Why are planes riveted?

We all know that an airplane needs to withstand a tremendous amount of turbulence to fly in the sky, so it should be connected in a strong and durable way. So, why is the aircraft shell riveted, and not the other way around? In fact, from the following aspects of the consideration.

1、Material before Boeing 787 and the Airbus A350 XWB, the main material used to make modern aircraft was aluminium alloy. One outstanding feature of this material is its poor weldability. After adopting the traditional welding method, there is stress concentration in the welding area, which makes the metal become brittle, and easy to produce defects such as sand hole, bubble, micro-crack, etc. , the performance of the structure at these locations is lower than that of the non-welded areas. This is unacceptable in aircraft manufacturing. The use of rivets to join parts into a whole, called riveting. The method of joining metals or other thermoplastic materials by heating, high temperature, or high pressure is called welding. The use of screws and nuts for connection, referred to as the bolt.

2、Working characteristics of the aircraft at high altitude high-speed flight, the fuselage skin is subjected to tension. There is vibration in the engine when it works, and the aircraft itself will produce vibration. The forces experienced by an aircraft during each flight are constantly changing, and fatigue is a problem. However, tensile force, vibration and fatigue are the main reasons for the deterioration of welding performance. Aircraft working in such an environment for a long time, it is possible to develop small cracks in the weld. What's more, the cracks would then spread along the weld, even causing the plane to break up in mid-air, resulting in a fatal crash. The riveting and screw connection have good anti-vibration, anti-fatigue and other characteristics, and because of the existence of connecting holes, the natural anti-crack continue to have the ability to expand.

3. The service life of special aircraft is more than 20 years. There are many complicated and precise instruments in the aircraft body. In the long-term use, all kinds of devices may be damaged in different degrees, riveted for easy maintenance and replacement. If welding is used, the aircraft's skin will be completely replaced, which will increase the cost of maintenance and a single maintenance difficulty. Even in the absence of any equipment failure, the aircraft will require regular inspection and maintenance, including the need to disassemble the joints for inspection and maintenance. Welding is a kind of non-detachable connection, once disassembled, the structure is destroyed.