| With the rapid and steady development of national economy, construction of large-scale open mine is in the ascendant, and demand of heavy mining dump trucks (MDT) which used as the main means of transport, also is in the rapidly growing. In recent years, as the reason of demands for its larger load mass and bad travel environment, it is crucial for the MDT to have the reliable and stable braking performance.The optimum design of the Mining electric wheel dump truck (SF33901) was been taken as an engineering example. The MDT braking performance was conducted a comprehensive analysis and optimization on the four aspects of the braking efficiency, the braking stability, the disc brake’s transient temperature field and anti-braking pitch. Main contents of this paper are as follows:1. The multi-body dynamic theory and the vehicle braking process were discussed, and then the mathematical modeling of the vehicle dynamics system and the way of obtaining the simulation model parameters were analyzed. The braking system, tire system, road system, suspension system and other subsystems were established, and impose the corresponding deputy campaign, force and torque, the virtual prototype of mining dump truck was established.2. Considering that the MDT is much more used to transport ballast, coal, ore, etc, it is mainly working on the off-highway outdoor; most of the road is sand-gravel pavement which is made up of gravel, brickbat, and slag and so on. According to the special road condition, sand-gravel pavement was chose as the simulation road, braking efficiency and braking stability were analyzed and evaluated based on the vehicle dynamics model in the following four simulation modes, such as braking on straight flat road, braking on8%downhill straight road, braking in a turn on flat road, braking in a turn on downhill road.3. According to the actual brake model, the three-dimensional model was established, and then the finite element model of disc brake was established after coupled with the relevant boundary conditions. The emergency braking simulation was operated by frictional heating method and heat flux method. Distribution of transient temperature field of brake disc was obtained, and the simulation results were compared. The loading boundary conditions of repeated braking simulation mode were determined based on the national industry standard "GB12676-1999automobile braking system structure, performance and test methods", and the heat flux method was used to get the brake disc temperature field distribution under the repeated braking simulation mode. Simulation results show that the brake disc highest temperatures under the two simulation modes were higher than the maximum continuous operating temperature, the disc brake needs to be further improved, then the measures were put forward, the improved brake can meet the requirements.4. The formula of vehicle pitching was derived, the factors influenced on the pitch angle were gotten for sensitivity analysis to determine the optimal variables, the MDT anti-brake pitch performance was optimized, the optimization result shows that the vehicle pitch angle peak decreased from4.24°to3.91°, with a7.79%reduction.Finally,ride comfort and handling stability of the optimized vehicle was simulated and analyzed for comprehensive consideration of vehicle performance. The simulation result shows that after the optimization, the vehicle ride comfort and vehicle handling and stability is good, the change of suspension structure parameters is acceptable. |
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