session 29 ic2011 schwarzkopf
DESCRIPTION
TRANSCRIPT
Tensile Properties of Individual Wood Flour Particles
Department of Wood Science and Engineering
Use: outdoor decking, railings, fencing, landscaping timbers, highway infrastructure applications, etc.
IntroductionWood Plastic Composites
Composition:oWood ParticlesoThermoplastics
oPS, PE, HDPE, PP, PVCoAdditives
Klyosov 2008
http://www.appropedia.org/File:Wood_Plastic_Composite.jpg
composites.wsu.edu/ navy/Navy1/materials.html
Known limitations: o durabilityo significant creepo thermo-expansiono weight/strengtho …
Motivation
Space for improvemento Durability Issueso Markets
Improvement strategieso 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?
Assumptions Short Fiber Theory Wood Plastic Composites
Well Defined Geometry
Non-Porous
Well Defined Interface –Predictable Bonding
http://urbana.mie.uc.edu/yliu/Images/short_fiber_composites.jpg
http://t2.gstatic.com/images?q=tbn:ANd9GcQRuVQHT1F2XZ5_l3BiwGMSgzqaiBTXhakgfKOOtB6gB7itCUqCRZ722N11
http://www.hindawi.com/journals/jnm/2010/453420/fig1/
BackgroundShort Fiber Composite Theory
Assumptions Short Fiber Theory Wood Plastic Composites
Well Defined Geometry
Non-Porous
Well Defined Interface –Predictable Bonding
measured particle sizes
0
0.2
0.4
0.6
0.8
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
length, mm
wid
th, m
m
Measurements
Particles:
A
B
C
D
Wang (2007) Hussain (2009)O’Dell (1997)
BackgroundShort Fiber Composite Theory
Assumptions Short Fiber Theory Wood Plastic Composites
Well Defined Geometry
Non-Porous
Well Defined Interface –Predictable Bonding
Can we apply the theory to WPC’s?
BackgroundShort Fiber Composite Theory
Objectives and Approach
Objectives
Characterize load transfer between wood particles and the polymer matrix
Verify the applicability of SFCT to WPCs
Approach
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
Strain distribution of embedded wood particlesSpecimen preparation
Wood flour added at a 0.25% (OD weight) loading rate
Reference: 1.0 mm sections of 0.2 mm copper wire added at the same rate
Compounded in Brabender Plasticoder Unit
Compressed in a steel mold to the thickness of ~0.6 mmPressing temperature (150°C)
Hot pressing @ ~150°C
Copper Wire - Reference Wood Particle
Stereo Microscope
Stepper Motor
Load Cell
F
ε
Field of view ~ 3 mm x 4 mm
Optical resolution ~ 2 μm/ pixel
Analysis Software
Strain distribution of embedded wood particlesTesting Method
Strain distribution of embedded wood particlesStrain Measurements – Various Angles
Oriented 45° to the direction of loading
σ11
σ11
σ11
σ11
σ11
σ11Oriented 90° to the direction of loading
Oriented 0° to the direction of loading
Strain distribution of embedded wood particlesStrain Measurements – Multiple Particle Interaction
σ11
σ11
σ11
σ11
σ11
σ11
Various Particle-to-Particle Interactions
0.00
5.00
10.00
15.00
20.00
25.00
0.0% 2.0% 4.0% 6.0% 8.0%
No
min
al S
tre
ss (
MP
a)
Strain
Stress-Strain Wire 0
Exx
0.10
0.05
0.00
εxx
σ11 σ11
Strain distribution of embedded wood particlesStrain Measurements - Analysis
0.00
5.00
10.00
15.00
20.00
25.00
0.0% 2.0% 4.0% 6.0% 8.0%
No
min
al S
tre
ss (
MP
a)
Strain
Stress-Strain Wire 0
Exx
σ11 σ11
0.10
0.05
0.00
εxx
Strain distribution of embedded wood particlesStrain Measurements - Analysis
0.00
5.00
10.00
15.00
20.00
25.00
0.0% 2.0% 4.0% 6.0% 8.0%
No
min
al S
tre
ss (
MP
a)
Strain
Stress-Strain Wire 0
Exx
σ11 σ11
0.10
0.05
0.00
εxx
Strain distribution of embedded wood particlesStrain Measurements - Analysis
0.00
5.00
10.00
15.00
20.00
25.00
0.0% 2.0% 4.0% 6.0% 8.0%
No
min
al S
tre
ss (
MP
a)
Strain
Stress-Strain Wire 0
Exx
σ11 σ11
0.10
0.05
0.00
εxx
Strain distribution of embedded wood particlesStrain Measurements - Analysis
0.00
5.00
10.00
15.00
20.00
25.00
0.0% 2.0% 4.0% 6.0% 8.0%
No
min
al S
tre
ss (
MP
a)
Strain
Stress-Strain Wire 0
Exx
σ11 σ11
0.10
0.05
0.00
εxx
Strain distribution of embedded wood particlesStrain Measurements - Analysis
Wire Particle
Wood Particle
Similar?
Bonded Length of the Fiber
SFCT
Strain distribution of embedded wood particlesStrain Measurements – Analysis
Optical Measurement
20 40 60 80 100 120 140
20
30
40
50
60
70
80
90
20 40 60 80 100 120 140
10
20
30
40
50
60
70
80
90
100
MPM SimulationShort Fiber Theory
Bonded Length of the Fiber
Strain distribution of embedded wood particlesStrain Measurements – Analysis
εσ
Eτ
Optical Measurement
20 40 60 80 100 120 140
20
30
40
50
60
70
80
90
20 40 60 80 100 120 140
10
20
30
40
50
60
70
80
90
100
MPM Modeling
Film Thickness Artifact
Strain distribution of embedded wood particlesStrain Measurements – Troubleshooting
Strain measurement of individual wood
particlesSample Preparation
Bridge
Wood Particle
Adhesive
Dimensions recorded for nominal stress calculation
Front Profile
≈ 0.2mm
≈ 1.0mm
Strain measurement of individual wood
particlesTesting - Method
F
F
Wood Particle Testing in Tension Optical Measurement
Strain measurement of individual wood
particlesAnalysis
0.00
75.00
150.00
225.00
0.0% 0.1% 0.2% 0.3% 0.4% 0.5% 0.6% 0.7%
Stre
ss (
MP
a)
Strain
(εxx)
-20
0
20
40
60
80
100
-0.5% -0.4% -0.3% -0.2% -0.1% 0.0%
Stre
ss (
MP
a)
Strain
(εxx)
-20
0
20
40
60
80
100
-0.5% -0.4% -0.3% -0.2% -0.1% 0.0%
Stre
ss (
MP
a)
Strain
(εxx)
Apparent Negative Strain in Tension
-0.0004
-0.0002
0
0.0002
0.0004
0.0006
Stra
in
Wood particle strain under no loading
Out of plane movement
Strain measurement of individual wood
particlesTroubleshooting
3D DIC Measurement Catadioptric System
Wood particleLight path
Cam
era
1
Planar mirror
Right angled mirror
25 mm
Strain measurement of individual wood
particlesTroubleshooting
“Left” View “Right” View
Strain measurement of individual wood
particlesTroubleshooting
Strain measurement of individual wood
particlesTroubleshooting
Conclusions
Good qualitative agreement of strain patterns around the embedded particle obtained comparing:
• Optical measurements
• MPM modeling
• Short fiber theory
3D 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
Acknowledgement
Questions?