peteroznewman
Subscriber

Here is how I would lay out the frequencies and the modes.



Please rerun the Modal analysis and request 12 modes and fill in the next few cells to see if you get close to 62 Hz.


When a structure is symmetric, ANSYS will report a double mode, one for each coordinate direction, but an experimental report will see only one mode, and will not report a double mode.  I haven't seen the shape of the modes but that could be happening for one of the closely spaced modal frequencies. You haven't shown the mesh, you might find that as you refine the mesh, you get slight movement in these frequencies. Please reduce the element size and rerun the Modal analysis.


While ANSYS shows mode shapes, what is in the experimental report on the mode shape?  How did they determine a resonance frequency?  Did they use accelerometers to measure the response of the structure?  How many locations did they monitor?  How many axes did they monitor? It is quite easy for a sensor to miss a mode that is calculated by ANSYS if a mode does not excite the motion at that particular location. That happened in this example.