I have been attempting to simulate the resonant frequencies of a composite shaft. So far I have been able to get relatively accurate (<4% offset from experimental) with my "standard" laminate. However, when I adjust ply angles or add/remove plies the simulation states the resonant frequency remains unchanged (IE standard laminate for a shaft with a diameter of 3'' and length of 38'' will give a frequency of x Hz while a shaft with the same dimensions but using a vastly different laminate will give a frequency of x[+/- 2] Hz). Soon I will add a mock-up of my simulation using the same constraints for your convenience. Thank you in advance for your help!
added files (assembly with referenced parts)