Thermal Deformation Analysis For Ventilated Brake Discs Of A Passenger Vehicle And Optimization Of Braking Judder

Brake disc is an important component and safety component in the brake system,and it is one of the main components that cause brake judder.When the vehicle is braking,the mechanical energy possessed by the vehicle is converted into thermal energy through friction,and most of the thermal energy is transferred to the brake disc through heat conduction,which causes the surface temperature of the brake disc to rise,resulting in thermal deformation.As a result,the brake disc thickness variation changes,which in turn causes fluctuation in the brake pressure and brake torque between the brake discs and the brake pads,resulting in brake judder,which seriously affects the safety and comfort during braking.Therefore,in the design process of the brake disc structure,it is particularly important to consider the performance of the brake judder,which has important engineering significance for the thermal deformation analysis of the ventilated brake disc and the optimization of the brake judder.In this paper,the vented brake discs of a passenger car with brake judder are taken as the research object,and their thermal deformation after 15 cycles of brake application is studied.The influence of various structural parameters of the ventilated brake disc on thermal deformation and its sensitivity were obtained through orthogonal experimental design method.The simulation analysis,bench test and real vehicle road test were used to obtain the ventilated disc brake structure with the best judder.First,the author created the three-dimensional model of the ventilated brake disc,meshed it,estimated the heat flux density and convective heat transfer coefficient of the brake disc,and established the thermo-structure coupling model.The fifteen cycles of braking were simulated by the finite element method,and bench test was performed to verify the result of simulation.At the same time,it was confirmed that the main cause of the brake judder of the passenger car is that the thermal deformation of the brake disc did not meet the standards.Then,through the analysis of the structure of the ventilated brake disc,and combined with the experience of previous engineering practice,the six main structures that affect the thermal deformation of the brake disc are obtained: thickness,cap height,angle,outer diameter,inner diameter,and radius.The orthogonal experimental design method is used to analyze the thermal-structural coupling of each group of ventilated brake discs with different structural parameters.It is concluded that the sensitivity of each structural parameter of the vented brake discs to thermal deformation from high to low is: thickness,cap height,angle,outer diameter,inner diameter,radius,The increase of thickness,cap height and angle leads to the increase of thermal deformation.On the other hand,when the outer diameter and inner diameter increase,the thermal deformation decreases.And the angle of 130°,the radius of 9mm,the cap height of 24 mm,the thickness of 30 mm,the outer diameter of 300 mm and the inner diameter of 160 mm are the combination which shows the best brake judder performance of this vented brake disc.Finally,through simulation analysis,bench test results,and road tests,it is verified that the optimized brake disc structure improves the performance of brake judder.