Cantilever Beam Natural Frequency

Question

Hello everyone, 
 I'm a student and I'm trying find the natural frequency of a flexible cantilever beam. For the model, I used a box as the body and then used the Fixed connector at one end of the beam. After that I tried to make the beam flexible. I used the Rigid to Flexible body option for that. I selected Aluminum as the material and then clicked on OK without getting to the advanced settings. After that I went to the simulation tab and after finding static equilibrium, I computed the linear modes with damping. Now I have two questions: 1- Why are the results wrong? whatever I do, I don't get the correct natural frequency. I have experimental data and the results do not match! 2- In the model tree, All Other, Materials branch, I can only find Steel! I have selected Aluminum as the material, why is it steel in the materials branch? 
 
 Thank you for your time.

Charlott Corcoran · Answer

2. The steel material in the model tree is a copy from the materials library. Aluminum material will also be copied to the model if you modify the rigid part mass properties to use aluminum density. 
 1. If you don't have aluminum in the tree browser, you have probably not set the mass and inertia properties of the rigid part.