Aircraft
Lightweight and strong load-bearing elements of aircraft
Industry
Composite materials enabled a quantum leap in aircraft engineering by increasing aircraft power and reducing their weight.
Air traffic is growing denser every year all over the globe. Air safety requirements are getting more stringent. Composite materials help to improve aircraft performance, reliability and safety.
Advantages of carbon composites
Carbon composites reduce aircraft weight by an average of 30% with the same structural strength.
This material is highly resistant to vibrations and corrosion. It ensures long life and safe operation of mechanisms.
Advantages of carbon fiber composite over metal alloy in aircraft parts:
- Weight
- High strength
- Corrosion resistance
- High fatigue performance
- Wear resistance
Carbon fiber reinforced plastic features a specific weight of 1.5 g/cm3 (versus 2.8 g/cm3 for aluminum alloys and 4.5 g/cm3 for titanium alloys).
A composite part may be up to 80% lighter than a metal part.
Carbon fiber reinforced plastic is about six times stronger and stiffer than steel of the most common grades.
Carbon fiber versus other materials
| Fiber type |
Tensile strength, MPa | Tensile modulus, GPa | Elongation at break, % | Density, g/cm3 | |
|---|---|---|---|---|---|
| Carbon fiber made of PAN precursor | high strength, standard modulus | 3500-5000 | 200-280 | 1.4-2.0 | 1.75-1.80 |
| high strength, intermediate modulus | 4500-7000 | 280-325 | 1.7-2.1 | 1.73-1.81 | |
| high modulus | 3500-5000 | 325-450 | 0.7-1.4 | 1.75-1.85 | |
| ultra high modulus | 2500-4000 | 450-600 | 0.7-1.0 | 1.85-1.95 | |
| Glass | E-glass | 2500-3800 | 70-75 | 4.5-4.7 | 2.5-2.7 |
| S-glass | 4000-4500 | 80-90 | 5.0-5.3 | 2.5 | |
| Organic | Aramid | 3000-3600 | 60-180 | 2.4-3.6 | 1.45 |
| Polyethylene | 200-3000 | 5-170 | 3-80 | 0.96 | |
| Steel | high strength | 1200-2800 | 200 | 3.5 | 7.8 |
| stainless | 800-2000 | 190 | 3.0 | 7.8 | |
| Basalt | 3000-4800 | 90-110 | 3.0 | 2.6-2.8 | |
| Boron | 3500-4000 | 350-400 | 0.5-0.7 | 2.6 | |
Applications
Composites are used to make some of the airliner elements.
They include:
- Air brakes
- Spoilers
- Ailerons
- Flaps
- Rudders and control vanes
- Structural members of multiple flaps
- Pylons
- Gearbox panels
- Gearbox hatches
- Propeller blades
- Vertical and horizontal stabilizer panels
- Airframe parts (center wing, torsion box, spars, stringers, ribs)
- Fuselage skinning components
- Interior framework elements (floor beams and panels, bulkheads)
- Parts of interior and trim
- Doors, cowls, and more
Carbon fiber composites are used to make:
- Main rotor blades
- Airframe parts
- Helicopter hulls
Aircraft wheel brakes have carbon composite parts weighing about 30% of the steel brakes.
3000 Landings
Brake gears made of these materials are designed to endure 3,000 landings.
Modern helicopters contain 15% of carbon composite materials.
Historical background
The history of using composites in aircraft engineering dates back to the 1930s when glass fiber reinforced plastic was first used to make molding tools.
The introduction of carbon fiber composites in 1961 was a revolution in aircraft engineering that offered an alternative to the heavier metals. Twenty years later, carbon fiber reinforced plastics were used in aircraft engineering all around.
Experience
The weight content of composites in modern aircraft is 50%.
The overall weight of Airbus A350 is made up by
52% composites, 20% aluminum, 14% titanium, 7% steel, and 7% other materials. Boeing 787 Dreamliner features a similar material content: 50% composites, 20% aluminum, 15% titanium, 10% steel, and 5% other materials.
Summary
The introduction of composite materials in aircraft engineering allowed to produce structural members of aircraft with the target parameters of strength, reliability, safety, and other operational characteristics.
Lightweight and strong carbon composites allow to improve designs of the modern aircraft, reduce fuel consumption, and extend their flight range.