Large aircraft and composite materials

Last year, I had the privilege of attending the Shanghai International Composite Materials Exhibition, where I also spoke with Toray Industries of Japan, a supplier of carbon fiber for the Boeing 787. The 787 is made up of 80% carbon fiber and resin materials, which makes it much lighter than traditional aluminum alloy materials; its strength and fatigue resistance have also improved significantly. However, it isn’t without its drawbacks. Below is an overview of the disputes between Boeing and Airbus. According to a report in The Times on the 7th, the American aircraft manufacturer Boeing is currently developing a passenger plane whose fuselage is made almost entirely of composite materials – the Boeing 787 Dreamliner. However, Airbus, the European company that recently succeeded in launching the world’s largest passenger plane, the A380, has raised doubts about the safety of planes with all-plastic fuselages. The two major aircraft manufacturing giants engaged in a fierce debate over this issue. The first composite material passenger plane: Airbus argues that all-plastic aircraft are unsafe because using composite materials made of plastic and carbon fiber to replace metal in aircraft construction is indeed a huge leap in the history of aircraft manufacturing, but the associated risks were not given sufficient consideration. The Boeing 787 Dreamliner will be the first passenger aircraft whose fuselage and wings are made of composites rather than aluminum. Composites are used in place of aluminum metal because metals can conceal damage, which progresses beneath the surface until the structure breaks apart and the damage is discovered. Synthetic materials do not have this problem. In fact, it has been 20 years since composite materials have been used to manufacture the rudders and tail fins of commercial aircraft, but no aircraft manufacturer had previously dared to use them for the airframe. Tennis rackets, fishing rods, bicycles, and Formula 1 cars are often made from composite materials, but the use of such materials in manufacturing commercial aircraft is different from that in these other items. After all, the Boeing 787 can carry 300 passengers, and if it were made from composite materials, it would be the largest composite structure ever built. In 1985, Airbus used composite materials to manufacture the tail fins of the A310 aircraft, becoming a pioneer in the use of such materials in aircraft construction. The company further utilized these composite materials to make the wings of the A350 aircraft, which was designed as a competitor to Boeing’s 787. The composite wings for this aircraft were manufactured in Broughton, North Wales. However, this European aircraft manufacturer claimed that using composite materials for the airframe was too risky, a move that angered Boeing greatly, as the company is using composite materials in the production of the Boeing 787. Are composite materials safe? Boeing chose to use composite materials instead of aluminum for manufacturing aircraft fuselages because these materials are lighter than aluminum and also result in lower maintenance costs. Boeing says the Boeing 787 will use 20% less fuel than current aircraft, and it will also reduce maintenance costs by 30%. Boeing was also cautious about using composite materials in the past, but ultimately decided to go further than Airbus in their use of these materials. A spokesperson for Airbus said, “Boeing didn’t take a few smaller steps in using composite materials; they made a big leap right away, so there are inevitably some risks involved.” ”The spokesperson noted that the fuselage is different from the wings, and it is easily damaged when colliding with baggage carts, supply vehicles, and aircraft passenger bridges. He said, “When people drive vehicles into an airplane, there are many opportunities to dent or damage the aircraft’s outer shell. A fuselage made of carbon fiber makes it harder to detect such damage; you can’t tell whether a crack of 6 inches, 10 inches, or even 20 inches has formed, nor can you determine whether that crack is on the left side or the right side.” Metal materials deform when they absorb energy, so it is easy to determine the location of damage, whereas casings made of carbon fiber materials do not deform before breaking. ” In fact, Airbus has encountered similar problems in the past; they were also questioned when using composite materials to manufacture rudders, and they had to defend their actions. In November 2001, at Kennedy International Airport in New York, the composite rudder of an A300 broke off shortly after takeoff, causing the plane to crash and resulting in 265 deaths. Investigators accused the pilot of overusing the rudder, but after defects were found in the rudders of two other A300 aircraft, authorities recently requested that the investigation into that accident be made public. Airbus believes that the Boeing 787, which is made of composite materials, has to remain on the ground for extended periods for repairs in case of problems, as composite materials are not as easy to repair as aluminum. In response to Airbus’ claims, Boeing also reacted strongly, stating that Airbus was trying to intimidate people in order to promote the sales of its A350 aircraft. The dispute stems from competing interests. The Boeing 787 is expected to enter service in 2008, two years earlier than the A350, and it is currently more popular than the A350; even First Choice Airways in the UK has placed orders for the Boeing 787. To date, Boeing has received orders for 291 Boeing 787 aircraft, while there are only 172 orders for the A350. Airbus has previously tried to copy Boeing’s safety ideas. Four years ago, Airbus claimed that four engines were better for long-haul aircraft, as the A340 is a plane with four engines, whereas its competitor, the Boeing 777, has only two engines. However, when developing the A350, Airbus stopped discussing whether it should have four engines or two, as the long-range version of the A350 also has only two engines. Dr. Paul Robinson, director of the Composites Centre at Imperial College London, said that the layers of composites can separate from each other without being visible on the surface. He said, “You can detect dents in metal structures with the naked eye, but such marks cannot be seen in composites.” ”But he added that Boeing could solve this problem by making the composite airframes extremely strong, strong enough to withstand the most severe collisions, although strict inspection procedures are still needed to ensure that the entire structure is properly inspected after a collision occurs. The problem for Boeing is that with aluminum structures, visual inspection is sufficient, but it’s not so easy to detect damage in composite materials; it requires more time and ultrasonic scanning to carry out such inspections. Due to the high workload of commercial aircraft, which have to cope with the pressures of tight schedules, they are prone to flying in dangerous conditions and may also overlook minor defects. But a Boeing spokesperson said, “Composites are very strong; if no damage can be seen, then no repair is necessary.” ”It seems that only time will tell whether composite materials are safe or not.

