Disc brake, also known as disc brake, is commonly used in modern cars, high-speed rail, aircraft and other vehicles on the braking system.
The diagram below, the hydraulic oil through a narrow tube is connected to the brake master cylinder and piston callipers, assuming that the piston area is thin metal tube channel k times the cross-sectional area, then according to PASCAL’s law, caliper piston will bear the brunt of the k times the brake master cylinder, the brake lining block press on the brake disc hover, using friction wheels in a halt.
Brake disc construction
Braking process is the process of mechanical energy into heat energy, under normal circumstances, more than 90% of the friction dissipation will be converted into heat, the performance of the brake disc and brake lining and other structures such as the increase in temperature.
Too high a temperature for a long time will affect the effective operation of the braking system, so there are usually holes in the disc or hollow structure, in order to increase the surface area, so that heat more quickly lost to the surrounding air.
Dynamic, temp-disp and Explicit analysis steps of Abaqus are adopted to complete thermoset coupling analysis of the braking process.
Thermosetting coupled finite element model of braking system
Assuming that 100% of the energy dissipated by friction in our model is converted to Heat energy, the Heat Generation dissipated energy conversion ratio can be set as the default value in the setting of contact property.
Friction heat generation setting
Considering the convective heat transfer between the braking disc surface and the air, the mesh is layered and encrypted towards the friction surface. The element type is C3D8RT, that is, the temperature-displacement coupling element.When the braking condition is analyzed, the wheel rotation effect is considered as the moment of inertia of the particle.
Low and medium speed brake temperature rise 30℃
Steady downhill 1s temperature rise 100℃
Constant speed downhill 10s braking temperature rise 250℃
In real life, the temperature rise of the brake disc is closely related to the braking condition.Normal urban driving, brake disc temperature within 100℃ is more reasonable;Downhill braking, it is also possible to reach about 600℃ (long downhill continuous or frequent braking), although many cars can withstand 800℃ brake disc high temperature, but the continuous high temperature damage to the brake system is relatively large, it is easy to induce potential danger.
According to the news in November 2018, the cause of the fatal traffic accident at the lanhai expressway lanzhou south toll station was the brake failure caused by the frequent braking on the 17-kilometer long downhill road. Therefore, the brake cannot be frequently applied on the long downhill road, and the engine braking or downhill auxiliary system should be combined to drive safely.