Figure 10. Tan (δ) vs. Log (N)
graph for the 6AL10b
specimen
Figure 11 (a) shows damping ratios of the 6AL10b and 6CFRP10b specimens
at a loading ratio of r = 0.6. At the same loading ratio, the damping
ratios of the aluminum specimen were found to be higher than those of
the CFRP specimen.
Figure 11 (b) shows the normalized cycle – Stiffness reduction graph
for 6AL10b and 6CFRP10b specimens. Stiffness calculated as maximum
applied load divided by maximum deflection for every
cycle31. Stiffness change with fatigue cycle shows the
same trend with damping ratio graphs. While normalized fatigue cycle
approaching the 1, stiffness decreases and dramatical stiffness
reduction observed at the end of lifetime.