Hello Simulia community,

In my FE model I have an analytical rigid surface contacting a shell model using 'General Contact'. I am performing linear perturbation Eigenvalue buckling analysis using subspace solver (because of presence of Contacts). I have created an intermediate step in which a displacement load is applied to ensure surfaces are contacting, followed by the Buckle step. The NLGEOM is ON because of Contacts. The resulting mode shapes and eigenvalues seems absurd. I am doubting this because of presence of non-linearity in the linear perturbation. I have tried both with and without friction and with and without separation of surfaces after contact. I have utilized linear elements (S4R). If I replace the contact surface with a kinematic coupling, the results seems appropriate but that is not the physics I am investigating. My aim is to obtain the mode shapes of perfect geometry and then use the IMPERFECTIONS in the following non-linear analysis. Any suggestions or tips on how should I be setting up my model for analysis ? Let me know if you need any more details about my model. Thanks in advance.