On Thu, 16 Apr 2015 19:52:00 -0400, Ed Huntress wrote:
And did that 11-ton truck have an overhead cam engine? Did it? Huh? DID
IT? Or did it have a PUSHROD engine because the designers knew it was
superior for the task of powering a big, manly truck?
(Sorry. Had to. Some passing stupidity wave, I think.)
On Thursday, April 16, 2015 at 7:52:04 PM UTC-4, Ed Huntress wrote:
The Wall Street Journal had an article on Jan 8th about the shift to Alumin
um. According to the article in ten years 18% of all vedicles made in the
U.S. will have aluminum bodies. It said there were four companies that cou
ld supply the aluminum sheet. Alcoa, Novells, Logan Aluminum, and Constel
lium. Did you find out who is supplying Ford? I would expect more than on
e company is making the aluminum.
On Fri, 17 Apr 2015 05:11:20 -0700, email@example.com wrote:
And controlled fusion will be practical. Wind power for everyone, too, so
we'll have a choice. Or we'll be transitioned to the "hydrogen
economy" (with molecular hydrogen appearing magically, because of course
it doesn't have to be _made_ from _water_ using way more energy than you
get out of it later).
And we won't be buying cars from the major manufacturers any more, because
they'll be 3D printed locally from 100% recycled aluminum cans and plastic
Damn, but it's a good thing I'm never cynical nor sarcastic!
manufacturer is in the process of developing, or is nearly ready to
produce, high-aluminum-content cars. Ford is looking into what they
can do with magnesium.
In the very short run, there appears to be a lot of development space
left for advanced high-strength steels. (AHSS). And the more
sophisticated vehicles are using a fair amount of boron steel in
hot-stamping, which achieves over 200,000 psi yield. Door pillars and
crush areas are major applications for hot-stamped steel.
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
On Sat, 18 Apr 2015 08:42:15 -0400, firstname.lastname@example.org wrote:
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
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. But its ability to resist dents and dings depends on the panel
shape -- in particular, how much it is curved, or crowned.
My big worry with aluminum and such alloys is fatigue resistance. All
the aluminum products I've had fail did so because a boss or weld or
the like fatigued and broke free. Typically not economically
repairable, although in a car the economics will differ.
That's true for aircraft. Fatigue is much less of a problem for
automobiles. Weld failures on highly stressed parts are a big problem
with aluminum, but the car makers aren't using much welding, except in
combination with adhesive bonding (weld-bonding).
Joining and assembly are perhaps half of the story about different
manufacturing methods for the aluminum-bodied cars.
With aluminum you need to make it stout enough that it doesn't move,
because ANY movement causes stress fatigue - unlike steel where as
long as you don't excede the elastic limit the stress does not build
On Sat, 18 Apr 2015 14:23:35 -0400, email@example.com wrote:
Hmmm....not quite. True fatigue occurs at cyclic loadings somewhat
below the yield strength of any common structural metal. The
differences between steel fatigue and aluminum fatigue have to do with
the "endurance limit" of steel. Below certain levels of loading, steel
will not fatigue.
That's not true for aluminum. Somewhere in the range of 10^6 and 10^7
cycles, steel's tendency to break from fatigue flattens out. With
aluminum, the curve never flattens. Even small loads, repeated often
enough, will cause aluminum (or copper) to break from fatigue.
But all of this occurs at loadings lower than the yield strength of
These two Wikipedia descriptions are pretty good, and succinct:
Or, if you're in need of a good read, here's ASM's discussion:
And mine is how will they hold up to all the deicing chemicals spread
willy-nilly on our roads all winter long?
I think the electric vehicles are going to have problems due to the
salt and cold too. Only time will tell I guess...
Heck they can't even keep their brake-lines from rusting through in the
rust belt. NHTSA says that people have to wash their vehicles more
On Saturday, April 18, 2015 at 10:01:17 AM UTC-4, Ed Huntress wrote:
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.
On 18/04/15 16:31, firstname.lastname@example.org wrote:
I guess we'll have to wait for the first serious fire in one and see
what's left afterwards. The British found out that aluminium
superstructures and exocet missiles don't go well together with the
resulting fire during the Falklands war.
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