Study On The Nonlinear Dynamics Of A Stick-slip Motion System

With the rapid development of railway transportation,the running speed of high-speed train is also increasing,so the performance requirements of train braking system are also increasing.In the train friction braking system,because of the complexity and diversity of its own influence parameters,the dynamic behavior of the system is complex and changeable,which seriously affects the braking performance of the train,so it is very necessary to systematically study and analyze the dynamic behavior of the train braking system.First of all,through the establishment of single degree of freedom mechanical model and the selection of appropriate friction model,theoretical analysis and numerical simulation,it is found that there are indeed Hopf bifurcation points in the friction vibration system,and the braking speed is the main factor affecting the vibration of the system;because of the track irregularity,the friction is more sensitive when the excitation frequency is in the low frequency range,It has a great influence on the motion state of the system and produces noise that has an impact on the surrounding environment.Secondly,based on the influence of the vibration of the frame on the braking system,it is found that the external excitation will seriously affect the frictional self-excited vibration,and the system is an alternating process from multi-period to chaos and then to multi-period under the condition of low frequency.When the excitation amplitude is small,the nonlinearity of the system is mainly caused by the nonlinearity of friction.As the amplitude increases,the amplitude caused by the external excitation is close to that caused by the dry friction.When the amplitude exceeds a certain limit,the nonlinear influence of friction on the system will be weakened rapidly.The influence of braking pressure on the friction system increases with the increase of pressure.In the case of low pressure,the system changes from the stable single period at the beginning to the multi-period state.When the pressure increases to a certain critical value,the system will inevitably vibrate.Finally,the influence of track irregularity on the friction braking system under the vehicle model is systematically studied,and the influence of four parameters of track excitation frequency,amplitude,braking speed and braking pressure on the dynamic characteristics of the system is analyzed.Orbital excitation frequency on the system the effects of main and modal frequency of the system,and the orbit of the amplitude of the system of incentive effect and friction self-excited vibration amplitude mainly about,when the excitation amplitude after reaching a certain interval,which will seriously affect the viscous friction self-excited vibration formation,lead to complex dynamic behavior evolution process.The effective range of braking speed on the system is small.When the system speed is small,the dynamic behavior of the system evolves frequently.When a certain limit is reached,the force of the friction pair will be reflected as an approximate constant force,and the system will be reflected as a linear state.The influence of braking pressure on the system is mainly reflected by the way of affecting the formation of viscosity.When the braking force is small,the nonlinear dissipation is not enough to affect the response of the track excitation,but mainly periodic motion.When the braking pressure is large,the friction self-excited vibration is the main vibration of the system.