Aero-Astro Magazine Highlight

Understanding explosive blast injuries will save lives, improve treatment

By Raúl Radovitzky

We have developed the most comprehensive model to date of the full human head containing all the relevant differentiated head and brain tissues and structures.

Raúl Radovitzky's work is motivated by the critical need to understand explosion-induced blast waves on structures and humans. (William Litant photograph)

Blast attacks have become a primary threat in both military and civilian contexts. It is estimated that at least 10 percent of the soldiers deployed in Iraq and Afghanistan are affected by traumatic brain injury resulting from improvised explosive devices. Paradoxically, blast protection has only recently become an important consideration in the design of personal or vehicle armor, which, in the past, was primarily driven by ballistic protection. New IED-protective vehicles have proven effective for mitigating the IED effects, but they are extremely heavy and expensive.

In the context of civilian aviation security, improvements in explosive detection technology have reduced the detection thresholds to a point that aircraft hardening becomes conceivable and affordable.
In the last several years, my research has been motivated by the critical need to increase our understanding of the effects of blast waves on structures and humans; as well as to develop rational strategies for the design of blast protection material systems.

Toward this end, my group develops analytical and numerical tools for the analysis of complex blast physics phenomena. Examples include advanced algorithms and constitutive for material and tissue response to extreme loading conditions, coupled fluid-structure interaction models, and large-scale simulation codes for coupled adaptive multiphysics analysis.

I have been leading the blast-protection research at the MIT Institute for Soldier Nanotechnologies where the emphasis has been on developing and optimizing the use of nanoengineered materials for protecting U.S. soldiers from blast threats. One of the main accomplishments in this activity has been an important theoretical result enabling the exploration of new strategies for air blast protection. The theory quantifies the fluid-structure interaction effect on the impulse transmitted by a blast wave to a structure in the presence of fluid compressibility, as is relevant in the case of airborne blast waves. It is found that the effect of compressibility is to exacerbate the impulse mitigation provided by fluid-structure interaction. This result is an important contribution to the understanding of blast loading of structures, which is now used by the blast research community.

I am also the MIT member of a team of faculty from University of Virginia; the University of California, Santa Barbara; Harvard; and Cambridge University developing cellular material concepts for force protection. As part of this Office of Naval Research Multidisciplinary University Research Initiative project, we have quantified passive and active approaches enabling prescribed mitigation levels.

Another main area of focus of my research has been on blast-related traumatic brain injury. I lead a multidisciplinary team of faculty and physicians from MIT, Purdue, the Hefner VA Medical Center, and the Defense and Veterans Brain Injury Center at the Walter Reed Army Medical Center focusing on traumatic brain injury caused by blast. This project, supported by the Department of Defense Joint IED Defeat Organization and the Army Research Office, is motivated by the high incidence of TBI produced by roadside bombs and IEDs in current conflicts, and aims to elucidate the physical and physiological mechanisms of injury to the brain at the cell and tissue level caused by blast waves. The goal is to develop a rational metric of blast injury and associated thresholds, which can then be used in combination with blast exposure sensing devices to aid in the clinical diagnostic and treatment of TBI, as well as in the conception and design of mitigation systems. As part of this project, we have demonstrated that the conditions the brain is subjected to during a blast event are well in excess of the threshold values of the accepted brain injury criteria for impact conditions. This suggests that the primary effects of a blast constitute a plausible cause for TBI. We have also developed the most comprehensive model to date of the full human head containing all the relevant differentiated head and brain tissues and structures. This model has been released to the medical and blast research community as the MIT/DVBIC Full Head Model.

As a result of this work, my group has established itself as one of the leading groups in blast-TBI research. Part of our leadership in this area has included my service as member of the Defense Science Board Improvised Explosive Devices Task Force Medical Panel, briefings to Senior DoD Leadership including the Army Surgeon General, the Navy Surgeon General and several Army Generals. Our work is also part of the 2007 Annual Report to Congress on the Efforts and Programs of the Department of Defense Relating to Prevention, Mitigation and Treatment of Blast Injuries.

Raúl Radovitzky is an Associate Professor of Aeronautics and Astronautics at the Massachusetts Institute of Technology. His interests include computational solid mechanics, mechanics of materials, and multi-scale modeling and simulation. He may be reached at rapa@mit.edu.