波形护栏板冷弯成型机组传动轴断裂失效分析及对策研究

针对波形梁钢护栏板冷弯成型机组在运行过程中轧辊传动轴突然发生断裂失效问题,对传动轴宏观断口形貌、成型辊道次、成型弯曲角度分配以及成型过程进行有限元模拟研究,分析了轧辊传动轴断裂的原因.结果表明,成型辊道次和成型弯曲角度分配设计合理,轧辊传动轴断裂属于应力过载失效.断裂部位位于轧辊传动轴φ60 mm与φ65 mm轴台阶过渡圆角根部,在强弯扭应力作用下发生断裂失效.针对以上结论,给出了相应的解决方案,减少了停机次数,提高了波形梁钢护栏板生产效率.     

某泥门传动轴断裂失效分析

本文针对泥门传动轴断裂失效的问题,对泥门传动轴进行了断口分析、受力分析、液压系统和控制系统分析,探究了泥门传动轴断裂原因,并给出优化改进方案。研究结果表明,泥门传动轴焊接工艺不完善是其失效的主要原因;泥门传动轴断裂耳板处位于受力薄弱点,在非正常工况下容易损坏;液压系统及控制系统存在的缺陷是泥门传动轴断裂失效的间接原因。     

驱动链轮齿部断裂原因诊断及采取的措施

在某125型摩托车发动机试生产的台架试验中,先后发生过几次驱动链轮断裂现象,宏观断口均为脆性断裂,且发生于齿根处。通过对断裂原因诊断,我们找到了解决问题的办法,在生产中加强品质控制,取得了较好的效果,现介绍如下。 1.驱动链轮技术要求 材料:20CrMo;渗碳有效硬化层深度:0.3～0.6mm;表面硬度:80±3HRA;心部硬度:27～40HRC;马氏体组织:1～5级;碳化物:1～5级。 驱动链轮示意图如图1所示:P=6.35,z=15。     

某传动装置主传动轴断裂原因分析

某特种车辆在试车过程中传动装置主传动轴断裂失效。在传动轴断口宏微观特征观察的基础上 ,综合主传动轴的金相组织、力学性能、硬度以及化学成分等 ,对主传动轴断裂失效的原因进行研究。结果表明 ,两根轴的断裂均是以振动疲劳为主的高、低周复合疲劳断裂。主传动轴工作中存在扭振 ,齿根转角R偏小和材料屈服强度偏低是导致主传动轴提前失效的主要原因     

液压泵传动轴断裂失效分析

某国产液压泵在试验验证过程中发生传动轴断裂。通过对断裂轴的使用工况、强度安全系数校核、工作应力有限元分析、宏观断口检查、微观形貌、化学成分、金相组织、材料硬度等方面的分析,发现液压泵传动轴失效的主要原因是阶梯轴处过渡圆角设计过小,从而造成局部高应力集中以及圆角处热处理未达到技术要求所致。给出了此类传动轴设计改进方法及工艺优化路线,为提高传动轴的使用寿命奠定了基础。     

某柴油机喷油泵传动轴断裂故障分析及改进

某船用柴油机在排放升级后进行可靠性耐久试验过程中,出现了传动轴断裂问题,通过对传动轴负载变化及传动轴结构分析,确定了根本原因为为满足排放升级,提高了喷油泵的喷射压力,而喷油泵喷射压力的提高导致喷油泵驱动扭矩增大,使得传动轴负载过大降低了传动轴的安全系数,并最终导致传动轴在最薄弱处发生断裂。根据分析结果对传动轴进行了四种不同方案的设计改进,并采用仿真分析方法,选出了改进方案中的最优方案;最终通过柴油机台架可靠性耐久试验,证实了方案的可行。     

汽车转向传动轴断裂原因分析

通过断口形貌与显微组织观察、化学成分测试等分析了汽车转向传动轴断裂失效的原因。结果表明:转向传动轴属扭转疲劳断裂,裂纹萌生于其外表面,表面粗糙的机加工痕迹形成裂纹源,是造成转向传动轴早期失效的主要原因。     

φ180无缝机组穿孔机传动轴扭矩测试与强度分析

实测了穿孔机上下传动轴的扭矩信号,对传动轴进行疲劳强度校核和静强度分析,得出传动轴断裂的原因是由于疲劳强度不足所致的结论,并提出增强疲劳强度,避免传动轴突然断裂的建议.     

