Natural frequency

Hi all,

 I am new in the blog, so I would like to appologies if this post is already published.

 I am doing a research in vibracion-based health monitoring based in CFRP beams. As a part of my research, I am modeling a composite beam in abaqus and apply transient analysis on it. Before I would like to validate my model with a very simple a easy model for this reason I have elaborated this procedure:

I want to know which method(steps) i will prefer to find frequency of cracked and uncracked beam.

Please give me suggestion about this problem quickly.

Thanks in advance.