The Mechanism Of The Effect Of The Damping Component With Grooved-structure On The Dynamical Characteristics Of The Sliding Friction System

Sliding friction is a very common physical issue in most mechanical systems and in everyday life.Generally speaking,the unstable vibration of the systems caused by sliding friction is able to result in some immeasurable harm to the mechanical equipment and the surrounding environment.Prominent examples are to reduce the working accuracy of mechanical equipment and emit the noise into the environment.Therefore,understanding of the friction-induced vibration,as well as identifying simple and efficient methods of reducing friction systems instability generated in the sliding friction process,and thus improving the stability of mechanical system is of very urgent problem that must be solved on the industrial modernization road.This paper proposed a research scheme of introducing grooved-structure damping components into systems to suppress the friction instability vibration,and further discussed the mechanism of the influence of the damping components on the dynamic characteristics of the system.Two custom-built test benches which were capable of simulating respectively friction-induced instability vibration at relatively high speed and stick-slip motion at low speed were designed and built.Finite element and numerical model simulation were conducted to verify the experimental results,which supports the experimentally observed phenomena.The following main conclusions can be made:1.The experimental results of introducing damping components having parallel-grooved structure into the friction systems show that the damping components could decrease the vibration amplitude of the systems and the energy at the dominant frequency,as well as improve wear conditions,thus suppress the instability vibration of the friction systems.In particular,the damping component having the structure of two parallel grooves shows the greatest potential in reducing the friction-induced vibration,and in improving wear condition.Moreover,the contact stress between the pad and disc in the process of sliding friction were analyzed using the finite element software.The results showed that the grooved-numbers of the surface of the damping components could alter the distribution of contact pressure.Compared with other damping components,the damping components having the structure of two parallel grooves can create a more favorable contact pressure distribution between the contact interfaces.2.The deformation of the damping components is the main reason for the variation of contact pressure distribution,which indirectly acts on the contact surface between the pad and the disc.Consequently,the damping component having the structure of two parallel grooves due to its special deformation behavior resulted in to reach a good match of contact interface and the most uniform distribution of contact pressure,which can well improve serious friction and wear of the contact interface and corresponding reduce the unstable vibration of the systems.3.Based on the research above,further explore the effect of introducing damping components having different depth parallel-grooved structure into the friction systems on the dynamic characteristics of the friction systems.And the capability of different damping components in suppressing the friction-induced vibration was evaluated.By comparing the test results of vibration and friction and wear characteristics of different friction systems,it is found that the influence of the damping components having grooved structure of different depth on the system dynamic characteristics is significantly different.Large amplitude fluctuation of friction force and small friction coefficient value could cause serious instability vibration of the systems.Moreover,the damping components with grooved-structure of a certain depth have the greatest capability on suppression of unstable vibration of the systems.4.Though in-depth analysis of the wear conditions at different positions on the surface of the pad,it can be found that the contact inclination angle between the pad and disc in the sliding friction process plays an important role in causing unstable vibration of the system.The experimental results showed that the smaller the contact inclination angle is,the more stable the system is,which was verified utilizing the numerical model simulation.Therefore,introducing the damping components with reasonable structure design into the friction systems could well adjust the contact inclination angle between the pad and disc,reduce eccentric wear,improve the contact state of the interface,and thus suppress the system instability vibration.5.Finally,the effect of the use of different damping component materials and the damping component having grooved-structure on the stick-slip propensity of the friction systems was investigated,using a custom pad-on-disc experimental test rig.The results showed that both kinds of damping materials can significantly suppress the stick-slip behavior of the system.And the damping component who’s the direction of surface groove is perpendicular to the rotation direction of the disc were able to completely eliminate the stick-slip motion,which shows the greatest potential in stabilizing the system.But the mechanism of two kinds of damping components on the suppression of the stick-slip is different.For the SBR damping components,shear deformation is the main reason for the suppression of the stick-slip behavior and the improvement of the wear performance.However,for the DA material,the main reason these affect the stick-slip behaviors is the damping capacity of the damping components rather than that of the deformation capacity.