I have some questions about the possible use of MIMO functions to develop ground vibration tests on aircrafts. At my university, we've always used the spectral testing module with casual excitement, but yesterday a colleague suggested I use the pseudo-random input and the MIMO module for my next tests. So I did some experimental tests on just a cantilever beam and I read the LMS manual, but I would like to have some suggestions before using this input also because I will not have much time to investigate the setting of the parameters during my next gvt. First of all, I would like to know why I have a very limited time to set up the channels (set ranging )and if I can extend it. Furthermore, I don't know if it would be best to use a random input instead of a pseudo-random. Finally, I wonder if the random test with the spectral testing module is equivalent to the MIMO test done with random input. If you have other suggestions, such as the number of blocks to set (which I suppose depends on the structural damping) or on the input profile, they will be greatly appreciated. Thanks for your help.
thanks a lot for your question. It is very relevant and i will try to reply as simply as possible.
First of all, let's shed some light on the two applications you are mentioning. Spectral Testing is a more general application, while MIMO FRF is newer, more complete and dedicated to perform structural dynamics testing and measure FRF with shakers.
For standard excitation profiles, such as random and burst random, the two applications are exactly equivalent, but MIMO FRF supports more dedicated and customizable excitation profiles, as well as a wider range of input channels.
Now coming to your more specific questions:
I hope i replied to your doubts. In case you have further question, feel free to contact our Customer Support via GTAC (https://www.plm.automation.siemens.com/en_us/support/gtac/ )
Best regards and have fun with your GVT
Product Manager Structural Testing Solutions