On Sun, 19 Apr 2015 12:59:08 -0400, Ed Huntress
wrote:

On Sun, 19 Apr 2015 07:54:40 -0700 (PDT), wrote:

On Saturday, April 18, 2015 at 12:12:22 PM UTC-4, David Billington wrote:
On 18/04/15 16:31, wrote:
On Saturday, April 18, 2015 at 10:01:17 AM UTC-4, Ed Huntress wrote:
On Sat, 18 Apr 2015 08:42:15 -0400, wrote:

On Sat, 18 Apr 2015 06:42:50 -0500, Pete Keillor
wrote:

A lot of the F-150's I see on the road aren't hauling anything in the
bed. But I wonder how they'll hold up for lawn service, plumbers,
farmers, etc. with a lot of stuff banging around in the back all the
time. I'm not a pickup or Ford guy, so don't really care that much.
Time will tell.
Look at all the dump trucks hauling gravel. LArge percentage are
aluminum boxes, and they stand up better than most steel boxes.

6061T6 or T653 is pretty tough stuff - and there are tougher alloya
apparently.
Remember that the stiffness and strength of a panel varies with the
*cube* of its thickness. An aluminum panel as strong as a steel panel
will still be much lighter than the steel panel. You can make the
aluminum panel a great deal stronger than the steel panel, and it is
still a lot lighter.

That's the whole principle behind replacing steel with aluminum. It's
not only lighter; it's also stiffer and stronger, in terms of plate
stiffness and strength. (Not to complicate this point, but the tensile
and compression strengths of aluminum alloys are nearly identical to
those of steel panels of equivalent weight. But we're talking here
about denting or bending a panel, which is where the cube rule
applies.)

Where it can get complicated is in things like dent resistance. This
can be a complex resolution of forces. When the aluminum panel is a
lot stiffer, that also means that the area surrounding a dent is
putting up a lot more resistance to being bent. So, instead of
oilcanning and bouncing back, as a thin steel panel might do, the same
blow to aluminum might cause a dent, because the surrounding aluminum
is resisting oilcanning and that can allow a concentration of the
denting force in one local spot.

A little thought about this makes it clear that you can't generalize
about the dent resistance of aluminum. It depends a lot on the shape
of the panel. That steel panel might resist oilcanning because it has
a curved shape; it might, therefore, dent more easily than an aluminum
panel. A completely flat steel panel, in contrast, might just spring
away, or "oilcan," when the same force is applied. But you'll notice
that there is more crowning of panels in vehicles today, which is done
to improve stiffness as high-strength steel panels keep getting
thinner. That's how they save weight with the high-strength steels
used in car bodies today. They have to recover the lost
stiffness by crowning and reinforcing the steel.

An aluminum truck can be stronger, stiffer, and lighter than a
steel one.
Now, I hate aluminum wire (versus copper wire) because of the increased fire factor.

I remember reading somewhere that "Aluminum fires are more tenacious", but compared to what, I don't know. I imagine the stuff can't be any safer than the steel that was used in car manufacturing back in the 1950's.

I guess we'll have to wait for the first serious fire in
one and see what's left afterwards.

Well, I hate to harp on Aluminum, but let see he The quote "Flammability of Aluminum" turns up 25,300 search results.
The quote "Flammability of Steel" turns up only 10 search results.

Try taking a piece of aluminum sheet and see if you can start a fire
with it.

When you get frustrated, come on back and we can talk about why that
happened.


And then grab a piece of steel wool, and light a match to it - let us
know what happened.