【作者】 杨月；

【导师】 谢基龙；

【作者基本信息】 北京交通大学 ， 车辆工程， 2009， 博士

【摘要】 盘型制动作为最有效的安全制动方式,已普遍被采用在提速和高速客车上。避免制动强摩擦与高热负荷所造成的制动盘早期热疲劳失效并预防崩盘恶性事故发生是制动盘选材和结构设计中需要考虑的重要环节。目前,国内高速列车上服役的制动盘均为铸铁或锻钢材料,由于制动盘属簧下质量,制动盘质量过大会增加能耗,并对转向架的动力学性能有不利影响,因此,研究开发适合于高速列车服役工况的具有重量轻、耐磨损和耐热性能好的制动盘,具有非常重大的实际意义。论文根据上述背景,以国家863计划资助项目“高速客车用金属基复合材料制动件的研究与应用”(2003AA331190)为支撑,对新开发的用于高速列车制动盘的SiCp/A356颗粒增强铝基复合材料的热循环特性、断裂机制、热疲劳性能进行了试验研究,采用有限元仿真技术与材料热疲劳试验相结合的方法,对制动盘热疲劳裂纹形成和扩展规律进行了深入的研究。主要内容包括:1.研究SiCp/A356颗粒增强铝基复合材料常温和高温的单调和循环拉伸特性、热物理性能以及各性能参数与温度的相关性,从而建立了SiCp/A356复合材料的热弹塑性本构关系。2.基于制动盘的循环对称结构特点,将泛函与热传导微分方程相结合,建立了制动盘三维瞬态温度场的数学模型,采用顺序耦合的数值计算方法,模拟了制动盘在不同制动工况下的循环应力应变响应规律,提出了热残余应力的形成机制以及制动盘盘面热残余拉应力在裂纹形成与扩展过程中的重要作用。3.通过SiCp/A356切口试样在20℃～300℃循环变温下的自约束热疲劳试验,确定了裂纹扩展速率与热循环次数的关系(a～da/dN),探讨了试样切口半径R和试样厚度对裂纹形成和扩展的影响。采用有限元仿真技术,建立了颗粒增强金属基复合材料细观体元的热弹塑性本构模型,重点针对热循环作用下体元的细观应力应变响应进行描述,提出了颗粒增强金属基复合材料界面开裂的细观机理。4.根据SiCp/A356颗粒增强铝基复合材料热疲劳试验获得的参数,建立与试验工况一致的有限元仿真模型,以裂纹长度与热循环次数及试样尺寸的关系为准则,提出了定量分析复合材料热应变寿命(△ε_T/2～2N_f)和热疲劳裂纹扩展速率曲线(da/dN～△K)的有限元方法。5.采用热弹塑性有限元法,确定了制动盘表面缺口的循环应力-应变响应特性和裂纹应力强度因子,提出了高速列车SiCp/A356复合材料制动盘热疲劳裂纹形成与扩展规律的评价方法。更多还原

【Abstract】 As the most effective brake mode,brake disc has been used in the high speed train.It is important to consider how to avoid early thermal fatigue failure due to strong friction and intense heat flux in brake disc material selecting and structural design.At present,Cast iron and forged steel are normally used for brake discs of high speed strain in our country.Brake disc belongs to unsprung weight,heavier weight of which makes more energy consumption and worse kinetics performance of bogie,so it is a real significant research subject to develop a brake disc with light weight, anti-abrasive and heat resisting material.With the support of National Basic Research and Development program of China (863 program,No.2003AA331190 Research and Application of Metal Matrix Composite Brake Part in High Speed Train),the dissertation studied the thermal cycle performance,fracture mechanism and thermal fatigue character of SiCp/A356 composite latest developed for brake disc of high speed train using experimental method.And thermal fatigue crack initiation and propagation were deeply investigated by Finite element(FE) simulation combined with thermal fatigue test.The main contents are as follows,1.In order to establish thermal elastic plastic constitutive relationship of SiCp/A356 composite,its monotic and cyclic tension performance,physical characters with temperatures were investigated.2.Combining the functional analysis method with the heat conduction differential equations the finite element mathematic model of the period cyclic symmetric structure, ig.brake disc,was constructed for 3D transient temperature field.The cyclic stress strain responses rule of disc under different braking conditions were simulated with the sequence-coupled numerical calculation method.The mechanism of thermal residual stress and its important function at crack initiation and propagation process of disc surface were presented.3.The relationship of crack propagation rate and thermal cycles(a～da/dN) was determined and the influence for crack coming with diameters and thickness of samples were discussed.The thermal elastic plastic constitutive model of micro-unit of metal matrix composite(MMC) reinforced by particle was established by FE simulation technology.The stress strain response of micro-unit was mainly described to open out interface crack mechanism.4.According to the parameters obtained from thermal fatigue test of SiCp/A356 notched sample,quantitative analysis of thermal fatigue crack initiation curve (Δε_T/2～2N_f) and propagation rate curve(da/dN～ΔK) of the material were achieved by finite element method(FEM),which realized forecast of thermal fatigue crack initiation and propagation rule.5.The notched cyclic stress-strain response and crack stress intensity factors are established by thermal elastic plastic FE.The assessment method of thermal crack initiation and propagation law of SiCp/A356 composite brake disc surface was put forward.更多还原