thedrifter
05-15-04, 12:59 PM
Issue Date: May 17, 2004
Services test spray-on vehicle armor
By William Matthews
Special to the Times
While the Army urges Humvee makers to speed up production lines and turn out more up-armored versions to send to Iraq, the Navy discovered that it might be possible to protect existing vehicles with a spray-on polymer armor that’s lighter, cheaper and — maybe — tough as steel.
The Office of Naval Research has achieved promising results with spray-on armor applied to Marine Corps Humvees, Rear Adm. Jay Cohen, the chief of naval research, told a House subcommittee in March.
Using photos of Humvees hit by mine blasts and a section of polymer-coated steel, Cohen demonstrated how the armor, sprayed on the bottom of the vehicles, could protect troops riding inside against explosions and shrapnel.
The Marine Corps Warfighting Lab at Quantico, Va., is testing the polymer armor to determine whether to start spraying it on Humvees headed for Iraq and possibly on Humvees already there.
If a spray-on, plasticlike coating seems an unlikely substance to protect troops against mines, roadside bombs and small-arms fire, it struck Navy engineers that way too, at first. “We don’t understand 100 percent how it works,” admitted Roshdy Barsoum, a program officer in the ship, hull, mechanical and electrical systems science and technology division of the Office of Naval Research.
“We have a panel trying to understand how it works.”
Traditional steel armor and newer ceramic armor “both have very high strength and toughness,” he said, so it is easy to understand how they repel bullets, shrapnel and the shock of explosions.
But with the polymer, “we’re talking about something more like rubber,” Barsoum said. Under ordinary circumstances, “people would have ignored it because it did not seem likely that it would be any good.”
The concept was born in the aftermath of the 1996 truck bombing at Khobar Towers in Saudi Arabia. That’s when the Air Force began searching for novel ways to harden buildings against bomb blasts.
In late 1999, the Air Force began experimenting with “an elastomeric polymer” that is used in the commercial world as a spray-on truck-bed liner.
Air Force Research Lab scientists reported that the truck-bed polymer is “flexible, ductile and has modest strength.”
But when sprayed on an unreinforced concrete block wall, the liner proved to be remarkably effective at keeping the blocks from shattering when exposed to a bomb blast.
The Air Force’s goal was to find a way to keep chunks of concrete, brick and other construction material from fragmenting and killing people inside buildings.
The Air Force’s success with spray-on polymers caught the Navy’s attention in 2000 after a bomb on a small boat in the Yemeni port of Aden blew a 40-foot hole in the hull of the destroyer Cole, killing 17 sailors.
Cohen said he received an e-mail suggesting that the interior of hulls be coated with the blast-mitigating polymer to prevent bombs from rupturing steel hulls.
Navy researchers tried it and discovered that when the steel plating of a ship is protected by the coating, a hull struck by a bomb blast “might have gross deformation, but no penetration — and the kids on board, the sailors, would remain alive,” Cohen said.
The explosive-resistant coating came to mind again last fall when the Marine Corps was searching for a way to protect Humvees and trucks from the roadside explosives widely used in Iraq.
Tests at the Army’s Aberdeen Proving Ground in Maryland showed the spray-on armor is effective, Cohen said. But the Marine Corps has not yet decided whether to use the armor on vehicles bound for Iraq, Barsoum said.
Although judged by the Air Force to be of “modest strength,” the polymer works as armor because it makes steel behave differently, Barsoum said.
“Most materials break under very high loading rates.” That’s what happens to steel when exposed to the blast of an explosion. But the polymer coating “makes it not do that.” Essentially, the polymer armor spreads out the shock of the explosion and limits the damage, Barsoum said.
The polymer armor is made of polyurethane, polyurea or a mixture of the two, according to Air Force researchers. It can be sprayed on, brushed on, poured on or fashioned into sheets and attached like steel armor, Barsoum said.
It can be applied to the inside or outside of Humvees and other vehicles to limit damage from bombs and prevent metal fragments from being blasted free and wounding or killing vehicle occupants, he said.
Compared with steel armor, the polymer armor is lightweight and cheap. It weighs about 5 pounds per square foot, Barsoum said — about an eighth the weight of steel. At a cost of about $20 to $30 a square foot, a Humvee could be armored for less than $10,000, he said. Current steel armor kits for Humvees cost much more, he said.
If sprayed or painted on, the polymer armor easily can be applied to existing vehicles. Troops in the field could do it with relative ease.
One potential drawback, however, is that spraying armor on Humvees and trucks could increase the temperature in the passenger compartment.
