Experimental investigation on vibration characteristics and damping factor of coir fiber reinforced polyester composite material

This research aimed to investigate the composite material composed of polyester with randomly oriented short coir fibers
with a length of 10 mm and varying weight percentages from 5 to 20%. The composite material was fabricated by the
hand layup method. The tensile strength, flexural strength, hardness, impact strength, free vibration analysis, and damping
characteristics were studied; the SEM images were used to analyze the fractured surface of the composite specimens.
The current empirical study identified a conspicuous association between the gradual escalation in fiber content for the
natural frequency and the damping attributes of the composite material. The test results showed that the composite
with 15% coir fibers worked best for several studies examining characteristics over a wide range of temperatures and
frequencies. Coir-based composite material yields a natural frequency of 61,862 Hz and a maximum damping ratio (ζ) of
0.29592, indicating enhanced rigidity and vibration absorption capabilities. The damping factor (tan δ) reached a notably
low value of 0.360 at a 10 Hz frequency with 15 wt.% fiber content, demonstrating improved energy dissipation. The
results show that polyester composites containing 15% wt.% coir fibers have the best mechanical and damping properties,
making them a sustainable choice for industrial uses that need to reduce vibrations.