CEE’s newest civil engineering faculty, Dr. Lauren K. Stewart, has a deep-rooted (and somewhat personal) commitment to blast mitigation research.
“On 9-11, when the terrorists attacked, we started getting calls asking if my Dad [a Department of Defense contractor] was alright, if he’d been injured,” said Stewart, who joined the CEE faculty in August. “He wasn’t in D.C. at the time, but he could have been. That really hit home.”
It also got Stewart to rethink her academic focus. Soon after she returned to school, she switched from earthquake engineering to impulsive blast mitigation – the study of high-speed, time-dependent explosive events.
“My focus as an academic — to have an impact on the world — hadn’t changed, but the means by which I would do it, did.”
Her dissertation explored the effects of vehicle-borne explosives on steel-reinforced structures. Inspired by the heinous 1995 Oklahoma City bombing, the research was entirely supported by a National Defense Science Engineering Grant (NDSEG) fellowship.
“We were looking for models that would predict collapse in structures that were targeted by car bombs,” she said.
Much of Stewart’s academic research since then has explored methods for mitigating blast impacts, including: the use of carbon as a reinforcement for concrete structures, the installation of devices to dissipate the energy of explosive mechanisms, and the design of catcher systems that will physically block flying debris from contact with humans and delicate equipment.
As a consulting blast engineer, Stewart has worked on more mundane applications. For instance, she helped one company to design storage containers to withstand high-intensity accidental blast, like those that sometimes occur at petrochemical and fertilizer facilities.
“We came up with structural system that will work around a product, which already is built to withstand seismic and wind loads,” she said. “it’s a simple steel stud connection detail that reinforced their weakest points. In two years it went from research to public use.”
Field testing – the construction and explosion of actual structures – will always be a part of Stewart’s work, but it is not everything. At Georgia Tech, her research team will use specialized equipment and computer modeling to better simulate and observe blast and shock loads.
“The actuator simulates the explosion by transferring momentum and energy to the specimen in a very short period of time – five milliseconds,” she said. “By comparison, your eye can detect change at around 17 milliseconds so, literally, you blink and you miss it. We can use high-speed photography to capture it.”
Stewart only recently wrapped up some DOD research on Hard Target Weapons – weaponry that needs to withstand some level of ancillary shock before detonation. She expects that she will always have some DOD-related research to complete – and that she will not always be able to discuss it openly.
She is philosophical about the seeming contradiction this presents to her ambitions as an academic.
“Usually in academia, there’s a lot of value placed on the number of publications you have or how widespread your citations are, but when you are working with the DOD, you have to know, yourself, that it’s positively affecting the world. The results of your research need to remain out of the public eye.”