Closed-form compressive buckling analysis of composite panels stiffened by hat-shaped stringers

Hat-shaped stringers in composite fuselage structures enhance structural stability and load-carrying capacity due to their high lateral bending stiffness. However, the absence of efficient analytical methods necessitates simplified boundary condition assumptions in current engineering practice, typically modeling the fuselage skin as simply supported, leading to overly conservative designs and potential structural mass penalties. While finite element analysis can accurately represent complex boundary constraints, it incurs significant computational costs. This paper presents a novel analytical methodology for determining the compressive buckling load of fuselages, explicitly incorporating the lateral rotational constraint provided by hat-section stringers. The rotational stiffness of the stringers is derived in closed form, and the skin’s critical buckling load under lateral rotational support is demonstrated to be a weighted average of simply supported and clamped boundary condition solutions. Finally, a numerical procedure is developed to solve the resulting governing equation for the critical buckling load, offering a computationally efficient tool for engineering design.