A simplified computational model of a twisted shrouded blade with impact and friction is established.In this model,the shrouded blade is simulated by a flexible Timoshenko beam with a tip-mass,and the effects of centr...A simplified computational model of a twisted shrouded blade with impact and friction is established.In this model,the shrouded blade is simulated by a flexible Timoshenko beam with a tip-mass,and the effects of centrifugal stiffening,spin softening,and Coriolis force are considered.Impact force is simulated using a linear spring model,and friction force is generated by a tangential spring model under sticking state and a Coulomb friction model under sliding state.The proposed model is validated by a finite element model.Then,the effects of initial gap and normal preload,coefficient of friction,and contact stiffness ratio(the ratio of tangential contact stiffness to normal contact stiffness)on system vibration responses are analyzed.Results show that resonant peaks become inconspicuous and impact plays a dominant role when initial gaps are large between adjacent shrouds.By contrast,in small initial gaps or initial normal preloads condition,resonant speed increases sharply,and the optimal initial normal preloads that can minimize resonant amplitude becomes apparent.Coefficient of friction affects the optimal initial normal preload,but it does not affect vibration responses when the contact between shrouds is under full stick.System resonant amplitude decreases with the increase of contact stiffness ratio,but the optimal initial normal preload is unaffected.展开更多
基金This project was supported by the National Natural Science Foundation(Grant No.11772089)the Fundamental Research Funds for the Central Universities(Grant Nos.N170306004,N170308028,N180708009,and N180306005)+1 种基金the Program for the Innovative Talents of Higher Learning Institutions of Liaoning(Grant No.LR2017035)Liaoning Revitalization Talents Program(Grant No.XLYC1807008).
文摘A simplified computational model of a twisted shrouded blade with impact and friction is established.In this model,the shrouded blade is simulated by a flexible Timoshenko beam with a tip-mass,and the effects of centrifugal stiffening,spin softening,and Coriolis force are considered.Impact force is simulated using a linear spring model,and friction force is generated by a tangential spring model under sticking state and a Coulomb friction model under sliding state.The proposed model is validated by a finite element model.Then,the effects of initial gap and normal preload,coefficient of friction,and contact stiffness ratio(the ratio of tangential contact stiffness to normal contact stiffness)on system vibration responses are analyzed.Results show that resonant peaks become inconspicuous and impact plays a dominant role when initial gaps are large between adjacent shrouds.By contrast,in small initial gaps or initial normal preloads condition,resonant speed increases sharply,and the optimal initial normal preloads that can minimize resonant amplitude becomes apparent.Coefficient of friction affects the optimal initial normal preload,but it does not affect vibration responses when the contact between shrouds is under full stick.System resonant amplitude decreases with the increase of contact stiffness ratio,but the optimal initial normal preload is unaffected.
