I am trying to understand the most efficient way to determine the magnitude of transmissibility at key points within a structure. The structures I design are subject to random vibration base excitation, and so I would like to predict their response. If I can do a “virtual sine sweep” in Creo Simulation, I can optimize the structure without having to do the physical sine sweep testing on a shaker table, and thus save design time.
There appears to be three ways to find the transmissibility using simulation:
1) Run a dynamic random analysis and observe the response at key points (using Measures) as compared to the response at the supports. The difficulty is in interpreting the Measures responses because they are in terms of G-rms²/ Hz.
2) Run a dynamic time analysis in the same way as the dynamic random. Results are in acceleration vs time, and must be converted to acceleration vs frequency via FFT to locate frequencies with the highest amplitude response.
3) Run a dynamic frequency analysis using the same technique as the dynamic random. Results are acceleration vs frequency plots that are same as you would get from a sine sweep.
I believe the dynamic frequency analysis is best for finding transmissibility magnitudes. But I have a couple of questions.
I may not answer all your questions but I made a try at this.
See attached information and demo CREO part on forced frequency response.
The difficulty with correlation will be the damping assumptions.
It was very helpful to see your FFR document. It perfectly verified the process I was trying to describe.
I get frustrated with the lack of background in the help files. Many terms have only a bare minimum of information, and this forces me to look for ways to sanity check every step.