船用柴油机曲轴连杆断裂原因

某船用柴油机运行约1 000 h后其曲轴连杆发生断裂。采用宏观观察、化学成分分析、力学性能测试、粗糙度检测、金相检验等方法,对该连杆的断裂原因进行分析。结果表明：该连杆的断裂性质为疲劳断裂,裂纹起源于过渡圆弧段,引起断裂的主要原因为过渡圆弧段处加工粗糙度较差,且局部曲率偏大,导致该处应力集中程度增大,从而引起疲劳裂纹的萌生和扩展,最终使连杆发生断裂。     

发动机连杆螺栓断裂原因分析

某汽车发动机连杆螺栓在发动机台架耐久试验中发生断裂。通过宏观检验、化学成分分析、扫描电镜分析、金相检验、能谱分析等方法,对螺栓的断裂原因进行了分析。结果表明:该连杆螺栓断裂模式为多源疲劳断裂;裂纹内部存在大量的磷和锌元素,说明在搓丝工序时螺栓已经产生了微小裂纹;在后期的磷化处理中,磷化液渗入微小裂纹中;台架耐久试验过程中裂纹逐步疲劳扩展并导致螺栓断裂。     

柴油发动机连杆断裂原因分析

应用金相、扫描电镜、能谱分析等手段，分析了柴油机连杆断裂原因。认为连杆的断裂是由于材料中存在的显微孔洞和夹杂物导致产生锻造裂纹，在随后调质过程中裂纹进一步扩展，致使使用时发生脆性断裂。     

柴油机连杆断裂分析

某柴油机在服役中其连杆小头产生纵向断裂、对断裂伯进行化学成分分析和宏、微观检验。结果表明,该连杆由于心部未淬透,不能保证足够的疲劳强度及结构强度、从而导致断裂。     

波音737-500飞机前缘襟翼操纵连杆断裂分析

对波音737-500型飞机2根前缘襟翼操纵连杆断裂进行了断裂性质、断裂原因分析,分析结果表明襟翼操纵连杆属于疲劳断裂,疲劳裂纹的产生与变截面及齿底应力集中有关.     

柴油机曲轴断裂分析

某6缸发动机曲轴在运行20000km后,从第七主轴颈与第六连杆颈之间的截面处断裂.对断裂曲轴进行了断口观察、化学成分分析、金相组织和力学性能检验.结果表明,曲轴属弯曲疲劳断裂,疲劳裂纹的主源位于第七主轴颈圆角过渡处.通过对相关件作进一步的调查分析,找出了曲轴断裂失效的原因,并提出了改进措施,取得了效果.     

汽车曲轴断裂原因

某汽车曲轴在进行耐久测试时发生断裂。采用宏观观察、化学成分分析、扫描电镜分析和金相检验等方法，对该曲轴的断裂原因进行了研究。结果表明：该曲轴的断裂性质为疲劳断裂，裂纹起源于过渡R处的表面，R处尺寸偏小以及车刀加工纹路较深，增大了R处的应力集中，在运行时，R处萌生裂纹，在交变载荷的作用下，裂纹发生疲劳扩展，最终导致曲轴断裂。     

不同装夹方式下的连杆疲劳寿命

目的分析大头间隙配合及大头小头均间隙配合这2种不同装夹方式,对连杆疲劳寿命的检测产生的不同的结果。方法采用MTS880±500 kN和MTS322±250 kN疲劳试验系统,采用不同的装夹方式模拟发动机工作状态,并通过"可靠性试验SAFL方法"进行数据处理。结果采用大头间隙配合装夹的连杆失效概率为5.2×10-5,大头小头均间隙配合装夹的连杆失效概率为0.87×10-5;并且2种装夹方式会影响连杆疲劳试验后的断裂位置。结论连杆疲劳试验中,采用大头小头均间隙配合装夹方式得到的连杆失效概率,较大头间隙配合装夹方式更小。进行疲劳试验需谨慎选择装夹方式。     

发动机连杆断裂原因分析

某发动机连杆在轿车行驶过程中发生断裂。采用化学成分分析、硬度测试、金相检验和断口分析等方法对连杆断裂的原因进行了分析。结果表明:连杆的断裂属高周疲劳断裂。雨水随空气进入燃烧室,压应力过载,导致连杆弯曲变形并最终发生疲劳断裂。     

高强度螺栓断裂原因分析

表面磷化处理的高强度螺栓在装配时发生断裂。对断裂螺栓进行宏观和微观检验、化学成分分析、金相检验、能谱分析和力学性能分析。结果表明：该螺栓的裂纹表面有氧化物且存在与螺栓表面相似的磷化物,裂纹处没有脱碳现象,说明裂纹在磷化处理前已存在,判断该裂纹是淬火裂纹。螺栓的断裂是由淬火裂纹造成的。     

甲烷制冷压缩机配件断裂分析

对甲烷制冷压缩机断裂活塞杆和连杆的材料成分,力学性能,显微主其断口和应力进行了试验分析,确定了其断裂模式为疲劳断裂,调质热处理工艺不当和活塞杆连接螺纹根部应力过大是产生疲劳断裂的主要原因,提出了预防断裂的措施。     

Failure Analysis of a Diesel Engine Connecting Rod

A failure investigation has been conducted on a diesel engine connecting rod. The fracture occurred at the small head of the connecting rod. Visual and scanning electron microscopy observations show that a lot of axial grooves appear on the internal surface close to the fracture and the fatigue cracks initiated from the axial grooves. Fractography indicates that the multiple-origin fatigue fracture is the dominant failure mechanism. The machining or assembling process was responsible for the formation of the axial grooves.     

