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Old 13th May 2010, 16:17   #16
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The news article does not say that the Qualis hit the tree head-on. From the picture and the damage caused, it looks as though the Qualis flipped (while taking a high speed turn) to its left and crashed into the tree.

Bull bars are useful in preventing damage to the bumper in case of very minor accidents. There is no way the Bull bar would transfer the impact in such a manner that it would completely fold the car in the middle.

Last edited by MAS : 13th May 2010 at 16:18.
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Old 13th May 2010, 16:22   #17
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I remember reading somewhere that bull bars on cars with monocoque bodies will nullify crumple zones in case of a collision. Not sure about cars with separate chassis/body arrangement.

If the Qualis had hit a tree after turning turtle, the point of impact on the roof would have been much wider imo - rather there would hardly have been any roof left, considering the huge girth of the highway trees. I too suspect the bull bar is the culprit here.

Last edited by Gansan : 13th May 2010 at 16:35.
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Old 13th May 2010, 16:25   #18
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The Qualis hit the tree going sideways and thereby its roof got hit. Its very well evident. No bull bar thing here.

Bull bar be there or not, it's front wouldn't have looked like this if it had hit head-on with the tree. How on earth can bull bar take that much impact and preserve the whole front thereby bending the middle!! Argument is absolutely pointless.

Last edited by clevermax : 13th May 2010 at 16:29.
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Old 13th May 2010, 16:37   #19
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I've seen an autorickshaw travelling at 20kph and crashing into
a wall. Since the 'top' part of the auto is weak it just folded up
like this one. reason could be the bottom part or chasis is strong
and hence the force is transfered to the weaker roof and the 'bend happens'.
When i saw this pic the immediate thing that came to my mind was that auto.

In my guess the Qualis wasn't travelling very fast.
maybe at around 45-60kph. and hence no other damage other than bending of the roof.
just a wild guess..
anybody with structural engineering experience in T-BHP, please comment..

Last edited by Daewood : 13th May 2010 at 16:41.
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Old 13th May 2010, 16:38   #20
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The driver must have been going fast, not concentrating, got caught out with a sharp bend, as he rolled the impact must have been with the tree, must be driver error, i see many qualis/scorpio/traxx etc vehicles pass my house frequently, mostly over loaded all driving like loonies and then smack into a 1ft high spead breaker, not even a flinch from driver or passengers, just a matter of time until we have a major accident here.
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Old 13th May 2010, 16:52   #21
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This does not look like a head on collision with a tree. Something hit this car from the roof.
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Old 13th May 2010, 17:01   #22
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i think something like this happened.
see the bottom part and the rod that 'folds up'.

and now imagine this on a car with 'bull bar'
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Old 13th May 2010, 17:10   #23
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I remember reading in the Innova Mannual that installation of Bull Guards on vehicles equipped with airbags would hamper their functioning.

The bull guard in this pic is completely intact along with the engine bay. It must have been the flipped over and hit the tree theory.
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Old 13th May 2010, 17:11   #24
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That is not a head on collision, Qulais hit the tree sideways, probably when it was already flipped on its side.

Bullbar is a bad idea for the safety of the occupants on most vehicles especially during a high speed crash, for both monococque and body-on-frame type, unless it is engineering in. For low speed impacts it might actually save the vehicle from major damages. Not to mention the increased damage it dishes out to pedestrians and other vehicles.
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Old 13th May 2010, 17:18   #25
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I think may be the bull bar had nothing to do with this particular case (since everyone is saying it was a side-on impact with a tree while the car was in rolling motion), but still the bigger question is a valid one: If and how does the bull bar affect the crumple zone? I think the thread starter had this question in mind.

Quote:
Originally Posted by Daewood View Post
anybody with structural engineering experience in T-BHP, please comment..
I think from structural engineering point of view, the answer may not be so simple. Yes, theoretically, the bull bar will affect the crumple zone. The degree of this effect will depend on the specific design details (details of the joint between the bull bar and the chassis), and the type of impact. One may not be able to give a general answer to this question. These are the kind of things that could be answered only after some simulations (Finite Element Analysis, for example).

However, assuming that original vehicle design has an optimal crumple zone, I would say any structural alternation (adding a bull bar may be one) is only likely to worsen it, because there is no way of improving the crumple zone effect and any aftermarket part was not included in the original design of crumple zone. However, if the original design was sub-optimal to start with, then the effects of structural alterations may or may not be that detrimental.

Further, the effect will be different for mono-coupe construction and ladder-frame construction. I am not even sure if crumple zone has much meaning for ladder-frame, so may be the effect is negligible in that case.
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Old 13th May 2010, 17:25   #26
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IMO this is not a head on collision with a tree! A Qualis with 6 people on board will be close to 2 tons! the Bull bars are are hollow steel sections with 1-2 mm guage meant to protect vehicle from very minor impact of stop and go traffic! No chance of it impeding the safety of a vehicle!
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Old 14th May 2010, 12:31   #27
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No way the bull bar is the culprit here. Plus had it been the bull bar the body would have telescoped forward and not bent double at midpoint. It was a side way flip and the impact was around the B pillar.
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Old 14th May 2010, 12:36   #28
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There is no structural engineering analysis required, This is not a head on collision whatsoever .period. And in no-way Bull-bar played any role in the car ending up like this.

Quote:
Originally Posted by Daewood View Post
In my guess the Qualis wasn't travelling very fast.
maybe at around 45-60kph. and hence no other damage other than bending of the roof.
And you think that the front of the car would look like that even after an impact at 50Kmph? Bull bar cannot protect the whole front from an impact even at speeds like that. Roughly calculate the momentum and imagine the bull bar getting hit first. One more thing, it's not only the roof, its the entire car that is bent, including the chassis.

It is high time that this thread is closed to avoid pointless discussion.

Last edited by clevermax : 14th May 2010 at 12:46.
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Old 14th May 2010, 12:44   #29
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This accident & damage thereof is not because of the bull-guard.

But, bull-guards are definitely harmful to the structural integrity of the car in case of accident & also hamper functioning of life saving electronics. They only give a false sense of security to the owner that the bonnet will be saved in case of accident.

Wonder why do people think of accidents when they claim to have lacs of kms driving experience & spend lacs buying their cars/ vehicles.
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Old 16th May 2010, 23:01   #30
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Very interesting thread. I was about to order a bull bar for my Endy, really more from a looks angle, but given what I am reading here, maybe it's a bad idea!
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