backtop


Print 43 comment(s) - last by goku.. on Dec 16 at 3:36 PM


Small Blast-proof glass panel after test  (Source: DHS S&T)
Inventin may lood to better looking Popemobile

High profile leaders and government buildings all around the world can be targets of terrorist attacks at any given moment. Many of these officials and buildings are protected with defenses that are designed to protect the people inside buildings and vehicles. One of the more common types of protection is glass that is both bullet and bomb resistant.

According to the Pentagon, glass shards are one of the leading causes of death in many bombing attacks. The problem with the blast-resistant glass on the market today is that the material is very thick and can’t fit into the windowpanes in existing buildings. The glass is said to be about as thick as a 300-page novel.

A team of engineers from the University of Missouri and the University of Sydney in Australia has developed a new type of blast-resistant glass that is much thinner than the current glass, but has the same blast-resistant properties as the thick stuff. The new glass is about a quarter-inch thick and is made from a plastic composite with an inert layer of polymer reinforced with glass fibers. The team testing the glass has already exposed a small test panel to an explosion.

Sanjeev Khanna, the project's principal investigator and an associate professor of mechanical engineering at Missouri said, "The results were fantastic. While the discharge left the pane cracked, the front surface remained completely intact."

The new glass gets its strength from the use of long glass fibers in a woven cloth that is soaked in liquid plastic and then bonded with adhesive. The resulting glass is very strong, thin, and clear. The current thick blast-resistant glass has a green tinge.

The new glass would also fit existing windowpanes.

"Designing an affordable, easy-to-install blast-resistant window could encourage widespread use in civilian structures, thereby protecting the lives of occupants against multiple threats and hazards," notes John Fortune, manager of the project for the Infrastructure and Geophysical Division at S&T.

Tests with larger explosions and larger glass sheets are planned.



Comments     Threshold


This article is over a month old, voting and posting comments is disabled

Other uses?
By Chapbass on 12/10/2010 9:47:48 AM , Rating: 2
quote:
"Designing an affordable, easy-to-install blast-resistant window could encourage widespread use in civilian structures, thereby protecting the lives of occupants against multiple threats and hazards," notes John Fortune, manager of the project for the Infrastructure and Geophysical Division at S&T.


I was going to say, if they can get this stuff cheap enough, any physics people want to chime in on how this might do in say, a tornado? Glass is such a brittle part of a building right now, you would think that if they could make it more stable and less dangerous (dangerous in extreme conditions at least), this could be huge.

Also: Would this give glass any more structure? I guess what I'm asking is, if we take the twin towers for example, would the building have any more resistance to impacts like that, or possibly have more strucutre to keep from crumbling in that type of environment? They said the glass was broken in the test, but obviously something is still holdinng it together...not really sure..




RE: Other uses?
By mmcdonalataocdotgov on 12/10/2010 9:58:35 AM , Rating: 2
Those towers were uniquely designed to fail in a way that no other building is. Ironic.

It was not the perimeter structure that failed on the twin towers, it was the core structure, which was held to the perimeter through floor joists on each floor (which eventually failed), and through roof trusses, which were the last thing to fail. The perimeter structure held up very well. A more durable glass like this would have popped out of the frames and gone sailing off throughout downtown like giant ninja stars. Not pretty.

Anyway, if the planes had hit a conventional sky scraper, it would not have failed in the same way since they use a more coherent internal structure.

These panes would protect the curtain wall somewhat, but if frames failed first, the panes become flying guillotines within the building structure. Lovely.


RE: Other uses?
By FITCamaro on 12/10/2010 12:01:16 PM , Rating: 3
I really doubt even bullet proof glass would stand up to several hundred tons going a few hundred miles an hour hitting it.

Buildings aren't designed to get hit by planes and never will be. Well except for nuclear power plants.


RE: Other uses?
By Smartless on 12/10/2010 2:02:23 PM , Rating: 5
Actually I'm pretty sure it WAS designed to withstand a plane hit. But they were thinking at the very largest a 737. The tower actually did hold until the jet fuel melted the fireproofing off the internal structure. Not everything can be designed like a nuclear power plant. I know, not your point, but as an engineer, yeah we'd love to build things to withstand atomic bombs and a hundred years of the environment but truth is its both ugly and expensive.

