中文摘要：

通过试验研究了铸铁表面法向接触的动力学性质,发现接触层的变形响应幅值一直存在蠕变和恢复特性,接触层的变形响应相对于激振力的滞后角也有类似特性,接触层的刚度和阻尼与接触历史有关。通过考察接触层在阶跃激励下的变形响应规律,发现阶跃响应曲线可以分为瞬时的弹性变形和持续时间较长的粘性变形两部分,粘性变形随时间的变化关系符合衰减指数规律。此外,还发现阶跃响应中粘性变形约占总变形的30%,在激振力幅值为22.7kPa~295kPa,预紧力为0.45 MPa~1.68MPa之间时,该比值基本保持恒定。通过考察接触层在简谐激励下的变形响应,发现接触层的变形幅值在法向载荷作用下存在逐渐减小的趋势,即接触刚度在法向载荷作用下不断提高,在载荷减小或者卸载后,经过一段时间后再次加载,发现接触振动的幅值有一定程度的恢复,即接触刚度有降低的趋势。通过分析简谐激振力信号和变形响应信号的相位还发现,接触层阻尼有随着载荷作用时间增大的趋势,载荷减小或者卸载后,经过一段时间后再次加载,发现接触阻尼会减小,接触层的振动幅值和滞后的相位都表现出明显的粘弹性性质。

英文摘要：

By means of experiments,dynamic characteristics of normal contact between surfaces of cast iron are studied,and then the amplitude of deformation responses of contact layer is found to have the creep and recovery characteristics all the time,and phase lag of deformation response to exciting force is found to have similar characteristics,too.Therefore,stiffness and damping of contact layer are believed to be related to contact history.The step excitation responses of contact layer are investigated,these are found that the response curves may be divided into two parts of instantaneous elastic deformation and relationship between viscous deformation and time conforms to decline exponential.Furthermore,viscous deformation is about 30% of total contact deformation,and when the amplitude of exciting force is between 22.7 kPa and 295 kPa,pre-pressure of contact layer is between 0.45 MPa and 1.68 MPa,the ratio remains nearly unchanged.The deformation responses of harmonic excitation of contact layer are investigated,results show that the amplitudes of deformation response have a decreasing trend under normal load,in other word,contact stiffness continuously will increase gradually under normal load.Reloading after unloading or reducing load and holding for some time,amplitude of contact vibration is observed to have a certain degree of recovery,namely contact stiffness has a decreasing trend.The results of the phase analysis between force signal and deformation response signal show that the damping of contact layer has the tendency of increase with time under load.Reloading after unloading or reducing load and holding for some time,damping of contact vibration is observed to decrease.The both of vibration amplitude and phase of contact layer show noticeable viscous-elastic characteristics in the experiments.