Effect of the stacking sequence on vibrational behavior of Sansevieria cylindrica/coconut sheath polyester hybrid composites

Abstract

This work reports on the static mechanical and modal analysis by free vibration response of hybrid natural fiber reinforced polymer composites. Modal analysis may predict the failure of structures prone to dynamic loading conditions. The composites were compression molded using recently identified short Sansevieria cylindrica fibers and coconut sheath mats in a polyester matrix. The study focused on the effect of the stacking sequence and fiber chemical treatment (alkali and silane) on the composite properties. Hybridization of coconut sheath and Sansevieria cylindrica fiber significantly enhanced all properties compared to single-fiber composites. For all composites (pure or hybrid), the increase in mechanical strength and natural frequency was noticed after chemical treatment. The trend in mechanical strength followed: untreated < alkali treated < silane treated. Interestingly, regarding vibrational behavior, coconut sheath/Sansevieria cylindrica/coconut sheath offered superior natural frequency in all three conditions. This highlights that higher modulus composites can be designed by keeping fiber mat as skin and short fiber as core. Morphological investigation revealed that the attraction between fiber–fiber and fiber–matrix is greatly enhanced after silane treatment.