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  1. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    Well I figure there isn't anything that could point to them. From what rb1957 had taught me above, I think I can calculate the stress in the part at a given load during compression, compare that to the yield we typically see during tension and make a judgement based from that. The mechanical...
  2. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    These parts are T6. I'm not familiar with the others you reference, I'll have to research them. Edit, I see, they are stress relieved through stretching. This wouldn't work well for the trouble parts, as the amount of stretch needed would pull the dimensions out of tolerance.
  3. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    IFRs, you are right; although, they are referencing the yield offset value of .2%. you can see the reference in the graphic from their print. We've only had issues with 2 out of 35 part numbers over the last 13 years, so we wouldn't want to introduce another alloy (sku) just to address a couple...
  4. jimmyjimmyv

    Vulcanizing pressures

    I'm wondering if there would be any pressures generated during the vulcanizing process where rubber is placed inside of a 6061 T6 aluminum tube with the dimensions of 4"OD, 3.5" ID, and 3" in length. Sorry I do not have much info about the process other than the tubes are filled with rubber...
  5. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    Yes, I think that is the problem. I think I've been blaming the .2% because that's the value that I have to meet, but as I've learned now, that .2% is what it is and cannot be changed. What needs changing is the load value. This is why I think I'm going to use a calculator that gives me the...
  6. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    Yeah, that's going to be my fault because I've dealt with the mechanical properties of aluminum forever, but never really looked at them any deeper than if they were in tolerance or not. I apologize for the delays in responses, I just now finished up our 5-day IATF audit, via Zoom no less. Aside...
  7. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    I just went back through 10 random tests from over the last 4 years, with samples having varying areas and lengths, plugged that data into my old calculator that I now know calculates length deformation under load, and the calculator almost always projects a length change of 0.45% So, your .4%...
  8. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    ok, I see where you were going with it. So, based on what you guys have said, it looks like I should be calculating the stress that will result with a given load in compression, when I'm trying to determine whether or not to accept a print, correct? Using the Stress Calculator at...
  9. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    You mean Fty, for yield strength, right? I would think going past Ftu would destroy the part. and the ASTM values for Fty and Ftu are 35ksi and 38ksi respectively.
  10. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    Unfortunately, I don't really have anything close to this at all.
  11. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    Yes, exactly
  12. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    The tube-end area is 0.1947 in2 yes, because the sample length is shorter after the compression. No, we would never do that, we take multiple samples from the 100' extruded part The rest of your questions appear to assume we are using the same part to test in both tension and compression...
  13. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    So, in your opinions, how should I determine whether we can, or cannot, meet these "Buckling Strength" compression test requirements going forward? Like I wrote earlier, I can't run a trial on a part that we don't yet make. And, I've already rejected a bunch of prints due to my use of the wrong...
  14. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    Yeah the same for your posts, printing them out to read it a couple of times.
  15. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    We have to tensile test 1 sample for every 1,000 lbs that we produce to verify alloy/temper; it is an ASTM standard B221. In addition, the part print states "Buckling Strength: permanent deformation after 38kN loaded shall be 0.07mm max. (38mm X .002) in the axial dir." And, no we don't relieve...
  16. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    I've been reading about the bauschinger effect all night, and the more I read, the more I believe we may be inducing this in our stretch/straighten after extrusion. We have to stretch the metal past it's elastic limit in order to straighten it. The effect would reduce the elastic limit in the...
  17. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    SWComposites, ok, yeah I can almost agree with it stated that way, but that also means the customer has unrealistic load requirements, and mainly because I don't believe there's a precise equivalency between the offset yield in tension and compression. They definitely would never be able to...
  18. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    rb1957, The material must meet the mechanical property specification for 6061 T6, which it always does, AND the amount of length deformation after compression cannot exceed .2% of the original length. We are required by ASTM to verify the material is within the limits for the alloy/temper, the...
  19. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    rb1957, sometimes. :) Unless the Bauschinger effect is interfering. But, yes I agree, my calculation is not the correct one to use, but I have to replace it with something.
  20. jimmyjimmyv

    Aluminum Compression Longitudial Deflection

    Dauwerda, I realize that, theoretically, the length should not suffer permanent deformation at a load that is less than the the yield strength, the problem is that yield strength under compression is not the same as it is in tension. I know this because I tensile test 1,0000s of samples per...

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