DIY tensile strength tester?
 

I have got to test a number of ropes, chain and fittings for ultimate
breaking load. All of the items are rated under about 15,000 pounds and I
am not worried about the strain curve. Just ultimate load. Way to many
tests to beg time on the local engineering school equipment.

I have a 10 ton dynamometer and a hydraulic cylinder capable of giving me
the throw and force in the push direction but not in pull. I am having
trouble coming up with a design that will work without putting a side load
on the cylinder rod.

Anyone have any ideas?

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

DIY tensile strength tester?
 

In article 5Ftjf.241$fz5.175@dukeread04,
"Glenn Ashmore" wrote:

I have a 10 ton dynamometer and a hydraulic cylinder capable of giving me
the throw and force in the push direction but not in pull. I am having
trouble coming up with a design that will work without putting a side load
on the cylinder rod.

Anyone have any ideas?

Things "rated" for 15,000 lbs may be out of range of a 20,000 lb
measuring device, if they are "well-rated" (overbuilt, have a reasonable
safety factor, etc).

As for turning push into pull, a lever would make sense. To remove side
loading, you could make both the end of the lever where the ram connects
and the mounting point for the base of the cylinder pivot; that mimics
how things are mounted on my backhoe, so it's probably good design.

Don't get in the way of the shrapnel.

--
Cats, coffee, chocolate...vices to live by

DIY tensile strength tester?
 

Glenn,
Just a though or two:
Modify a 20T H frame shop press (20T to be sure of a stiff frame as you
only need 10T) that puts the bottle jack at the bottom area. The
adjustable
table will be above the jack ram and a lower shelf will be needed to
catch the
jack (at rest). A yolk assembly is made to hold the jack (bottom) that
passes around the jack and table terminating in a pull eye or clamp
above the table plus travel clearance required.
When set up and operating, the jack ram presses against the table
bottom
and presses against the yolk pushing the yolk down, thus the DUT
(device
under test) will be stretched as the upper end is clamped (hung) on the
H frame
top bridge. The table has the support blocking and rods above and
below.
Next, add a pressure gauge to the jack cylinder calibrated based on the
internal cyling bore.
BEWARE!!! The external ram is **NOT** the cylinder diameter.
Unscrew the top and pull out the ram/piston enough to measure the bore.
Area times gauge = force.
Be safe. Be careful.
RichD, Atlanta (built my own 50T press after destroying a 20T marked as
30T)




Glenn Ashmore wrote:
I have got to test a number of ropes, chain and fittings for ultimate
breaking load. All of the items are rated under about 15,000 pounds and I
am not worried about the strain curve. Just ultimate load. Way to many
tests to beg time on the local engineering school equipment.

I have a 10 ton dynamometer and a hydraulic cylinder capable of giving me
the throw and force in the push direction but not in pull. I am having
trouble coming up with a design that will work without putting a side load
on the cylinder rod.

Anyone have any ideas?

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

DIY tensile strength tester?
 

Go to mhforce.com (Morehouse) and look under "Universal Calibrating
Machines". Your ram goes on top. Pressure is where the blue object is, or
tension is in the bottom space.
Don Young
"Glenn Ashmore" wrote in message
news:5Ftjf.241$fz5.175@dukeread04...
I have got to test a number of ropes, chain and fittings for ultimate
breaking load. All of the items are rated under about 15,000 pounds and I
am not worried about the strain curve. Just ultimate load. Way to many
tests to beg time on the local engineering school equipment.

I have a 10 ton dynamometer and a hydraulic cylinder capable of giving me
the throw and force in the push direction but not in pull. I am having
trouble coming up with a design that will work without putting a side load
on the cylinder rod.

Anyone have any ideas?

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

DIY tensile strength tester?
 

Glenn Ashmore wrote:
I have got to test a number of ropes, chain and fittings for ultimate
breaking load. All of the items are rated under about 15,000 pounds and I
am not worried about the strain curve. ...
I have a 10 ton dynamometer and a hydraulic cylinder capable of giving me
the throw and force in the push direction but not in pull. ...
Anyone have any ideas?
Glenn Ashmore

I've used a 4 ton lever cable puller between two large oak trees to
test tensile strength.

Next time I plan to use a 10-ton porta-power pullback cylinder mounted
on a log-splitter beam. http://www.toolprice.com/product/1446Q

jw

DIY tensile strength tester?
 

"Glenn Ashmore" wrote

Anyone have any ideas?


Can you use trigonometry to your advantage? Pushing _transversely_ on a
string can put a lot more tension in it than the force your pushing device
needs to put out. You do need a strong frame of course, and a way to know
the _geometry_ at the moment the string breaks.

-- TP

DIY tensile strength tester?
 

On Fri, 2 Dec 2005 01:32:34 -0500, "tonyp"
wrote:


"Glenn Ashmore" wrote

Anyone have any ideas?


Can you use trigonometry to your advantage? Pushing _transversely_ on a
string can put a lot more tension in it than the force your pushing device
needs to put out. You do need a strong frame of course, and a way to know
the _geometry_ at the moment the string breaks.

-- TP

That's a good idea!

Call the distance between rigid immovable supports X , and the
perpendicular distance the rope is pulled away from a straight line as
Y. Calculate an angle theta that is the arctangent of Y/X.
With force F pulling sideways on the rope, tension in the rope is

F / (2 * sin(theta) )

Example: X = 10 feet (120 inches), Y = 6 inches For 100 lbf of
force, the tension in the rope is 1001 lbf. The magnification
doesn't drop as low as 2 (200 lbf tension for 100 lbf force) until Y =
30.984 inches in this case.