The US Naval Research Laboratory (NRL) is conducting research to help the Department of Defense (DoD) better understand how the shape of the helmet matters in an improvised explosive device (IED) environment.
A part of an effort across the DoD to protect soldiers from IEDs, the research is expected to help the department pursue helmet designs that combine protection for multiple threats and capabilities.
The US Army is seeking helmet prototypes with optional parts to protect the face and jaw from various threats, including blast waves.
From initial research carried out in collaboration with Allen-Vanguard in 2008, the agency found that the mannequin was getting additional spikes in the pressure on the forehead after the initial wave hit.
NRL aerospace engineer Dr Dave Mott and colleagues Ted Young and Doug Schwer then ran computer simulations of the experimental setup that showed the incoming wave of pressure can infiltrate the gap between the head and the helmet shell and then converge under the helmet.
The resulting high pressure was found to be capable of sending a wave back toward the blast source, which caused the forehead sensor to 'pick up a spike as that wave was exiting from under the helmet'.
The team then tested four configurations of an army helmet prototype against computer simulations of blast waves from various directions, and concluded that wave behaviour was directly proportional to the complexity of helmet variant.
Mott said: "[The army] was interested in seeing how different combinations of the optional components, including the face shield ... [and] the mandible protection, affected the blast loading on the head.
"When you start adding these extra pieces of equipment, you don't always get what you expect. Multiple shocks interacting with each other can amplify the pressure, as can reflections off the structures that are in the suspension."
The US Army recently concluded a programme at the Natick Soldier Research, Development and Engineering Center called the helmet electronics and display upgradeable protection (HEaDS-UP) system, which was a multi-year initiative to develop integrated headgear technologies.
HEaDS-UP programme lead Donald Lee II said: "As the army looks to develop and field personal protective systems for the future, we need to get a better understanding of how this equipment affects the soldier.
"Characterising blast overpressure is still a relatively new endeavour, and the work conducted by NRL is one piece of a very large puzzle."
The team is planning to conduct additional studies to determine the best possible helmet combination, as the research undertaken so far used a rigid head and body.
Mott said: "The direction we're going is including the material response, including more complete body geometry and other equipment."
In addition, Mott is interested in testing other design modifications to the helmet and suspension, and different ways to integrate the helmet with body armour.
Image: The NRL evaluated four configurations of an army helmet prototype against computer simulations of blast waves from various directions. Photo: courtesy of the US Naval Research Laboratory.