Wear and tear cause damage to most solid materials, especially when the movement of solid materials occurs during a short time, such as during an earthquake. But engineers at the University of Missouri's College of Engineering have developed a flexible material that can withstand the movements in multiple directions caused by an earthquake. The materials are based on a lattice structure (see the figure) and can survive the simultaneous forward-and-backward and side-to-side motions caused by earthquakes, perhaps helping to lessen the destruction caused to buildings by earthquakes (Figure 2).
The engineering team was led by Guoliang Huang, a James C. Dowell professor in the mechanical and aerospace engineering department at the University of Missouri College of Engineering. “Our elastic material can stretch and form to a particular surface, similarly to a wrap on a vehicle,” Huang said. “It can be applied to the surface of an existing building to allow it to flex in an earthquake. What is unique about the structured lattice type material is that it protects against both types of energy waves—longitudinal and sheer—that can travel through the ground.”
On smaller scales, the material also has the potential to diminish the effects of vibration in many military mechanical systems, such as aircraft and submarine engines. “For over 20 years, no one had a natural solution for this issue in a solid material,” Huang said. “Now we’ve designed, modeled, and fabricated a new material with properties that do not exist naturally for what we believe is a nearly perfect protective device.”
The U.S. Army Research Office, part of the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory (ARL), provided funding for the material development at the University of Missouri and is encouraged by the results from Huang’s team.
“The results that the University of Missouri team has recently published are encouraging,” said Dan Cole, program manager at the Army Research Office. “This research could lead to new strategies for steering mechanical waves away from critical regions in solid objects, which could enabler novel capabilities in soldier protection and maneuvering.” The results of the research at the University of Missouri were detailed in two technical papers within Physical Review Letters, a journal of the American Physical Society: “Polar Metamaterials: A New Outlook on Resonance for Cloaking Applications,” and “Physical Realization of Elastic Cloaking with a Polar Material.”