Synergy of fiber length and content on free vibration and damping behavior of natural fiber reinforced polyester composite beams

• Short sisal and banana fibers reinforced composites offer better modulus values.
• Effect of fiber content influence more than the fiber length on free vibration.
• Natural fiber composites offering higher damping values.
• Sisal composites found with greater interfacial bonding than the banana composites.
• Based on results, the fabricated composite can be used for structural applications.

This work addresses the results of experimental investigation carried out on free vibration characteristics of short sisal fiber (SFPC) and short banana fiber (BFPC) polyester composites. Influence of fiber length and weight percentage on mechanical properties and free vibration characteristics are analyzed. Composite beam specimen is fabricated with random fiber orientations at17 MPa compression using compression molding machine. Natural frequencies and associated modal damping values of the composite laminates were obtained by carrying out the experimental modal analysis. It is found that an increase in fiber content increases the mechanical and damping properties. For SFPC, 3 mm fiber length and 50 wt% fiber content yielded better properties, whereas for BFPC, 4 mm fiber length and 50 wt% fiber content was the best combination. Scanning electron microscopy was performed to study the interfacial mechanism.