Flapwise free vibration characteristics of a rotating composite thin-walled beam under aerodynamic force and hygrothermal environment

The flapwise free vibration characteristics of a rotating composite beam under aerodynamic force and hygrothermal environment are studied in this work. The partial differential equation governing the flapwise free vibration of the beam is derived based on D'Alembert's principle. The modal problem is handled utilizing the assumed-modes method. The effects of temperature, humidity, aerodynamic force, rotational speed and ply orientation on the natural frequencies and damping ratios are investigated. Results show that the hygrothermal environment, aerodynamic force, rotational speed and ply orientation have vital influences on the flapwise free vibration characteristics of the beam. The hygrothermal environment and ply orientation have more remarkable effects on the natural frequencies and damping ratios at low rotational speed. The aerodynamic force has small influences on natural frequencies and great effects on damping ratios.