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(b)
(a)
4500
6000
y = 21.78x - 11726 r= 0.883
y = 11.16x - 4749 r=0.898
5500
4000
MDF9
PB9 PB16 PB18 PB25
5000
3500
MDF12
4500
3000
MDF15
4000
2500
MDF18
3500
2000
3000
600 650 700 750 800 ρ /(kg/m 3 )
ρ /(kg/m 3 )
(c)
6000
y = 29.18x - 10979 r=0.735
PW9
5000
PW15
4000
PW18
3000
PW25
2000
400
450
500
550
600
ρ /(kg/m 3 )
Fig. 1. Relationship between storage modulus and density for full-size panels for (a) particleboard (PB), (b) medium density fiberboard (MDF), and (c) plywood (PW) Table 4. Linear Regression Equations and Parameters Relating Storage Modulus with Density between Three Types of Panels
Correlation Coefficient ( r)
y = ax + b
No. of Panels
F- statistic
Level of Significance
Panel
a
b
PB
69 67 58
21.78 11.16 29.18
-11726
0.883 0.898 0.735
230 279 65.8
0.001 0.001 0.001
MDF
-4749
PW
-10979
Note: PB, particleboard; MDF, medium density fiberboard; PW, plywood
Relationship of loss modulus (E ” ) with logarithmic decrement In the process of vibration, logarithmic decrement ( Δ ) is an important index for measuring material damping ratio. Figure 2 shows the relationship between E ” and Δ among the three types of panels tested. Through the R language modeling, the test data was also analyzed in the same way as the E ’ values. The linear regression equations and the related parameters are listed in Table 5. Figure 2 and Table 5 show that there was a positive linear
4599
Guan et al . (2016). “Dynamic viscoelasticity,” B io R esources 11(2), 4593-4604.
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