航空燃油泵柱塞弹簧断裂分析

本文以航空燃油泵柱塞弹簧为研究对象，立足于工厂生产实践，从故障分析的角度论述了柱塞弹筑工作中的应力特点，总结了柱塞弹簧断裂的常见类型，提出了防止其早期断裂的措施，对于指导生产有一定价值。     

关于柱塞弹簧在制造工艺过程中的表面腐蚀

本文以柱塞弹簧在工厂制造工艺过程的实践为基础,应用金属腐蚀理论,着重探讨了柱塞弹簧表面腐蚀的常见形态、表面腐蚀与工艺过程之间的关系、表面腐蚀对使用性能的影响及防止腐蚀的工艺措施等,对认识柱塞弹簧的表面腐蚀故障、提高其生产合格率、克服生产薄弱环节具有实用价值。     

高压燃油泵柱塞弹簧自动装配工作站设计

该文介绍了某公司的GDI高压燃油泵自动化装配生产线的柱塞弹簧装配工位,设计了自动化装配工作站,通过自动化移载机构配合专用夹具和机构,将燃油泵的柱塞弹簧、泵体、半锥和弹簧保持器装配在一起,该工位同时具备装配质量检测功能。移载机构设计采用伺服直线模组形式,驱动专用夹具进行运动,专用夹具采用夹钳结构并配合真空技术完成高压燃油泵的零件拾取和装配。     

水压机柱塞失效分析

用光学显微镜，扫描电镜和能谱仪对水压机柱塞表面孔坑，沟槽进行了分析，结果表明，由于夹杂物（尤其是表层夹杂物）与块状铁素体的存在以及淬硬层分布不均匀，使柱塞在使用过程中出现点蚀，并在高压水冲击下形成沟槽，导致柱塞密封失效。     

安全阀弹簧失效原因分析与改进措施

弹簧式安全阀是用于催化装置上的重要部件，在常温下露点腐蚀是弹簧式安全阀失效的重要原因。针对大连石化公司二催化装置T302解吸塔塔顶安全阀的失效，利用电子能谱（EDX）、SEM电镜扫描等手段对失效安全阀弹簧进行检测分析，得出安全阀弹簧失效的主要原因是安全阀接触的介质舍有H2S、SO2、H2O，这些介质在30—40℃，常压的务件下在安全阀弹簧的表面形成酸性露点而腐蚀表面形成点蚀坑，这些点蚀坑引起应力集中导致弹簧断裂，并针对具体情况提出解决方案。     

柱塞剥落掉块与材料显微组织关系的初步分析

本文对柱塞零件剥落掉块进行了试验分析,结果表明:柱塞失效属于接触疲劳损伤,损伤柱塞与国外柱塞比较,在材料的显微组织、碳化物数量、大小、形态、分布等方面均存在一定差异。     

发动机气门弹簧断裂原因分析

对3个典型的发动机气门弹簧断裂件进行了理化检验和扫描电镜断口分析。结果表明:3个气门弹簧的失效机理均为疲劳断裂,而引起疲劳断裂的原因均与气门弹簧的表面质量有关;1号气门弹簧的断裂原因是表面存在非金属夹杂物,2号气门弹簧的断裂原因是表面存在锈蚀坑,3号气门弹簧的断裂原因是表面存在折叠缺陷。因此,控制原材料质量和避免表面缺陷是提高气门弹簧服役寿命的关键举措。     

特种车辆半轴折断分析

半轴的折断失效，其损坏形式为高频率低应力弯曲疲劳损坏。原因为其承受弯矩最大处为９０度尖角，及有车刀切削痕迹，以致产生了严重的应力集中；其次是材料的热处理质量不合格，致使疲劳抗力较低。     

俄罗斯E420-18．8—560KT型锅炉主蒸汽管道弹簧吊架失效分析

通过对A发电厂1号锅炉37号弹簧吊架和2号锅炉65号弹簧吊架失效的分析，查找到引起失效的原因，并提出合理措施，以防发生重大安全生产事故。     

为什么红火一时的弹簧度盘秤悄然从集贸市场隐退

在全国城乡农贸市场固定摊点禁止使用杆秤，以弹簧度盘秤、电子计价秤取而代之的最初阶段，我们曾在1995年5月对本区最大的农贸市场——沿山市场进行过调查，由于弹簧度盘秤价格适宜，在该市场上固定摊位使用的计量器具中占有率高达朗叽。然而几年后的今天，整个市场却仅有18台弹簧度盘秤，只占6．8％。我们不禁要问，为什么弹簧度盘秤如此之快惨遭淘汰，在激烈的市场竞争中，由于国内弹簧度盘秤计量性能差，质量低，受到了用户的另眼看待。通过检定，我们发现了影响弹簧度盘秤计量性能的主要因素。1．零点调节螺母旋不动，置零装置严重失效…     

