stiffener

A stiffener is a structural element used to increase the stiffness and buckling resistance of plates, shells, or panels. By adding local curvature or increasing moment of inertia, stiffeners help distribute loads and prevent premature deformation. They can be attached to the surface or integrated into the member and are common in metal, composite, and aerospace structures as well as ships.

Stiffeners are commonly categorized as longitudinal or transverse. Longitudinal stiffeners, or stringers, run along the length of a panel to increase its axial stiffness. Transverse stiffeners, such as ribs or frames, cross the panel to resist distortion and buckling under transverse loads. Other forms include corrugated stiffeners, which use a wave-like profile for higher stiffness with less weight, and gussets or doublers used at joints to transfer forces.

Applications: In shipbuilding, hull plates rely on stiffeners to prevent local buckling and distribute stresses at seams. In aircraft, stiffened skins use stringers and ribs to maintain aerodynamic shape and withstand bending and torsion. In civil and mechanical engineering, stiffeners reinforce steel plates, panels, and bridge decks, and are used in pressure vessels and storage tanks.

Materials and fabrication: Stiffeners are typically made of steel, aluminum, or composite materials. They are attached by welding, riveting, bolting, or adhesive bonding. Design considerations include stiffness contribution, buckling mode, end conditions, spacing, corrosion resistance, and fatigue performance.