Modeling of Paintball Impact Ocular Trauma: A Path Towards Development of an Improved Blunt Trauma Predictive Capability, 18-R9664

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Principal Investigators
Walt Gray
Amber Bonivtch
Carl Weiss
William Sponsel, The University of Texas Health Science Center at San Antonio (UTHSCSA)
Frank Scribbick, UTHSC-SA

Inclusive Dates:  10/01/06 – Current

Background -  Because of the increasing number of blast and impact injuries experienced in the Iraqi theater of operations, there has been increased interest in the proper design of equipment to prevent blunt trauma injuries. Currently, the physics of injury is poorly understood and limited predictive capabilities exist within industry and government. Thus, blunt trauma modeling and prediction represents a potentially high growth business area. Fortunately, blunt force trauma modeling is a natural extension of existing biomechanics, impact physics, and extensive computational capabilities at the Institute. However, discussions with potential government clients revealed that only through successful demonstration could SwRI gain the necessary credibility for future contract award. Partnership with The University of Texas Health Science Center at San Antonio (UTHSC-SA) could provide much-needed medical expertise and allow SwRI to pursue market opportunities not otherwise open to it.

Approach - The research objective is to develop suitable geometric and material models of human tissue and organs, implement them into physics-based codes, validate them through an extensive experimental program, and demonstrate the validity of the models by application to a real-world impact and blunt trauma problem. A suitable demonstration problem was suggested by ophthalmologists at UTHSC-SA who noted an alarming increase in the number of catastrophic un-repairable eye injuries due to paintball impacts.

Accomplishments - Eye models were developed for implementation into both an impact physics code, CTH, and a finite element code, LS-DYNA. The models include anatomically correct representations of the exterior and interior eye structures, as well as robust constitutive models for the ocular tissues, fluids, and bone. Using the models, calculations are performed and results compared to an extensive series of paintball impact experiments on instrumented porcine (pig) eye specimens. UTHSC-SA personnel are conducting detailed post-impact pathologies (autopsy) of the eyes in an effort to correlate level of trauma with the impact conditions. Preliminary results reveal that the model predictions are in general agreement with the types and severity of injury observed in the pathology. The models predict highest strains and deformation in areas where the most severe damage occurs, and low strain and deformation where no injury is observed.

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