So this is a little scary

[BowHTR]

Vehicles that can't move are a lot safer.....

 

[F22RaptorDude]

Hurts don't it?

The bottom of my left arm was dark purple, bleeding at the wrist, few hours later it just turned a pinkish color and 2 days later its back to my normal Pale color.

I have to say yes, it hurt like a mother ******, I thought my arm was broken

[F22RaptorDude]

Car I was in, the Chevy Malibu

That was where we hit


Air bags


all these were taken an hour after the crash by me

[Penguin]

One of the considerations when we bought our '08 Wrangler was its ability to handle collisions. Adding extremely rugged off road bumpers and additional armor (that stiffens the body/frame) results in even better crash performance. Just remember that the roof adds almost not strength to the vehicle and the doors do little more than keep out the weather. This is one very stout vehicle. I know a guy who caused a 5 car chain reaction crash when he plowed his Wrangler into a line of stopped traffic. Two cars were totaled. The 2006 Jetta he hit directly and a 2001 Civic in front of the Honda. A 2007 F-150 was considerably damaged (I think he said that the claim was for $4700). He drove his Jeep to the dealer where they found no damage to the Jeep, but recommended that he replace the beat-up bumper cover. His total repair cost? $112 plus 1 hour labor. Didn't even require an alignment.

http://www.youtube.com/watch?v=Y8MLVXh37ig

http://www.youtube.com/watch?v=bfKeB43irVU&feature=endscreen&NR=1

Was the Wrangler up-armored, like yours?  Would  larger crumple zones have prevented the pileup?  Does the stock Wrangler have adequate crumple zones in order to prevent such events?  Did the up-armoring of your Wrangler remove crumple zones, or simply make the cabin into a bomb-shelter?

I'm sorry if I sound like an interrogator, but I don't want to jump to conclusions.

-Penguin

[clerick]

There are a lot of variables in a crash. While a 20mph v 20mph head on may have the same closure rate as a 40mph v 0mph crash, the type of collision can be vastly different.

You have inelastic collisions. This is, simply put, where the two masses collide and stay as "one mass" afterwards. In this type of collision, momentum is conserved.


Then there are elastic collisions. These are where the two masses collide, but then separate afterwards. In these types of collisions, total kinetic energy is the same before and after the collision, although the kinetic energy of each object will be different.



What all this means is that depending on what you hit and how you hit it, the amount of energy you receive from the collision can be different.

[Penguin]

Cool!  Do you know more?  Cars are anything but point-masses on a frictionless plane.

-Penguin

[smoe]

There are a lot of variables in a crash. While a 20mph v 20mph head on may have the same closure rate as a 40mph v 0mph crash, the type of collision can be vastly different.

Actually that crash probably wasn't that bad. The driver probably would survive ok, legs may be a little banged up. The car hit the wall on the drivers side front bumper only (no impact on the passenger side front bumper).

Actually a 20mph v 20mph head is like hitting a wall at 20mph assuming the vehicles are the same weight and hit each other the same way. Both cars decelerate from 20 to 0 same as hitting a wall.

Now a semi-truck going at 20mph v a car at 20mph. The people in the car will feel an impact similar to hitting a wall at 40mph.

Now a SUV vs a car half its weight. The SUV will feel a little more like hitting a wall at 10mph and the car will feel more like hitting a wall at 30mph.

Come on guys, this is simple high-school physics. But then again I was pretty good in high-school physics that I got a B+ (~89% on the grade curve). The funny thing is I would have gotten a A+ (~99%) had I not refused to do my homework because I thought is was too boring. The homework was worth 10% of my total physics grade curve.

[mensa180]

Oh man I remember those problems from physics.

[Widewing]

Was the Wrangler up-armored, like yours?  Would  larger crumple zones have prevented the pileup?  Does the stock Wrangler have adequate crumple zones in order to prevent such events?  Did the up-armoring of your Wrangler remove crumple zones, or simply make the cabin into a bomb-shelter?

I'm sorry if I sound like an interrogator, but I don't want to jump to conclusions.

-Penguin

My friend's Wrangler was factory stock... The best way for him to prevent the pile-up was not to be dicking around with his GPS while driving on a commuter road. I've added armor (steel skidplates) to the underside, which stiffens the frame as well as adding greater protection of vital mechanicals. I also have rock rails (protecting sheet metal from damage). I have a very strong off road front bumper, which I will not install until spring. The stock bumper is quite stout, but can receive cosmetic damage to the polymer cover. The replacement bumper increases approach angle, and handle impacts with rock and boulder. My Jeep is fitted with front and side airbags, a reinforced roll cage with additional padding. Wranglers (since 2007) have break-away fenders. You can simply grab one and partially rip it off. This is to minimize trail damage. I keep a plastic bag aboard with enough replacement clips to reattached two fenders should I need to. I have added heavy-duty differential covers, and welded on reinforcement gussets to the axle mounts and "Cs". I've also made other improvements, all geared to minimize the risk of damage in severe terrain.

[clerick]

Come on guys, this is simple high-school physics. ... (self-aggrandizing mumbo jumbo)

You get but a taste of the physics involved in high school. This concept isn't usually covered in any real depth until you hit your second semester of college.

