Frequency-dependent orthotropic damping properties of Nomex honeycomb composites

In this paper, the orthotropic damping behavior and mechanism of Nomex honeycomb composites are investigated. The needed specimen sizes for the measurement of the frequency-dependent transverse shear moduli (TSM) and fundamental damping coefficients of the honeycomb cores were analyzed at first. Then, the effects of cell side length and beam orientation on the orthotropic damping properties were explored. The results reveal that relatively high TSM (GLT) and damping values (eta(WT)) can be obtained by decreasing the cell side length without adding any additional weight. The analytical results of the damping mechanism indicate that the difference in the damping contributions of the interfacial phase to the honeycomb core in different directions leads to the orthotropic damping behavior of the honeycomb core. This study is helpful to guide the TSM measurement and structure design of honeycomb composites.