Figure 18. Typical stressstrain curve and bilinear elastic characteristic of the
laminate.
Table 3. Sequential tests of tensile coupons to develop optimum layup for the FRP
W-beam.
Nominal
Test result
Coupon
No. of
thickness
tensile strength
batch
coupons
(in.)
Resin
Laminates
(psi)
RL
10
0.5
Derakane
4 lam 1.5 oz CSM
30,000
470 vinyl ester
6 lam 24 oz woven
4 lam 1.5 oz CSM
CRREL-1
6
0.1875
Iso-Polyester
10 lam 6 oz woven
24,992
CRREL-2
6
0.1875
Iso-Polyester
11 lam 8 oz unstitched
37,825
CRREL-3
5
0.1875
Iso-Polyester
4 lam 9 oz woven
38,138
7 lam 8 oz unstitched
CRREL-4
5
0.3125
Iso-Polyester
11 lam 10 oz unstitched
62,232
CRREL-5
5
0.3125
Iso-Polyester
8 lam 10 oz unstitched
65,255
2 lam 9 oz S-2 woven
CRREL-6
5
0.3125
Iso-Polyester
9 lam 10 oz unstitched
42,773
2 lam 5.4 oz S-2 woven
CRREL-7
5
0.25
Iso-Polyester
9 lam 10 oz unstitched
55,822
2 lam 3.6 oz woven graphite*
* Graphite fiber was used as an exploratory test.
SI conversion factors: 1 in. = 25.4 mm, 1 oz = 28.35 g, 1 psi = 6.89 kPa.
17
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