i have done experimental, analytical and numerical modal analysis of simply supported beam. the analytical and experimental results are in corellation.

i have a problem with numerical analysis. i modeled the beam in ansys and solved the problem with the follong boundary conditions:

- restricted the DOF's along the length at both ends
- restricted the DOF's along the thickness of the beam at both ends

the modal analysis of the above model gave me 0 Hzs as the first natural frequency which is not the case with exp and analytical methods.

can some one help me in this regard are my boundary condition's wrong ???