have designed a prototype of a car and
want to submit it to a crash test. The car will crash into the back wall if you do not shift the
transmission from reverse to forward even though you have designed the prototype of the car
perfectly. As a result, your prototype will be destroyed and you will not be able to collect any crash
test data.
In this analogy, shifting the transmission of the car is similar to changing the polarity of a float signal
because you can effectively reverse the direction that the crosshead moves during a test run.
Because of this, it is important to validate the polarity settings with a disposable specimen to ensure
that you receive the anticipated crosshead movement before you test real specimens.
When designing a new test, the following settings that affect polarity are available on the Resources
subtab of the Define tab:
76 | MTS TestSuite
Design Guidelines