Ring Expansion Test
Ring Expansion Test
(OP)
How can a ring of a material be outwardly expanded in the radial direction using a loading mechanism?
I want to set up an experiment to study the dynamic tensile failure of materials. Materials of interest would be ceramics and metals.
There already exist methods of expansion by press fitting a ring around a cylinder and putting explosives inside said cylinder and that detonation will expand the ring.
I am wondering if a more simple set up to uniformly expand a ring exists already.
Thank you!
I want to set up an experiment to study the dynamic tensile failure of materials. Materials of interest would be ceramics and metals.
There already exist methods of expansion by press fitting a ring around a cylinder and putting explosives inside said cylinder and that detonation will expand the ring.
I am wondering if a more simple set up to uniformly expand a ring exists already.
Thank you!





RE: Ring Expansion Test
RE: Ring Expansion Test
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P.E. Metallurgy, Plymouth Tube
RE: Ring Expansion Test
RE: Ring Expansion Test
Some folks use a hydraulic cylinder to pull on the screw in place of a wrench or impact.
For more even expansion maybe sliding up a gradual taper.
Diameters?
Wall thickness?
RE: Ring Expansion Test
Drill/ream a hole to a precision starting diameter, then insert a lubricated high strength thin-wall sleeve on a expansion mandrel into the hole, then 'pull' the mandrel thru the sleeve to cold expand the hole.
Perhaps a variation on this method might work in low ductility materials? NOTE. Since the mandrel typically pulls toward the 'hydraulic puller' [duhhhh], the opposite side of the hole is typically loaded in expansion first... and then the rest of the hole is loaded in compression as the mandrel progresses thru. http://www.fatiguetech.com/products-split-sleeve-c...
Also there is a fastener that has very high shank expansion: Monogram Aerospace Fasteners [MAF] Radial Lok. The expansion forces can be controlled from ~very light [larger hole] to very high [slightly smaller-tighter hole]. This is the ONLY blind bolt I respect for fatigue critical applications.
http://www.monogramaerospace.com/products/blind_bo...
Or, perhaps...
The MAF Adjustable Bushing system provides 'pure' radial expansion... the illustration clearly shows how the system works. Testing/instrumentation would be able to define stresses during the torqueing of the nut. http://www.monogramaerospace.com/products/adjustab...
Regards, Wil Taylor
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