Effectiveness of eye armor during blast loading
- 523 Downloads
Ocular trauma is one of the most common types of combat injuries resulting from the interaction of military personnel with improvised explosive devices. Ocular blast injury mechanisms are complex, and trauma may occur through various injury mechanisms. However, primary blast injuries (PBI) are an important cause of ocular trauma that may go unnoticed and result in significant damage to internal ocular tissues and visual impairment. Further, the effectiveness of commonly employed eye armor, designed for ballistic and laser protection, in lessening the severity of adverse blast overpressures (BOP) is unknown. In this paper, we employed a three-dimensional (3D) fluid–structure interaction computational model for assessing effectiveness of the eye armor during blast loading on human eyes and validated results against free field blast measurements by Bentz and Grimm (2013). Numerical simulations show that the blast waves focused on the ocular region because of reflections from surrounding facial features and resulted in considerable increase in BOP. We evaluated the effectiveness of spectacles and goggles in mitigating the pressure loading using the computational model. Our results corroborate experimental measurements showing that the goggles were more effective than spectacles in mitigating BOP loading on the eye. Numerical results confirmed that the goggles significantly reduced blast wave penetration in the space between the armor and the eyes and provided larger clearance space for blast wave expansion after penetration than the spectacles. The spectacles as well as the goggles were more effective in reducing reflected BOP at higher charge mass because of the larger decrease in dynamic pressures after the impact. The goggles provided greater benefit of reducing the peak pressure than the spectacles for lower charge mass. However, the goggles resulted in moderate, sustained elevated pressure loading on the eye, that became 50–100 % larger than the pressure loading experienced by the unprotected eye after 0.2 ms of impact of blast wave, for lower as well as higher charge mass. The present model provides fundamental insights of flow and pressure fields in the ocular region, which helps to explain the effectiveness of the eye armor. Since the measurements of these fields are not trivial, the computational model aids in better understanding of development of PBI.
KeywordsOcular trauma Primary blast injuries (PBI) Blast loading Eye armor Military Combat Eye Protection (MCEP) Fluid–structure interaction
This research was supported by US Army Medical Research, Vision Research Program under grant number W81XWH-10-1-0766. Meshes of the head and eye armor were provided by WMRD, US Army Research Laboratory, Aberdeen MD. We thank Professor R. Mittal and Dr. Adam Fournier for helpful discussions. R.B. gratefully acknowledges financial support from Department of Science and Technology, New Delhi, through fast track scheme for young scientists.
Conflict of interest
The authors declare that they have no conflict of interest.
Supplementary material 1 (avi 2311 KB)
Supplementary material 2 (avi 1369 KB)
Supplementary material 3 (avi 748 KB)
Supplementary material 4 (avi 1692 KB)
Supplementary material 5 (avi 769 KB)
Supplementary material 6 (avi 2121 KB)
- Bailoor S, Soti AK, Bhardwaj R, Nguyen TD (2013) Effectiveness of eye armor during blast loading. In: Proceedings of the ASME 2013 summer bioengineering conference, Sunriver, OR, USAGoogle Scholar
- Bentz V, Grimm G (2013) Joint live fire (JLF) final report for assessment of ocular pressure as a result of blast for protected and unprotected eyes (Report number JLF-TR-13-01) U.S. Army Aberdeen Test Center, Aberdeen Proving Ground, MDGoogle Scholar
- Bhardwaj R, Ziegler K, Seo JH, Ramesh KT, Nguyen TD (2014) A computational model of blast loading on the human eye. Biomech Model Mechanobiol 13(1):123–140. doi: 10.1007/s10237-013-0490-3
- Duma S, Kennedy E (2011) Final report: eye injury risk functions for human and FOCUS eyes: hyphema, lens dislocation, and retinal damage. Technical report, U.S. Army Medical Research and Material Command Fort Detrick, Maryland. http://www.facstaff.bucknell.edu/eak012/Reports_n_Papers/Eye_Injury_Risk_Functions_for_Human_and_FOCUS_Eyes-FinalReport_W81XWH-05-2-0055-July2011Update.pdf. Accessed 21 Feb 2015
- Esparza E (1992) Spherical equivalency of cylindrical charges in free-air. 25th Department of Defense Explosives Safety Seminar, 18–20 August 1992. Available at www.dtic.mil
- Esposito L, Clemente C, Bonora N, Rossi T (2013) Modelling human eye under blast loading. Computer Methods in Biomechanics and Biomedical Engineering. doi: 10.1080/10255842.2013.779684
- Hamit HF (1973) Primary blast injuries. Ind Med Surg 43(2):14–21Google Scholar
- Kingery CN, Bulmash G (1984) Airblast parameters from TNT spherical air burst and hemispherical surface burst. Defence Tech Rep Report ARBL-TR-02555, U.S. Army BRL, Aberdeen Proving Ground, MDGoogle Scholar
- Slotnick JA (2010) Explosive threats and target hardening understanding explosive forces, it’s impact on infrastructure and the human body. In: Fourth international symposium on tunnel safety and security, Frankfurt am Main, Germany, 17–19 March 2010Google Scholar
- Stitzel JD, Weaver AA (2012) Computational simulations of ocular blast loading and prediction of eye injury risk. ASME SBC 2012: SBC2012-80792Google Scholar