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  1. EnginerdNate

    Built up beam allowable stresses

    That's a fair criticism. I guess other than "I built it myself" I don't have any guarantees. I did measure to make sure the screws were landing mid-thickness in the caps and spaced away from one another several D but once the second shear web goes on it is basically uninspectable.
  2. EnginerdNate

    Built up beam allowable stresses

    Good to see my numbers and yours line up when I apply your 1.5FS. "I would never spec something like this on a project and I would not recommend using this design." Any specifics there that make it substantially worse than a typical I beam? As far as stability is concerned, my thought had...
  3. EnginerdNate

    Built up beam allowable stresses

    Looks like it only attached one of my sheets.https://files.engineering.com/getfile.aspx?folder=84d37871-971d-4185-a21a-c12d934dcb13&file=PXL_20221012_174517904.jpg
  4. EnginerdNate

    Built up beam allowable stresses

    Hi all, Aero guy here doing some basic work on a beam for a personal project, wondering if anyone here can help me out. Pics attached show the beam dimensions and configuration, along with some napkin math. This was done to learn a bit more about wood construction as much as anything. I realize...
  5. EnginerdNate

    Square shaft design

    All valid points! To follow up on MintJulep's train of thought, if it doesn't need to come apart again, there's loads of geartrains out there where the gears are shrunk fit to shafts without any other retaining feature, and even simpler, loctite makes some really foolproof retaining compounds...
  6. EnginerdNate

    Square shaft design

    The two flats recommendation is good, but you could take it a step further depending on torque requirements. D-shaped shafts are very common. A singe flat eliminates the need for indexing the flat on an otherwise round part. If you do need to make it square, a collet in a square collet block is...
  7. EnginerdNate

    Strain gauging--Transverse Correction Factors

    It is an aerospace application but I thought the question was too general for the aero forum. In any case I think I have the answers I need!
  8. EnginerdNate

    Career Advice for a Recent Graduate

    My experience entering the workforce a couple years after the 2008 crash felt rough but I can't imagine trying to start out in 2020. So my congratulations and condolences. It took my 4 months to find my first job. I'd banked on getting a position from my internship manager (implicitly promised...
  9. EnginerdNate

    Strain gauging--Transverse Correction Factors

    Didn't see a better place to put this on first glance, since it's a general structural test procedure question and not specific to aero or another subspecialty. Is there a test engineering/structural testing subforum? I'd taken the "structural engineers" subforum here to have more of a civil...
  10. EnginerdNate

    Strain gauging--Transverse Correction Factors

    We wandered off topic a bit after your question about composite vs aluminum structure got me off on a tangent. The short answer is it doesn't. I think these days the correction factors are so low they likely contribute little to the final results, but my decision in this particular case is to...
  11. EnginerdNate

    Strain gauging--Transverse Correction Factors

    Good reading here: https://iris.unipa.it/retrieve/handle/10447/241137/450146/j.1475-1305.2002.00031.x.pdf
  12. EnginerdNate

    Strain gauging--Transverse Correction Factors

    The short answer I've been able to glean so far from revisiting my mechanics of materials and doing a bit of searching is that the principal strain calculations are unaffected, but that if you want to calculate principal stresses you need to do some work to determine the the difference in...
  13. EnginerdNate

    Strain gauging--Transverse Correction Factors

    Yes, I have 6mm HBM stacked rosettes to use for this test. I have thought of one question, and I'll share it while I refresh my memory on this detail at risk of exposing my shoddy memory in this area. When computing principal strains from a rosette attached to a composite substrate, will the...
  14. EnginerdNate

    Factor of Safety - Equipment to be lifted (not lifting equipment)

    Another consideration is if any load imbalance could develop during the lift. When I compute factors of safety for lifting devices with multiple lift points (Say 4x hoist rings at each corner of a cubic structure) I typically calculate my minimum factor of safety by doing a 60/40 split in each...
  15. EnginerdNate

    Potential problems with Retooling using CAD model converted from STEP to parametric

    A happy medium could be taking the difficult to recreate organic forms and extracting them from the step model and incorporating them into a parametric model that lets you adjust other features while the organic stuff stays static.
  16. EnginerdNate

    Factor of Safety - Equipment to be lifted (not lifting equipment)

    All of the components that are 'lifting devices' (eyes, hooks, etc) should be rated for lifting and of course rated to lift your load (Some shackles, eyes, hooks, etc are only rated for pulling, not lifting.) Anything on your actual device being lifted that is not in the above category would...
  17. EnginerdNate

    Strain gauging--Transverse Correction Factors

    rb1957-Aaaaah! Can't believe I mistyped that. Thanks for the correction. It's a panel measurement. Composite. Ron-That was my suspicion. In any case it's a simple calculation to do once a script is setup to do it for you. Thanks, Nathan
  18. EnginerdNate

    Preferred Shear Testing Method for Lamina Data

    At my last job we specifically chose our material system because it had well established A-basis material properties data you could purchase. It came back to bite us when the big customers who paid to develop those properties came in and bought up all the stock every couple of years when they...
  19. EnginerdNate

    Strain gauging--Transverse Correction Factors

    ...This question was brought on by the many simplifying assumptions Vishay makes in several places in their paper, such as simplifying. (1-nu*k) ~= 1. That said, it only took a few minutes to add the correction factors to the calculation and now that I've done it once I have a template to use...
  20. EnginerdNate

    Preferred Shear Testing Method for Lamina Data

    Interesting. I had read a number of opinion pieces that seemed to think that the SBS tests imparted localized compressive stresses in the laminate that skewed results.

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