VIBRATION BEHAVIOR OF THERMOPLASTIC COMPOSITE WITH DIFFERENT GLASS FIBER CONTENTS UNDER LOW-TEMPERATURE CONDITIONS

Glass fiber-reinforced thermoplastic composites are continuously finding their application especially in the field of aerospace and marine due to their stiffness-to-weight advantages. Accordingly, it has gained prominence to evaluate the behavior of composites under diversified environmental conditions where vibration inputs are common. In this research, effect of various environments on the free vibration response of long glass fiber-reinforced polypropylene (PP) composites with different fiber ratios is investigated. Free vibration under an impulse response of thermoplastic composite samples is studied experimentally in a vibration test setup with fixed support. Numerical simulations are also performed through 3D FE models. The present study has revealed that the decrease in temperature increases the natural frequency of the PP composites by over 20%, exceeding 20 Hz. Moreover, whether the composites have 20 wt.% or 40 wt.% long glass fiber content, the damping factors of thermoplastic composites are highly dependent on temperature. The damping ratio distinctly decreases to below 0.008 at -70degree celsius while it increases by over 50% at 0degree celsius relative to the value at room temperature.