Brian Flinn’s job is to build a better composite, to create materials that are “stronger, stiffer, smarter and safer for applications in aerospace and automobiles.” Flinn, a research associate professor with the University of Washington Department of Materials Science and Engineering, gave a talk last week as part of the Science Café series sponsored by the Pacific Science Center and KCTS television.
Flinn noted that composites have been around for a long time, but “they’ve been in the news a lot in Seattle recently because of a certain airplane,” the Boeing 787.
Historians tag different epochs with the names of the dominant material of the time.
“If you look at the history of man, it was the Stone age, the Bronze Age, the Iron age,” Flinn said. He then played a clip from the 1967 film “The Graduate,” in which Mr. McGuire told Benjamin Braddock about plastics. “As a materials scientist that’s one of my favorite movie clips,” he quipped.
By then the polymer age was in full swing. Now composites are really booming, though Flinn said they aren’t all that complicated.
“A composite is where you take two different materials and mix them together to make a new material,” Flinn explained. “This new material isn’t just an atomic mix or a material like an alloy or a solution. You actually have two or more distinct phases that retain some of the properties of what you mixed together.
“The objective is really to try to take the best properties from two different materials, put them together, and use what’s called the principle of combined action to get an average of the properties that is not available in either one of the materials by themselves.”
This is especially important in aerospace applications where weight is a penalty, because you can design materials that are both strong and light, Flinn said. That’s where the 787 is so revolutionary in his view: the plane is about half composites by weight but 80 percent composites by volume. The non-composite components are much heavier.
Much of Flinn’s work these days involves figuring out how to assemble composite parts. If you bolt them together it’s bad, because holes drilled in the parts weaken the composite, and bolts or rivets add weight.
“If you glue them together it’s much better,” he said. “The question is, how much do you trust your glue?”
It’s a good question. One way around it is to build larger parts that are essentially molds that don’t need fastening. Some aircraft doors, for example, are now being created as one piece.
Another area of research involves finding ways to learn if composite parts are damaged. Adding sensors and wires adds weight and complexity. Instead, they’re working on smart composites.
“What we want to do is called molecular engineering,” Flinn said. “You actually design your molecules that you add into the composite that will tell you things about what’s going on there. These are called molecular sensors.”
Composites are already in wide use in spacecraft and aerospace, but Flinn noted more industries are catching on to the advantages. Medicine and wind energy are a couple of examples. The auto industry is another. A new Lamborghini that can do 0-to-60 in about 2.5 seconds is largely made of carbon fiber composite. And Flinn expects composites to be key to design of a better electric car.
A video of Flinn’s talk will be archived on the KCTS website.