Ballistic Helmets: Their Design, Materials, and Performance Against Traumatic Brain Injury

Abstract

a b s t r a c tProtecting a soldier's head from injury is critical to function and survivability. Traditionally, combat helmets have been utilized to provide protection against shrapnel and ballistic threats, which have reduced head injuries and fatalities. However, home-made bombs or improvised explosive devices (IEDs) have been increasingly used in theatre of operations since the Iraq and Afghanistan conflicts. Traumatic brain injury (TBI), particularly blast-induced TBI, which is typically not accompanied by external body injuries, is becoming prevalent among injured soldiers. The responses of personal protective equipment, especially combat helmets, to blast events are relatively unknown. There is an urgent need to develop head protection systems with blast protection/mitigation capabilities in addition to ballistic protection. Modern military operations, ammunitions, and technology driven war tactics require a lightweight headgear that integrates protection mechanisms (against ballistics, blasts, heat, and noise), sensors, night vision devices, and laser range finders into a single system. The current article provides a comparative study on the design, materials, and ballistic and blast performance of the combat helmets used by the US Army based on a comprehensive and critical review of existing studies. Mechanisms of ballistic energy absorption, effects of helmet curvatures on ballistic performance, and performance measures of helmets are discussed. Properties of current helmet materials (including Kevlar Ò K29, K129 fibers and thermoset resins) and future candidate materials for helmets (such as nano-composites and thermoplastic polymers) are elaborated. Also, available experimental and computational studies on blast-induced TBI are examined, and constitutive models developed for brain tissues are reviewed. Finally, the effectiveness of current combat helmets against TBI is analyzed along with possible avenues for future research.

Helmet efficacy against concussion and traumatic brain injury: a review

“…There has been a general trend in the modern era for both civilian and military helmets, in which the focus has shifted from protection against lethal, penetrating TBI toward protection against the more frequently incurred blast injury and concussion. 50,109…”

“…78 The protective mechanism of helmets, especially combat helmets, in response to blast events is relatively unknown in the literature. 50 Another factor contributing to the complexity of the data on helmet protection from concussion is the varying, inconsistent standard for helmet development.…”

“…It is difficult to balance the needs for maximum protection against concussion with appropriate design for the specific sport or use, affordability, low weight, and comfortable fit, and still develop an effective helmet. 50…”

Modeling of Impact on Multiple Layers With Unidirectional Yarns

“…Literature gave simualtion of woven frabrics under impact [6], [7], [8]. For this type of flexible panels for ballistic protection, thermoplastic polymers are used, but for other applications (like helmets [9], [10] or vehicle armors [11], [12], the matrix is rigid.…”

Assessment of head injury risk caused by impact using finite element models

“…This part of the Thesis is dedicated to the study of the protection provided by combat helmets under ballistic loading conditions. Specifically, the focus will be set on a specific injury type which is the Behind Helmet Blunt Trauma (BHBT), caused by the blow delivered from the inner part of the helmet shell (called backface deformation (BFD)) to the head [223][224][225]. This nonpenetrating injury is the consequence of the large deformations that composite combat helmets can sustain without allowing bullet perforation.…”