Prototype tube assemblies, with clevis joints attached via three proposed fastening methods, have been tested for tensile strength by the Bodycote Materials Testing laboratory in Santa Fe Springs, CA.  Results are summarized below.  The images show the remnant parts after application of a destructive tensile load.  The plots show the % elongation of each tube assembly as a function of applied force, with the failure point (in tensile load) shown in the side bar of each plot.

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RESULTS:

Epoxy (6061 Al tube with 7075 Al joints, Hysol 9394 adhesive, epoxy work performed by Anita personnel per Hysol recommended procedure for Aluminum-Aluminum bonds)  --  Assembly failed at 5,075 lbs. in the epoxy joint.




Stick-welded (6061 Al tube & joints, welds performed by UCI shop personnel)  --  Assembly failed at 7,408 lbs. in the weld joint.




Pulse-welded (6061 Al tube & joints, welds performed by the Technapulse magnetic pulse-welding company in Hauppage, NY)  --  Assembly failed at 9,336 lbs. in the 1/2" diameter clevis pin hole.

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SUMMARY:

As predicted, the magnetic pulse-welding process produced the strongest joint.  For this fastening method, the plot illustrates that at the transition point to plastic deformation for the 6061-T6 Aluminum clevis pieces, a load of 2,844 lbs. was still sustainable.

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To further evaluate the magnetic pulse-welding process, we have repeated the above tensile test with two additional pulse-welded tube assemblies.  These were both temperature cycled between -60 and +180 degrees Farenheit in an environmental chamber (BlueM oven)  at UCI, prior to testing.  The pieces were held at the high and low temperatures for a minimum of 15 minutes, and each temperature extreme was achieved three times over a period of two days.  A temperature probe was placed in physical contact (continuously, throughout the cycling processes) with the thickest portion of the tube assemblies to verify that the pieces being thermally cycled actually reached the desired temperatures.

After thermal cycling, the assemblies [one short (~14 inches), and one long (~33 inches)] failed in the pin holes of the clevis joints, as before.  The shorter assembly failed at 9,627 lbs. and the longer assembly failed at 9,614 lbs.  These loads are slightly higher than that tolerated by the non-thermally cycled assembly in the initial testing.


Piece_1.ps                                                                                             Piece_2.ps

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