Effective Damping of a Flexible-Matrix-Composite Laminate With a Negative Effective Poisson’s Ratio

Abstract

Two very important factors which determine the effectiveness of a pump are its volumetric and energy efficiencies. Yin and Ghoneim constructed a prototype of a flexible body pump with a very high volumetric efficiency or pumping potential (the relative volume reduction due to a relative input stroke) [1]. The high volumetric efficiency is attributed to the geometry of the pump’s structure (hyperboloid) as well as the high negative effective Poisson’s ratio of the 3-layer ([θ/β/θ]) flexible-matrix-composite (carbon/polyurethane) laminate adopted for the body of the pump. The energy efficiency was not evaluated. An important factor in assessing the energy efficiency of flexible-body pumps is the effective damping (a measure of the energy dissipation per cycle) of the flexible body material. An objective of the current work is to determine the effective damping inherent in the 3-layer laminate, as a function of the two angle orientations θ and β, employed for the design of the flexible body pump. Thereby, the best fiber angle orientation, for the highest volumetric as well as energy efficiency, can be considered. The contribution of this work is twofold: 1) viscoelastic characterization (longitudinal, transverse, and shear complex moduli, as well as the in-plane complex Poisson’s ratio) of the polyurethane/carbon composite, used in the Geo-polymer lab at RIT; the results may be utilized as benchmarks for other researchers using similar carbon/polyurethane in dynamic applications, and 2) provide a comprehensive study of the effect of the two angles θ and β on the effective damping factors of the three-layer laminate. Together with the similar study on the negative Poisson’s ratio [1], a better design of the laminate for the most efficient flexible-body pump performance can be established.