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10/10/22 Tensile Testing

10/10/22 Tensile Testing

Owned by William Beckson (RIT Student)
Last updated: Oct 12, 2022

Date

Attendees



Goals

Discussion items

ItemProcedureMediaAnalysis
General
  • Performed with Professor Rho in Golisano 1190
  • Used MTS 45G Tensile Tester
  • Performed test according to ASTM D5868
  • Graphs generated in Excel


Load vs Displacement for All Samples

Load vs Displacement for All Samples Until Failure

Alignment of CF Dog Bone in Fixture

Alignment of Lap Shear Sample in Fixture

Comparison of Surface Finishes of IREC 2022 (bottom) and 9/17 (top) winds

  • All samples follow a similar modulus of elasticity. This suggests that the behavior of each bond is similar
  • Sample 1 experienced significant slippage and therefore experienced significant displacement
  • It was difficult to effectively use the shims 
    • Some shims were slightly too big
    • Even at best the samples were not perfectly vertical
    • The shims sometimes slipped in the fixture
  • All tests were performed using a strain rate, however in an actual application each load would be instantaneous
  • The surface finishes of each CF sample were significantly different
    • The IREC 2022 wind had a more uniform and smoother surface finish on the inside face
    • The 9/17 wind had divots and blemishes, resulting in stress concentrations in certain parts of the sample
  • Stress could not be calculated due to complex part geometry

Conclusion:

  • Surface finish/wind quality matters
  • The epoxy matrices failed first, followed by the CF fibers
  • Preparation of an adhesion joints is important
Lap Shear
  • Used 3 in grip separation
  • Created and used shims to align samples vertically
  • Tested Aluminum-Aluminum, Aluminum-CF, and CF-CF bonds
  • Used strain rate of 13mm (0.5in) per min
  • Labelled parts 1 through 7
  • Tightened bottom jaw first

  • 1: Al-Al
  • 2: Al-CF (9/17 wind)
  • 3: Al-CF (9/17 wind)
  • 4: CF-CF (9/17 wind)
  • 5: CF-CF (9/17 wind)
  • 6: CF-CF (2022 IREC wind)
  • 7: CF-CF (2022 IREC wind)

Load vs Displacement for Lap Shear tests (omitting Sample 1)

Load vs Displacement for Lap Shear Tests Until Failure

  • Sample 1 broke in fixture. Need to reapply epoxy
  • Sample 2 broke at bond
  • Sample 3 broke at CF part, failed due to poor surface finish
  • Sample 4 broke at CF part, failed due to poor surface finish
  • Sample 5 failed at CF part, however no significant deformation. CF part buckled
  • Sample 6 failed at bond, epoxy bonded better with exterior surface finish
  • Sample 7 failed at bond, epoxy bonded better to interior surface finish
  • Samples 2 through 5 were the strongest of the lap shear samples
    • Samples 3, 4, and 5 failed at the CF
    • Sample 2 failed at the bond
  • Samples 6 and 7 were the weakest
    • They failed the same way
    • the bonds were not as strong?
Dog Bone
  • >1in in each jaw
  • Used strain rate of 13mm (0.5in) per min
  • Labelled parts 8 through 13
  • CF samples
  • Tightened top jaw first

  • 8-9: 2022 IREC wind
  • 10-13: 9/17 wind

Load vs Displacement for Coupon Tests

Load vs Displacement for Coupon Tests Until Failure

  • All parts failed near jaws
    • Jaws are flat, part is slightly curved. This caused stress concentrations
  • Epoxy matrix failed first, then the CF fibers
    • Buckling =/= total failure?
    • After failure (the maximum load) each sample deformed prior to complete failure
  • Samples 8 and 9 were the strongest
    • This could be attributed to a better surface finish
    • Better surface finish = stronger part?