Quoting Rob P <fristpenny@xxxxxxxxxxx>:
> On the Mopar Mailing List there was recently a discussion indicating that
> MoPar police cars survived crashes better than F*rd and Ch*vy because then
> were uni-body cars. The stiff structure is often a disadvantage in an
> accident, particularly at high speed.
Unibody is not necessarily less stiff. In fact, unibody, if done right, can be
much stronger because the frame and body deform as a unit. That is the
explanation, I think, why the survivability was better with the Chrysler cars.
Modern unibodies lost strength mainly due to super thin steel.
The stiff structure is at a disadvantage when a much stiffer structure is
impacted, like a bridge pillar. But in most cases the obstacle will actually
"give", in which case the stronger structure is more likely to run through the
obstacle and/or maintain structural strength.
> I don't agree that the structure of a newer car will be more likely to be
> compromised. Extensive studies go into not allowing the passenger
> compartment to be breached. They design the drivetrain and other heavy items
> to shear off and NOT travel into the passenger compartment. Many of our
> Imperials don't even have collapsible steering columns. Meaning we are
> sitting behind a spear with inadequate seatbelts.
Rob, as you know, in engineering everything is a compromise. The energy
absorbing design also compromises structural strength in order to gain better
degree of safety at lower speed impacts with solid objects. You gain here, you
lose there. Also, in modern cars, its important to improve gas mileage, which
often means a compromise in structure, compared to the old monster cars. We
are comparing vehicles with completely different design criteria. All these
crush design features of modern cars are very necessary given their far weaker
structures. Without these design features, the modern cars would have been
death traps.
D^2
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