Researchers with the Naval Research Laboratory have concluded that the Conformal Integrated Protective Headgear System, or CIPHER helmet system showed blast waves could bounce off the added components producing unexpected pressures.
Tests were conducted in all configurations: helmet only, helmet and visor, helmet and jaw protection, and the full-face coverage of visor and jaw protector.
NRL’s findings showed that adding face protection didn’t necessarily mean lessening blast-wave impact. For example, according to the report:
■ In a front-facing blast, pressures on the forehead were higher with the jaw protector, or mandible, in place and with the mandible-visor combination than they were with the helmet alone.
■ Wearing just the jaw protection for a front-facing blast doubled the strength of the secondary shockwave pressure on the forehead from 2 atmospheres (one atmosphere is a little less than 15 pounds per square inch) to 4 atmospheres.
■ In a rear-facing blast, pressures on the forehead were more than twice as high for the mandible-visor combination than for the helmet alone.
Test protocols centered around the helmet’s suspension geometry; expressed in less technical language, what is between the wearer’s head and the outer shell.
David Mott, an NRL aerospace engineer explains;
“You need that standoff for that blunt-impact and ballistic-impact protection … that’s the way the helmets work. We had seen that blast waves can infiltrate that gap.”
The prototype, which was designed under the Helmet Electronics and Display System-Upgradable Protection, or HEaDS-UP, program by Army researchers in Natick, Massachusetts, is far from finished with testing. Mott offered a series of steps that could improve future findings:
■ Blast reaction. “We’re moving toward including the material response of the head and the helmet” to the explosion, he said. The latest tests were conducted using “stationary, stiff bodies.”
■ Torso tracker. “Although we had a very detailed model for the head and helmet for these calculations, we had a pretty simple torso and shoulders,” he said. A more realistic mannequin would yield better data, especially when measuring ricochets off the body.
■ More gear. That torso will need a tactical vest, at least — Mott said knowing what soldiers likely will wear in theater will help fully track the blast waves. “We don’t have all the relevant geometry in the calculations yet,” he said.
Mott and colleagues Ted Young and Doug Schwer are optimistic they can find “combinations of geometry, either for the accessories themselves or for the suspension, that may reduce those pressure loads that we’re seeing,”
Source: Army Times, “Research raises concerns for new Army helmet design”