Researchers from the University of Maryland School of Medicine (UMSOM) and the University of Maryland's A. James Clark School of Engineering have developed a new military vehicle shock absorbing device that may protect troops from traumatic brain injury (TBI) after a land mine blast. Over the past 18 years of conflicts in Iraq and Afghanistan, more than 250,000 troops have suffered such injuries. Prior to this study, most research in this area focused on the effects of rapid changes in barometric pressure, also known as overpressure. "This is the only research so far to model the effects of under-vehicle blasts on the occupants," said Dr. Gary Fiskum. "We have produced new insights into the causes of TBI experienced by vehicle occupants, even in the absence of significant pressure changes." The research has led to the development of materials and vehicle frame design that greatly reduce injury caused by under-vehicle explosions. Dr. Fiskum and Dr. William Fourney, PhD, Associate Dean of the Clark School, Keystone Professor of Aerospace and Mechanical Engineering and Director of the Dynamic Effects Laboratory, were the first to demonstrate how the enormous acceleration (G-force) that occupants of vehicles experience during under-vehicle blasts can cause mild to moderate TBI even under conditions where other vital organs are unscathed.
"Intense acceleration can destroy synapses, damage nerve fibers, stimulate neuroinflammation, and damage the brain's blood vessels," said Dr. Fiskum. The researchers also elucidated the molecular mechanisms responsible for this form of TBI.
Dr. Fourney, Ulrich Leiste, PhD, assistant research engineer in the Clark School's Department of Aerospace Engineering, and doctoral researcher Jarrod Bonsmann, PhD, developed highly advanced shock absorber designs that incorporate polyurea-coated tubes and other structures to reduce the blast acceleration experienced by vehicle occupants by up to 80 percent.
"Essentially, it spreads out the application of force," Dr. Fourney said. "Polyurea is compressible and rebounds following compression, resulting in an excellent ability to decrease the acceleration," he says.
These results were combined with those of Dr. Flaubert Tchantchou, PhD, UMSOM research associate who demonstrated that mitigation of g-force by the elastic frame designs virtually eliminates the behavioral alterations in lab rats and loss of neuronal connections observed using small scale vehicles with fixed frames.
Continued collaboration between the labs of Drs. Fiskum and Fourney has the potential to lead to the next generation of armor-protected military vehicles that will further protect occupants. An important next step will be testing a larger scale model. "If the data holds up for those, it will hold true for full scale," Dr. Fiskum said.