Welding is a widely used technology in modern manufacturing industry, which has the advantages of fast speed, good sealing and so on, and can make great use in aerospace, shipbuilding and automobile manufacturing. So, can airplanes also use welding processes during manufacturing? The answer is no. The main reasons are as follows:
The first is caused by the aircraft’s manufacturing materials. Before the advent of Boeing 787 and Airbus $literal, the main manufacturing material for modern aircraft was aluminum alloy. This material has a prominent characteristic-welding performance is very poor. After welding with traditional welding mode, the local stress concentration in the welding area makes the metal brittle, and it is easy to produce the defects such as sand hole, bubble and microcracks, so that the performance of the structure is lower than the non weld zone. This is unacceptable in aircraft manufacturing.
Although there are some special welding processes, such as friction stir welding and laser welding, but the related technology is too complex, and difficult to ensure the stability of the process. For the same material, the thinner the less easy to weld. Aircraft skin thickness is generally only about 2 millimeters, even if it can be welded, the difficulty will be very large, non-general operators can be competent, not conducive to mass production of aircraft.
The Boeing 787 and the Airbus $literal body are mainly composite materials, which are made of a variety of single material through a composite method, which is more difficult to weld than aluminum alloy, and manufacturers hardly use welding.
Second, the aircraft’s working characteristics caused. When the plane is flying at high altitude, the fuselage skin is under the tensile force. The engine vibrates at work, and the aircraft itself generates vibrations. The various forces that a plane undergoes on every flight are constantly changing, and there will be fatigue problems. The tensile, vibration and fatigue are the main causes of the deterioration of welding performance.
A plane that works long hours in such an environment may generate small cracks at the weld. What is more frightening is that the cracks will continue to expand along the weld seam, and even cause the plane to disintegrate in the air, causing the tragedy of destroying people. And the riveting and the screw connection have good anti-vibration, anti-fatigue and other characteristics, and because of the existence of the connecting hole, naturally has the ability to resist crack to expand.
Finally, the use of aircraft caused by the characteristics. The life of the aircraft is generally more than 20 years, the body has a lot of sophisticated and sophisticated instruments, in the long time to use the process, various devices are likely to appear different degrees of damage, the use of riveting easy to repair and replacement. If the use of welding, the aircraft’s skin will be all replaced, this will increase maintenance costs and single maintenance difficulty. If no equipment failure occurs, the aircraft must be inspected and maintained on a regular basis, including the need to disassemble the connecting parts for inspection and maintenance. Welding is an irreversible connection, and once opened, the structure is destroyed.
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Post time: Aug-29-2017