Materials for engineering, 3rd Edition - (Malestrom)

200
Materials for engineering
100
Specific stiffness (GPa)
80
60
40
20
Aligned SiC monofilament in aluminium
Particulate SiC in aluminium
0
0 10 20 30 40 50 60
Volume fraction of reinforcement (%)
6.8 Improvements in specific stiffness of MMCs with increasing
carbide.
Load
Matrix
Filler
6.9 Lamellar composite with loading axis perpendicular to the
lamellae.
ε c = f f ε f + (1 – f f ) ε m
ffσ
= +
E
f
⎛ 1 – f
⎝ E
m
f
⎞
σ
⎠
The modulus of the composite is σ/ε, so that
E
c⊥
ff
f
=
⎛
+ 1 –
⎝ E E
f
f
m
⎞
⎠
–1
[6.4]
When plotted, equations [6.3] and [6.4] appear as shown in Fig. 6.10, and
these values of composite moduli indicate why fibre-reinforced composites
are so anisotropic in their properties. For example, the modulus of wood
measured parallel to the fibres is about 10 GPa, but it is only about 1 GPa