摩擦阻尼器-拉索系统振动特性试验研究

Experimental Study on Vibration Characteristics of Friction-damper-cable System

为研究拉索摩擦阻尼器的减振效果,开展了附加摩擦阻尼器拉索的自由振动和强迫振动特性试验.首先进行铜-钢金属摩擦阻尼器模型的力学性能试验,得到螺栓扭矩与摩擦力之间的关系.然后进行摩擦阻尼器-拉索系统模型自由振动特性试验研究,由试验测得的自由振动位移衰减曲线得到对数衰减率,分析得到对数衰减率随振幅的变化规律,并与现有理论进行对比.通过快速傅里叶变换和小波变换对自由振动加速度时程进行频谱分析和时频分析得到模态频率变化情况.最后进行拉索-摩擦阻尼器系统的不同激振力-控制强迫振动试验,通过扫频方式得到拉索振幅与激振频率的关系,研究摩擦阻尼器对拉索共振幅值的影响.试验结果表明摩擦阻尼器可以有效地减小小幅与大幅激振力时强迫振动的共振幅值;两者相比,摩擦阻尼器在大幅激振力作用下减振效果更显著.

Vibration characteristics of cable models with friction damper are studied experimentally.Firstly,the mechanical properties of the friction damper model made of copper and steel were tested.The relationship between torque and friction force of the damper bolt was obtained.Secondly,the experimental study on the free vibration characteristics of the friction damp-cable model was carried out.The logarithmic decay rate was obtained from the free vibration decay of displacement.The relationship between the logarithmic decay rate and vibration amplitude was analyzed and compared with theoretical results.The free vibration acceleration time history was analyzed by the Fast Fourier Transform and Wavelet transform to derive the change of frequency spectrum with time.Finally,forced vibration tests of the friction damper-cable system were carried out.The relationship between cable amplitude and excitation frequency was obtained by sweep-frequency technique.The mitigation effects of friction damper on cable resonance amplitude were investigated.The test results show that the friction damper can effectively reduce the resonance amplitude of forced vibration under small or large amplitude excitation.Friction damper was more efficient for the mitigation of amplitude excitation.