HI
I attach an example of a steel rod subjected to normal stress
The bar is divided into two sections
_ A static analysis was carried out both by applying an axial, compressive and tensile force and the results are correct
_ A bucklin analysis was carried out always applying both a compressive and traction axial force and the results would not seem correct as in both cases the load multiplier is always <1 (even for the traction force !) and the deformations are not congruent
_ as a check, a frequency analysis was also carried out and the results appear to be correct
I have used both Pardiso, Pastix and Spooles but the result does not change.
I don’t understand where the error is
Thanks for your help
I don’t think *CONTACT PAIR even with Pressure-overclosure=Tied works with buckling even though it does work with *FREQUENCY. In the solution, the contact seems to be completely disconnected. Maybe use *TIE instead.
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If you want to analyze nonlinear buckling, you can use *STATIC with NLGEOM. Otherwise, you have to follow the assumptions of the eigenvalue (linear) buckling procedure so no nonlinearities (only in the preload step preceding the buckling one). Same in frequency analyses but there contact state is just frozen and can be noticed in mode shapes (it still makes more sense to use tie constraints there too though).
Tied contact may work just like tie constraint but it’s not the same. The former still uses the nonlinear contact algorithm and just doesn’t allow for any relative motion. Tie constraint is much more efficient.
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