Buckling of circular ring joint with cylindrical shell

In the paper by Filippov (2005) the buckling of the cylindrical shell reinforced by a ring of rectangular cross-section was studied. Only the stiffness of the ring has been taken into account. The typical buckling mode for this case is shown in Figure 1. This mode, which we call the mode of the first type, is similar to the buckling mode of the shell without a ring.