基于线性回归的单柱塞泵单向阀参数优化

针对单柱塞泵系统中配流单向阀参数不合理所导致的吸油不充分、系统响应慢等问题,提出了一种基于线性回归的多参数优化方法。首先,通过AMESim软件进行单柱塞泵系统仿真分析,并利用MATLAB拟合工具箱分别探讨了不同单向阀参数（弹簧预紧力、弹簧刚度和阀芯质量）与进油口流量的关系。然后,在利用主成分分析法消除各参数之间相关性的基础上,以进油口流量为因变量,弹簧预紧力、弹簧刚度和阀芯质量为自变量,各参数的取值范围为约束条件,建立了基于线性回归的单向阀参数优化模型,并采用遗传算法进行优化求解。最后,根据优化前后的单向阀参数,对单柱塞泵系统进行仿真分析和实验验证。仿真结果表明,优化后进油口流量提高了21.3%;实验结果表明,优化后进油口的实际流量提高了16.8%。研究表明,所提出的多参数优化方法是一种有效的方法,可为单柱塞泵系统中配流单向阀的参数优化提供参考。     

注塑机导柱断裂原因分析

注塑机导柱使用约1a（年）即发生断裂失效。采用化学成分分析、显微组织观察、裂纹及断口特征分析等方法对注塑机导柱失效断裂的原因进行了综合分析。结果表明,导柱材料误用是造成导柱断裂的主要因素,导柱的断裂属于多源疲劳断裂。     

Handling hostile environments at a stroke

Premature seal failure in reciprocating pumps present users with both operational and maintenance problems. In general, standard elastomers in the plunger packing fail due to frictional heat and abrasion generated by the mechanical movement of the plunger. In this article Fred Pipper of Utex Industries, describes the development and testing of a new nitrile-based elastomer system for sealing reciprocating pumps, which possesses high wear and anti-abrasion properties.     

Investigation of failure in main fuel pump of an aeroengine

There was an accident to a fighter aircraft. Investigation revealed that the accident was caused due to loss of power in the engine as a result of failure in the main fuel pump (MFP). The MFP was multi-plunger type. On dis-assembly, the MFP was found severely damaged and there were fractures in one plunger and four springs. Through systematic metallurgical investigation and analysis, the sequence of events leading to the failure in the MFP was established. The primary failure in the MFP was the fatigue fracture of springs. The fatigue crack initiation could be attributed to pitting corrosion on the surface of the springs. Because of multiple fractures in one of the springs, there was impact load on the corresponding plunger, which resulted in generation of an overload crack. This crack had further propagated progressively by fatigue mechanism culminating in fracture and loss of material from the side wall of the plunger. Subsequently, there was fuel leakage internally in the MFP with the resultant reduction in the fuel delivery pressure. Due to insufficient fuel supply, there was winding down of the engine RPM leading to loss of thrust. After establishing the sequence of failure in the MFP, investigation was carried out to identify the cause for the corrosion on the surface of the springs. It was established that the raw material (wires) used for the manufacture of the springs had developed corrosion pits on the surface due to improper storage.     

Failure analysis of the suspension spring of a light duty truck

In this paper the failure of the rear suspension spring is analyzed in detail. The rear axle suspension system of the truck and fractured flat spring is investigated. Fracture surface, mechanical and chemical properties and microstructure of the spring material is analyzed. Forces acting on the spring is determined and strength calculations are carried out. Later, failure behaviour and cause of fracture is revealed after carefully analysis of microstructure and results of calculations. At the end precautions to be taken to prevent a similar failure is recommended.     

