title: Effect of helmet liner systems and impact directions on severity of head injuries sustained in ballistic impacts: a finite element (FE) study.
abstract: The current study aims to investigate the effectiveness of two different designs of helmet interior cushion, (Helmet 1: strap-netting; Helmet 2: Oregon Aero foam-padding), and the effect of the impact directions on the helmeted head during ballistic impact. Series of ballistic impact simulations (frontal, lateral, rear, and top) of a full-metal-jacketed bullet were performed on a validated finite element head model equipped with the two helmets, to assess the severity of head injuries sustained in ballistic impacts using both head kinematics and biomechanical metrics. Benchmarking with experimental ventricular and intracranial pressures showed that there is good agreement between the simulations and experiments. In terms of extracranial injuries, top impact had the highest skull stress, still without fracturing the skull. In regard to intracranial injuries, both the lateral and rear impacts generally gave the highest principal strains as well as highest shear strains, which exceed the injury thresholds. Off-cushion impacts were found to be at higher risk of intracranial injuries. The study also showed that the Oregon Aero foam pads helped to reduce impact forces. It also suggested that more padding inserts of smaller size may offer better protection. This provides some insights on future's helmet design against ballistic threats.
authors.affiliation: Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117576, Singapore. tsekm.research@yahoo.com.|Department of Mechanical Engineering, University of Melbourne, Parkville Campus, Melbourne, VIC, 3010, Australia. tsekm.research@yahoo.com.
authors.forename: Kwong Ming
authors.identifier: http://orcid.org/0000-0002-8170-0775
authors.initials: KM
authors.lastname: Tse
authors.affiliation: Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117576, Singapore.
authors.forename: Long Bin
authors.initials: LB
authors.lastname: Tan
authors.affiliation: College of Automobile and Traffic Engineering, Nanjing Forestry University, 159 LongPan Rd, Nanjing, 210037, People's Republic of China.
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
authors.affiliation: Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117576, Singapore.
authors.forename: Vincent Beng Chye
authors.initials: VBC
authors.lastname: Tan
authors.affiliation: Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117576, Singapore. mpeleehp@nus.edu.sg.|National University of Singapore (Suzhou) Research Institute, 377 Lin Quan Street, Suzhou Industrial Park, Suzhou, 215123, Jiang Su, People's Republic of China. mpeleehp@nus.edu.sg.
authors.forename: Heow Pueh
authors.initials: HP
authors.lastname: Lee
mesh_terms: D001930:Brain Injuries / Q000517:prevention & control; D003198:Computer Simulation; D006259:Craniocerebral Trauma / Q000517:prevention & control*; D004867:Equipment Design; D020342:Finite Element Analysis; D044709:Forensic Ballistics / Q000379:methods*; D006257:Head / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006260:Head Protective Devices; D006801:Humans; D007427:Intracranial Pressure; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D012886:Skull / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D014948:Wounds, Gunshot / Q000517:prevention & control
keywords: Brain injury; Bullet; Head model; Helmet; Interior cushion