Al/Cu Inertia weld strength

[frayedknot]

In a nutshell:
A member comprised of 3" dia. 6061-T6 Al and 2" dia. Cu (cold-drawn) that has been inertia welded together. The aluminum piece is welded to aluminum pipe (3" Sch. 40) of varying lengths depending on product size. The inertia welded part is assembled onto a hinge.

Problem:
What is the strength of the inertia weld? The end of the blade will rotate from a vertical position to horizontal-impacting a stop to end its rotation. Will the impact force cause a failure?

Any suggestions on how I can progress?

Thanks in advance!

 

[aybee]

your initial hurdle is working out the force acting..there are a number of threads on this subject in the Eng tips... its not an easy thing to do
I would be very tempted to do test to destruction to prove fitness for purpose

 

[EnglishMuffin]

Concerning just the friction weld part of your question, I would say that in tension your assembly would be weaker than a 2" bar of aluminum. If properly carried out, dissimilar friction welds are often almost as strong as the weakest of the parent metals as far as the material goes, but not quite. For one thing, the grain flow in a friction weld is not likely to be as ideal as the parent metal. But then you will also have stress concentration effects etc. Is the weld flash removed ? If you want an accurate answer, do an FEA, including the flash shape if present, using whatever loading conditions you are likely to have in practice, and compare the Von-Mises stresses with the tensile properties of aluminum (assuming the highest stresses occur at the interface or somewhere in the aluminum). You will of course have different E and poisson ratios for the two materials. If you want the ultimate answer, test it to destruction as aybee says.