国产汽车链的多冲特性及失效机理研究

通过试验与分析,研究了汽车发动机正时链的多冲特性、失效机理以及销轴、套筒和滚子等元件摩擦表面的磨损形貌特征.结果表明,汽车发动机正时链的主要磨损机制是疲劳磨损,销轴、套筒零件表面的裂纹生成、扩展与剥落是其主要磨损失效机理.保证滚子零件具有足够的强度与塑性,并采用合理的成形工艺,是提高滚子零件多冲抗力的有效方法.     

汽车发动机正时链的多冲特性

为了提高国产正时链条的性能,研究了05BT—1汽车发动机正时链的磨损失效机理以及销轴、套筒和滚子等元件摩擦表面的磨损形貌特征．结果表明,汽车发动机正时链的主要磨损机制是疲劳磨损,销轴、套筒零件表面的裂纹生成、扩展与剥落是其主要磨损失效机理．因此,保证滚子零件具有足够的强度与塑性,并采用合理的成形工艺,是提高滚子零件多冲抗力的有效方法．     

空心和实心车轴微动磨损行为的对比研究

建立轮轴过盈配合部位的微动磨损有限元仿真模型,研究磨损轮廓随载荷循环周次的变化,对比分析空心与实心车轴微动磨损行为及其对接触参量的影响。仿真结果表明:车轴配合边缘的应力集中程度由于微动磨损而缓解,新的应力集中位于磨损与未磨损的过渡区域;磨损区域随着循环周次的增加而增加,导致应力集中远离轮轴配合边缘;在靠近配合边缘的区域,空心车轴的滑移幅值大于实心车轴,导致空心车轴的微动磨损大于实心车轴。     

评定钢丝的微动摩擦磨损参数研究

以点接触式提升钢丝绳为研究对象，在实验室建立了钢丝绳中钢丝的微动磨损模型．在自制的钢丝微动磨损试验机上进行微动磨损实验，考察了接触载荷、微动时间和振幅的变化对钢丝试样磨损深度的影响，并用综合参数pv值和pvt值评定微动磨损深度的变化．结果表明，相同微动时间下磨损深度随pv值的增加而增大，相同接触载荷下磨损深度随pv值增大而减小，磨损深度和综合参数pvt值之间基本成线性关系．同时通过微动过程中摩擦系数的变化、磨损产生的磨屑以及磨痕形貌，分析微动磨损过程中磨损机制随微动实验条件的变化规律。     

提升钢丝绳的钢丝微动摩擦磨损特性研究

钢丝绳内部钢丝的微动磨损和微动疲劳是造成钢缆寿命降低的主要原因之一 .以 6× 1 9点接触式矿用提升钢丝绳为研究对象 ,在自制的钢丝微动磨损试验机上进行了钢丝的微动磨损实验研究 .以摩擦系数和磨损深度作为评定微动磨损的参数 ,考察了不同载荷下摩擦系数的变化规律以及载荷、循环次数的变化对钢丝试样磨损深度的影响 ,同时研究了钢丝试样在矿用钢丝绳内部增摩油脂的润滑状态下摩擦系数和磨损的变化规律 .利用钢丝试样在不同工况下的磨损形貌分析了微动磨损过程中的磨损机制     

AM60B镁合金在滑移区的微动磨损行为研究

研究了AM60B镁合金在滑移区的微动磨损行为。考察了摩擦因数和磨损体积随循环次数、载荷和频率的变化及磨损表面形貌，探讨了其微动磨损机理。结果表明：AM60B镁合金的微动磨损可分为开始阶段、二体接触向三体接触过渡阶段和稳定阶段3个阶段。在不同的阶段，摩擦因数和磨损体积的变化及磨损机制各有特点；此外，磨损体积随着法向载荷的增加而增大，但随着频率的增大而减小。     

聚甲基丙烯酸甲酯的扭动微动摩擦学特性

在新型扭动微动试验机上,进行聚甲基丙烯酸甲酯(PMMA)与Ф40 mm GCr15钢球在扭动角位移幅值为0.5°~10°和法向载荷为100N的扭动微动试验。在摩擦动力学行为研究的基础上,分析材料磨损机理。结果表明,PMMA存在有平行四边形和椭圆两种T-θ曲线;低扭转角时,T-θ曲线随着循环次数的增加从平行四边形向椭圆形发展;大扭转角时,T-θ曲线始终为平行四边形。PMMA的扭动微动磨痕沿半径方向,可依次分为粘着区、微裂纹区和剥落区。在低角位移幅值(θ≤2.5°)时,扭动微动损伤较轻微;随角位移幅值的增大,粘着区变小,损伤加重,表面出现纺锤状剥落坑自中心呈放射状分布,其尺寸随角度增大而变宽。对磨屑的GPC分析结果表明PMMA在扭动微动条件下分子量变小,PMMA扭动微动的磨损机理主要为剥落与表面裂纹。     

钛合金材料防微动磨损涂层性能研究

采用超音速火焰喷涂工艺在TC4钛合金基体材料表面制备碳化铬系耐磨涂层,通过自制微动磨损试验设备测试不同对磨副、不同位移副值试验条件下带涂层的TC4钛合金材料的摩擦因数、磨损量等微动磨损性能,利用SEM、EDS、XRD等分析手段,对比分析微动磨损表面形貌、成分和相组成的差异.结果表明:不同摩擦副和位移副值条件下的摩擦因数...     