链轮轮辐断裂焊接修复一例

制造烧结用带式鼓风冷却机时，尾部从动链轮在热装过程中因热应力控制不当造成一处轮辐断裂(如图1所示)。为保证设备如期投入使用，减少经济损失，公司决定采用焊接方法修复链轮。通过合理制定焊接工艺，链轮的修复取得满意效果。     

发动机机油泵轴失效分析

依据实物,对机油泵传动轴键槽处滚切和断裂失效成因进行宏观和计算分析。     

某大桥扣索钢铰线断丝失效分析

对大桥施工中发生的扣索钢绞线断丝进行了成分、显微组织、断口及裂纹分析，找出了断裂原因，采取了措施。分析结果表明，扣索钢绞线断丝的断裂性质为疲劳断裂，其裂纹源的产生是由于扣索在索鞍轮处弯曲过大，内侧受到较大交变接触应力所致。风振及反复张拉调整，使裂纹不断扩展。     

基于nCode Design-Life传动轴可靠性分析

根据链传动提升系统的结构,计算了提升传动轴的受力。基于ANSYS Workbench对其做静态分析得到其应力分布云图,将有限元分析结果导入至疲劳分析软件nCode Design-Life中,对传动轴进行疲劳可靠性分析,得到传动轴在循环载荷作用下的疲劳结果云图以及各节点的疲劳寿命图,验证了传动轴的可靠性。     

Using stress relief grooves to reduce stress concentration on axle drive shaft

The axle drive shaft has important roles such as transferring power and changing the steering angle between the axle and the wheel in a power train system. It is used in most heavy construction machinery, where a high degree of reliability is required in the power train system. However, for axle drive shafts with a long span axle, failures are common at the snap ring cut that is machined on the drive shaft when there is significant fatigue damage under repeated loading conditions. Stress relief grooves have been applied at the snap ring cut to reduce the stress concentration and improve the fatigue life of an axle drive shaft. Although several studies have described how the stress concentration can be reduced by the stress relief grooves, details of the geometries of the stress relief grooves have been subject to debate and even controversy. We investigated the effects of the stress relief grooves on the stress concentration, and estimated the fatigue life of the drive shaft by using finite element analysis, taking into account the geometric parameters such as size and location of the stress relief grooves. As a result, the stress relief grooves presented by non-dimensional geometric parameters for an r/h = 1.2 and a d/b = 2.0 enabled a 22.3% reduction of the stress concentration, and a maximum improvement in the fatigue life that was approximately 3.3 times that of drive shaft with no stress relief grooves applied. These can be an index for selecting optimal geometric shapes of the stress relief grooves.     

应力集中和表面完整性对平尾大轴抗疲劳性能的影响

某型飞机平尾轴在进行台架试验时发生断裂,失效分析表明,该轴的断裂性质为疲劳断裂,裂纹起源于大轴筒体内腔变截面过渡圆弧根部的加工刀痕谷底。通过对大轴进行扫描电镜观察分析,发现使用过的旧大轴内表面存在10～16 μm厚的“疏松”层,疏松层内有较多的疲劳微裂纹和孔洞,该“疏松”层是大轴服役中氧化腐蚀和疲劳损伤所形成的。“疏松”层的存在破坏了大轴的表面完整性,降低了大轴材料的抗疲劳性能。有限元建模分析表明,变截面台阶造成的结构应力集中和粗糙加工刀痕形成的附加应力集中是造成大轴疲劳断裂的力学因素,两种应力集中因素的联合作用降低了大轴的疲劳寿命,导致大轴在变截面过渡圆弧根部的加工刀痕谷底萌生疲劳裂纹。综合分析表明,大轴内表面“疏松”层的存在以及变截面台阶造成的结构应力集中和粗糙加工刀痕形成的附加应力集中是大轴发生疲劳断裂的主要原因。     

The effect of rubber contact on the fretting fatigue strength of railway wheel tire

