【作者】 余为高；

【导师】 于学华； 曲杰；

【作者基本信息】 华南理工大学 ， 车辆工程， 2010， 硕士

【摘要】 制动器是汽车制动系统的核心部件,制动过程是一个典型的热—机耦合过程,制动器摩擦副温度和应力场的耦合分析计算是制动器设计的重要内容和选择摩擦副材料的重要理论依据。本文应用有限元方法对制动过程中的热—机耦合现象进行仿真分析,并预测了制动盘的热疲劳寿命。首先,以目前轿车上普遍采用的通风盘式制动器为例,应用Catia软件进行三维建模,利用Hypermesh软件进行网格划分,推导盘式制动系统的三维瞬态温度场热传导方程,并确定其热流输入边界条件和对流散热边界条件,应用非线性有限元软件Abaqus建立制动系统的热—机完全耦合有限元分析模型,对汽车紧急制动过程进行模拟,在模拟计算中考虑到了因摩擦生热导致的旋转移动热流的产生和分配,以及温度、接触压力与应力之间相互耦合问题,并考虑到制动盘各界面的对流换热系数随制动盘转速而变化。其次,通过对热—机耦合制动过程的仿真分析,揭示制动盘在移动热源和对流换热作用下的瞬态温度场、接触压力场和应力场的分布规律,探讨制动盘在交变循环应力作用下盘面常见的径向裂纹的产生原因,研究制动过程中制动盘的翘曲和厚度变化的热变形,并根据热变形对接触状态和接触压力的影响来分析制动过程中制动盘摩擦表面出现的“热点”和制动时的热抖动问题。最后,基于热—机耦合分析结果,应用Manson-Coffin公式来预测制动盘的热疲劳寿命,并研究制动初速度和制动压力对制动盘使用寿命的影响。更多还原

【Abstract】 Brake is the main components of the vehicle brake system. The braking process is a typical thermal-mechanical coupling process. The coupled temperature and stress field analysis and calculation is an important part of brake design and its results are the important theoretical foundation in for selecting friction materials. The paper simulated the thermal-mechanical coupling phenomenon for a ventilated disc brake and predicted the thermal fatigue life of the disc.Firstly, a ventilated disc brake which is currently widely used for passenger cars was chosen as an example, the 3-D model of disc brake system was established using the software Catia, and was meshed using the software Hypermesh. The three-dimensional transient temperature field of heat conduction equation of the disc brake system was derived, and its heat input boundary conditions and convection boundary conditions were identified. And the thermal-mechanical coupled finite element model for braking system was established using the non-linear finite element software Abaqus. The transient temperature field, contact pressure and stress field of the disc are simulated during emergency braking. The effect of the heat due to friction caused by rotational movement of the heat generation and distribution, the coupling of the temperature, contact pressure and equivalent stress were taken into account during the course of numerical simulation. And the change of the heat transfer coefficient for each interface of the forced convection state of the brake disc was taken into account.Secondly, based on the results of the simulation of the thermal-mechanical coupling, the distribution of the transient temperature, contact pressure and stress field of the disc were analyzed under the condition of the time-varying moving thermal load and the convection heat transfer. With the alternating cycle of stress, the radial cracks which are common on the disc surface were studied. The thermal deformation of warping and the thickness variation of the disc were investigated. And according to the thermal deformation the disc influence on the contact state and contact pressure, the“hot spots”which are on the disc surface and hot judder were analyzed during braking process.Finally, the thermal fatigue life of the disc was predicted according to Manson-Coffin equation. The effect of the initial braking speed and brake pressure to the brake disc life were also studied.更多还原