列车制动系统用杠杆螺栓S-N曲线试验研究  

Experimental Research on S-N Curve of Lever Bolt for Train Brake System

作　　者：张亚军[1,2] 赵春光 陈沛 党恒耀[1,4] 张欣耀 ZHANG Yajun;ZHAO Chunguang;CHEN Pei;DANG Hengyao;ZHANG Xinyao(725 Research Institute of China State Shipbuilding Corporation Limited,Luoyang Henan 471023,China;The key Laboratory of Technology and Application of Structural Materials for Ship and Ocean Equipment in Henan Province,Luoyang Henan 471023,China;Beijing Zongheng Electro-Mechanical Technology Co.,Ltd.,Beijing 100094,China;National New Material Production and Application Demonstration Platform(Advanced Marine Engineering and High-Tech Ship Materials),Luoyang Henan 471023,China)

机构地区：[1]中国船舶重工集团公司第七二五研究所,河南洛阳471023 [2]河南省船舶及海工装备结构材料技术与应用重点实验室,河南洛阳471023 [3]北京纵横机电科技有限公司,北京100094 [4]国家新材料生产应用示范平台(先进海工与高技术船舶材料),河南洛阳471023

出　　处：《中国铁道科学》2021年第4期129-136,共8页China Railway Science

基　　金：中国铁路总公司科技研究开发计划重点课题(2014J004-G)。

摘　　要：以表面经过硬化处理的某列车制动系统用杠杆螺栓为例,采用X射线法测量其表面残余应力;分析杠杆螺栓受力特征,在保证弯曲应力不变、仅改变施力点位置的情况下,试验时将施力点向杠杆螺栓中心平移以增加力臂,降低试验载荷;基于杠杆螺栓受载点处拉伸应力与弯曲应力的关系,采用变更施力点后的4点弯曲加载方式,试验获得不同存活率下的杠杆螺栓S-N曲线,并采用扫描电镜观察断口形貌。结果表明:杠杆螺栓表面残余压应力为-256~-579 MPa,压应力会阻碍疲劳裂纹的萌生与扩展,使得疲劳裂纹并未萌生于螺栓表面,而是萌生于表面硬化层和内部材料的结合处;理论预测的杠杆螺栓断裂位置与实际试验结果一致,证明变更施力点加载方法的合理性;不同存活率下杠杆螺栓的S-N曲线方程均可用幂函数模型进行较好的表达,说明杠杆螺栓与常见金属材料的S-N数据分布规律具有相似性。Taking the lever bolts with hardened surfaces for train brake system as examples,the residual stress on the surface was measured by X-ray method.The mechanical characteristics of the lever bolts were analyzed and the loading points could be transferred to the center of the lever bolt in order to increase the force arm and decrease the test load under the condition of constant bending stress and changed loading point positions only.Based on the relationship between the tensile stress and bending stress at the loading points of lever bolts,the SN curves of lever bolts at different survival rates were attained by the test of applying four-point bending loading method after altering the loading points,and the fracture morphology was observed by scanning electron microscope.The results showed that the residual compressive stresses on the surface of lever bolts were-256--579 MPa,which would retard the initiation and propagation of fatigue crack,and make the fatigue crack initiate in the junction of the surface hardened layer and the inner material instead of the surface of lever bolts.The predicted fracture positions of level bolts by theory were consistent with those in field tests,which verified the method of the loading-point altering was rational.The S-N curve equations of the level bolts with different survival rates could be expressed preferably by power function model,which showed that the S-N data distribution law of lever bolts was similar to that of common metallic materials.

关 键 词：列车 制动系统 杠杆螺栓 表面残余应力 S-N曲线 断裂位置 4点弯曲加载 幂函数 

分 类 号：U270.35[机械工程—车辆工程]