Analytical approximations to the viscous glass-flow problem in the mould-plunger pressing process, including an investigation of boundary conditions

Industrial glass is produced at temperatures above 600°C, where glass becomes a highly viscous incompressible fluid, usually considered as Newtonian. In the production two phases may be distinguished, namely the pressing phase and the blowing phase. This study will be concerned with glass flow in the pressing phase, which is called thus because a blob of fluid glass (called a gob) is pressed in a mould by a plunger, such that the glass flows between mould and plunger, in order to obtain the preform of a bottle or jar, called a parison. In the blowing phase (not considered here) the parison is subsequently blown into the final shape of the product. By application of the slender geometry of mould and plunger and a cylindrical symmetry, a form of Reynolds's lubrication flow equations is obtained. These equations are solved by utilizing the incompressibility of the glass, by which the flux at any axial cross section is determined for prescribed plunger velocity, leading to analytical results in closed form for velocity field and pressure gradient. The glass level is implicitly defined by the integral over the varying volume which is to remain constant. The pressure may then be determined by integration. Special attention is given to the required boundary conditions. It is known that, depending on several problem parameters like temperature, pressure, and smoothness of the wall, the glass flow slips, to some extent, along the wall. Therefore, this study includes a general formulation of the boundary condition of partial slip in the form of a linear relation between shear stress and slip velocity, also known as Navier's slip condition. The coefficient of this relation, a positive number, may vary in our solution with axial position, but depends on the problem and is to be obtained from (for example) experiment. Two special cases, which seem to be relevant in practice, are considered as examples: (i) no slip on both plunger and mould; (ii) no slip on the mould and full slip (zero friction) on the plunger. The results are compared with fully numerical (FEM) solutions of a Stokes-flow model, and the agreement is good or excellent. Since in any practical situation it is not the plunger velocity which is prescribed, but (within practical limits) the force applied by the plunger, the problem of a prescribed plunger force has also been investigated.     

An instrument for measuring the voltage standing-wave ratio of a generator

Conclusions The comparison results confirm the relatively high accuracy of measurement of the standing-wave ratio by means of the above instrument.The instrument can also be used for matching the generator when its potput is insufficiently decoupled and there is a possibility of the results being distorted by the reaction of the adjustable plunger on the generator. For avoiding this reaction another hole should be made in the body of the plunger, and an absorbing sliding wedge placed in it. The protruding wedge lowers the standing-wave ratio of the instrument and decreases its effect on the generator. When the instrument is used for accurate measurements of the standing-wave ratio the absorber is pushed inside the plunger and produces hardly any effect on the operation of the instrument.     

低温泵缸套柱塞防磨损和提高密封性的措施

介绍在KL 15A型制氧制氮车研制过程中 ,解决与之配套的往复式低温柱塞泵缸套柱塞使用寿命短、磨损严重、泄漏量大的方法 ,提高设备运行的可靠性 ,取得一定的经济效益     

Evaluation of a leaf spring failure

The determination of the point of failure during an accident sequence of a rear leaf spring in a sport utility vehicle is presented in terms of fracture surface analysis and residual-strength estimates. Marks at the scene of the accident pointed to two possibilities for the point of failure: marks in the roadway at the start of the accident sequence and a rock strike near the end of the sequence. Evidence from rust and chemical contamination on the fracture pointed to the spring having been cracked in half prior to the accident. Extensive woody fracture and secondary cracking at the midplane of the spring was evidence for segregation and weakness in the spring. Stress estimates for the effect of both the weakness and prior cracking on the residual strength of the spring revealed reductions in strength of the spring that could produce fracture at the start of the accident sequence. The point of failure of the spring was placed at the start of the accident sequence.     

Failure assessment of a leaf spring eye design under various load cases

This paper analyzes the capability of various leaf spring eye designs to prevent failure under braking, cornering, and pothole striking loading conditions. A leaf spring is a vital suspension component of heavy trucks, such that the failure of leaf spring eyes could cause fatal accidents. However, the current design of leaf spring support eyes is solely estimated based on the maximum vertical loads exerted on the leaf spring. The actual torsion or shear loads exerted by the ground to the leaf spring eye extremely high, but the experimental proving ground methods are too expensive to perform load analysis. In this analysis, the forces exerted on the spring eye are simulated under extreme load cases, such as braking, cornering, and pothole striking. The magnitudes of the different loadings were extracted from a multibody dynamics model and were used as the load inputs to the finite element explicit simulation. The principal surface stresses of four different spring eye designs were obtained and compared to the material yield and the ultimate tensile strengths to evaluate the sustainability of the spring eye during extreme load cases. Results show that a minimum thickness of 17 mm is sufficient for the leaf spring eye design to prevent failure under extreme torsional loadings. This research provides insightful analysis of leaf springs to prevent the occurrence of failure during engineering design.