前轮毂旋转弯曲疲劳断裂分析

采用化学分析，金相检验，力学性能测试及扫描电镜分析方法对轿车前轮毂早期断裂原因进行了分析。结果表明，冷却不足使组织中出现网状及小块状铁素体，导致硬度偏低，加之磨削加工痕迹较粗是引起前轮毂早期断裂的原因。     

某汽车轮毂轴断裂原因分析

某汽车在行驶过程中,其后轮毂轴在安装轴承附近发生断裂,该车累计行驶里程为17km,轮毂轴材料为65Mn弹簧钢。通过外观检查、断口宏微观观察、能谱分析、化学成分分析、硬度检测和金相检验等实验,确定了轮毂轴的失效性质及失效原因。结果表明:轮毂轴失效性质为疲劳断裂;轮毂轴内部存在锻造裂纹是轮毂轴发生疲劳断裂失效的主要原因;锻造裂纹的产生可能为切削量不足导致轮毂轴原材料料头端部存在块状缺陷。     

电站连接螺栓断裂失效分析

采用宏观检验、化学成分分析、力学性能测试、金相检验、扫描电镜分析等方法,分析了某核电减速机轮毂与辐条连接螺栓的断裂失效原因。结果表明:螺栓断裂是由于螺栓松动后,辐条上下滑动,使螺栓承受较大的剪切应力,最终导致其多源双向疲劳断裂;螺栓材料中存在大量超尺寸脆性硅酸盐类夹杂物,在一定程度上加速了疲劳裂纹的形成和扩展。     

汽车铝合金轮毂涂装线的工艺及设备简介

介绍了汽车铝合轮毂涂装生产线的涂装工艺和设备,并给出了设备的主要技术参数,此工艺和设备同样也适合行摩托车和铝合金轮毂涂装生产线的应用。     

某铝包复合材料芯软铝型线绞线断裂原因分析

某输电线路用铝包复合材料芯软铝型线绞线在架线后不久即发生断裂。通过宏观分析、力学性能试验、机电性能试验、断口分析、金相检验等方法对导线的断裂原因进行了分析。结果表明:该断裂导线的复合材料芯棒在包覆铝管前已多处受损及断裂,复合材料芯棒断裂的导线在架线后,所有张力都由软铝层和铝管承担。因夜间温度降低,且风载荷作用引发线路舞动,使得导线所受张力超过软铝层和铝管的强度极限,最终导致导线断裂。     

摩托车从动轴断裂原因分析

采用断口分析、金相检验,力学性能测试和化学分析等方法,对摩托车传动轴断裂的原因进行了失效分析.结果表明,断口宏观上有明显的贝纹线花样,贝纹区面积较小,瞬断区面积较大,因此轴的断裂属于早期疲劳断裂.该轴环形键槽R小,在热处理时应力大而集中,是导致早期断裂的主要原因.     

摩托车减振器断裂失效分析

摩托车在行驶过程中发生减振器断裂失效。采用断口分析及金相分析方法对摩托车后减振器断裂原因进行了分析。得出产生断裂的主要原因是由于焊接工艺不当造成严重的未焊透，致使焊接区强度降低，摩托车在行驶过程中遇到侧向冲击应力时使减振器发生脆性解理断裂。     

摩托车后轮毂压铸模设计

摩托车后轮毂压铸模具精度要求高,且结构复杂.为满足铸件的技术要求,要合理选用压铸设备,合理地设计模具结构.分析了摩托车后轮毂的结构特点,介绍了摩托车后轮毂压铸模的结构,并详细说明了模具浇注系统、溢流系统、冷却系统、推出机构的设计.     

