The first few microseconds after an explosion are the most important moments for Arun Shukla, because that's when the first hint of damage occurs to nearby structures. As one of the world's leaders in the field of fracture mechanics, he can decipher a great deal about the explosion and about the damaged materials by those first tiny cracks and how they expand.
The Simon Ostrach Professor of Mechanical Engineering at the University of Rhode Island, Shukla has been working since the early 1980s with the U.S. military and, more recently, with Homeland Security, to learn how things break apart and how much force it takes to break them. His goal is to create stronger materials that will mitigate the damage from blasts.
Using powerful computers, a three-dimensional digital image correlation system, and one of the world's fastest cameras, which takes pictures at 200 million frames per second, Shukla can visualize the precise moment of impact. He has used this equipment to improve bulletproof vests, understand how underground bunkers withstand multiple impacts, and strengthen concrete, among other projects.
For the last several years, he has turned his attention to blast mitigation research for the U.S. Navy to help submarines, ships and other naval facilities withstand explosions.
"When an explosion happens in the water, its intensity is far greater than a similar explosion in the air," said Shukla, a resident of Wakefield, R.I. "So we're working to understand how damage happens in air and under water and developing the architecture of new carbon fiber and glass fiber materials to mitigate the damage."
He is also taking what he has learned from this Navy research and applying it to the development of blast resistant materials for buildings, bridges and tunnels in a project funded by the Department of Homeland Security. He is not only studying the structural materials of these buildings, but also such things as blast resistant glass and special coatings on materials that will make them less likely to fail.
"We test these materials at pressures comparable to a large blast using a shock tube," Shukla said, referring to a 23-foot long device that simulates the shock wave from an exploding bomb. "By using the shock tube very close to the materials we are testing, we can get the same results as by testing much larger explosions farther from the materials. And it's much safer."
Shukla's latest project is a collaboration with the U.S. Air Force to develop new materials that can be used in the construction of high-tech airplanes that can fly into space.
"We're creating what are called functionally graded materials," he said. "These materials must have thermal properties on the outside to withstand the tremendous heat that occurs when it re-enters the atmosphere, but they also have to have mechanical properties on the inside to withstand the great load or pressure that will be exerted on the plane."
Source: University of Rhode Island (news : web)
Explore further: Research team explores a novel way to fabricate preforms for composites