Characterizing vibration damping response of composite laminates containing silica nanoparticles and rubber particles

This research aims to characterize the damping properties of fiber/epoxy composites containing different degrees of silica nanoparticles and rubber particles. Conventionally, adding rubber particles into fiber/epoxy composites would lead to dramatic reduction of stiffness although the vibration damping could be improved accordingly. In order to enhance the damping properties of the fiber composites without sacrificing the stiffness, silica nanoparticles together with rubber particles were introduced into the epoxy resin through the sonication process. The epoxy resin was then treated as matrix and impregnated into the fiber layer by means of the vacuum hand lay-up process to form the composite laminates. The vibration damping as well as the flexural stiffness of the fiber composite was measured using the forced vibration technique together with the half-power method. In addition, the vibration damping of the composite laminates, consisting of silica nanoparticles and rubber particles, was characterized using the micromechanical analysis. The repeated unit cell with the fibers displaying randomly in the matrix was employed to represent the microstructures of the unidirectional composites. The loss factor as well as the moduli obtained from the micromechanical analysis were regarded as the effective properties homogenizing within the fiber composites. In conjunction with the modal shapes, the vibration damping of the composite laminates with stacking sequence of [0](10), [90](10), [+/- 45](2s), and [90/0](2s) was calculated using the finite element analysis. Experimental results indicated that with the incorporation of the silica nanoparticles together with the rubber particles, the reduction of flexural stiffness of fiber composites, especially for the [90](10) laminates, was diminished while the damping properties of laminates were improved. Moreover, it was found that the effect of the particles in the [0](10) laminates is relatively minimal. The vibration damping responses of composites laminates obtained using the micromechanical analysis together with the modal analysis exhibit an agreement with the experimental data.