On Sun, 23 Nov 2014 08:48:09 -0800 (PST), Sandarpan Mukherjee
wrote:
On Sunday, 23 November 2014 12:32:13 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 21:14:38 -0800 (PST), Sandarpan Mukherjee
wrote:
On Sunday, 23 November 2014 06:33:42 UTC+5:30, Ed Huntress wrote:
On Sat, 22 Nov 2014 18:25:32 -0600, Martin Eastburn
wrote:
On 11/22/2014 10:42 AM, Ed Huntress wrote:
On Sat, 22 Nov 2014 07:36:14 -0800 (PST), Sandarpan Mukherjee
wrote:
http://www.amazon.com/XMark-Commerci.../dp/B00JKM3BZU
The bar in the above link claims to have 240000 psi UTS and made out of a chrome-moly steel? Is it possible for such a high strength steel to be non-brittle enough for the application?
"Chrome-moly" usually means AISI 4340 steel or equivalent. 240 kpsi is
about the maximum, and elongation falls off sharply above 200 kpsi. At
225, it's down around 5/%.
Is that enough for your bar? I don't know. Maybe the real-world
application is no problem. At 5%, as a general matter in structural
applications, you begin to expect sudden failures. But maybe it's OK
for such a bar.
Be sure to watch the movie clip in the picture choices. Nice drop
tests that passed.
Martin
The video is interesting, but I was more impressed with the bending
test done in a machine. It's hard to tell what the actual load is on
the bar in those drop tests.
--
Ed Huntress
The actual load in the drop tests is easy to tell. Each plate is 45 lbs.
But that doesn't tell you what the load is on the bar, as a result of
being dropped with the weights on it.
For example, dropping it straight down and with the bar horizontal
imposes very little load on the bar.
Dropping it on a 45-degree angle to horizontal imposes a higher, but
unknown load. Note that the bar doesn't bend much in that test. The
load is not really very high, although it is more of an impact load.
--
Ed Huntress
http://www.roymech.co.uk/Useful_Tabl...cs_Impact.html
The above page gives approximate formulae to calculate impact stresses.
I really don't think that would answer it for you. When a bar is held
at 45 deg. to horizontal and dropped, the impact of the lower weights
is not transferred to the bar. It's absorbed by whatever is on the
ground.
The impact imposed by the upper weights depends on a complex set of
forces and deflections, which involve tracing the forces from the
upper weights, through the bar, to the lower weights, to where the
lower weights contact the ground.
Good luck with that. g
--
Ed Huntress