Crumple zone difference in a collision

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SUMMARY

The discussion focuses on the differences in crumple zones between modern and older cars during collisions. Modern cars, designed with tighter crumple zones, decelerate faster in crashes, resulting in less deformation compared to older models. For instance, in a frontal offset crash test at 64 km/h, a new car may crumple approximately 50 cm, while an older car could deform over a meter. The interaction between a modern car and an older car of similar weight leads to increased damage to the older vehicle due to the softer crumple zone of the older car acting as a mutual crumple zone, resulting in a collision effect akin to a higher speed impact.

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mike_J25
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Hi there!

I would like to ask about different crumples zones in cars.

The thing is that modern cars have tighter crumple zones, which makes new cars decelerate faster than old ones in a crash of the similar speeds, in fact at 64km/h frontal offset crash test the new car might deform somthg like 50 cm, whereas the old one would crumple more than a meter. I was looking at a real life frontal offset car collisions and what i have noticed is that for example if two similar weight modern cars collide at the same speed, say 55 km/h - there would be one amount of damage, most of the time it is the same for both cars. But if we replace the second car with the old one of the similar weight, say produced in 1990, then we get something very different, at least that's what i have noticed. Even if the old car would be designed to withstand an offset collision at a 55km/h with another car of the similar weight and crumple so that passenger cell of the old car wouldn't deform, the very different picture can be observed in a collision with a modern car. It seems like when the old car collides with the new one of the similar weight, the crumple zone of the old car is being "eaten" by the new one and that results in more damage to the old car and less to the new one, which might be something like damage in a ~50km/h collision against a wall for the new car and ~60km/h for the old one instead of 55km/h for both.

Well as i think of it-it's like in an offset collision the crumple zone is one front side of the car. That front side might weigh something like 7-10 percents of the whole car's weight. So in a collision that side has a relatively small inertia, which means that it stops relatively fast and then acts like a spring or peace of rubber placed between two cars. And as that front side of the old car is softer than the new car's side - both cars use it as mutual crumple zone, which leaves the old car with smaller stopping time and the new one with a longer, than they both were originally designed to at such speeds- hence more damage to old one and smaller to the new one.

Is it a realistic scenario and am i right about that mutual crumple zone? because it really seems to me like that...
 
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I think your explanation is plausible. "Equal and opposite reactions" would say that the resistance from a crumple zone on one car would act to slow the other car down. It would be interesting to try a simplified experiment to test this - perhaps toy cars with some sort of bumper made of aluminum foil or paper etc.
 
thx.
 

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