V9 - Aero - Lead Story

C3 Performance:  Optimizing Tests that Emply Cross-coupled Actuation

MTS aerospace product manager Dr. Christoph Leser discusses how an AeroPro software utility helped Cessna add tremendous speed to tests with highly coupled actuation schemes.

Q: What particular challenge did Cessna face?

Leser: Cessna test engineers were facing increased pressure to get higher-performing aircraft into the marketplace sooner. Doing so requires conducting extremely complex — and potentially time-consuming — structural test to validate performance.

In addition, many structural tests at Cessna require highly coupled actuation schemes, in which multiple actuators exert different forces on the same portion of the test article simultaneously. To preserve test efficiency and data accuracy under such testing conditions, compensations must be made for the influences of all actuators present.

Historically, compensating for how cross-coupled actuators affect one another during tests has required expensive proprietary coding or the time of valuable internal resources. Both measures have a tendency to be lengthy in test preparation and increase costs.

Q: How did MTS help resolve this issue?

Leser: At the same time Cessna communicated this testing challenge to MTS, we were in the final stages of developing a new cross-coupling compensation utility for AeroPro software, C3 Performance (or C-cubed), which automatically compensates for highly coupled actuation schemes.

The C3 Performance utility seemed like a promising solution for addressing the challenges Cessna was facing. So we invited them to participate in a pilot program, in which their test engineers would use the C3 Performance utility running MTS FlexTest® control hardware for its structural testing.

Since Cessna has been a longtime user of MTS application software, control systems and consultation, the pilot would also allow us to compare performance data of the new utility to that of the legacy MTS equipment currently in use at Cessna. By doing so, we could glean accurate insight into how this utility enhances testing performance in a real-world structural application.

Cessna agreed to participate in the pilot, and in September 2006, the C3 Performance utility and FlexTest hardware were installed at Cessna’s Wichita, Kansas, aerospace testing facility.

Q: For what applications did Cessna use the software utility? What were the results?

Leser: Cessna used the C3 Performance utility and FlexTest control hardware to help resolve two urgent manufacturing issues. The first issue involved horizontal tail movement, and the second involved landing gear. Both tests required the employment of highly coupled actuation schemes.

Cessna reported overwhelmingly positive results for both tests run on the C3 Performance utility and FlexTest platform. Tests ran twice as fast compared to the MTS legacy equipment in terms of cyclic rate, and accuracy levels went up 1.5 times. The error coefficient also increased from 98% to more than 99%. Using the new MTS tools, Cessna was able to resolve both issues in weeks instead of months, which is the expected turnaround time for such complex testing.

All this efficiency was achieved without introducing any additional strain to the test articles. The same desired loads were applied, only in a much more efficient fashion.

Since this original pilot program at Cessna, the C3 Performance utility has achieved similar positive performance results in real-world comparison tests at several other customer sites.

Q: Will the C3 Performance utility be made available to other aerospace test labs?

Leser: Yes. We will be offering this utility as a standard feature in an upcoming release of MTS AeroPro software.

Q: What further improvements are you planning to make to this utility?

Leser: We will be adding the capability to automatically generate required coefficients by playing out existing load profiles. This capability will be made available in a multi-box environment, so up to 360 channels can be accounted for in cross-correlation compensation.

With the introduction of the C3 Performance utility, we look forward to setting the new standard for how efficiently aerospace test labs address highly coupled actuation schemes during structural testing.

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