airframe 机身 stringer 纵梁
bending 弯曲应力 bulkhead 舱壁
rivet 铆接【'rɪvɪt】
shear strength 剪切强度
substance 物质 torsion 扭曲力
deformation 变形 frame 框架
rib 支撑肋材 bracket 拖架
rivet 铆钉 bolt 螺栓
screw 螺钉 nut 螺母
Aaircraft has five main structural units which consist of the fuselage, the wings, the
stabilizers, the flight control surfaces and the landing gears.
The structure of each unit of an aircraft is made up of airframe components. Here for
example, the nose forward fuselage.
Airframe components are made up of various parts which are called structural
members and include stringers, frames, bulkheads, ribs and other member which are
mentioned in a later lesson. Structural members are connected to each other using
brackets, rivets, bolts, screws and nuts which give strength to the fuselage.
These structural members are designed to carry a load or resist stress. Generally,
stress is created by the internal force of a substance which opposes or resists
deformation. An aircraft can be affected by different types of stress during take-off,
flight or landing.
Five major types of stress that can affect the structure of an aircraft are tension
compression, torsion, shear and bending.
Tension is stress that resists the forces which pull it apart. For example, engine thrust pulls the aircraft forward, but air resistance holds the aircraft back and thus the result is tension. In order to calculate the tensile strength of a material, divide the load (in pounds) of the material by its cross-section area (in square inches). The result is psi.
Compression is stress that resists a crushing force. It causes the aircraft part to
shorten or squeeze together. Generally, you can also measure compressive strength
in psi.
Torsion is stress that causes twisting. In this example, this happens when the rudder
is deflected.
Shear is stress which resists a force which causes a layer of material to slide over an
adjacent layer of material. When there are 2 riveted plates that are under tension.
Shear stress causes the rivets to be affected by a shearing force. Shear strength of a material is usually either equal to or less than its tensile or compressive strength.
Bending stress is a combination of compression and tension. In this example,
compression occurs on the lower side of the fuselage and tension occurs on the
upper side of the fuselage.
