Civil Engineering Reference
In-Depth Information
TABLE 3.10
Typical Mechanical Properties for High-Modulus Graphite/
Epoxy Unidirectional Composites with
V
f
= 0.6
Elastic Constants
GPa
10
6
psi
Longitudinal modulus,
E
L
220
32
Transverse modulus,
E
T
6.9
1.0
Axial shear modulus,
G
LT
4.8
0.7
Poisson's ratio,
v
LT
(dimensionless)
0.25
Strength Properties
MPa
10
3
psi
760
110
Longitudinal tension,
F
L
tu
690
100
Longitudinal compression,
F
L
cu
28
4
Transverse tension,
F
T
tu
170
25
Transverse compression,
F
T
cu
70
10
In-plane shear,
F
L
su
Interlaminar shear,
F
isu
70
10
Ultimate Strains
%
0.3
Longitudinal tension, ∈
tu
0.3
Longitudinal compression, ∈
cu
0.4
Transverse tension,
∈
tu
2.8
Transverse compression, ∈
cu
1-6
In-plane shear,
γ
u
LT
Density, kg/m
3
(lb/in.
3
)
1.64 × 10
3
(0.059)
Source:
Courtesy of Zweben (1989).
It is evident that the two sets of coupons have drastically different strengths,
even though they are made of the same materials. This is due to the fact
that the second set (with two plies) has a higher fiber volume fraction. To
overcome this difficulty, the net fiber area is used.
Properties for the net fiber area:
For the first three coupons,
2
2
2
A
=
0.043in /
inin
×
1 0.043in (27.74
=
mm
)
f
3.382
0.043
f
=
=
78.65k 542.6)
si
Pa
fu
f
78.65
0.022
fu
E
=
ε
=
=
3575k 24.66
si
GPa
)
f
.
fu
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