The cause of the ICE train derailment, which occurred in 1998 at Eschede, was fatigue failure originating on the inside of the wheel tire. Rubber-sprung resilient wheels were used for the trailer cars. The wheel tire is mounted on the wheel disc. Thirty-four rubber pads were arranged between the wheel disc and the wheel tire. It was postulated that fretting fatigue between the rubber block and the inner side of the tire might have an influence on the initiation of the incipient crack. In order to clarify the influence of the rubber contact on the fatigue strength of the tire, fretting fatigue experiments under rubber contact conditions were performed. During the fundamental fretting fatigue test using bridge pads and small size carbon steel specimens, no typical fretting damage such as fretting wear and minute cracks were observed due to contact of the rubber. Stress conditions of the rubber-sprung wheel under vertical and lateral wheel loads were evaluated by a three-dimensional elastic stress analysis. Since the rubber is a super-elastic material, the Mooney-Rivlin model was used in the FEM calculation. It was found that the wheel tire is subjected to a cyclic stress during one revolution of the wheel and the maximum stress occurred at the center of the inner surface of the tire where the fatigue crack initiated. Fatigue strength of the wheel tire was determined by the rotating bending fatigue testing of specimens taken from the tire. It was found that the tire with an 862 mm diameter at a wheel load of 80 kN had a safety factor more than 3.5 from a fatigue limit diagram with a failure probability of 0.01. To confirm the fretting damage under the rubber contact and the result of the fatigue strength evaluation, fatigue tests of a full size wheel were made. After 20 million cycles at the wheel load of 280 kN, which was just below the endurance limit estimated by the endurance limit diagram, no fretting damage and no fatigue cracks were observed. The wheel was, however, fractured at 1.56 million cycles under the maximum load of 308 kN, which was just above the endurance limit. The estimation of the safety factor of 3.5 estimated from the endurance diagram was confirmed by the full size fatigue testing. It was concluded that there was no effect of fretting due to the rubber contact on the fatigue strength of the rubber-sprung single-ring railway wheel.     

某型主战坦克扭力轴的疲劳断裂分析与寿命计算

应用断裂力学理论和有限元分析方法对某型主战坦克扭力轴进行疲劳断裂计算和分析，论述裂纹尖端的奇异三角形单元划分技术，在有限元法计算的基础上求解裂纹尖端应力强度因子和裂纹形状系数，并结合Paris公式对某坦克扭力轴的疲劳寿命进行计算。     

车轮多边形激励下的滚动接触疲劳裂纹瞬态扩展行为研究

利用ANSYS/LS-DYNA建立带车轮多边形的三维轮轨滚动接触疲劳裂纹扩展模型,将真实轮轨间瞬态滚滑和高频动力作用考虑在内,分析车轮多边形和连续钢轨裂纹造成的瞬态接触载荷对钢轨裂纹动态扩展行为的影响。速度250 km/h牵引工况的结果表明:零间隙多裂纹对法向轮轨力的影响甚微,但会造成切向轮轨力不可忽略的波动;车轮多边形会造成法向和切向轮轨力显著的周期性波动,如0. 1 mm波深23阶多边形会使得各裂纹面最大法向和切向接触力较圆顺工况分别增长19. 6%、34. 1%;任一裂纹面内法向和切向接触应力在接触斑滚过的0. 22 ms内发生了复杂的瞬态变化,进一步导致各裂纹的最大裂尖应力场强度因子的周期性波动,影响裂纹动态扩展行为;随着车轮多边形波深和阶数的增加,上述各种波动的幅度均会变大,加速裂纹扩展。     

228D减速器断轴分析与改进设计

228D减速器皮带式抽油机的主减速传动装置,减速器运行3个月发生高速齿轮轴断裂事故。经查找分析表明,该轴结构设计存在带轮悬臂过长、危险截面处弯矩过大、应力集中突出、疲劳强度的安全系数过低等缺陷及材料金相组织存在魏氏体,都是造成断轴原因。最后提出了改进设计措施。     

高速列车车轮多边形对齿轮箱疲劳寿命的影响

车轮多边形是高速列车运行过程中常见的磨耗现象,该现象使轮轨作用力增大,齿轮箱持续异常振动,并会影响其疲劳寿命.为研究高速列车车轮多边形对齿轮箱疲劳寿命的影响,建立了含有齿轮箱支撑轴承的驱动系统和柔性齿轮箱的刚柔耦合整车动力学模型,采用数值仿真分析方法,通过分析不同车轮多边形幅值下轮轨垂向力和齿轮箱垂向振动加速度确定极端...     

离心轮内部疲劳裂纹扩展及其无损定量表征

为研究某离心轮内部疲劳裂纹扩展及其无损定量表征,开展了高速低循环旋转疲劳试验以及多种无损检测定量表征、断口分析、疲劳裂纹扩展仿真对比研究.研究结果表明:疲劳裂纹到达表面后,疲劳裂纹处于非稳定扩展阶段;20000～21700循环间,区间疲劳裂纹扩展速率仿真值与无损表征值接近;21700～21789循环间,区间疲劳裂纹扩展...