As for thinner ballistic glass, using it requires a lot of thought. Fire departments don't like it but security firms do. The armed forces are really going to love this but I'm sure the best use would be transporting whales in a Klingon Bird-of-Prey.


RE: Other uses?
By Solandri on 12/10/2010 4:39:34 PM , Rating: 2
According to the architect, they were designed to withstand the impact of a 707, the largest plane in service at the time the WTC was designed. Overdesign meant they were able to survive the impact of a considerably larger 767 at a much higher velocity than is typical at those altitudes.

That they collapsed due to the fire is completely independent of their impact resistance. Frankly, I was amazed that the second tower managed to stay standing as long as it did. After the second plane hit, you could clearly see half of the structural support members on one face were completely severed. But the thing kept standing.

BTW, a google search turned up this eerie exchange from 2000:
http://www.airliners.net/aviation-forums/general_a...


RE: Other uses?
By lyeoh on 12/10/2010 2:06:07 PM , Rating: 2
That's why flying cars as popularly envisioned are a stupid idea (as long as buildings aren't designed to get hit by them).

Once you have thousands of flying cars in the city the odds of a crash go up significantly. And the average kinetic energy involved goes up.


RE: Other uses?
By PAPutzback on 12/10/2010 10:00:22 AM , Rating: 2
I think in the case of the twin towers if the glass didn't break then less oxygen would have come in to feed the fire.


RE: Other uses?
By Omega215D on 12/10/2010 10:26:07 AM , Rating: 3
Unlike that gaping hole that the plane created when it punctured the building at that speed and I doubt anything would have held up to the intense heat created by burning jet fuel.


RE: Other uses?
By PAPutzback on 12/10/2010 10:31:10 AM , Rating: 2
If this glass is really blast proof it would of prevented other windows from blasting out. I wonder how high of a temperature this new glass can take before melting. A high enough temperature can tear through glass like tissue paper.


RE: Other uses?
By Solandri on 12/10/2010 2:53:34 PM , Rating: 3
quote:
I was going to say, if they can get this stuff cheap enough, any physics people want to chime in on how this might do in say, a tornado? Glass is such a brittle part of a building right now, you would think that if they could make it more stable and less dangerous (dangerous in extreme conditions at least), this could be huge.

Actually, you want the windows to pop out in a tornado. That's what's called a controlled failure - a component of the structure is designed to fail first in order to protect the rest of the structure. Without the windows blowing out, you can get a more destructive event, like the roof popping off.

Here's a similar design on the Southwest Airlines plane which depressurized last year:
http://aviationblog.dallasnews.com/archives/2009/0...
The panel was deliberately designed with a weak ring whose sole purpose was to fail before the rest of the panel. When a fracture developed within the panel (part of the skin of the aircraft), it spread, until it hit this weak ring, at which point the ring blew out. The plane depressurized, but the damage was contained to the area within the ring. If you don't design such failure modes into your structure, the fracture could spread along the entire panel, "unzipping" the skin of the aircraft and resulting in a much more catastrophic failure. Like what happened to Aloha 243:
http://www.aviationchatter.com/wp-content/uploads/...

The main problem with glass windows is that they shatter into sharp shards. Tempered glass and plexiglass which avoid this have been available for decades, but their cost is high enough that it's cheaper to just replace the glass in the few cases where it does shatter and pay for any consequential medical bills. Even in California where a large number of windows break during an earthquake, people still go with regular glass and replace it if it does break. I sincerely doubt this new glass is cheaper than tempered glass or plexiglass, so I don't see it being any more successful than those two at replacing regular glass.


RE: Other uses?
By makken on 12/11/2010 12:08:54 AM , Rating: 2
^This.

As I understand it, in a tornado, you have high winds over the top of your roof. If your windows hold, the air under your roof is stationary, creating a pressure differential that can literally pop off your roof. If your windows pop, however, you have air flowing both above and below your roof, lessening the pressure differential, and potentially saving your roof.

see: http://en.wikipedia.org/wiki/Bernoulli%27s_princip...
and: http://en.wikipedia.org/wiki/Lift_force


RE: Other uses?
By goku on 12/16/2010 3:36:52 PM , Rating: 2
plexiglass shatters btw.. I think you mean lexan. But plastic scratches too easily so it depends on the application but for longevity, a tempered glass solution would be best.


"We don't know how to make a $500 computer that's not a piece of junk." -- Apple CEO Steve Jobs











botimage
Copyright 2014 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki