Page 29 - Mechanics Analysis Composite Materials

14 Mechanics and analysis of composite materials

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0.2 \
\. Stainlesssteel

Fig. 1.9. Temperature dependence of high-temperature fibers normalized strength (in comparison with
stainless steel).

mechanical properties matches that of the loading environment. The principle of
directional properties can be traced in all natural materials that have emerged as a
result of a prolonged evolution and, in contrast to man-made metal alloys, are
neither isotropic nor homogeneous. Many natural materials have fibrous structures
and utilize high strength and stiffness of natural fibers listed in Table 1.2. As can be
seen (Tables 1.I and 1.2), natural fibers, having lower strength and stiffness than
man-made fibers, can compete with modern metals and plastics.

Table 1.2
Mechanical properties of natural fibers.

Fiber Diameter Ultimate tensile Modulus, Specific
(Pm) stress, ii (MPa) E (GPa) gravity

Wood 15-20 I60 23 1.5
Bamboo 15-30 550 36 0.8
Jute 10-50 580 22 1.5
Cotton 15-40 540 28 1.5
Wool 75 170 5.9 1.32
Coir 10-20 250 5.5 1.5
Bagasse 25 180 9 1.25
Rice 5-1 5 IO0 6 1.24
Natural silk 15 400 13 1.35
Spider silk 4 1750 12.7
Linen 270
Sisal - 560
Asbestos 0.2 1700 160 2.5