Hello Wang,

The main benefits of a 2D approximation is, it reduces computation time because no. of elements is less, so accurate mesh can be generated.All 2D approximations like plane stress criteria, plane strain criteria, axis symmetric criteria reduces 3D problems into 2D problem.

Two conditions are required to use a 2D axisymmetric model instead of a 3D model;  The process geometry should be axisymmetric. Boundary conditions (velocity and displacement) and loading shall be applied axsymmetrically as well.

If you are sure about these two conditions you’d better use a 2D model, if each of these requirements is not met you have to use a 3D model.

Good luck

you can 2D with considerable lower computation time if the domain has no gradient of any properties/variables in circumferential direction.

In the buckling and post-buckling analyses we can lose local (non-axisymmetric) forms, which may have lower critical values than axisymmetric forms.