| 曲轴开裂拉瓦失效分析 |
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| 引用本文： | 颜婧,冯继军,余政宏,卢柳林,高勇. 曲轴开裂拉瓦失效分析[J]. 失效分析与预防, 2019, 14(4): 275-279. DOI: 10.3969/j.issn.1673-6214.2019.04.012 |
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| 作者姓名： | 颜婧 冯继军 余政宏 卢柳林 高勇 |
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| 作者单位： | 东风商用车有限公司技术中心,武汉,430056;东风商用车有限公司发动机厂,湖北十堰,442001 |
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| 摘 要： | 卡车的大马力发动机在行驶过程中突然异响，经拆解发现，发动机第5缸连杆瓦拉瓦、抱轴，第5缸连杆轴颈拉伤并出现与轴向呈45°的裂纹，其他轴瓦检查主轴承下瓦有轻微拉伤。通过宏观痕迹分析、断口分析、金相分析、化学分析、硬度检测等手段，研究其失效形式及原因。结果表明:曲轴先开裂后，轴颈表面形成刀口，导致了拉瓦、抱轴事故的发生；曲轴的裂纹起源于油道内壁（淬硬层以下）的扭转疲劳开裂，与曲轴受到异常的扭转力有关。非调质钢曲轴基体中存在大量聚集成排的MnS夹杂物，是疲劳裂纹起源的另一个诱因。后续通过对配对的扭振减振器进行台架试验检测，发现扭振减振器已失效。
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| 关 键 词： | 曲轴 拉瓦 扭转疲劳开裂 油道内壁 扭振减振器 |
| 收稿时间： | 2019-05-13 |
Analysis of Cracking and Locking of Crankshaft |
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| YAN Jing,FENG Ji-jun,YU Zheng-hong,LU Liu-lin,GAO Yong. Analysis of Cracking and Locking of Crankshaft[J]. Failure Analysis and Prevention, 2019, 14(4): 275-279. DOI: 10.3969/j.issn.1673-6214.2019.04.012 |
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| Authors: | YAN Jing FENG Ji-jun YU Zheng-hong LU Liu-lin GAO Yong |
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| Abstract: | Abnormal sound suddenly occurred in the high horsepower engine while a car was running. After opening the engine, it was found that the crankshaft had cracked at the fifth cylinder and the bearing had damaged and locked. In order to find the failure cause, macro trace observation, fracture analysis, metallographic analysis, chemical analysis, and hardness measurement were carried out. The results show that the crankshaft first cracked, leading to sharp edge on the surface, and then resulting in the damage and locking of the bearing. The crack of the crankshaft is torsion fatigue crack initiating from the oil duct wall (under the hardening layer). The crack was mainly caused by abnormal torsional stress. There were lots of MnS nonmetallic inclusions in the non-quenched steel matrix, which promoted the initiation of the fatigue crack. Then tests showed that the torsional damper had failed. |
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