Verify id torsional frequencies follow the blow rule or not

Verify id torsional frequencies follow the blow rule or not.

                                         w µ Ö1/L

1. Use Aluminium E = 70GPa and dimensions T = 5mm, W = 30 mm to define a torisional motion in comsol with one end of the beam locked. The length is L = n× W, n = 1…40. Select values of Dn = 1,….,5 small changes at beginning and coarser at the end. Calculate at least 12 values.
2. Plot f_torsion versus Ö1/L. If it is linear the rule is true, if the graph is not linear the rule is wrong.