Damping Behavior of Planar Random Carbon Fiber Reinforced 6061 Al Matrix Composites Fabricated by High-Pressure Infiltration Casting

Abstract

This paper describes the damping behavior of carbon fiber reinforced aluminum matrix composites. The composites were fabricated by high-pressure infiltration casting technique using planar random carbon fiber mats as the reinforcement and 6061 Al as the matrix. The damping measurements were carried out on cantilever beam specimens vibrated at resonant frequencies in the first three modes of flexure vibration. The damping capacity of the matrix aluminum and the composites (0.10 ≤ Vf ≤ 0.36) are reported in terms of loss factor η up to a resonant frequency of 12 kHz. Two damping peaks were found in the frequency range between ∼850 and ∼4700 Hz for composites with fiber fractions from 0.1 to 0.36. The modal peak damping and the off-peak damping of the composites depend on their fiber volume fraction. The frequency of the damping peaks was not particularly sensitive to fiber fraction. In conclusion, the squeeze cast carbon/aluminum composites offer improved damping capacity, which is over an order of magnitude greater than those of the aluminum matrix and up to six times that of the carbon fiber.