共查询到18条相似文献,搜索用时 187 毫秒
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正曲轴是内燃机最重要的零件之一,其主要功能是传递与输出动力,承受缸内的气体压力、往复和旋转质量惯性力、扭转力等的作用,对柴油机的可靠性及性能具有重要意义。曲轴断裂事故的实际分析证明,曲轴的失效形式主要是弯曲疲劳破坏,而弯曲疲劳的裂纹集中在曲轴曲柄至连杆轴颈的过渡圆角处,因此,分析曲轴弯曲失效对曲轴使用寿命很关键,本文利用ANSYS及FE-SAFE软件,对曲轴进行应力及疲劳模拟分析,进而通过曲轴弯曲疲劳试验台进行验证,为改善曲轴的疲劳性能提供了有 相似文献
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大型柴油机曲轴断裂失效分析 总被引:2,自引:0,他引:2
用化学分析、力学性能试验、扫描电镜等方法分析了某大型柴油机曲轴早期断裂的原因.结果表明:宏观断口上有明显的疲劳源区和宏观疲劳条纹,曲轴属于疲劳断裂.疲劳裂纹萌生在曲轴油孔内表面的缺陷处(缺陷尺寸为767 μm×500 μm),该缺陷是机械加工油孔时刃具刀尖崩裂造成的,在工作交变扭转应力作用下缺陷萌生疲劳裂纹并扩展,导致曲轴发生早期疲劳断裂. 相似文献
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浅谈曲轴的冷滚压强化工艺 总被引:1,自引:0,他引:1
张焕洲 《机械工人(热加工)》2004,(1):83-84
内燃机曲轴的主要破坏形式是断裂和轴颈磨损,其断轴率为0.5%~2%,这是因为曲轴的结构及其所受的载荷使其应力分布极不均匀,在主轴颈、连杆轴颈与曲拐相连接的过渡圆角处产生了比曲拐同截面的名义应力高出数倍的集中应力峰值所导致的。过渡圆角处的最大弯曲应力占80%,扭转应力仅占20%,一系列的应力分析和大量的曲轴断裂实例表明,断裂一般发生在连杆轴颈过渡圆角与主轴颈过渡圆角的对角线上。 相似文献
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某往复式甲烷压缩机曲轴在运行过程中发生断裂,通过断口宏观和微观形貌观察、化学成分分析、显微组织观察和力学性能测试等方法,研究了曲轴断裂的原因。结果表明:曲轴发生了扭转疲劳断裂;在交变扭转应力的作用下,曲轴主轴颈不规则且粗糙的过渡圆角和油孔附近粗糙的机械加工痕迹处产生应力集中,导致微裂纹萌生;组织中严重的带状回火屈氏体、大小不均匀的晶粒以及非金属夹杂物导致曲轴的力学性能变差,加速了疲劳裂纹的扩展;建议严格控制曲轴的热处理和制造工艺,优化曲轴结构设计,防止类似事故的再次发生。 相似文献
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Yue SHI Lihong DONG Haidou WANG Guolu LI Shenshui LIU 《Frontiers of Mechanical Engineering》2016,11(3):233-241
Crankshaft is regarded as an important component of engines, and it is an important application of remanufacturing because of its high added value. However, the fatigue failure research of remanufactured crankshaft is still in its primary stage. Thus, monitoring and investigating the fatigue failure of the remanufacturing crankshaft is crucial. In this paper, acoustic emission (AE) technology and machine vision are used to monitor the four-point bending fatigue of 42CrMo, which is the material of crankshaft. The specimens are divided into two categories, namely, pre-existing crack and non-preexisting crack, which simulate the crankshaft and crankshaft blank, respectively. The analysis methods of parameter-based AE techniques, wavelet transform (WT) and SEM analysis are combined to identify the stage of fatigue failure. The stage of fatigue failure is the basis of using AE technology in the field of remanufacturing crankshafts. The experiment results show that the fatigue crack propagation style is a transgranular fracture and the fracture is a brittle fracture. The difference mainly depends on the form of crack initiation. Various AE signals are detected by parameter analysis method. Wavelet threshold denoising and WT are combined to extract the spectral features of AE signals at different fatigue failure stages. 相似文献
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曲轴因工作环境恶劣,在实际工作中易发生弯曲、磨损,导致失效.为节约材料和能源,在发动机曲轴再制造加工中使用表面强化工艺恢复或提高曲轴的使用性能. 相似文献
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曲轴是发动机中最重要的零件之一。大量研究表明,曲轴的主要失效形式表现为:疲劳破坏和断裂。特别是随着发动机的动力性和可靠性要求的提高,其强度问题变得更加重要。简要介绍了可靠性设计基本理论,指出设计决定了产品的可靠性水平。阐述了基于可靠性的抗疲劳设计理论,并总结了三种典型的抗疲劳设计方法,以及疲劳寿命的预测方法。最后运用相关理论对曲轴的疲劳寿命进行了估算。 相似文献
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J.A. Becerra Villanueva F. Jiménez Espadafor F. Cruz-Peragón M. Torres García 《Mechanical Systems and Signal Processing》2011,25(8):3168-3185
Diesel engines used in power plants and marine propulsion are especially sensitive to outage events. Any advance in the early detection of failure will increase the reliability of the electricity supply and improve its productivity by reducing costly power outages. Fault detection and diagnosis is important technology in condition-based maintenance for diesel engines. This article presents a classifier based on neural networks for identifying failure risk level in crankshafts, the engine component of greatest cost concern. The authors have developed a finite element model for crack growth that fits well with fracture appearance and produces the evolution of crankshaft stiffness with crack depth. A lumped system model of the engine uses this evolution as input, giving the instantaneous speed at the engine flywheel as a function of crack depth. All the results shown in the paper come from outputs of the simulation models which have been built from real engine data. Measurements of the instantaneous flywheel speed were not available due to the crankshaft failure. All data are extracted from this speed and are then classified using a Radial Basis Function neural network. 相似文献