小应力循环对C70_E型车体疲劳损伤的影响研究  

Influence of Small Stress Cycles on the Fatigue Damage of C70_E Car Body

作　　者：赵方伟[1] 谢基龙[1] 

机构地区：[1]北京交通大学轨道车辆结构可靠性与运用检测技术教育部工程研究中心,北京100044

出　　处：《机械工程学报》2014年第10期121-126,共6页Journal of Mechanical Engineering

基　　金：国家自然科学基金重点(U1134201);铁道部科技研究开发计划(2011J014-A)资助项目

摘　　要：在北京—成都铁路通用线路上做动应力测试试验,试验车组由一辆被测试的C70E型通用敞车和一辆搭载测试设备的NX70型通用平车组成。实测得到C70E型敞车车体疲劳关键部位的应力时间历程。为更准确地研究C70E型敞车车体的疲劳强度,对比分析编制应力谱时取舍应力循环的不同方法,设置不同取舍门槛值,采用雨流计数法将线路实测的时域信号转化为频域信号,编制应力谱。结合Miner线性累积损伤理论,对比分析不同门槛值求得的应力谱对应的疲劳损伤,结果表明小应力循环对车体疲劳损伤有影响。综合考虑结构强度分析的工作量和小应力循环对疲劳损伤的影响程度,以应力范围(最大应力幅值-最小应力幅值)的5%作为编制应力谱的取舍门槛值较为合理。对比各关键部位损伤值,得出车体相对比较薄弱的部位是靠近一位端侧的一位枕梁下盖板与中梁焊接部位和大横梁与侧梁焊接部位。估算C70E型敞车车体的疲劳寿命,满足650万km的设计和运行要求。Dynamic stress tests are carried out on the line of Beijing to Chengdu,with the test car unit composed of one C70E general open wagon and one NX70 general flat wagon equipped by the test devices.The stress-time histories of different critical locations are gained for the C70E gondola car body.To research the car body fatigue strength of the C70E gondola with high accuracy,different fatigue threshold values are chosen to compile the stress spectra.The signals are transferred from time domain to frequency domain by the rain flow counting method,to establish spectra.Under the Miner linear accumulative damage law,fatigue damage accumulations are calculated from different spectra gained by different fatigue threshold values and the results show that small stress cycles contribute to the fatigue damage.Considering both the amount of work required and the influence level of the small stress cycles,it is reasonable to choose 5％ of the stress range （the difference of the maximum amplitude and the minimum amplitude） as the threshold value for compiling stress spectra.By comparing the fatigue damage for different critical locations,it is observed that the relatively weak parts of the car body are located in the welded joint with bolster cover plate and center sill and the welded joint with large cross beam and side beam near an end side.The fatigue life of C70E open wagon is assessed,which satisfies the design and operational requirements.

关 键 词：小应力循环 C70E车体 应力谱 疲劳损伤 

分 类 号：U272[机械工程—车辆工程]