Assessment of Dynamic Young’s Modulus and Damping Ratio of Bamboo Fiber Reinforced Polymer Composites using Shock Wave

In recent years, polymer composites using natural fibers have attracted attention. To evaluate the aging process of the polymer composites caused by ultraviolet rays, one has to apply non-destructive tests. In this paper, we established an assessment system using laser-induced plasma shock wave as an impulse excitation to evaluate a Young’s modulus and a damping ratio of polymer composites composed of bamboo fiber and phenolic resin. A shock wave is generated when laser-induced plasma expands at a high velocity throughout the ambient. Measuring responses of the composites by a laser Doppler vibrometer, we obtain absolute value of Fourier spectra and their natural frequencies. We used those to determine dynamic Young’s moduli and damping ratios of the composites. We made the composites which were fabricated by a hot press using a mold. There were the same trend between the dynamic Young’s moduli obtained by our system and the ones measured by a three-point flexural bending test. We could additionally obtain the damping ratios of the composites.