The fibers orientation angle has a big effect on the
natural frequency of the drive shaft. As we can se
in figure 7, the fibers must be oriented at zero
degree to increase the natural frequency by
increasing the modulus of elasticity in the
longitudinal direction of the shaft. The drive shaft
loses 38% of its natural frequency when the
carbon fibers oriented in the hoop direction at 90º
instead of 0º. The cost factor plays a role in
selecting only one layer of carbon/epoxy. The
stacking sequence has no effect on the natural
frequency since there is no load applied when
defining the natural frequency.