The more composite materials are used, the more it reflects the level of technology

Calling it a composite material is too general; it’s actually carbon fiber. Carbon fiber is produced by using propylene as a raw material, which reacts with ammonia to form acrylonitrile; acrylonitrile is then polymerized to yield polyacrylonitrile fibers. These fibers undergo high-temperature carbonization – the first stage of this process yields primary carbon fiber, while the second stage results in advanced carbon fiber. The strength of this material is similar to that of steel, while its density is only one-sixth that of steel. The price of carbon fiber is in the hundreds of thousands of yuan per ton; using carbon fiber in aircraft would result in a significant increase in their cost. However, due to the lower weight of such aircraft, a large amount of aviation kerosene can be saved. The entire investment can be recovered in no time

Composites consist of at least two materials, right? Carbon fiber should be a reinforcing material ； There should also be a matrix material, I’m not sure what it is; some kind of engineering plastic?

It’s still very difficult to find jobs for professionals in materials engineering

Carbon fiber is a fibrous carbon material. It is a new type of material with strength greater than that of steel, density lower than that of aluminum, corrosion resistance superior to that of stainless steel, heat resistance better than that of heat-resistant steels, and electrical conductivity similar to that of copper; it possesses many valuable electrical, thermal, and mechanical properties. Aircraft made of composite materials consisting of carbon fiber and plastic are not only lightweight but also consume less power, generate more thrust, and produce less noise ； Using carbon fiber for the disks of electronic computers can increase their storage capacity and processing speed ； Using carbon fiber reinforced plastics to manufacture spacecraft such as satellites and rockets results in high mechanical strength and low weight, which allows for significant fuel savings. During the war in Kosovo, part of the Federal Republic of Yugoslavia, in 1999, NATO used graphite bombs to disrupt most of the country’s power supply. The mechanism behind this was the creation of clouds of carbon fibers that covered a large area; these conductive fibers caused short circuits in the power supply systems. The first step is that the raw material for carbon fiber is petroleum, from which propylene is produced through catalytic cracking of petroleum. Step 2: Acrylonitrile is produced by the reaction of propylene and ammonia. Step 3: Acrylonitrile is polymerized to produce polyacrylonitrile fibers. Step 4: Heat pre-oxidation to convert the linear molecular chains of polyacrylonitrile into a heat-resistant ladder structure. Step 5: High-temperature carbonization: Heating at 1200–1600 degrees in an inert gas results in the formation of ordinary carbon fiber. Step 6: Graphitization: Heating to 2000–3000 degrees in high-purity argon to produce carbon fibers. 1 ton of carbon fiber can be produced from 50 tons of petroleum.

Carbon fiber: the quality of what’s produced domestically is still quite poor, sigh

Composites are currently well-treated, at least at the 621 and 625 institutions in Beijing.

Well, that’s absolutely correct~~ China’s large aircraft will be developed successfully soon! China’s former Yun-10 was also a highlight……