QAl9-4铝青铜转向油缸接头断裂失效分析

材料为QAl9-4铝青铜的船用推进器转向油缸接头,在下水投入使用8个月后出现早期断裂失效。从断口形貌、化学成分、力学性能、显微组织等方面,对QAl9-4铝青铜油缸接头进行断裂原因分析。结果表明:QAl9-4铝青铜原材料力学性能偏低,铅、铁元素含量超标,增加了合金的脆性并降低了合金的耐腐蚀性;基体组织严重偏析,在交变载荷及环境腐蚀的作用下在表面腐蚀锈斑处萌生裂纹源,发生应力腐蚀开裂并最终导致脆性断裂。     

摩托车曲柄断裂分析

采用化学成分分析、硬度测定、金相检验以及断口宏、微观分析等方法,对断裂的摩托车曲柄进行了分析.检验结果表明,曲柄的显微组织中存在大量的铁素体.铁素体的存在大大降低了曲柄的力学性能和疲劳寿命,在外力作用下造成断裂.     

Fatigue fracture of an AMX aircraft main wheel

A forged 2014-T6 aluminium alloy main wheel of an AMX aircraft failed during pre-flight taxiing.Failure occurred on the wheel housing hub and its origin was located on the interior edge of the bearing cup housing. The wheel experienced high cycles fatigue. A plastic deformation was produced during the wheel mounting operations caused an abnormal stress concentration. It has been identified as cause of a progressive fracture mechanism. Consistent optical, metallographic and electron microscopy evidences were collected. Moreover, Finite Element Analysis (FEA) demonstrated that the observed defects produced the stress level needed to fatigue to initiate. Recommendations were issued in order to improve the Non-Destructive Techniques (NDT) used to monitor the wheel structural integrity. Laboratory tests showed that ultrasounds in this case would be far more efficient than the prescribed eddy currents.     

Fatigue cracking of an aircraft wheel

Failures of different aircraft components are revealed and examined generally by the use of non-destructive examination methods. In further explanation and interpretation of failures fractographic and metallographic methods are indispensable. The paper deals with a crack on aircraft wheel rim. The wheel was made from 2014-T6 aluminium alloy. The crack was revealed during regular control by the maintenance unit for non-destructive examination of the Slovenian air carrier Adria Airways. The crack on the rim investigated was a typical fatigue crack. It was branched, with a size lower than the critical size for fast fracture.     

摩托车链轮螺栓的失效分析和工艺改进

摩托车链轮螺栓在装配时及在装配好放置几天后出现断裂。应用扫描电镜、光学显微镜和化学分析等检测手段，对链轮螺栓断裂原因进行了探讨。结果表明，链轮螺栓发生脆性断裂属氢脆特征，电镀前酸洗过度是造成螺栓发生瞬间脆性断裂的主要原因，加上模具成型产生折叠缺陷，除氢不彻底等因素的综合影响，加速了螺栓的断裂。提出了提高链轮固定螺栓综合强度的工艺改进方案。     

门式起重机变速机轴断裂分析

大型门式起重机因变速机轴断裂致使起吊物料下坠而造成安全生产事故。通过宏观和微观分析方法对变速机轴断裂原因进行了分析,结果表明,变速机轴在长期服役运行过程中,因局部疲劳开裂并扩展而引发了瞬间脆性断裂,其断裂与轴的制造质量不高和长达50a（年）的服役时间有关。     

Controlled wear of vitrified abrasive materials for precision grinding applications

The study of bonding hard materials such as aluminium oxide and cubic boron nitride (cBN) and the nature of interfacial cohesion between these materials and glass is very important from the perspective of high precision grinding. Vitrified grinding wheels are typically used to remove large volumes of metal and to produce components with very high tolerances. It is expected that the same grinding wheel is used for both rough and finish machining operations. Therefore, the grinding wheel, and in particular its bonding system, is expected to react differently to a variety of machining operations. In order to maintain the integrity of the grinding wheel, the bonding system that is used to hold abrasive grains in place reacts differently to forces that are placed on individual bonding bridges. This paper examines the role of vitrification heat treatment on the development of strength between abrasive grains and bonding bridges, and the nature of fracture and wear in vitrified grinding wheels that are used for precision grinding applications.     

