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Session 29 ic2011 schwarzkopf

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  • 1. Tensile Properties of Individual Wood Flour Particles Department of Wood Science and Engineering
  • 2. Introduction Wood Plastic CompositesComposition: oWood Particles oThermoplastics oPS, PE, HDPE, PP, PVC oAdditives composites.wsu.edu/ navy/Navy1/materials.htmlUse: outdoor decking, railings, fencing, landscaping http://www.appropedia.org/File:Wood_Plastic_Composite.jpg timbers, highway infrastructure applications, etc.Known limitations: o durability o significant creep o thermo-expansion o weight/strength o… Klyosov 2008
  • 3. Motivation Space for improvement o Durability Issues o Markets Improvement strategies o Trial and Error  Need more $$  Need more time o Virtual Prototyping  Need better fundamental understanding – Component properties – Load transfer between components  Would existing short fiber composite theory (SFCT) be sufficient to do this?
  • 4. Background Short Fiber Composite Theory http://t2.gstatic.com/images?q=tbn:ANd9GcQRuVQHT1F2XZ5_l3Biw http://www.hindawi.com/journals/jnm/2010/453420/fig1/ GMSgzqaiBTXhakgfKOOtB6gB7itCUqCRZ722N11 http://urbana.mie.uc.edu/yliu/Images/short_fiber_composites.jpg Assumptions Short Fiber Theory Wood Plastic CompositesWell Defined Geometry Non-PorousWell Defined Interface – Predictable Bonding
  • 5. Background Short Fiber Composite Theory measured particle sizes 0.8 Measurements Particles: 0.6 A B Cwidth, mm D 0.4 0.2 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 length, mm O’Dell (1997) Wang (2007) Hussain (2009) Assumptions Short Fiber Theory Wood Plastic Composites Well Defined Geometry Non-Porous Well Defined Interface – Predictable Bonding
  • 6. Background Short Fiber Composite Theory Can we apply the theory to WPC’s? Assumptions Short Fiber Theory Wood Plastic CompositesWell Defined Geometry Non-PorousWell Defined Interface – Predictable Bonding
  • 7. Objectives and ApproachObjectives Characterize load transfer between wood particles and the polymer matrix Verify the applicability of SFCT to WPCsApproach Measure deformation and strain distribution in and around wood particles embedded in a polymer matrix Simulate the load transfer with morphology-based material point method modeling (MPM) Compare the measurements with MPM and SFTC predictions
  • 8. Strain distribution of embedded wood particles Specimen preparationWood flour added at a 0.25% (OD Compressed in a steel mold to theweight) loading rate thickness of ~0.6 mm Pressing temperature (150°C)Reference: 1.0 mm sections of 0.2 mmcopper wire added at the same rateCompounded in Brabender Plasticoder Hot pressing @ ~150°CUnit Copper Wire - Reference Wood Particle
  • 9. Strain distribution of embedded wood particles Testing Method Stereo Microscope ε Analysis SoftwareStepper Motor F Field of view ~ 3 mm x 4 mm Optical resolution ~ 2 μm/ pixel Load Cell
  • 10. Strain distribution of embedded wood particles Strain Measurements – Various Angles Oriented 0° to the σ11 σ11 direction of loading Oriented 45° to the σ11 σ11 direction of loading Oriented 90° to the σ11 σ11 direction of loading
  • 11. Strain distribution of embedded wood particles Strain Measurements – Multiple Particle Interaction σ11 σ11Various Particle-to-Particle Interactions σ11 σ11 σ11 σ11
