Session: 05-02-02: Injury and Damage Biomechanics II

Paper Number: 73556

Start Time: Wednesday, 01:40 PM

73556 - On a Framework to Integrate Performance of Helmet Systems for Blast, Blunt Impact and Thermal Loading 

Motivation/Rationale: Helmets have evolved over the past 50 years through improvements in shell and suspension materials, as well as better designs for absorbing energy in ballistic and blunt impacts. In the past 20 years, threats to US Warfighters have increased with the prevalence of buried improvised explosive device (IED) blast events and in theaters with extreme desert conditions. Two new threats now must be considered in helmet systems design: blast overpressure effects with and without fragments, and thermal management for safeguarding warfighter heath and effectiveness in extreme desert conditions. However, even the latest combat helmets with the pad suspension system do not provide adequate protection from all three of these threats in the theater (i.e., blast, ballistics and blunt impact) and heat management. To date, no research results have been reported on integrating the effects of multiple threats to head-brain with a helmet system into an overall performance measure and using such a measure to design suspension systems for enhanced helmet performance. Integrating multiple types of loadings into a design framework to develop a design tool for a trade space analysis will be the scope of this paper.

Objective: The objective of this research is to develop a design methodology to generate new multifunctional helmet suspension systems for multiple combat theater relevant threats (i.e., blast, ballistics and blunt impacts) and Warfighter thermal management.

Methods and Results: The paper will discuss results from computational modeling and simulation of helmet systems, such as, helmet shell, suspension configurations and retention system, and the head model subjected to blast loading, and blunt and ballistic impacts. A critical aspect of thermal performance of a suspension design is whether the air between the helmet shell and the head becomes saturated during perspiration, or if the pad arrangement enables air flow to exchange this saturated air with less-humid ambient air.  Simulations of the flow generated by both buoyancy-driven natural convection (i.e., the flow generated by the body’s thermal plume) and by forced convection due to an ambient wind will assess each design’s efficiency in facilitating evaporative cooling via perspiration by predicting the transport of moisture-laden air away from the head. The key challenge is the development of a single design criterion that can combine individual criteria for blunt loading, blast overpressure and thermal loading. Two or more loading types (blast loading and blunt impact) along with thermal loading will be used for two or more configurations of the helmet suspension systems. The results from the simulated cases and their analyses will be presented to suggest a framework for combining the effects of these threats into a single measure that can be used to assess the helmet systems design. Our hope is that we can suggest ways to generate a multi-dimensional map (or functional representation) of the performance for the three types of threats.

Presenting Author: Amit Bagchi US Naval Research Laboratory

Authors:

Amit Bagchi US Naval Research Laboratory
Yu Yu Khine US Naval Research Laboratory
David Mott US Naval Research Laboratory
X Gary Tan US Naval Research Laboratory