William Matthews is a staff writer for Defense News.
http://www.marinecorpstimes.com/story.php?f=0-MARINEPAPER-2890071.php
Ellie
Services test spray-on vehicle armor
By William Matthews
Special to the Times
While the Army urges Humvee makers to speed up production lines and turn out more up-armored versions to send to Iraq, the Navy discovered that it might be possible to protect existing vehicles with a spray-on polymer armor that’s lighter, cheaper and — maybe — tough as steel.
The Office of Naval Research has achieved promising results with spray-on armor applied to Marine Corps Humvees, Rear Adm. Jay Cohen, the chief of naval research, told a House subcommittee in March.
Using photos of Humvees hit by mine blasts and a section of polymer-coated steel, Cohen demonstrated how the armor, sprayed on the bottom of the vehicles, could protect troops riding inside against explosions and shrapnel.
The Marine Corps Warfighting Lab at Quantico, Va., is testing the polymer armor to determine whether to start spraying it on Humvees headed for Iraq and possibly on Humvees already there.
If a spray-on, plasticlike coating seems an unlikely substance to protect troops against mines, roadside bombs and small-arms fire, it struck Navy engineers that way too, at first. “We don’t understand 100 percent how it works,” admitted Roshdy Barsoum, a program officer in the ship, hull, mechanical and electrical systems science and technology division of the Office of Naval Research.
“We have a panel trying to understand how it works.”
Traditional steel armor and newer ceramic armor “both have very high strength and toughness,” he said, so it is easy to understand how they repel bullets, shrapnel and the shock of explosions.
But with the polymer, “we’re talking about something more like rubber,” Barsoum said. Under ordinary circumstances, “people would have ignored it because it did not seem likely that it would be any good.”
The concept was born in the aftermath of the 1996 truck bombing at Khobar Towers in Saudi Arabia. That’s when the Air Force began searching for novel ways to harden buildings against bomb blasts.
In late 1999, the Air Force began experimenting with “an elastomeric polymer” that is used in the commercial world as a spray-on truck-bed liner.
Air Force Research Lab scientists reported that the truck-bed polymer is “flexible, ductile and has modest strength.”
But when sprayed on an unreinforced concrete block wall, the liner proved to be remarkably effective at keeping the blocks from shattering when exposed to a bomb blast.
The Air Force’s goal was to find a way to keep chunks of concrete, brick and other construction material from fragmenting and killing people inside buildings.
The Air Force’s success with spray-on polymers caught the Navy’s attention in 2000 after a bomb on a small boat in the Yemeni port of Aden blew a 40-foot hole in the hull of the destroyer Cole, killing 17 sailors.
Cohen said he received an e-mail suggesting that the interior of hulls be coated with the blast-mitigating polymer to prevent bombs from rupturing steel hulls.
Navy researchers tried it and discovered that when the steel plating of a ship is protected by the coating, a hull struck by a bomb blast “might have gross deformation, but no penetration — and the kids on board, the sailors, would remain alive,” Cohen said.
The explosive-resistant coating came to mind again last fall when the Marine Corps was searching for a way to protect Humvees and trucks from the roadside explosives widely used in Iraq.
Tests at the Army’s Aberdeen Proving Ground in Maryland showed the spray-on armor is effective, Cohen said. But the Marine Corps has not yet decided whether to use the armor on vehicles bound for Iraq, Barsoum said.
Although judged by the Air Force to be of “modest strength,” the polymer works as armor because it makes steel behave differently, Barsoum said.
“Most materials break under very high loading rates.” That’s what happens to steel when exposed to the blast of an explosion. But the polymer coating “makes it not do that.” Essentially, the polymer armor spreads out the shock of the explosion and limits the damage, Barsoum said.
The polymer armor is made of polyurethane, polyurea or a mixture of the two, according to Air Force researchers. It can be sprayed on, brushed on, poured on or fashioned into sheets and attached like steel armor, Barsoum said.
It can be applied to the inside or outside of Humvees and other vehicles to limit damage from bombs and prevent metal fragments from being blasted free and wounding or killing vehicle occupants, he said.
Compared with steel armor, the polymer armor is lightweight and cheap. It weighs about 5 pounds per square foot, Barsoum said — about an eighth the weight of steel. At a cost of about $20 to $30 a square foot, a Humvee could be armored for less than $10,000, he said. Current steel armor kits for Humvees cost much more, he said.
If sprayed or painted on, the polymer armor easily can be applied to existing vehicles. Troops in the field could do it with relative ease.
One potential drawback, however, is that spraying armor on Humvees and trucks could increase the temperature in the passenger compartment.
William Matthews is a staff writer for Defense News.
http://www.marinecorpstimes.com/story.php?f=0-MARINEPAPER-2890071.php
Ellie