Free vibration of stiffened laminated shells of revolution with a free-form meridian and general boundary conditions

•The free vibration of stiffened laminated shell with a free-form meridian is solved in an analytical form.•The stiffeners are modeled as curved beams in space based on the displacement field of the shell without involving extra degrees of freedom.•The equations for the stringers and ring stiffeners are introduced in the same form.•The effect of elastic boundary conditions is considered using a modified Ritz approach.