Study on installation location of dry friction damper for helicopter supercritical tail drive shaft
The influence of location of the dry friction damper on dynamics of the shaft/dry friction damper system was studied to ensure that the vibration of the shaft can be suppressed effectively as crossing the first and second critical speeds.Firstly,the nonlinear finite element dynamic model of the shaft/damper system was established based on the theories of Timoshenko beam and nonlinear rub-impact.The responses of the system were obtained by numerical calculation.The typical response of the shaft as crossing critical speeds and the influence of damper location were further analyzed.The results showed that there existed four stages when the shaft passed through critical speeds,including periodic no-rub motion,quasi periodic rub-impact motion,synchronous full annular rub-impact motion,and finally back to periodic no-rub motion.With the damper located at the middle node,the vibration of the shaft can be effectively suppressed when crossing the first critical speed.With the damper located at the one-quarter node and three-eighth node,the vibration of the shaft when crossing the first and second critical speeds can be both effectively suppressed.However,the shaft may not work normally when the damper was located at the three-eighth node.
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