Study On Friction Heat-structure Coupling Of Vehicle Drum Brakes

In recent years, the accident of drum brake broken and ignition tire at high temperature often found in newspapers. In March, 2010 Yu Yi highway one speed with heavy track drum brake suddenly burst, the debris hit the lane of vehicle assistant driving case. In May of the same year, Zhaoyuan traffic in high-speed patrol found a truck which right rear wheel was smoking with high temperature. There were also some material debris dropped on the ground. The traffic intercept inspection found that the drum brake has been completely broken. In 2012 Hang Zhou Hubin events, he was hit by a debris of drum brake and killed when he was driving a bus on the highway. So the research of the safe operation of brake has academic significance and value of technology to understand the reason of drum brake burst and provides structural optimization theory.In this paper a heavy commercial vehicle drum brakes as the research object. We analyzed the friction heat and structure stress characteristics during braking brake. Using the CATIA three dimensional software to establishment the simplifies break model. Then using the ANSYS finite element analysis software to analyze vehicle, which in different load and road conditions for contact and thermal-structure coupling analysis.(1) Study on brake contact. The pressure distribution on the brake drum and friction plates is not a theory of sine. The pressure distribution of the friction plates mainly in the upper and lower ends. The maximum pressure is 78.7MPa. The pressure of the brake drum mainly focus on the force points of the brake shoe. The maximum pressure is 23.7MPa. The maximum pressure’s size and location will changed when the torque is applied on the drum. Stress focused on the brake drum and base junction. The maximum pressure is168 MPa. The pressure on the brake shoe is mainly focused on the stiffener which near the rotating pin hole. The maximum pressure is116 MPa. Learned from the friction pressure distribution, that the friction plate will deformation under the stress, so the contact with the drum is non-contact. This will lead to severe wear and reduce the service life of the brake drum.(2) Brake friction heat-structure-coupling analysis. Simulation analysis of the brake which was in emergency and continuous condition, in order to get the stress and temperature field. Result showed that the brake in emergency and continuous braking temperature change were first increased and then decreased, and the maximum temperature is not appear at the end of braking moment, when brake drum heat inflow and lost to balance time to reach the maximum temperature. The highest temperature of the brake drum in one emergency brake reached122°C. While the highest temperature of the brake drum in one continuous brake reached 323.2°C. Under the condition of high temperature the brake will easy heat fading, which have a seriously affect the braking performance, the high temperature also make the tire occurrence which was endangering the traffic safe.