Any experts know why this has just happened?
Discussion
This happened on my old MG ZR many years ago. It was put down to a difference in temperature, I had the heater on full blast and it was about -8 outside, but I have never been able to understand how the hundreds of cars I see every day don't have spontaneously exploding rear windows.
Seems strange happening in a garage like that.
Seems strange happening in a garage like that.
300bhp/ton said:
Assuming you can rule out vandalism of some kind (even a sneaky kind).
Then it does seem rather odd. Was there anyway anything could have fallen on it?
Tailgate not twisted and no chips in the screen (before obviously) plus its cool in the garage.
When tempered glass is made, the surface is rapidly cooled by blowing air onto it. This causes it to solidify before the inner part of the glass. As the rest of the glass solidifies and cools it contracts, setting up compression forces in the surface. This makes the glass stronger, but any damage to the surface can lead to the balanced forces being upset causing cracks to propagate instantly across the whole pane. This means you get the small pieces you see there rather than the very sharp shards you get from untoughened glass.
A defect such as a scratch or chip could easily cause failure like that along with a temperature change. It is also possible for it to fail spontaneously without there being external damage, due to impurities in the glass during manufacture.
A defect such as a scratch or chip could easily cause failure like that along with a temperature change. It is also possible for it to fail spontaneously without there being external damage, due to impurities in the glass during manufacture.
Edited by tank slapper on Friday 21st June 16:06
tank slapper said:
When tempered glass is made, the surface is rapidly cooled by blowing air onto it. This causes it to solidify before the inner part of the glass. As the rest of the glass solidifies and cools it contracts, setting up compression forces in the surface. This makes the glass stronger, but any damage to the surface can lead to the balanced forces being upset causing cracks to propagate instantly across the whole pane. This means you get the small pieces you see there rather than the very sharp shards you get from untoughened glass.
Yup. Have a look on youtube for Prince Rupert Drops on youtube to learn more:http://www.youtube.com/watch?v=xe-f4gokRBsý
http://en.wikipedia.org/wiki/Prince_Rupert's_Drop
Although spontaneous breakage can (albeit extremely rarely) occur, much breakage is called "spontaneous" just because there is no easily visible cause.
Excessive heat build up, or sudden temperature changes; a gas strut failing; warping in the frame; corrosion, stress breakage (from a foreign object lodged somewhere near the edge of the glass) or even a piece of concrete/debris/screw falling from above can all be possible causes, but then I've known people to be driving along and with no other car or person in sight, BOOM!
"I reckon it was a sniper," some usually say
Excessive heat build up, or sudden temperature changes; a gas strut failing; warping in the frame; corrosion, stress breakage (from a foreign object lodged somewhere near the edge of the glass) or even a piece of concrete/debris/screw falling from above can all be possible causes, but then I've known people to be driving along and with no other car or person in sight, BOOM!
"I reckon it was a sniper," some usually say
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