转K2型转向架承载外簧疲劳断裂分析  

Fatigue Fracture Analysis of An Outer Bearing Screw Spring for Bogie Type K2

作　　者：王凯 刘德义[2] 刘世程[2] 

机构地区：[1]中车齐齐哈尔车辆有限公司热工艺部,黑龙江齐齐哈尔161002 [2]大连交通大学材料科学与工程学院,辽宁大连116028

出　　处：《大连交通大学学报》2017年第4期138-141,163,共5页Journal of Dalian Jiaotong University

摘　　要：对疲劳试验中断裂的转向架弹簧,从材料质量、断口、表面划痕及其对疲劳寿命的影响等方面进行了分析,结果表明:材料及热处理质量符合标准要求,SEM断面分析亦未发现夹杂物等材料缺陷;断口及表面观察发现疲劳裂纹从应力最大的簧圈内表面的划痕形成;划痕与簧丝轴向垂直,其引起的应力集中使等效对称循环切应力增大12.7%,疲劳寿命降低74%,是早期疲劳断裂的原因;划痕是生产中不当操作造成的.Analysis of material characteristics, fracture surface, surface scratch and its effect on fatigue life were carried out for a screw spring used for Bogie Type K2 fractured in fatigue test. The results show that the quality of the material and the heat treatment process of the spring satisfy the related requirements. No non- metallic inclusions and other metallurgical defects are identified by SEM fraetographic analysis. However, a surface scratch is observed at the inner surface of the coil where the shear stress reaches the maximum value, and the fatigue crack originates at the surface scratch. The surface scratch is perpendicular to the axis of the spring wire. Estimation indicates the surface scratch results in a stress concentration that increases equivalent shear stress of completely reversed cycles of stress by 12.7% with a fatigue life reduced by 74%. It is concluded that the surface scratch is the cause of fatigue failure, and the surface scratch is induced by an improper handling.

关 键 词：弹簧 疲劳断裂 表面划痕 应力集中 等效切应力 

分 类 号：U270.33[机械工程—车辆工程]