Fiber reinforced composite materials

Under specific couplings of the elastic constants of orthotropic media, a very important family of orthotropic materials degenerates into the class of either transversely isotropic or isotropic media. Most of the engineering composites, especially fiber-reinforced, are of transversely isotropic media. Hence, for different composites, the norms are calculated for each material (Radwan, 1991) in Table 3. From the table, it can be clearly concluded that B(4)/N5505 has the strongest stiffness effect among the five composites. From Table 4, the most isotropic composite is E-glass/epoxy, and the most anisotropic composite is T300/5208. From the latter table, it was possible to measure the degree of anisotropy for several composites.

Materials

Cu

C

v_22

C

v_12

C

v-23

C

‘-44

C55

Norm

T300/5208

184.60

13.94

5.88

7.06

3.44

7.17

174.06

B (4)/N5505

208.08

25.04

95.72

12.70

6.17

5.59

284.62

AS/H3501

141.80

12.20

85.08

6.21

3.00

7.10

222.11

E-lass/Epoxy

41.12

11.57

21.38

6.04

2.77

4.14

62.58

Kev 9/Epoxy

78.66

7.53

53.49

3.86

1.83

2.30

132.92

Table 3. Elastic constants and norms for transversely isotropic materials, GPa

Material

N

iso

N.

aniso

N

N

iso

N

N.

anis

N

T300/5208

99.67

142.64

174.06

0.56

0.82

B (4)/N5505

223.39

176.37

284.62

0.78

0.62

AS/H3501

173.04

139.24

222.11

0.78

0.63

E-glass/Epoxy

55.01

29.84

62.58

0.88

0.48

Kev 49/Epoxy

105.13

81.34

132.92

0.79

0.61

Table 4. The Norm ratios for transversely isotropic materials, GPa