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Phil Holman <piholmanc@yourservice> wrote:

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Phil Holman <piholmanc@yourservice> wrote:

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Phil Holman <piholmanc@yourservice> wrote:

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Phil Holman <piholmanc@yourservice> wrote:

This guy is lucky to be alive after having his head run over
by
a
truck.

http://www.madison.com/tct/news/index.php?ntid=133934

But did this really happen? Some think his head would have
been
squished
like a bug?

Phil H

Some think Elvis is still alive, but I digress...

Heads are rather strong by themselves. Put a decent helmet
around
one
and you have a system that is going to take a lot of abuse.

We know the compressive strength of the skull, it's the load
from
a
truck wheel that's up for discussion.

Phil H

From the article it was a delivery truck, so not much more than
a
car.

Given that's all the information you have, what more can be
said?

If you want more detail, call the people mentioned in the
article
and ask.

Do you really think they would be able to calculate the dynamic
force
of
such an event. This is absolutely the right place to discuss this.
Some
points to ponder.

First you have to have something to discuss other than wild
conjecture.

Was he run over by the front wheel, the rear, or both?

Got a rough weight for the truck?

How about the weight on the wheels which is different from front to
rear?

1/ It was turning right so the wheel that ran over the
cyclist's
head
was probably unweighted.

Unweighted?

How in the world do you come to this conclusion?

Errr, if the truck goes around the corner fast enough, it could be on
two wheels. Don't you think the inside wheels would be less loaded
than
the outer wheels .....you know, something about an overturning
moment.
You did read the article, right.

And if the truck is going fast enough, it over turns. Yeah, so what?

You yourself said it was a weight problem so figuring out the weight
distribution is part of the solution.

The article didn't say whether he was hit by an inside wheel, an
outside wheel, a front wheel, or a rear wheel.

Did you call anyone to get these details or are you content to just
conjecture?

Feasibility. The truck was turning a corner, it is reasonable to
conclude that there was less truck weight on the inside wheels. We would
probably be reading his obituary if it had been an outside wheel.

2/ The load created would depend on the mass of the wheel
assembly
as
its suspension compressed to accommodate the 'bump in the road'.

How about the weight of the truck on the wheel, which ever it was?

You think truck wheels float?

Two things; the weight of the truck and the dynamic effect of the
wheel
compression. You don't think the whole truck was physically raised by
the head diameter do you?

It would have been if it had stayed on his head long enough.

Well it didn't so we don't have to consider a dynamic load that raised
the whole truck but only the load to raise the unsprung weight of the
wheel assembly.

You don't think the suspension system does anything to reduce the
weight of the wheel/vehicle system or reduce the pressure on whatever
the wheel is on, do you?

It doesn't reduce the wheel load due to the weight of the vehicle but it
does reduce the dynamic load of going over a bump because, for the most
part, only the unsprung weight is raised over the bump.

3/ The speed of the truck as it turned the corner.

That would determine how long it was on his head, but not much
else.

This is a pressure from weight problem, not a collision problem.

Try riding your bicycle up a curb and get back to us.

Apples/oranges on so many levels.

In both cases the dynamic load will be significant even at moderate
cornering speed.

Unless you have something constructive to add, please don't respond.