  • 12. Strain distribution of embedded wood particles Strain Measurements - Analysis εxx 0.10σ11 σ11 0.05 Stress-Strain Wire 0 25.00 20.00 Nominal Stress (MPa) 15.00 10.00 Exx 5.00 0.00 0.00 0.0% 2.0% 4.0% 6.0% 8.0% Strain
  • 13. Strain distribution of embedded wood particles Strain Measurements - Analysis εxx 0.10σ11 σ11 0.05 Stress-Strain Wire 0 25.00 20.00 Nominal Stress (MPa) 15.00 10.00 Exx 5.00 0.00 0.00 0.0% 2.0% 4.0% 6.0% 8.0% Strain
  • 14. Strain distribution of embedded wood particles Strain Measurements - Analysis εxx 0.10σ11 σ11 0.05 Stress-Strain Wire 0 25.00 20.00 Nominal Stress (MPa) 15.00 10.00 Exx 5.00 0.00 0.00 0.0% 2.0% 4.0% 6.0% 8.0% Strain
  • 15. Strain distribution of embedded wood particles Strain Measurements - Analysis εxx 0.10σ11 σ11 0.05 Stress-Strain Wire 0 25.00 20.00 Nominal Stress (MPa) 15.00 10.00 Exx 5.00 0.00 0.00 0.0% 2.0% 4.0% 6.0% 8.0% Strain
  • 16. Strain distribution of embedded wood particles Strain Measurements - Analysis εxx 0.10σ11 σ11 0.05 Stress-Strain Wire 0 25.00 20.00 Nominal Stress (MPa) 15.00 10.00 Exx 5.00 0.00 0.00 0.0% 2.0% 4.0% 6.0% 8.0% Strain
  • 17. Strain distribution of embedded wood particles Strain Measurements – Analysis SFCTWire Particle Similar? Bonded Length of the FiberWood Particle
  • 18. Strain distribution of embedded wood particles Strain Measurements – Analysis Optical Measurement Short Fiber Theory MPM Simulation ε E σ τ100 9090 808070 Bonded Length of the Fiber 7060 6050 5040 4030 3020 2010 20 40 60 80 100 120 140 20 40 60 80 100 120 140
  • 19. Strain distribution of embedded wood particles Strain Measurements – Troubleshooting Film Thickness Artifact 100 90 80 70Optical Measurement 60 50 40 30 20 10 20 40 60 80 100 120 140 90 80 70 MPM Modeling 60 50 40 30 20 20 40 60 80 100 120 140
  • 20. Strain measurement of individual wood particles Sample Preparation ≈ 1.0mm Adhesive ≈ 0.2mm BridgeWood Particle Front Profile Dimensions recorded for nominal stress calculation
  • 21. Strain measurement of individual wood particles Testing - Method F FWood Particle Testing in Tension Optical Measurement
  • 22. Strain measurement of individual wood particles Analysis 225.00 Stress (MPa) 150.00 75.00 (εxx) 0.00 0.0% 0.1% 0.2% 0.3% 0.4% 0.5% 0.6% 0.7% Strain 100 80 Stress (MPa) 60 40 (εxx) 20 0 -0.5% -0.4% -0.3% -0.2% -0.1% 0.0% -20 Strain
  • 23. Strain measurement of individual wood particles Troubleshooting 0.0006 0.0004 Apparent Negative Strain in Tension 0.0002 Strain 0 100 -0.0002 80 -0.0004Stress (MPa) 60 Wood particle strain under no loading 40 (εxx) 20 0 -0.5% -0.4% -0.3% -0.2% -0.1% 0.0% -20 Strain Out of plane movement
  • 24. Strain measurement of individual wood particles Troubleshooting 3D DIC Measurement Catadioptric System Wood particle Right angledLight path mirror 25 mm Planar mirror Camera 1
  • 25. Strain measurement of individual wood particles Troubleshooting “Left” View “Right” View
  • 26. Strain measurement of individual wood particles Troubleshooting
  • 27. ConclusionsGood qualitative agreement of strain patterns around theembedded particle obtained comparing: • Optical measurements • MPM modeling • Short fiber theory3D DIC of single wood particles is possible • Single wood particle strain values can be obtained and the modulus of these particles can be determined. • Refinement of sample preparation and testing
  • 28. Acknowledgement
  • 29. Questions?