Testing the blast response of foam inserts for helmets

S Bloodworth-Race,R Critchley,R Hazael,A Peare,T Temple

doi:10.1016/j.heliyon.2021.e06990

S Bloodworth-Race, R Critchley + Show 3 more

Open Access

https://doi.org/10.1016/j.heliyon.2021.e06990

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Abstract

Modern era combat helmets have different iterations and configurations to offer greater protection from blunt impact or ballistic penetration to suit the theatre of operation, although there are currently no standards for blast protection. Moreover, incorporation of blast protection into the same constrained mass-volume envelope is extremely challenging as there is very little space for a material to absorb or dissipate the shockwave. Foam padding is fitted in contemporary combat helmet designs for comfort and standoff purposes. Examples were subjected to blastwaves generated from an air-driven shocktube, along with open cell polyurethane foam specimens of varying pores per inch and thicknesses to. Whilst the range of samples tested did not afford any superior blast mitigation behaviour over the foam already present in helmets, they exhibited comparable performance with a lower mass. There also appears to be positive correlation between increased mass and increased impulse transmitted through the foam. The literature suggests that multiple mechanisms of damage for blast induced mild Traumatic Brain Injury (bTBI) can be caused by the helmet itself, therefore additional protection from a blunt or ballistic impact may increase the risk of damage from a blast insult.

Highlights

The most common weapon seen in recent conflicts is the Improvised Explosive Device (IED) with injuries caused by fragmentation and blast as opposed to ballistic penetration or blunt impact [1, 2]
Low peak overpressures and short positive impulse time durations can result in Blast-Induced Mild Traumatic Brain Injury (TBI), manifesting as anxiety, behavioural changes, even loss of fine motor control, symptoms which can often be confused with Post Traumatic Stress Disorder (PTSD) [5]
This study investigated the energy absorption properties of materials commonly used in contemporary combat helmet design, to prevent the blast wave passing through the helmet

Summary

Introduction

The most common weapon seen in recent conflicts is the Improvised Explosive Device (IED) with injuries caused by fragmentation and blast as opposed to ballistic penetration or blunt impact [1, 2]. Improvements in ballistic and impact protection of body armour and helmets has led to increased rates of survival, shifted the focus of the injuries to the exposed head and neck areas [3]. IED blast can cause severe damage to vehicles, structures and personnel, with increasing prevalence of Traumatic Brain Injury (TBI) noticed amongst survivors [4]. Low peak overpressures and short positive impulse time durations can result in Blast-Induced Mild TBI (bTBI), manifesting as anxiety, behavioural changes, even loss of fine motor control, symptoms which can often be confused with Post Traumatic Stress Disorder (PTSD) [5]. The engineering approach to mitigation of bTBI is concerned with preventing or reducing the peak overpressure transmitted to the brain, the response to this has been improved head protection. Modern combat helmets have been through several phases of improvements leading to the inclusion of different variants offering greater protection for blunt impact or ballistic projectiles [7], but incorporating blast protection into the same mass-volume envelope is extremely challenging [8]

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Discussion

Conclusion