7. E modeling

7.1. Characteristics of modeling

Same as modeling A.

7.2. Characteristics of the mesh

Same as modeling A.

7.3. Tested sizes and results

We test the calculation of the greatest natural frequency of the structure, by manually exchanging the roles of the mass and stiffness matrices. In particular, it is necessary to transfer the Lagrange degrees of freedom from stiffness to mass.

The modal calculation is carried out on the one hand with TYPE_RESU =” GENERAL “, which returns an eigenvalue (critical load) \(\mathrm{\mu }\); in this case, the formula \(\frac{-1}{2\mathrm{\pi }\sqrt{\mathrm{\mu }}}\) must be applied to convert the value into an eigenfrequency. On the other hand with TYPE_RESU =” DYNAMIQUE “, which returns a natural frequency \(f\); in this case, you must apply the formula \(\frac{1}{{(2\pi )}^{2}f}\) to find the right natural frequency.

The value thus calculated serves as a reference for the D modeling.