Microscale wear of vitrified abrasive materials

The study of bonding hard materials such as aluminium oxide and cubic boron nitride (cBN) and the nature of interfacial cohesion between these materials and glass is very important from the perspective of high precision grinding. Vitrified grinding wheels are typically used to remove large volumes of metal and to produce components with very high tolerances. It is expected that the same grinding wheel be used for both rough and finish machining operations. Therefore, the grinding wheel, and in particular its bonding system, is expected to react differently to a variety of machining operations. In order to maintain the integrity of the grinding wheel, the bonding system that is used to hold abrasive grains in place will react differently to forces that are placed on individual bonding bridges. This paper examines the role of vitrification heat treatment on the development of strength between abrasive grains and bonding bridges, and the nature of fracture and wear in vitrified grinding wheels that are used for precision grinding applications.     

Comparative assessment of fatigue and fracture behaviour of cast and forged railway wheels

A comparative evaluation of fatigue and fracture behaviour of commercially produced cast and forged rail wheels has been made using specimens extracted from various locations of the wheel quadrant. A systematic investigation in the web and rim regions of the wheel quadrant with various notch orientations showed that the forged material exhibited a better intrinsic resistance to fatigue crack growth than the cast material. Since linear elastic fracture mechanics (LEFM) based fracture toughness could not be validated for both the cast and forged wheel material, elastic plastic fracture mechanics (EPFM) based characteristic fracture toughness was used. Results showed that fracture resistance of the forged material is superior to that of the cast material. Cast wheel specimens exhibited unstable crack extension in comparison to substantial stable tearing in forged specimens. Microstructural and fractographic analyses showed that the cast wheel material contained large amounts of inclusions. The poor fracture resistance of cast wheel material is therefore attributed to the inferior material quality.     

Praxisrelevante Bewertung des Radbruchs vom ICE 884 in Eschede

Usage related evaluation of wheel fracture from ICE 884 at Eschede The high speed train ICE 884 accident on June 3, 1998 in Eschede was generated by a fracture of the wheel rim of the used resilient wheel type BA 64 after an usage of 1.889 Mill. km. The fracture was initiated on the inner side of the wheel rim, which had an outer diameter of D^A = 862 mm (new: D^A = 920 mm). After the accident a lot of analyses and investigations were carried out, which treated different aspects of the wheel fracture. All these analyses resulted in the conclusion that the train accident was generated by the fatigue fracture of the wheel rim and that for this fracture the wheel design and wheel rim dimensions were decisive. Based on these analyses the lowest allowable rim thickness for the operational usage on the high speed train correspond to the wheel diameter of D^A = 880 mm, which is significantly higher than the allowed limit value of D^A = 854 mm; so far a total fracture of the wheel in Eschede with D^A = 862 mm was to be expected. This validation was confirmed by additional initial fatigue cracks on the resilient wheels on other ICE 1 trains. The tests carried out before the wheels BA 64 were released for the usage on high speed trains were not sufficient to guarantee the required safety.     

Failure analysis for power car wheels based on contact positions and tread slope

During service operation, the thermal cracks and shelling at power car wheel are initiated before a regular profiling of railway wheel. The damaged railway wheel is reprofiled prior to regular inspection and the maintenance cost for the railway wheel is sharply increased. Therefore, it is necessary to analyze and understand the damage mechanism of power car wheel in order to reduce maintenance cost.In the present paper, to analyze the damage cause and reduction for the power car wheel with tread brakes, the observations of by replication test was performed and fracture characteristics depend on contact zones are carried out. Contact stress is analyzed with respect to the wheel tread slope and contact positions. The result shows the zone between tread center and wheel rim demonstrated white layer by higher hardness and lower fracture toughness and faster crack growth rate in view point of fracture mechanic characteristics. The 1/20 of wheel tread slope can effectively mitigates surface damage of power car wheel.     

齿轮轴断裂分析

齿轮轴热处理后,在校正过程中发生横向断裂。采用了宏观和微观检验、化学成分分析及扫描电镜断口观察等方法对该断裂轴进行了分析。结果表明,原材料夹杂物级别较高,加上存在不允许的缺陷、力学性能不符合技术要求等因素,最终导致该轴在校正过程中发生断裂。