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  1. davepenney

    Back-calculating strain in tooling

    Thanks CoryPad, I didn't know if you could just do a straight subtraction of the bar's force/displacement over 3Kn from the total force/displacement of the bar and sample over 3Kn, but that seems to be what your equation is inferring. Sometimes I'm wary over the obvious, simple solutions, but...
  2. davepenney

    Back-calculating strain in tooling

    No worries Corypad, I don't think you're being difficult at all! I appreciate that the whole system is straining, but the load is about 3Kn, not much, and the threaded bar is the obvious weak point. The other parts of the tooling are massive in comparison. I have pulled a piece of the...
  3. davepenney

    Back-calculating strain in tooling

    Yes, compliance correction is what I want to achieve. I am pulling an M4 insert out of a piece of carbon fibre using a length of M4 threaded bar/studding. Unfortunately I haven't any other stronger M4-threaded equipment to pull it with, and I know it's straining. I just wondered if there was an...
  4. davepenney

    Back-calculating strain in tooling

    I am currently testing a composite coupon in tension. I am using the crosshead displacement for the extension - I have no means to attach extensometers or strain gauges. The problem is, I know that a part of the tooling is adding to the strain. If I can work out the elastic modulus of the...
  5. davepenney

    Mechanical testing of notched specimens

    Yes sorry about that, I knew it wasn't a steel actually, slip of the keyboard! Because it has no Fe, is that why the tri-axial stress concentration strengthens it? Is the strengthening phenomonon of tri-axial stress only applicable to some non-Fe materials? Thanks again, Dave
  6. davepenney

    Mechanical testing of notched specimens

    Hi there, Good info, thanks for that. It's MP35N, the mother-of-all steels as far as I can tell. It's got ridiculous properties, but is apparently a good 25% stronger as a notched specimen. Thanks again, Dave
  7. davepenney

    Mechanical testing of notched specimens

    Hi there, I am currently testing a certain metal in a notched tensile test piece and standard dog-bone/straight test piece. The notched test piece average ultimate stress is HIGHER than the straight test piece ultimate stress. Any reasons for this? I thought the notch would act as a...

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