Transcript Effect of Hygroscopic Swelling on Push Load of Wood Dowel Joint

Wen-Ching SU and Yiren WANG*
Effect of Hygroscopic
Swelling on Push Load of
Wood Dowel Joint
Dept. of Forest Products Science
National Chiayi University
Chiayi
Taiwan
Dowel joints have been commonly
used in furniture due to its ease of
assembly. When the joints are exposed
to humidity change, the circular shape
of dowel and hole would change and
result in a new stress state.
Objectives:
1. effect of hygroscopic swelling on push load
2. stress states
factor
species
level
maple
factor
level
RH（%）
oak
65
90
R or T
board
quarter
ring angle（°）
0
R or T
flat
45
R or T
dowel dia.(mm)
10
L
L
90
L
Result
ANOVA table
source
species
board
ring angle
error
df
1
1
2
132
befor swelling
MS
F
p
43.3
0.12 0.735
0.0
0.00 0.997
271.3
0.72 0.488
376.5
（a）
after swelling
MS
F
p
4.7
0.01 0.904
3540.3
10.95 0.001
2367.4
7.32 0.001
323.4
（b）
Distributions of normal stress of maple dowel after hygroscopic swelling;
(a) quarter sawn member with 0° ring angle;
(b) flat sawn member with 90° ring angle.
Conclusions
1. The push load was higher after hydroscopic swelling.
2. The push loads of specimens with 90° ring angle with
respect to the longitudinal direction of hole member
were higher than those with 0° and 45° ring angle.
3. The push load of quartersawn hole member was higher
than that of flatsawn hole member.
4. Deformations of wood due to moisture change could be
accurately predicated by finite element method in
cooperation with orthotropic material properties.
5. The difference between the predicted push loads of
simplified dowel joints by finite element method and
the measured ones were between -5.29% to 11.72%.