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Gunner Asch[_6_] Gunner Asch[_6_] is offline
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Default Steel for Olympic Barbell

On Sun, 09 Nov 2014 19:49:09 -0600, F. George McDuffee
wrote:

On Sun, 9 Nov 2014 15:20:59 -0500, "Carl Ijames"
wrote:

"Ignoramus16121" wrote in message
...

On 2014-11-09, wrote:
On Sunday, November 9, 2014 12:47:43 PM UTC-5, Sandarpan Mukherjee wrote:

The bar will be at least 190000 psi tensile strength with 170000 psi
yield strength.
Thanks

I can not imagine needing that kind of strength for something that a
human in going to use. What diameter is the bar? What is the
maximum weight that is going to be on the bar? My guess is that an
ordinary barbell is made of something like A36.


It is a thin bar, holding possibly 500 lbs on ends, held possibly in
almost one point.

i
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Just for grins I ran the numbers for a bar 2.2 m long 28 mm dia simply
supported at the ends with 1000 lbs concentrated at the center. That is
equivalent to supporting the bar at the center and putting 500 lbs at the
very end of each side. The deflection at the center if the bar doesn't
yield will be 6.44 inches and the maximum stress will be 165,000 psi. I'll
never stress a bar that much (at least not using just one hand :-) :-) :-)),
but depending on the actual weight (one poster said about 300 kg as a
reasonable max which is 660 lbs), and adding in some margin of safety since
it will be a live load (3x? like a floor or deck that people walk on), the
OP's specs aren't unreasonable as goals and may be low. In reality the
center of gravity of the weights will be at least 8-10" from each end, and
the lifts with maximum weight will be with two hands probably 24" apart.
Using those dimensions (bar 20" shorter supported in two places 24" apart)
and 500 lbs at each end gives much more reasonable results, max deflection
2.4" at the center and max stress of 81,000 psi. The real win would be
going up in diameter; even 32 mm (1.26") makes the bar 1.7 times stiffer and
stronger. If this is a custom bar aimed at world record weights, I think it
is reasonable to assume adult-sized hands so think about making the bar
bigger unless some sanctioning body has a rule specifying the dimensions.
If you can't make it bigger, at least try to squeeze the weights as close to
the center as you can.

-----
Regards,
Carl Ijames

===================================
Anything to be gained by pre stressing the bar [assuming it
is hollow] by putting some sort of tensioning device in the
center such as a high strength (1/2"?) steel rod
w/tensioning nuts on the end caps?


Ive got an Olympic class bar with my weight set. Its solid bar stock.
Get a few hundred pounds on a hollow bar..its called a pipe..and it
will bend in a heartbeat.

Gunner

"At the core of liberalism is the spoiled child,
miserable, as all spoiled children are, unsatisfied,
demanding, ill-disciplined, despotic and useless.
Liberalism is a philosophy of sniveling brats."
PJ O'Rourke