An abstract of the thesis of

Time(msec)
E
(M
P
a
)
0 Damping
1000 Damping
Figure 4.3. Dynamic effects on modulus. 

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95 
4.3 Results and Discussion
4.3.1 Numerical Modeling of OSB in Bending Mode
All calculations were done using two-dimensional, explicit MPM code (Nairn 
2005a). To insure the simulation was in the elastic region, the plastic energy was tracked 
and the deformation was limited to small strains. The small deformation was done by 
applying a small load; the specimen was loaded with constant 
P
= 2 N (or moment, M = 
2h
0
[1-C] N*mm because h=[1-C]*h
0
, where C is level of compaction and h
0
=16mm).
2000
3000
4000
5000
6000
7000
8000
0.00
0.01
0.02
0.03
0.04
0.05
1/Dt(mm/MPa)
M
O
E
 (
M
P
a
)
1% Glue
25% Glue
PF
20%
10%
0%
Figure 4.4. Numerical and analytical results of bending MOE versus 1/Dt for different 
level of compaction with gaps (strand length 150 mm, gap 30 mm). 
Figure 4.4 shows bending MOE versus 1/
D
t
for different levels of compaction. 
The MOE in this calculation is much higher than the MOE calculation in tension in the 
previous study (Nairn and Le 2009, chapter 3). This is because the surface strands with 
the higher stiffness carried more load then when loaded in tension.

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96 
Figure 4.4 also shows an overlay of different adhesive coverages (in previous 
study chapter 2) at 1% and 25%; 100% close to 1/D
t
= 0. At 20% compaction, there was 
about 3.5% increased in MOE for the case of 1% to 25% adhesive coverage, there was 
about 19% increase in MOE from 1% to 100% adhesive coverage, and there was 15% 
increase in MOE from 25% to 100% adhesive coverage. From the previous study in 
tension (chapter 3) at 20% compaction, there was about 3.3% increase in MOE for the 
case of 1% to 25% adhesive coverage, there was about 15% increase in MOE from 1% to 
100% adhesive coverage, and there was about 11% increase in MOE from 25% to 100% 
adhesive coverage. As these results show, there was slightly more increase of MOE in 
bending than MOE in tension.
Comparing the MOE in bending and MOE in tension (from chapter 3), on 
average, MOE in bending is roughly about 1.35 to 1.4 times higher than MOE in tension. 
The difference is a consequence of the structure of the OSB panels with the stiffness of 
the strands larger on the surfaces. 
4.3.2 Plywood 
(
OSB with No Gaps
)
 
To look at strand undulation effects, an OSB simulation with no gaps was done. 
The analysis specimen was 100 mm in length and had an initial height of 16 mm. The 
specimen was held on one end and the other end was under shear loads on the top and 
bottom in the opposite direction to develop upward curvature. Figure 4.5 shows MOE as 
the function of 1/
D
t
for different levels of compaction. MOE increased as the level of 
compaction increased. Unlike in tension, where the no-gaps results showed no effect of 
glue line stiffness (chapter 3), in bending, the MOE still depends on the glue line 
stiffness. 
Figure 4.5 also shows an overlay of different adhesive coverages (from previous 
study chapter 2) at 1% and 25% (100% is close to 1/D
t
= 0). At 40% compaction, there 
was about 4.5% increase in MOE from 1% adhesive coverage to 25% adhesive coverage, 
there was about 10% increase in MOE from 1% adhesive coverage to 100% adhesive 
coverage and there was about 5.7% increase from 25% adhesive coverage to 100% 
adhesive coverage. There was similar behavior in MOE at others levels of compaction. 

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97 
These results show that, good glue-line interfaces are important for composites that are 
loaded in bending even in the absence of strand undulation.
4900
6900
8900
10900
12900
14900
0.00
0.01
0.02
0.03
0.04
0.05
0.06