Buckling Analysis of a Cylinder With End Caps - Fixtures Help Required

Hello all,

I'm aiming to complete a buckling analysis of a cylinder with ends caps subjected to external pressure.

My question comes as to which fixture to use?

Should I prevent all translation of the faces of the end caps? and then apply the external pressure to cylindrical surface?

All help and theory on the matter is greatly appreciated,

Thanks!

SolidworksSimulation