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Old 22nd April 2004, 11:28   #1
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Default Windshield broken without a reason?

Some time the windshield of cars breaks without any external hit .
Like you park in a safe area , suddenly the glass breaks with a blasting sound , often it becomes very tricky to decide and go ask for warranty (if the vehicle is under warranty)
Can anyone explain why and how this phenomenon happens and how to identyfy the cause !!
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Old 22nd April 2004, 14:47   #2
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Stresses in the windscreen + sudden changes in temperatures - try putting hot water on a cold windscreen - sometimes the windscreen might have faults but the beauty is that no one can prove anything except for laminated windscreens
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Old 22nd April 2004, 20:09   #3
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This has happened in Camry , parked and early morning the glass exploded
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Old 23rd April 2004, 01:22   #4
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it is due to expansion and. see night time sub zero temperature and in morning there is direct sun light...! amd maybe due to the fast heat accumulation there is a crack!
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Old 23rd April 2004, 01:39   #5
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how early in the morning did this happen? I've personally never heard of such things happening.

Regards...
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Old 23rd April 2004, 04:43   #6
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anways happens a lot in the middle east!!!! hot afternoon sun and that can be disastrous...!
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Old 23rd April 2004, 06:14   #7
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Ive never previously heard of this happening!
As people have said before i guess its due to different rates of heating and cooling as well as different co-efficients of expansion of the glass and metal around it, producing differences that are greater than the tolerances.
However, car windshields cracking when u pour hot/cold water on them is incredibly rare...but is quite likely to happen with thinner glass.

cya
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Old 23rd April 2004, 08:03   #8
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It was around 5.30 in the morning .
This phenomenon happens in many cars , but very rarely. But the symptom or phenomenon is not clear !
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Old 25th July 2008, 16:25   #9
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It is more likely to occur in thick glass...
1> because glass is a good insulator,
2> if the inside is cold and the outside is hot or vide versa
3> then there is differential expansion of the glass [the hotter part expands faster than the inner part]
4> this leads to comparatively huge stress levels in the glass which can cause it to shatter.

5> or something like that
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Old 25th July 2008, 20:06   #10
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A reply after 4 years in "not a nick in time".

Quote:
Originally Posted by Sprucegoose View Post
It is more likely to occur in thick glass...
1> because glass is a good insulator,
2> if the inside is cold and the outside is hot or vide versa
3> then there is differential expansion of the glass [the hotter part expands faster than the inner part]
4> this leads to comparatively huge stress levels in the glass which can cause it to shatter.

5> or something like that
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Old 5th September 2013, 15:53   #11
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Default Re: windshield

Reviving a very old thread.

This happened in my building this morning:

Windshield broken without a reason?-santro.jpg

Let me give a brief history.

The vehicle is a old santro owned by an old lady. A driver comes at 7am in the morning and drives her to the temple and they return by 8:30am and the car is parked like this for the full day.

The driver and lady give no history of any knocks / pebbles / etc hitting the back nor have the opened the boot in months.

The car cleaner doesn't lift the wiper to wash.

The driver returned at 8:30am and parked the car. The servants and watchmen were near the vehicle at approx 9am (half an hour later) when they heard a creaking noise and they saw the glass cracking. Watchman says it happened to another car in the opposite building a year ago under similar circumstances.

The local drivers say it happens due to gases expanding in the car. But i'm not convinced. The lady rolls her window down everyday. This happened in thirty minutes of parking the car in approx 28°C with no rain or water being thrown on the vehicle. The car is not so well insulated that the air has no escape. At 9am, the sun was still not so high up in the sky to have full effect.

So what could have happened?

I clicked the pic exactly 30 minutes after it happened and you can see the shadow angle that the sun wasn't even directly behind the rear glass.
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Old 5th September 2013, 15:59   #12
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Default Re: windshield

Last year a laminated glass door in my wardrobe broke after a small glass bottle hit it. My wife threw the tiger balm bottle, I missed the catch and it landed on the wardrobe.

A very tiny crack appeared. After a couple of seconds that crack started growing and spread all over the glass.

It totally freaked us out.
The glass looked like this and noise was quite loud as the cracks kept growing.

Its quite possible that a stray pebble maybe kicked up by a passing car hit this screen.
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Old 5th September 2013, 16:52   #13
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Default Re: windshield

Quote:
Originally Posted by Tejas@perioimpl View Post

Let me give a brief history.

The vehicle is a old santro owned by an old lady. A driver comes at 7 am in the morning and drives her to the temple and they return by 8:30 am and the car is parked like this for the full day.

So what could have happened?
I still feel the pressure difference would have caused this problem of the glass to shatter.

http://www.team-bhp.com/forum/commer...views-132.html

I have the same doubt as the same incident happened when I was travelling to Chennai by a Volvo 9400 where the wind shield cracked all of sudden when the bus was in motion. Only good thing was that the bus was not at high speeds else the driver + passengers would have been seriously injured. Both the driver and the front row passengers were shocked to see the wind shield crack without an reason.

Anurag.
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Old 5th September 2013, 17:42   #14
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Default Re: windshield

Quote:
Originally Posted by a4anurag View Post
I still feel the pressure difference would have caused this problem of the glass to shatter.

http://www.team-bhp.com/forum/commer...views-132.html

I have the same doubt as the same incident happened when I was travelling to Chennai by a Volvo 9400 where the wind shield cracked all of sudden when the bus was in motion. Only good thing was that the bus was not at high speeds else the driver + passengers would have been seriously injured. Both the driver and the front row passengers were shocked to see the wind shield crack without an reason.

Anurag.


Hi Anurag

Tempered glass breaks in a unique way. If any part of the glass fails, the entire panel shatters at once. This distinguishes it from normal glass, which might experience a small crack or localized breakage from an isolated impact. Tempered glass might also fail long after the event that caused the failure. Stresses continue to play until the defect erupts, triggering breakage of the entire panel. (quoted from the Web)
Most rear windscreens are made from Tempered glass. Hence the Volvo & Santro above also could have had such a situation of an impact earlier and it leading the final breaking.
Unlike a laminated/ normal glass that will handle a chip/ impact locally and not result in its spreading immediately, a tempered glass will fail in a spectacular manner with a lot of audio visual drama. Even if its held in place with a film the crack/ breakage will happen due to internal stress that is caused when the glass undergoes tempering.
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Old 6th September 2013, 12:08   #15
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Default Re: Windshield broken without a reason

First came the laminated glass where a small impact would create a local crack and that portion became opaque. Now this results in loss of visibility and resultant accidents. So modern windshield glass just cracks and crumbles into rounded pieces, so that in a second or so the windshield is no longer there. This is purported to be safety feature.

The crack may take some time to manifest itself. In fact if it was extremely minor, it would not propagate on its own. But expanding air in the interior as happens when the morning sun hits the metal, can be the trigger that shattered the glass.
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