20th June 2012 by Bob Yancey
This post is taken from Simulate to Innovate
I recently shared my thoughts on how composites are strengthening aviation with IndustryWeek. The article touches upon the pros and cons of the advanced material, as well as the importance of simulation for design and testing. Here’s a preview of the article:
Increasingly, aircraft designers have been turning to composites to help make their vehicles lighter, more fuel-efficient and more comfortable for passengers.
Half of the Boeing 787 and the Airbus A350, for example, are constructed of composite materials, and other manufacturers, like Bombardier, are adopting composites for a variety of aircraft sections. Composites present a number of substantial advantages to aircraft designers — as well as potential problems.
Pros and Cons of Composites
Composites do have some attractive material properties. First of all, composites offer a very high stiffness-to-weight ratio. Very stiff fibers (usually carbon or glass) are embedded in a matrix (usually some sort of plastic).
The fibers provide the stiffness, and the matrix provides the glue to produce a stiff structure that is very light. Plastics and the fibers generally are less dense than metals, but the fibers have greater stiffness, providing for a larger stiffness-to-weight ratio.
Since composites are composed of a matrix reinforced with a fiber, it’s rare for large cracks to develop in them. Small cracks ordinarily stop when they run into a stiff, neighboring fiber. When extreme forces are applied to the structure, composites indeed may crack, but the energy required for complete fracture is significant.
Metals are susceptible to both fatigue and corrosion — each of which has resulted in high-visibility calamities over the years. The famous Aloha Airlines disaster in the 1980s was the result of fatigue. Aircraft operate in very corrosive environments, and inspections for corrosion damage are carried out often. Composites don’t corrode, which is a plus, and they are also not subject to fatigue damage to the extent of metal structures.
Because of this, new aircraft with composite fuselages, such as the Boeing 787, can provide some additional passenger comfort amenities not available on a metal aircraft. For example, the pressure in the cabin in flight can be higher, producing less ear popping on landing. This is possible since the pressurization differences between the inside cabin and the outside air can be higher for a composite fuselage.
Check out IndustryWeek for the full article.