A shear beam finite element for the damping analysis of tubular laminated composite beams

The paper presents a three-dimensional beam element developed for predicting the damping of composite blades with hollow laminated cross-sections. The unified theoretical framework for synthesizing the equivalent damping properties of a tubular composite blade section is outlined. Building upon the damping mechanics, a damped three-dimensional shear beam finite element is developed, which explicitly provides damping, stiffness and mass matrices. A methodology for analyzing the damped free-vibration response of tubular beams is formulated, and modal frequencies and modal damping values are predicted. Application examples illustrate the ability of the beam element to predict the modal damping and modal frequencies of hollow blades of various uniform circular, elliptical and box sections. The results further quantify the ability of the element to capture the strong effect of skin laminations, as well as the contribution of shear to the modal damping of the beam.