Featured Research

from universities, journals, and other organizations

Blast Waves May Cause Human Brain Injury Even Without Direct Head Impacts

Date:
August 27, 2009
Source:
DOE/Lawrence Livermore National Laboratory
Summary:
New research on the effects of blast waves could lead to an enhanced understanding of head injuries and improved military helmet design.

The Army's Advanced Combat Helmet replaced the older Personal Armor System for Ground Troops helmet. Its Kevlar shell provides ballistic and impact protection, and its reduced edge cut, although reducing area of coverage, improves soldiers' field of vision and hearing.
Credit: Photo courtesy U.S. Army

New research on the effects of blast waves could lead to an enhanced understanding of head injuries and improved military helmet design.

Using numerical hydrodynamic computer simulations, Lawrence Livermore scientists Willy Moss and Michael King, along with University of Rochester colleague Eric Blackman, have discovered that nonlethal blasts can induce enough skull flexure to generate potentially damaging loads in the brain, even without direct head impact.

Traumatic brain injury (TBI) results from mechanical loads in the brain, often without skull fracture, and causes complex, long-lasting symptoms.

TBI in civilians is usually caused by direct head impacts resulting from motor vehicle and sports accidents. TBI also has emerged among military combat personnel exposed to blast waves. As modern body armor has substantially reduced soldier fatalities from explosive attacks, the lower mortality rates have revealed the high prevalence of TBI.

There has been extensive research on how head impacts, for example from automobile accidents, cause traumatic brain injury. But TBIs resulting from blast waves without head impacts have not been well understood.

To tackle this puzzle, the team used three-dimensional hydrodynamic simulations to prove that direct action of the blast wave on the head causes skull flexure, producing mechanical loads in brain tissue comparable to those in an injury-inducing impact, even at nonlethal blast pressures as low as 1 bar above atmospheric pressure.

In particular, the team showed that blast waves affect the brain very differently from direct impacts.

The primary source of injury from direct impacts is the force resulting from the bulk acceleration of the head. In contrast, a blast wave squeezes the skull, creating pressures as large as an injury-inducing impact and pressure gradients in the brain that are much larger. This occurs even when the bulk head accelerations induced by a blast wave are much smaller than from a direct impact.

“The blast wave sweeps over the skull like a rolling pin going over dough,” said King, LLNL co-principal investigator.

Although the simulations show that the skull is deformed only about 50 microns (the width of a human hair), “this is large enough to generate potentially damaging loads in the brain,” according to Moss.

Because blast waves and direct impact affect the head in fundamentally different ways, armor systems that are designed to protect soldiers from impacts and projectiles may not be optimal for blast wave protection.

The team studied how helmets and their suspension systems influence the blast-induced mechanical loads in the brain.

They looked at two common systems: a nylon web system formerly used in the Personnel Armor Systems Ground Troops infantry helmet and viscoelastic foam pads like those in advanced combat helmets. Both helmets were modeled as hemi-ellipsoidal Kevlar shells.

In the first case, the 1.3 centimeter gap between the webbing and the shell allows the blast wave to “wash” under the helmet. In this case, the blast wave is focused by the shape of the helmet and the pressures under the helmet exceed those outside, so the helmet doesn't prevent the rippling deformation of the skull and pressure gradients in the brain.

In the second case, this “under wash” effect is mostly prevented by the presence of the foam pads, but under blast loading, the pads can become stiffer so that the blast wave-induced motion or deformation of the helmet is transferred to the skull. This can result in dangerous loads in the brain.

“The possibility that blasts may contribute to traumatic brain injury has implications for injury diagnosis and improved armor design,” Moss said.

Blackman added, “By comparing the effect of blasts on the head with the effect of head impacts we'd be able to make some sense of the distinct mechanisms of injury, the damage a solider might incur, and how a helmet might be designed to minimize both.”

The research appears online Aug. 26 in Physical Review Letters.


Story Source:

The above story is based on materials provided by DOE/Lawrence Livermore National Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

DOE/Lawrence Livermore National Laboratory. "Blast Waves May Cause Human Brain Injury Even Without Direct Head Impacts." ScienceDaily. ScienceDaily, 27 August 2009. <www.sciencedaily.com/releases/2009/08/090826152713.htm>.
DOE/Lawrence Livermore National Laboratory. (2009, August 27). Blast Waves May Cause Human Brain Injury Even Without Direct Head Impacts. ScienceDaily. Retrieved April 24, 2014 from www.sciencedaily.com/releases/2009/08/090826152713.htm
DOE/Lawrence Livermore National Laboratory. "Blast Waves May Cause Human Brain Injury Even Without Direct Head Impacts." ScienceDaily. www.sciencedaily.com/releases/2009/08/090826152713.htm (accessed April 24, 2014).

Share This



More Mind & Brain News

Thursday, April 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Could Marijuana Use Lead To Serious Heart Problems?

Could Marijuana Use Lead To Serious Heart Problems?

Newsy (Apr. 24, 2014) A new study says marijuana use could lead to serious heart-related complications. Video provided by Newsy
Powered by NewsLook.com
Study Says Most Crime Not Linked To Mental Illness

Study Says Most Crime Not Linked To Mental Illness

Newsy (Apr. 22, 2014) A new study finds most crimes committed by people with mental illness are not caused by symptoms of their illness or disorder. Video provided by Newsy
Powered by NewsLook.com
How Smaller Plates And Cutlery Could Make You Feel Fuller

How Smaller Plates And Cutlery Could Make You Feel Fuller

Newsy (Apr. 22, 2014) NBC's "Today" conducted an experiment to see if changing the size of plates and utensils affects the amount individuals eat. Video provided by Newsy
Powered by NewsLook.com
Do We Get Nicer With Age?

Do We Get Nicer With Age?

Newsy (Apr. 22, 2014) A recent report claims personality can change over time as we age, and usually that means becoming nicer and more emotionally stable. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins