University R&D advances novel ideas to ground-breaking applications.
School may be out for the summer, but researchers at universities across the country are still hard at work on projects to advance composites. This year’s annual article on university research and development presents five projects highlighting a wide scope of investigations. They range from materials development (turning coal into carbon fiber) to processing advancements (joining in the automotive sector) and cutting-edge applications (a space suit for travel to Mars). So sit back and do a little summer reading on these industry innovations.
Joining Dissimilar Material Systems
Project: Multimaterial joining
School: Michigan State University
Location: East Lansing, Mich.
Principal Investigator: Mahmood Haq
Mahmood Haq’s research on multimaterial joining made headway in 2012 when the assistant professor in civil and structural engineering at Michigan State University (MSU) received a three-year grant from the U.S. Army to study joining composites to steel and aluminum for military ground vehicles. “That was the turning point,” says Haq, a faculty member in MSU’s Composite Vehicle Research Center (CVRC). “We learned a lot of valuable lessons about the challenges of taking this work to an assembly line. Joints that take four to six hours to cure in an oven are not feasible for automotive applications, where cycle times are measured in minutes and seconds.”
Haq says the importance of researching automotive structural joining is simple. “Joints are the weakest link,” he says. “If you can understand the joints well, then you can design the structure well.” That is a relatively simpler task when similar materials are joined. But the focus on lightweighting cars to increase fuel efficiency and reduce greenhouse effects has led to strategic replacement of some metal components with composite ones.
“When you replace a few components with composites and the rest are metal, you have a new problem,” says Haq. “Joining similar substrates – such as composites to composites and metal to metal – is relatively easy. But how do I join composites to metal?” Traditional methods don’t work. For example, drilling a hole in composites sacrifices up to 60 percent of the load carrying capacity, says Haq. “The minute you drill a hole, the fibers become discontinuous, you create stress concentrations around the hole and you cause delamination, all of which act as failure initiation points, thereby weakening the resulting joints.”
Adhesive bonding also presents challenges. “That is a one-time cure,” says Haq. “Once the adhesive cures, the joint can’t easily be undone. To repair a part, you have to change the entire component rather than fix a small part of it.”