To reduce the excessive vibration of a high-speed rotor system at the critical speed, a friction damper with a flexible support structure is introduced. The mechanism of vibration reduction and support characteristics...To reduce the excessive vibration of a high-speed rotor system at the critical speed, a friction damper with a flexible support structure is introduced. The mechanism of vibration reduction and support characteristics are analyzed and a friction damper is designed. The effect on an unbalanced response is studied. Results show that the stiffness factor and the friction-damping factor of the damper are related to the cone angle and the friction factor of the inner-ring when adopting a proper structure. By changing these parameters and the Z-directional stiffness of the outer-ring, the stiffness and the damping characteristic of the damper can be varied. Introducing a friction damper into the support can reduce the stiffness and increase the damping of the support, thus decreasing the critical speed to avoid the operating speed, suppress the resonant response of a rotor system, and attenuate vibration forces to the outside.展开更多
On the basis of analysing the outer performance degradation of shock absorber on suspenson and from the relationship between outer and inner performances of the shock absorber, an internal relationship between the str...On the basis of analysing the outer performance degradation of shock absorber on suspenson and from the relationship between outer and inner performances of the shock absorber, an internal relationship between the structure design and degradation of the shock absorber is discussed in the paper. From dynamic property, analysed the dynamic cause for degradation, the paper proposes a technical method of improving outer performance and a concept of critical velocity, and discusses what effects the critical velocity and the outer performance mance degradation has.展开更多
Based on the free vibration test method for extracting flutter derivatives,an experiment on flutter stability of a long-span bridge under simultaneous actions of wind and rain was carried out in a wind tunnel.A separa...Based on the free vibration test method for extracting flutter derivatives,an experiment on flutter stability of a long-span bridge under simultaneous actions of wind and rain was carried out in a wind tunnel.A separated twin-box girder section model was employed as the specimen.The flutter derivatives and critical flutter wind speed of this girder subject to both wind and rain(with various rainfall intensities,wind speeds and attack angles)were obtained,then the flutter stability of the bridge influenced by rainfall was analyzed.Experimental results showed that the flutter derivatives of this bridge depend on the angles of attack of wind flow in the wind and rain fields.Also,rainfall has great effect on three flutter derivatives(H2*,H4* and A4*)and has less effect on other three flutter derivatives(H1*,H3* and A3*).With the increasing rainfall density,the critical flutter velocity first increases and then decreases.Low density of rainfall has the effect of increasing mass,stiffness and damping on bridge decks,and higher density of rainfall has the effect of random inhomogeneous impact on bridge decks.展开更多
文摘To reduce the excessive vibration of a high-speed rotor system at the critical speed, a friction damper with a flexible support structure is introduced. The mechanism of vibration reduction and support characteristics are analyzed and a friction damper is designed. The effect on an unbalanced response is studied. Results show that the stiffness factor and the friction-damping factor of the damper are related to the cone angle and the friction factor of the inner-ring when adopting a proper structure. By changing these parameters and the Z-directional stiffness of the outer-ring, the stiffness and the damping characteristic of the damper can be varied. Introducing a friction damper into the support can reduce the stiffness and increase the damping of the support, thus decreasing the critical speed to avoid the operating speed, suppress the resonant response of a rotor system, and attenuate vibration forces to the outside.
文摘On the basis of analysing the outer performance degradation of shock absorber on suspenson and from the relationship between outer and inner performances of the shock absorber, an internal relationship between the structure design and degradation of the shock absorber is discussed in the paper. From dynamic property, analysed the dynamic cause for degradation, the paper proposes a technical method of improving outer performance and a concept of critical velocity, and discusses what effects the critical velocity and the outer performance mance degradation has.
基金supported by the Key Program of the Major Research Plan of the National Natural Science Foundation of China (Grant No.90815022)the National Natural Science Foundation of China (Grant No. 50908069)
文摘Based on the free vibration test method for extracting flutter derivatives,an experiment on flutter stability of a long-span bridge under simultaneous actions of wind and rain was carried out in a wind tunnel.A separated twin-box girder section model was employed as the specimen.The flutter derivatives and critical flutter wind speed of this girder subject to both wind and rain(with various rainfall intensities,wind speeds and attack angles)were obtained,then the flutter stability of the bridge influenced by rainfall was analyzed.Experimental results showed that the flutter derivatives of this bridge depend on the angles of attack of wind flow in the wind and rain fields.Also,rainfall has great effect on three flutter derivatives(H2*,H4* and A4*)and has less effect on other three flutter derivatives(H1*,H3* and A3*).With the increasing rainfall density,the critical flutter velocity first increases and then decreases.Low density of rainfall has the effect of increasing mass,stiffness and damping on bridge decks,and higher density of rainfall has the effect of random inhomogeneous impact on bridge decks.