添加微细铬铁粉对烧结钢摩擦磨损性能的影响

研究了加入不同含量的微细铬铁粉对烧结钢干摩擦磨损性能的影响,并借助于扫描电镜观察分析其磨损形貌,探讨摩擦磨损机制。研究结果表明:添加微细铬铁粉可改善烧结钢的强度、硬度和摩擦磨损性能,铬的质量分数为1.5%时,耐磨性最佳。磨损造成一定厚度的塑性变形,硬度较高的材料塑性变形层较薄。磨损早期,磨粒磨损是主导机制,磨损后期,由于塑性变形导致亚表层产生裂纹,进而发生的剥层磨损是主导磨损机制。     

基于有限元的离合器壳体和套筒泄漏分析

为了分析某汽车自动变速器中离合器壳体和套筒的泄漏问题,建立离合器壳体和套筒的有限元模型.利用有限元方法对离合器壳体和套筒的装配进行模拟验证表明,泄漏的原因是在装配时两者过盈配合导致的.同时,对该泄漏问题提出了改进方案,并经试验测试结果表明,改进方案是有效可行的.     

Effect of fretting amplitudes on fretting wear behavior of steel wires in coal mines

Given that fretting wear causes failure in steel wires, we carried out tangential fretting wear tests of steel wires on a self-made fretting wear test rig under contact loads of 9 and 29 N and fretting amplitudes ranging from 5 to 180 μm. We observed morphologies of fretted steel wire surfaces on an S-3000N scanning electron microscope in order to analyze fretting wear mecha-nisms. The results show that the fretting regime of steel wires transforms from partial slip regime into mixed fretting regime and gross slip regime with an increase in fretting amplitudes under a given contact load. In partial slip regime, the friction coefficient has a relatively low value. Four stages can be defined in mixed fretting and gross slip regimes. The fretting wear of steel wires in-creases obviously with increases in fretting amplitudes. Fretting scars present a typical morphology of annularity, showing slight damage in partial slip regime. However, wear clearly increases in mixed fretting regime where wear mechanism is a combination of plastic deformation, abrasive wear and oxidative wear. In gross slip regime, more severe degradation is present than in the other regimes. The main fretting wear mechanisms of steel wires are abrasive wear, surface fatigue and friction oxidation.     

Comparison of Biotribology of Swine Compact Bone Against UHMWPE

A pin-on-disk tribometer was used, in a comparative test to observe the tribological behavior of the swine femoral bone against UHMWPE with dry friction, physiological water and human plasma lubrication. The wear mechanisms of swine bones and UHMWPE were investigated by SEM. The experimental results of these wear tests demonstrated that both the friction coefficient and wear rate of UHMWPE were the lowest when human plasma lubrication was used. The wear mechanism of the compact bone was mainly fatigue wear with dry friction, corrosive wear under physiological water lubrication and abrasive wear with human plasma lubrication. For UHMWPE, the wear mechanism was adhesive wear and plastic deformation with dry friction, serious ploughing and fatigue fracture wear under physiological water lubrication, fine ploughing and plastic deformation with human plasma lubrication. An analysis of nitrogen elements on the wear surface of UHMWPE indicated that the content of nitrogen in worn areas was 16 times higher than that in unworn areas, which proved that serum protein deposition occurred on worn areas.     

Low-Frequency Reciprocating Fretting Wear Testing System Design and Experiment Research

The fretting wear is resulted from different or same sample’s surfaces by the small variationand leads to mechanism failures. The main factors consist of the variation of normal load and oscillation frequencies, among which surface topography of different materials are the main factors to the problems of the fretting wear. Therefore, a novel low-frequency reciprocating fretting wear test system is designed upon the principle of Friction coefficient measurement. Four metal and non-metallic samples are measured under various normal load and oscillation frequencies to obtain the instantaneous friction coefficient in the repeat experiments. In fact, the experimental results show that CoF curves of different samples with the increase of the normal load are the similar exponential decay or parabolic shapes, which are consistent with the literatures to verify the rational design and reliable-operation of the system under the conditions of different frequencies.     

粘结石墨基固体润滑涂层的微动摩擦磨损性能

为了探讨粘结石墨基固体润滑涂层的微动摩擦磨损性能的作用机理,使用SRV微动摩擦磨损试验机对粘结石墨基固体润滑涂层在微动试验条件下的摩擦学性能以及抗承载能力进行研究,对其磨痕形貌和对偶转移膜进行分析。研究结果表明：粘结石墨基固体润滑涂层的磨损率随着试验载荷和摩擦速度的增大而减小;而摩擦因数随着试验载荷增大而减小,随摩擦速度增大而缓慢增大;在微动摩擦过程中,高载高速可以促进高质量转移膜在对偶表面形成,从而使得粘结石墨基固体润滑涂层具有良好的抗承载能力和优异的抗磨减摩性能。     

Failure analysis of wear of main clutch separating ring of heavy vehicles

The severe wear of separating ring is considered to be a main reason which leads to the improper declutch of the main clutch of heavy vehicles. The wear mechanism of the separating ring is not well understood. Scanning electron microscopy and transmission electron microscopy were employed to analyze the surface features and dislocation characteristics of the separating ring. The typical features of furrows and rolled tongue-like metal were found on the surface of separating ring by scanning electron microscopy observation, which can be considered as a major indi cation of the grain-abrasion. A zone of high density dislocation was noted on the subsurface of the separating ring by transmission electron microscopy observation, which implies the contribution of the severe impact on the surface of the separating ring in the wear process. The influences of the structure of the separating ring, the service condition and the in-service stress distribution on the wear behavior, were also analyzed. The results show that the failure of separating ring results from the impact wear and grain-abrasion together with the plastic deformation.