I have just recently begun running modal frequency simulations, and the results have me scratching my head as they don't seem to be aligning with my understanding of modal frequency behaviour. I am simulating a thin dome-shaped part of 63.5mm diameter, 6mm in dome height, parabolic in curvature, 0.1mm in wall thickness, and the material is Alumina. The part is fully constrained on its outer diameter edge in the simulation setup. The solver is requested to look for the first 8 modes above 100Hz and below 40,000Hz.
What I expect to see on completion of the analysis is some series of discrete natural vibrational modes, each of which lie at progressively higher frequencies. However I DO NOT see this in the results....
What I DO see are 8 vibrational modes all clustered around the SAME centre frequency - nominally 16,000Hz.
This doesn't seem right...why is the simulation outputting this cluster of different modes all sitting at the same nominal frequency?
Attached are screenshots of these 8 modes, with each screenshot also showing the drop down list of the 8 modes all sitting at very nearly the same frequency...