I'll use my SUV as an example.  It weighs nearly 4.5 tons. If I collide head on (inelastic collision) with another vehicle that weighs, lets say 2 tons, I'm bringing a whole lot more energy to this party, 2.25 times as much. The smaller car will receive a lot of that energy in order to balance the system out. If i hit a stationary car, they are more likely to bounce off (elastic collision) and they will receive less energy.

[quig]

So much for public transportation: http://www.youtube.com/watch?v=2gvuGeRNHMU

 

[dedalos]

So at student driving school  we were hydroplaning in the parking lot before we went to go grab pizza to show how the car reacts and how to regain control.

You just love a good beating, don't you 

[Shuffler]

I don't believe 2 cars going 20 equal a 40mph impact. That might be the rate of closure but it's still just a 20mph impact.

Actually you have to take into consideration the inertia of both vehicles in opposite directions.

The ford was also hitting an immovable object which increases damage.

[Babalonian]

So at student driving school  we were hydroplaning in the parking lot before we went to go grab pizza to show how the car reacts and how to regain control. Well we took a turn to sharp and rammed into the curb doing 30 and the bags deployed, no one in the car was hurt and the only damage was the dash where the bags came out.

Anyway that got me to thinking about how my F-150 would stand up to a crash, on the roads here my average speed taken from posted signs is around 50, This is a crash test video at 40 mph, its kinda scary knowing that would it could look like and I know the driver would either be dead or seriously injured

http://www.youtube.com/watch?v=6Wb66PzljP8

*cough* Somebody *cough* oversteered and accelerated.  The car either senced the loss of traction and that is why it deployed the airbags at such a relatively low impact, or it's just designed to do so at that speed and such an abrupt stop.

That said, I actually got lucky one occasions and to two degrees at about a 50 HO impact.  I was driving down highway 5 here in central CA, veering freely from the oncomming lanes at a high-speed was a rolling full-spare tire.  The person next to me had been paralleling me for a few minutes and braked in unison with me, pinning me in my lane pretty much, only had a couple seconds if that to make any decisions or maneuvers - the choices were the shoulder at speed, force an impact with the paralleling car to avoid the HO impact, or brake and eat it and maybe pray it veers outa the lane in time.  Tried my best to stop n' slow down as it was all I could do, but still took it square on the front grill probabley doing ~50 after slowing only a second or two.  So first bit of luck is actually going for it and eating it dead center on the grill and bumper, as at the time (~'04), insurance policies/practices (3-major components/$5k or less cost, otherwise scrap), vehicles's value ('01 Honda Accord), etc. it worked out to being repairable and fully covered.  The radiator and bumper pretty much ate it, along with the leading edge of the hood and got folded and shoved up against the engine.  The wild spare got bounced almost straight up and cleared the rest of the hood and windshield and even the rest of the highway landing in some farmer's field.  And because I took it dead center on the bumper and frame and radiator, it missed all five forward airbag sensors (I think a sixth or more if it broke the engine off its mounts/brackets), otherwise it would have been a dangerous and unecessary deployment.  If I recall, there was a high and low sensor on both front corners, around the headlamps, but only one on the lowest-most front-center frame around the grill/radiator region (and the tires size + maybe a little bounce just barely verticly cleared it... had it been something protruding forward-most lower to the ground like a baricade or curb, it would of nailed the sensor (if not the other two lower-front ones).

But anywho, if you're curious how your truck might handle impacting a curb vs a tree or vs a whatever, I think most vehicles have all their crash/collapse/crumple/folding zones and airbag sensor locations published online, I did a bit of research after my incident wondering why the airbags did or didn't deploy.

[PuppetZ]

But anywho, if you're curious how your truck might handle impacting a curb vs a tree or vs a whatever, I think most vehicles have all their crash/collapse/crumple/folding zones and airbag sensor locations published online, I did a bit of research after my incident wondering why the airbags did or didn't deploy.

What you refer to as airbag sensor are really deceleration sensor. A mere impact on one sensor will not activate a modern SRS(Suplemental restrain system). An impact sensor works like a switch activated at a set Acceleration force (G). A hit like a tire hitting your bumper will hardly decelerate your car. Thus the SRS will not trigger. Even a direct impact to a front sensor will not trigger it. There are redundant trigger system built in these devices. A front SRS system will usually comprise 2 front crash sensor mounted on or near the corners of the car and a center airbag sensor usually mounted inside the car under the central console. For the SRS to trigger airbags deployment, you got to have at least 2 sensor trigger, including the center airbag. Also, modern SRS are armed only at speed exceeding 15-20 MPH. All in all, even a direct hit to a sensor would not trigger the airbags.

The way many of these sensor are built is a a simple steel cylinder stuck to a magnet. When the sensor(and the car along with it) is decelerated abruptly, the inertia of the steel cylinder cause it to unsitck from the magnet and make contact with 2 leads inside the assembly, closing the signal circuit.


magnet type sensor


spring type sensor

You can clearly see why a hit on the sensor would not cause is to be triggered unless there is tremendous deformation(usually not experienced during light impact).