Aircraft structures for engineering students - part 5

Các yêu cầu cấu trúc khác nhau của máy bay được thiết kế cho vai trò hoạt động khác nhau dẫn đến một loạt các công trình xây dựng cánh. Ví dụ, máy bay tốc độ cao yêu cầu phần cánh tương đối mỏng, hỗ trợ trội cánh cao. Để chịu được áp lực bề mặt tương ứng cao và để có được đủ sức mạnh, da dày hơn là cần thiết. | 230 Principles of stressed skin construction Fig. Wing ribs for the European Airbus courtesy of British Aerospace . The different structural requirements of aircraft designed for differing operational roles lead to a variety of wing constructions. For instance high-speed aircraft require relatively thin wing sections which support high wing loadings. To withstand the correspondingly high surface pressures and to obtain sufficient strength much thicker skins are necessary. Wing panels are therefore frequently machined integrally with stringers from solid slabs of material as are the wing ribs. Figure shows wing ribs for the European Airbus in which web stiffeners Hanged lightness holes and skin attachment lugs have been integrally machined from solid. This integral method of construction involves no new design principles and has the advantages of combining a high grade of surface finish free from irregularities with a more efficient use of material since skin thicknesses are easily tapered to coincide with the spanwise decrease in bending stresses. An alternative form of construction is the sandwich panel which comprises a light honeycomb or corrugated metal core sandwiched between two outer skins of the stress-bearing sheet see Fig. . The primary function of the core is to stabilize the outer skins although it may be stress-bearing as well. Sandwich panels are capable of developing high stresses have smooth internal and external surfaces and require small numbers of supporting rings or frames. They also possess a high resistance to fatigue from jet efflux. The uses of this method of construction include lightweight planks for cabin furniture monolithic fairing shells generally having plastic facing skins and the stiffening of flying control surfaces. Thus for example the ailerons 7 A Fabrication of structural components 231 Fig. Sandwich panels courtesy of Ciba-Geigy Plastics . 232 Principles of stressed skin construction and rudder of the .

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13    16    1    01-07-2022
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