Study On Nonlinear Dynamic Characteristics Of Disc Brake System

The brake system is one of the core components of the vehicle,which plays a role in ensuring the safe driving of the vehicle.The disc brake is most widely used because of its simple structure and stable braking efficiency.During braking,the friction between the friction plate and the brake disc is used to realize deceleration.During braking,the friction and normal contact force between the friction interfaces are timevarying,so the braking system shows strong nonlinear dynamic characteristics.The research on nonlinear dynamic characteristicsof disc brake system can provide theoretical support for the suppression of brake noise,and has important engineering value and practical significance.The main contents of this paper are as follows:1.Based on the research literature at home and abroad,the existing dynamic models and research methods of disc brakes are summarized,and the application scope and characteristics of the dynamic models and research methods are briefly analyzed.2.The lumped mass conveyor belt model is established,and the exponential dry friction model is selected for numerical analysis using Matlab.It is found that the tangential vibration of the friction plate will change from a stable state to a stick slip self-excited vibration state when the brake disc speed is lower than the critical value.The influence of damping coefficient,stiffness,braking pressure and friction coefficient on tangential vibration of friction plate is also discussed.3.A simplified finite element model of the disc brake is established,and the stick slip motion in the braking process is simulated by using the transient dynamic analysis method.The changes of the indirect contact force pressure,friction force and contact state of the friction interface when stick slip occurs are studied,and the influence of different parameters on the stick slip motion characteristics of the system is explored by changing different working condition parameters.4.The thermal mechanical coupling model of the disc brake is established by using the finite element software,and the causes of the contact pressure fluctuation between discs and discs during the braking process are investigated.The results show that the thermal deformation of the brake disc during braking will cause dynamic changes in the distribution and size of the contact pressure.5.The dynamic model of the three degree of freedom disc brake is established.The contact pressure between the brake disc and the friction plate is introduced to stimulate the change.The numerical analysis is carried out using Matlab.The influence of the contact pressure fluctuation on the global dynamic characteristics of the system is analyzed.It is found that the brake system appears the phase of relative equilibrium point,and the phenomenon of incomplete viscosity appears in the tangential stick slip vibration.Based on the three degree of freedom model,the influence of the system parameters on the tangential vibration of the friction plate is further investigated.