Multi-scaled enhancement of damping property for carbon fiber reinforced composites

In this paper, a multi-scaled methodology by using flax fibers and carbon nanotubes (CNTs) was proposed to enhance the damping property of carbon fiber reinforced epoxy composites. The damping property was measured by free vibration test and the strength and modulus were obtained by tensile and flexural tests. Effects of stacking sequences of flax fibers and the addition of CNTs on both the damping property and the mechanical properties of carbon fiber reinforced composites were investigated. Results clearly showed that the damping property of carbon fiber reinforced composites was improved greatly by laying flax fibers on the outmost layers of the composites. With the addition of CNTs, the damping property was further enhanced. Damping modification mechanisms by hybridization with flax fibers and addition of CNTs were analyzed with the aid of the scanning electronic microscopy (SEM) and theoretical analysis. Results showed that the improved damping property of the hybrid composites was due to the internal sliding friction inside the flax fibers caused by the unique multi-scaled microstructure of the fibers and the stick-slip action of CNTs.