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  1. DuncanGibbons

    Approaches for measuring deflection for pin-type bearing tests

    Hi all, I am wanting to perform some pin-type bearing tests per ASTM E238. I unfortunately dont have access to the templer extensometer suggested in the standards. Is there an alternative approach for measuring bearing deflection, ideally with a standard tensile extensometer? Additionally, can...
  2. DuncanGibbons

    Axial fatigue specimen fractured at threaded ends

    Hi all, I recently performed some axial fatigue tests (ASTM E466) on a metal alloy. A handful of the specimens fractured in the threaded grip sections. Is this a common failure type for axial fatigue? Could it be due to poorly machined threads or that the thread pitch (1mm pitch was used) was...
  3. DuncanGibbons

    Procedure, materials and tips for surface finishing Ti-6Al-4V

    Last question, what media (isopropanol, water etc.) should be used to clean the surfaces after each grit and before starting the next?
  4. DuncanGibbons

    Procedure, materials and tips for surface finishing Ti-6Al-4V

    Thanks for the tips, I will try SiC sandpaper/abrasive pads of grit 220, 400 then 800, I suppose using an angle grinder with the pads will give better results than sanding by hand? I see online that SiC is preferred to aluminium oxide for titanium and hard metals. For the finishing polish is...
  5. DuncanGibbons

    Procedure, materials and tips for surface finishing Ti-6Al-4V

    Hi all, I am wanting to improve the surface finish on some Ti-6Al-4V ELI test specimens and a demonstrator component. These parts are in two surface conditions currently, some in the machined conditions +/- 1 um Ra and +/- 6.5 um Rz, and some in the electropolished condition, +/- 3.3 um Ra and...
  6. DuncanGibbons

    Frequency and length of fatigue testing

    The material is Ti64 ELI, specimen type will be the standard round ASTM E466 (Specimens with a continuous radius between ends). For a research project and the aim is to perform an initial characterization of the production process, but yes within the aviation field.
  7. DuncanGibbons

    Frequency and length of fatigue testing

    Shingley's Mechanical Design textbook states "Historically, there have been many ways of plotting the data obtained for general fluctuating stresses, with such names as Goodman diagram, modified-Goodman diagram, master fatigue diagram, and Haigh diagram." It also states that Basquin's equation...
  8. DuncanGibbons

    Frequency and length of fatigue testing

    One source says its recommended, other source says its a must. Link Link Page 27, think its specific for this class SHingley's Mechanical Design textbook also states "The typical S-N diagram is only applicable for completely reversed loading." Page 307
  9. DuncanGibbons

    Frequency and length of fatigue testing

    Thanks for the info and tips. I am planning fully reversed axial and unnotched (I have read various sources say only full reversed fatigue should be plotted on SN curves). Yes, two samples at four different loads.
  10. DuncanGibbons

    Frequency and length of fatigue testing

    I'm generating material data for a specific material and process, so haven't done any fatigue analysis other than review literature on data generated for similar material and process conditions.
  11. DuncanGibbons

    Frequency and length of fatigue testing

    Thanks for the reply. Where does a factor of 5 come from? I just chose 2 mil for the calculation [bigsmile] I am planning to test 8 specimens. 4 in 10^3 to 10^6 cycle region and 4 in 10^6 to 10 ^7 cycle region.
  12. DuncanGibbons

    Frequency and length of fatigue testing

    Hi all, I am wanting to calculate how long a fatigue test will take per specimen. ASTM E466 states that up to 100 Hz test frequency for constant amplitude axial fatigue test is acceptable. If the test is performed at 100 Hz and say for 2 million cycles, am I correct in saying the test will...
  13. DuncanGibbons

    Using V notched tensile grips to recover poorly threaded tensile specimens

    Thanks all for the info. I haven't received the specimens back yet, they are still sitting at the testing facility. I will inspect them when I received them. Hopefully, they can be rethreaded or I will just pull them with V grips.
  14. DuncanGibbons

    Using V notched tensile grips to recover poorly threaded tensile specimens

    Hi all, We recently had some ASTM E8 number 3 specimens machined and threaded, a handful of the specimen's threads wouldn't turn into the threaded grips. Is it possible to test these with V notch wedge grips and if so can/should some of the threaded material be machined away to reduce the risk...

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