MTS Multipurpose Elite - Manual (Page 26)

If you inadvertently run a modified test and have to undo the changes you made to the test before you ran it
(and the application automatically saved it), you must do so manually.
3.2.6.0 Test Design Considerations
3.2.6.1.0 Consider Your Station Setup
When you are designing or running a custom test, it is important to consider the following components of
your station setup or you may receive unintended test results.
Polarity
When creating a custom test, the test designer can optionally configure the test to check that the polarity of
the system corresponds correctly to the template using the IsSignalPolarityInverted function. This function
automatically checks the polarity setting of the station and returns a True or False value. When designing a
test, you can add this function as a condition to an If-Else condition activity at the beginning of a test and
determine how the test should proceed based upon whether or not the polarity is inverted. In most cases,
you can prompt the operator to change the polarity of the station if it is incorrect.
Most MTS-supplied tests contain this function. However, if you a running a custom test that was not supplied
by MTS and you don't use this function, it is important that the test designer communicates to the operator
which polarity mode (tension positive or compression positive) should be used when running the test.
Caution:
Running a test using the incorrect polarity setting can cause unintended results, which
may result in unexpected actuator movement.
Unexpected actuator movement can result in injury to personnel or damage to the
equipment and the specimen.
Always be aware of which polarity mode a test should be run using before running the test. If,
for example, you run a test that assumes compression is positive and you set tension as positive
when you install fixturing, you may receive “inverted” test results, the actuator may move in the
opposite direction that was intended, or the test may not run at all.
Limits
When you design a test, it is important to be aware of the specimen and fixture limits (referred to as “station
limits”) set on the station, and it is good practice to set proper limits to protect your fixturing and specimen
from damage. You can configure limits in the Set Up node of the Explorer tree. If these station limits are
turned on and assigned an action, they operate in tandem with the test limits you set within the test procedure.
For example, if you set up a test limit for a maximum of 100 N of compressive force, and the station limit is
set to only allow 80 N of compressive force, the limit will trigger when the actuator exceeds 80 N of compressive
force regardless of what the test design commands. In this case, you can resolve this issue by either raising
the limit on the station to 100 N or changing the test design so it only commands 80 N of compressive force.
In addition to the specimen, fixture, and test limits, there are also machine limits, such as the 5 G actuator
acceleration limit. Machine limits cannot be disabled and are used to protect the machine from damage.
26 Multipurpose Elite Test Design Guide
3.0 Designing a Test