My model have 7 rigid components and beam belt which have more the 200 parts . when i calculate natural frequency than i got many natural frequencies and each frequency is very close to each other.for example 1.2345 HZ, 1.343 Hz
This software is used for Bio-mechanical Engineering purposes, However, in Automotive field, CATIA V5 is the most used one, I recommend you to go for it , it is easier and can fulfill your requirements with definite elements analysis.