进口氢气压缩机螺栓断裂原因分析

通过宏观检验、化学成分分析、金相检验以及断口分析等方法对氢气压缩机的地脚螺栓和连接螺栓发生断裂的原因进行了分析.结果表明:由于压缩机机座安装倾斜,造成地脚螺栓受剪切应力首先断裂;连接螺栓受振动引起的剪切应力和轴向拉应力共同作用,并且其预紧应力超过最大允许预紧应力,最后发生疲劳断裂;另外螺栓本身存在的材料缺陷致使强度不足...     

某天然气压缩机组联轴器断裂故障诊断

大型往复式压缩机的曲轴-连杆-活塞结构因其产生的不平衡力,极易发生疲劳断裂,对断裂原因进行有效分析对故障消除措施的制定具有重要作用。本文针对某气田压缩机组联轴器的多发性断裂故障,首先对断裂螺栓进行理化分析,再通过仿真计算系统扭振固有频率,并对系统进行扭振及轴功率、扭矩测试,诊断出故障产生原因是系统第五阶次扭振共振且峰值扭矩超标,继而采用在压缩机组光轴段加装一个惯性飞轮对系统扭振特性进行调频处理,使螺栓断裂故障得以根治。本文将理论和测试结合,该故障诊断方法可用于其他类似问题,具有理论和工程实际意义。     

连杆无飞边锻造工艺及模具系统研究

目的研究连杆无飞边锻造工艺,以及闭模锻造过程中中间工序件的设计和所需的模具系统。方法通过建立有限元模型,分析连杆的预锻和终锻过程中金属流动长度、成形载荷和模具寿命,为模具设计提供数据支持。结果数值模拟结果表明金属充模效果良好;连杆大端主要在预锻中成形,而连杆小端和杆部主要在终锻中成形;预锻和终锻的最大成形载荷分别为437 t和850 t;连杆大端的模腔圆角为模具失效危险区。结论通过辊锻制坯、预锻分配物料和终锻精密成形,实现了连杆的无飞边锻造。     

20CrMo连杆断裂失效分析

采用光学金相和电子探针分析仪等分析手段，对20CrMo嘉陵摩托车连杆的断裂进行了分析。结果表明：连杆在热处理过程中在其表面层形成了粗大的马氏体针状组织是造成断裂的主要原因，并在其显微断口上形成沿晶断口。     

Failure analysis of a failed connecting rod cap and connecting bolts of a reciprocating compressor

Connecting rod cap and connecting bolts of a reciprocating compressor are subjected to complex dynamic loads therefore they are of critical machine elements. The causes for the failure of connecting rod cap and connecting bolts after approximately 175,200 h in service have been investigated. To determine the failure mechanism of the connecting system and to figure out which of the connecting rod cap and connecting bolts was broken first, material characterization and numerical analysis are conducted on the connecting rod and connecting bolts. Scanning electron microscope (SEM) and optical microscope are applied to analysis the macro and microstructures. The chemical composition and metallographic structure investigation are carried out to study characteristics of the materials. Tensile tests, hardness and impact tests are performed to check the mechanical properties of the connecting rod cap and three connecting bolts. A finite element analysis of the connecting system is employed to evaluate the overall stress distribution with maximum stress criterion. Results of this investigation indicate that the reason of failure was high cycle fatigue and the initial crack location was consistent with high stress concentration at the curvature mutation position of connecting rod cap which was broken before the connecting bolts.     

Failure analysis of a special vehicle engine connecting rod

This paper presents failure analysis of the connecting rod used in a 12-cylinder diesel engine set on a special vehicle. The fracture of the connecting rod occurred during the engine test in laboratory conditions. Chemical and metallographic analysis as well as mechanical testing have confirmed that the material properties of the connecting rod met the requirements of standard specification and technical documentation. Linear finite element (FE) analysis was performed to evaluate stress state of the connecting rod under maximum load. The results of FE analysis showed that the position of the fracture is consistent with the zone of highest stress. Fractographic analysis has not been able to reveal the main cause of mechanism of fracture due to substantially damaged fracture surface.Inadequate machining, absence of polishing and highest stress in the region of fracture were identified as the main causes of failure. Finally, the engine had been working at maximum load for a longer period of time that also led to the breakage of the connecting rod.     

压缩机活塞杆断裂原因分析

通过宏观断口观察、微观断口观察、能谱分析、金相显微观察及受力等分析方法,分析了某厂连续重整压缩机2