Research On Failure Of Heavy Truck Brake Disc Crack

The thesis is selected from the technology research project of Zhucheng Yihe Axles Co.Ltd..With the requirements of vehicle safety, braking comfort and vehicle lightweight standing out, the speed of automobile front axle brake changing from drum brake to disc brake is becoming faster and faster, and more and more automobile front axles are with disc brake. In the process of vehicle operation, the failure of brake disc cracked caused by the crack propagation once happened. It causes a great deal of security risks. Therefore, developing the fatigue life analysis research of heavy truck brake disc with damage crack, analyzing the influence that brake disc crack has on the fatigue life of brake disc, and then determining the judgment used to judge that brake disc is of failure or not, providing an effective analysis and calculation method for the reliability design of brake disc, preventing the brake disc from damaging because of the brake disc cracks extension, is the company’s key technical problems to be solved.In this paper, according to the high-load bench test defined in the standard, the finite element dynamic analysis of the braking process of the heavy truck disc brake is carried out by using LS-DYNA software to simulate the dynamical behaviors of the full braking process.The fatigue strength analysis of the heavy truck brake disc is carrying out by ANSYSWORKBENCH software.Through above works, some conclusions are gotten as follows:1. For the heavy truck brake disc manufactured by HT250 homogeneous material without considering the crack effect, under the high-load test condition, Misses stress is small, fatigue life is more than 100000 times, that is not enough to cause the fatigue damage;2. The brake disc fatigue life is inversely proportional to the crack length and depth. When the crack length being longer and depth being deeper, the brake disc fatitue life would be lower, otherwise fatigue life would grow. When crack length or depth come to a certain value, brake disc fatigue life is lower than the allowable value and then fatigue faliure would be liable to occur in brake disc using proccess;3. Material mechanical performance has an important effect on the fatigue life of the brake disc with vertical crack, improving the material mechanical performance could improve the fatigue life of brake disc with vertical cracks. Therefore, through selecting gray iron with the better mechanical performance or improving the mechanical performance of gray iron by using different measures, the fatigue life of the brake disc with vertical crack could be improved and the service life of brake disc could be longer;4. Penetrating crack has an important effect on the fatigue life of brake disc, and the penetrating crack on the outer loop has more important effect on the fatigue life of brake disc than the penetrating crack on the inner loop. When the length of penetrating crack is longer than 10mm, fatigue faliure would occur in brake disc.In this paper, the fatigue life analysis of the heavy truck brake disc with damage crack is studied, an effective analysis method is provided for the reliability design of brake disc.