Study On The Matching Between Brake Pads And Bionic Coupling Models Of Gray Cast Iron

With the development of high-speed and lightweight automobiles,disc brakes are increasingly used in cars.For trucks and buses,drum brakes still occupy a major position.Drum brake has a strong braking force,but its heat dissipation is worse than disc brake limited by its structure.Especially when brake drum is used in truck goes on complex road conditions with heavy loads,with a large amount of heat which aggravates the wear of brake drum and brake pad,it often fails with cracking caused by strong thermal fatigue and surface stress.Increasing the risk to driving safety.According to the coupling bionic principle,using the laser melting surface treatment technology,the bionic unit with different shapes can be processed on the surface of the brake drum,which can greatly improve the wear resistance and fatigue resistance of the brake drum.However,due to the higher hardness of the bionic unit and the unevenness of the surface,it is easy to scratch the brake pads.Especially during the running-in period of the brake friction pair,problems such as mismatch of friction pair and unstable braking will also occur.As a result,the service life of brake padis greatly shortened.At the same time,during the use of the friction pair,temperature changes will have a certain influence on the organization and structure of substrate and bionic unit,and changes the physical properties of the biomimetic surface.Therefore,the friction characteristics of biomimetic surface after thermal fatigue still need a further study.In this paper,by adjusting the distribution of bionic unit on the surface of brake drum,the matching relationship between different models of bionic brake drum and different types of brake pads is explored.Also,the wear behavior under different degrees of thermal fatigue of brake drum is studied.The relationship between bionic coupling element and thermal fatigue and wear resistance of brake drum is clarified.Results show that the bionic surface has a great improvement to the wear resistance of the brake drum,and at the same time it has increased the wear of the brake pads in different degree.There are some matching relationships between the bionic model and the brake pads,among which the semimetallic brake pads and a 45-degree grid-like biomimetic model,NAO brake pads and 45-degree stripe-like biomimetic models all show a good matching relationship.After the thermal fatigue process,the increase in wear resistance of bionic specimens maintained to a certain extent compared with blank specimens.At the same time,due to the decrease in hardness,the wear of the brake pads gradually decreased,indicating that the bionic surface keeps a good strengthening effect in the entire period of use of the brake drum.Among the biomimetic models,the sample with model formed by stripe and frame has the best thermal fatigue resistance,and at the same time it can maintain high wear resistance under high fatigue degree,showing a high application value.