strange results doing modal analysis

Hello,

From my experience, modal analysis results in Code-Aster are comparable to those obtained with other codes, so there are probably some problems with your model.

You should first check:
1) the units: use SI units (for materials & geometry) or this millimeter set of units: L=mm, F=N, W=ton, T=s, E=mJ... (with these units Youngs modulus and density will be in the order of 1e3 & 1e-9 respectively).
2) use quadratic elements: in Salome/MESH (version 3.2.x) you can convert your mesh to/from quadratic elements (last button on the right). Then renumber the nodes & elements and finally export the mesh once again. If you used linear 3D tetrahedra before, it should singnificantly change the results (linear tetrehadrons should absolutely avoided...).
3) you can also try to use \"reduced integration\" quadratic elements (specify 3D_SI instead of 3D in AFFE_MODELE)

If your results are still not coherent, you can try to post some more details on your analysis (.comm, .mess, reference results etc...)

Regards,

J.Cugnoni
www.caelinux.com