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Elastic Properties of K13D2U/Epoxy Prepreg

Elastic Properties of K13D2U/Epoxy Prepreg. Mark E. Tuttle, University of Washington tuttle@u.washington.edu. Elastic Properties of K13D2U/Epoxy Prepreg Preliminary Comments.

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Elastic Properties of K13D2U/Epoxy Prepreg

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  1. Elastic Properties of K13D2U/Epoxy Prepreg Mark E. Tuttle, University of Washington tuttle@u.washington.edu

  2. Elastic Properties of K13D2U/Epoxy Prepreg Preliminary Comments • Current design of L0 support structure involves a six-ply [0/20/-20]s laminate (used in outer castellated shell) and a three-ply [0/90/0] laminate (used in inner cylindrical tube) • The elastic properties of the [0/20/-20]s and [0/90/0] laminates will differ substantially • By measuring the in-plane properties listed below for an individual ply, in-plane elastic properties of any multi-angle laminate can be predicted using lamination theory: E1 and E2 (moduli parallel and perpendicular to fiber direction) n12 (“major” Poisson ratio) G12 (shear modulus)

  3. Elastic Properties of K13D2U/Epoxy PrepregObjectives • To measure unidirectional properties (E1, E2, n12, and G12) exhibited by the K13D2U/epoxy composite delivered by Fermilab to the UW • Use lamination theory to predict Ex and nxy exhibited by a [0/20/-20]s laminate • To compare predictions to measurements obtained using a [0/20/-20]s tensile specimen machined from a prototype castellated outer shell (…subsequently, updated FEA analyses of the L0 support structure was performed by C.H. Daly, based on measured elastic properties)

  4. Technical ApproachMeasurement of unidirectional properties • E1 and n12: Measured using biaxial strain gages rosettes, mounted back-to-back on a [0]6 tensile specimen • E2: Measured using uniaxial strain gages, mounted back-to-back on a [90]6 tensile specimen

  5. Technical ApproachMeasurement of unidirectional properties • G12: Measured using biaxial strain gages rosettes, mounted back-to-back on a [45/-45]s tensile specimen(This technique described in Whitney, Daniel, Pipes, Experimental Mechanics of Fiber Reinforced Composite Materials, Chapter 4, ISBN 0-912053-01-1)

  6. Technical ApproachMeasurement of Ex and nxy for [0/20/-20]s laminate • Ex and nxy: Measured using biaxial strain gages rosettes, mounted back-to-back on a [0/20/-20]s tensile specimen machined from prototype outer castellated shell

  7. Preparation of [0]6, [90]6, and [45/-45]s Specimens • Three flat rectangular panels with required stacking sequences were prepared using a Tetrahedron MTP Programmable Hot Press • One surface of the panels was adjacent to an aluminum plate coated with release agent (the “tool” side), while the opposite surface was adjacent to a porous teflon release ply (the “fabric” side) • Cure cycle imposed using the hot press (pressure, temperature, time) simulated the autoclave cure cycle used to produce prototype outer and inner shells • Tensile specimens were machined from these panels using a diamond-coated abrasive cut-off wheel

  8. Specimen Preparation - Unidirectional Tests • (Nominal) physical dimensions: • [0]6 specimens: 0.0140 x 0.7450 x 7 in • [90]6 specimens: 0.0140 x 0.7450 x 6 in • [45/-45]s specimens: 0.0120 x 0.7450 x 6 in • Comments: • Nominal ply thickness was 0.0024 in for [0]6 and [90]6 specimens and 0.0030 for [45/-45]s specimens • To conserve material, specimens were much thinner than is “customary”, and aspect ratios did not meet ASTM specification of 10-12

  9. Test Equipment • Instron Model TM-M-L table-top test frame • Vishay Series 2100 strain gage amplifiers • Mac IIci equipped with National Instruments A/D board and LabView Software package

  10. [0]6 Specimen

  11. [0]6 Specimen

  12. [0]6 Specimen

  13. [0]6 Specimen

  14. [90]6 Specimen

  15. [90]6 Specimen

  16. [45/-45]s Specimen

  17. [45/-45]s Specimen

  18. [45/-45]s Specimen

  19. [45/-45]s SpecimenCalculation of G12 The shear modulus implied by these measurements is*:(Whitney, Daniels, Pipes, Experimental Mechanics of Fiber Reinforced Materials, Chapter 4, ISBN 0-912053-01-1)

  20. Summary of Measured Unidirectional Properties and Predictions for a [0/20/-20]s Laminate • Summary of measured unidirectional properties: E1 = 59.5 Msi n12 = 0.39 E2 = 0.806 Msi G12 = 0.595 Msi • Predicted properties for a [0/20/-20]s laminate: Ex = 38.4 Msi nxy = 3.0 Ey = 1.08 Msi Gxy = 4.55 Msi

  21. [0/20/-20]s Specimen

  22. [0/20/-20]s Specimen(Predicted Ex = 38.4 Msi)

  23. [0/20/-20]s Specimen(Predicted nxy = 3.0)

  24. Sensitivity StudyVariation in Exx for [0/+q/-q]s Laminates

  25. Sensitivity StudyVariation in nxy for [0/+q/-q]s Laminates

  26. Sensitivity StudyVariation in Eyy and Gxy for [0/+q/-q]s Laminates

  27. Only one measurement has been made for all specimen types; results obtained are not valid in a statistical sense Specimen thickness is smaller than is customary, and in-plane aspect ratios are lower than ASTM specifications Nevertheless, comparisons between measurement and prediction for a [0/20/-20]s laminate are reasonable Given material costs, measured properties are sufficient for present purposes Discussion

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