Vibration And Noise Reduction Mechanism Of Friction Brake Based On Magnetic Field

Braking noise and vibration are widespread in all types of vehicles,which seriously affect the performance of vehicle braking NVH and driving comfort.It not only brings noise pollution to the city,but is also a problem that the entire automotive industry needs to solve.Tribological studies have shown that the microscopic characteristics of friction pair interfaces are one of the main causes of frictional noise and vibration.Magnetic field has a certain influence on the micro characteristics of friction interface,so it can be considered to use magnetic field to intervene and suppress the friction noise and vibration.However,there are few researches on the influence of magnetic field on the friction noise and vibration of brake.Therefore,the research on the influence law and mechanism of magnetic field on frictional braking noise and vibration has important theoretical significance and practical value for improving the performance of automobile braking NVH and reducing frictional noise pollution.It can also provide reference for the government of friction noise and vibration in other fields.This dissertation takes friction brake as the research object,and takes active suppression of brake friction noise and vibration as the research goal.Through experimental exploration and theoretical analysis,the influence law and mechanism of magnetic field on vibration and noise reduction were studied.First,the characteristic parameter set of brake friction performance,noise and vibration was extracted,the brake DC magnetic field application device,noise and vibration signal acquisition system was designed,and the test bench for simulating braking sound and vibration of friction brake was built,which provides a necessary test methods for studying the effect of magnetic field on brake friction noise and vibration.Secondly,the test scheme of sound-vibration performance under the action of a magnetic field was designed and a large number of braking tests were carried out to master the influence law of magnetic field on brake friction noise and vibration.The results show that when the magnetic induction intensity is less than or equal to 0.24T,the magnetic field can be significantly suppressed of brake noise and vibration and the probability of brake squeal.The greater the magnetic induction intensity is,the more obvious the suppression effect of magnetic field on noise and vibration is.Among them:the incidence of brake squeal can be reduced by up to 19%,the equivalent continuous A sound level can be reduced by up to 10d B,and the vibration acceleration can be reduced by up to 0.87gm/s~2.The magnetic field,as an external field environment,helps to improve the friction characteristics,stabilize the friction coefficient,reduce friction vibration,and reduce friction noise.Thirdly,the friction vibration signal is decomposed and reconstructed by harmonic wavelet packet transform,and the evolution behavior of the wear debris under the action of the magnetic field is analyzed.Combined with the micro-characteristic analysis test of the friction plate under and without magnetic field,the effect mechanism of magnetic field on vibration reduction and noise reduction is revealed.The results show that the reason why the magnetic field can suppress friction noise and vibration is that the magnetic field reduces friction wear,suppresses unstable vibration,promotes the thinning of wear debris and the oxidation of friction interface,thereby achieving vibration reduction and noise reduction.Finally,based on the above test data and analysis results,the prediction model between the magnetic field and the incidence of brake squeal was established based on the LSTM neural network,and the prediction model was optimized,which can basically realize the prediction of brake squeal incidence under different braking conditions.The prediction of the occurrence rate can provide a data model for the intelligent regulation of brake friction noise based on magnetic field intervention.Through the above research,this dissertation has grasped the influence law and mechanism of magnetic field on friction brake vibration reduction and noise reduction,established a prediction model between magnetic field and brake squeal incidence,and lays a theoretical and technical foundation for the future development of Brake Vibration and noise reduction control based on magnetic field.There are 41 figures,7 tables and 150 references in this thesis.