Longeron

Stringers longitudinal stiffeners that increase the rigidity of large -area components and prevent them from buckling. You are in shipbuilding and in lightweight airplanes, but also used in rocket construction.

Together with the frames forming the supporting frame stringer of an aircraft, wherein the stringers so that usually extend at right angles to the ribs and parallel to the longitudinal axis of the component.

See also: Angle Brackets

Development

• It starts with the design principle keel and frames, in which a keel is laid first on the frames at right angles are fixed and last the planking is attached. Thus, spatial constructions are possible, their size ( in contrast to the dugout ) exceed that of the largest single part. They are easy to construct on the drawing board by decomposition into two-dimensional sections.
• With the resolution of forces into train - and pressure- structural elements of the design principle of ribs and spars was, as it is currently in aircraft today. Airplanes must be verbiegungssteif in each level; a single keel is too heavy and too little in its transverse plane stable. For the production of such objects, a design framework is needed, almost a " keel for taking out ", which is removed from the structure once it has enough inherent stability.
• Adds one now encourage stability ever finer bars and thereby reduces the cross -section of the bars in the construction, one arrives at Holme, stringers and frames and last stringers and frames, a precursor to self -carrying outer skin. High Torsion is not yet to achieve as there are still 90 ° angles are available.
• The next more sophisticated construction, the geodetic construction. This is largely dispensed with ribs, the structure-directing and load-bearing structural elements are diamonds and triangles formed by spirally around the object extending, strip-shaped stringers. For this purpose it is necessary to construct the planned hull shape first in conventional cross-sections, and then calculate a spiral settlement. The hull can be formed by riveting the bands in the predicted node intervals last. The British Bomber Vickers Wellington is one example. The mesh size is variable, depending on how much load must be included and how exactly the contours must be formed. For submarines is such a construction is not feasible, since ring frames are much more stable.
• With modern composite materials, the self-supporting outer skin has become possible; but it is very expensive, because that is economically, much effort is needed. About rigid foam cores can be laminated such skins, but the production is expensive and difficult repairs. The effort is worthwhile for individual units.
• Latest designs of airplanes, submarines, bridges and roofs, mostly combine stringers, frames, geodesic construction and self-supporting outer skin. This provides a high economy has become accessible, however, requires the design process of computer- aided design. This design is also regarded as a bionic principle, because after the outer form was set to compete different realization possibilities in the static, economic and aesthetic disciplines until it turns out, what design is best for what detail is. Then, the combination of individual methods is illuminated in terms of the durability and feasibility and considered again economically. It may well be that a detail to realize very good for a special approach could, but it would be too expensive to include an additional design principle to the concept for this detail only, another would be uneconomical in detail, but on the whole economy.