Heat state of pendulum sliding bearings under seismic effects

Issues in the choice of self-lubricating antifrictional materials for pendulum sliding bearings used as seismic dampers are discussed. Such bearings are used in supports of essential constructions (including offshore drilling platforms) and other objects located in seismically dangerous regions to protect buildings from loads caused by earthquakes and other power effects. The heat state of seismic dampers is studied using various computer programs. The computation method suggested allows the selection of antifrictional materials for sliding bearings with account for their temperature resistance.     

Tribological behavior of frictional seismic dampers of pendulum type

Frictional pendulum bearings have universal properties that can meet various requirements at service of buildings, bridges, and industrial constructions. The formulas for the average dimensionless wear rate and friction coefficient of the bearings are obtained. The use of the bearings as seismic dampers of shell drilling rigs is described and characteristics of the frictional pendulum bearings are given.     

梯度自润滑滑动轴承的研制

介绍了梯度功能材料的发展过程,同时根据梯度材料的原理研制了梯度自润滑滑动轴承,并介绍了梯度自润滑滑动轴承的优化设计方法及制备工艺,通过性能测试表明在相同工况条件下梯度自润滑轴承的承载能力、极限ｐｖ值、耐磨性及使用寿命等均明显优于均质自润滑轴承。     

磷酸酯偶联剂改性衬垫对自润滑关节轴承性能的影响

利用 Instron5944型电子万能材料试验机和自制的关节轴承摩擦磨损试验机,研究磷酸酯偶联剂接枝改性处理衬垫对自润滑关节轴承黏接性能和摩擦磨损性能的影响。结果表明：磷酸酯偶联剂接枝改性处理衬垫可以有效提高轴承衬垫的黏接性能;自润滑关节轴承的摩擦磨损性能与摆动频率呈现明显的相关性,摩擦因数和磨损量均随摆动频率的增大而减小,而摩擦温度随之升高;衬垫经改性处理的轴承摩擦因数、磨损量以及摩擦温升均明显降低,表明衬垫经改性处理后改善了自润滑关节轴承的摩擦学性能。     

Friction and Thermal Effects of Engineering Plastics Sliding Against Steel and DLN-Coated Counterfaces

Polymers are increasingly used in tribological applications, because of their self-lubricating ability, corrosion resistance and chemical compatibility. However, their performance depends strongly on the parameters of the total tribological system. Not only polymer characteristics, but also counterface properties become important because of their influence on friction and wear, on surface energy and on the thermal conductivity of the total system. Applying a Diamond-Like Nanocomposite (DLN) coating on a steel counterface can improve the tribological behaviour of the sliding couple under certain conditions. In the case of metal sliding against DLN, the high hardness and the wear resistance of the coating is advantageous for better tribological properties. However, for polymers sliding against DLN, the lower thermal conductivity of the DLN coating compared with a steel mating surface dominates friction and wear. In case of polyamides this results in worse tribological performance in contact with the DLN coating, because of polymer melting. In the case of more rigid polymers, such as, e.g., POM-H and PETP, lower coefficients of friction lead to lower frictional heat generation. In these cases, the thermal characteristics of the counterface are less important and the lower surface energy of the DLN coating is favourable for decreased adhesion between the polymer and the coating and consequently better tribological properties.     

发动机的摩耗与其集成设计

结合发动机的工业生产实际经验总结与理论研究,这里提出了摩擦学设计过程。基于常用分析设计工具,提出了发动机的集成设计框架。对发动机摩擦副的摩耗统计分析,提出以活塞环组／缺套,滑动轴承的设计为核心的集成设计方法。     

Influence of Ultrasonic Modified Liners on the Adhesive and Tribological Performances of Self-Lubricating Radial Spherical Plain Bearings

For self-lubricating spherical plain bearings, poor interface bonding strength between the polytetrafluoroethylene (PTFE)/aramid fabric hybrid woven liners and the outer rings can influence the full play of tribological performance of the self-lubricating liner. To solve this problem, the liners were modified by ultrasonic treatment. The adhesive performances of the modified and unmodified liners and the tribological performance of the self-lubricating radial spherical plain bearings with two kinds of liners were tested and compared. Results show that ultrasonic modification can improve the bonding performance of the liners significantly; compared to unmodified liners, the modified liners can decrease the friction coefficient, wear loss, and friction temperature of the bearings, which shows that ultrasonic modification can improve the tribological performance of self-lubricating spherical plain bearings. Bearings with modified liners only produced slight adhesive wear, but bearings with unmodified liners produced moderate adhesive wear and slight abrasive wear during test procedures.     

Tribological behaviour of modified polyacetal against MC nylon without lubrication

Compared with other polymers, polyacetal or polyoxymethylene (POM) which is widely used as bearing, guide, gear and other sliding parts, has high strength and stiffness, excellent chemical resistance and superior antifriction and wear resistance. To improve the toughness and self‐lubrication capacity of POM due to its higher crystallizability, other components, which include toughening phase and solid lubricants, are often added to the POM matrix. This paper deals with the friction and wear behaviours of POM which was modified by the toughening phase polyurethane (PU) and filled with polytetrafluoroethylene (PTFE) and silicone oil, during rubbing against MC nylon without liquid lubrication. Friction and wear tests show the tribological performance of the modified POM (M‐POM) with 10 wt% PU is better than those of pure POM and POM blended with PTFE under dry friction. The frictional coefficient of the M‐POM decreases with increasing nominal load. The sliding velocity has a more obvious effect on the tribological properties of the M‐POM than the nominal load. The higher sliding velocity leads to thermal degradation and melting of the experimental polymers because of the frictional heat. This revised version was published online in June 2006 with corrections to the Cover Date.     

Influence of different surface modification technologies on friction of conformal tribopair in mixed and boundary lubrication regimes

Moving machine assemblies are generally designed to operate in full film lubrication regime to ensure high efficiency and durability of components. However, it is not always possible to ensure this owing to changes in operating conditions such as load, speed, and temperature. The overall frictional losses in machines are dependent on the operating lubrication regimes (boundary, mixed or full-film). The present work is thus aimed at investigating the role of different surface modification technologies on friction of a sliding bearing/roller tribopair both in boundary and mixed lubrication regimes. A special test rig comprising of two bearings was built for the experimental studies. Tribological tests were conducted in a wide speed range to enable studies in boundary and mixed lubrication regimes. The influence of application of different surface modification technologies on both the sliding bearing and the roller surfaces on friction has been studied. The rollers used in these studies were provided with five different coatings (hard DLCs and a soft self-lubricating coating). Additionally, two uncoated rollers having different surface roughness were also studied. Uncoated bearings were used in all tribopairs except two. These two bearings were coated with DLC and phosphate coatings respectively and uncoated rollers were the mating counterparts. Friction measurements were made on the new as well as the previously run-in surfaces. It was found that the rollers with self-lubricating coating resulted in lowest boundary friction closely followed by the rollers with the hardest DLC coatings. The DLC coating applied on to the bearing showed lower boundary friction after running-in. Mixed friction has been found to be mainly dependent on the surface topography characteristics of both the original and the run-in surfaces of bearings and rollers. The harder DLC coatings and the phosphated bearing showed the lowest mixed friction due to an efficient running-in of the bearing surface.     

Seismic isolators for petroleum and gas platforms of the “Sakhalin-2” project

Friction pendulum bearings have universal properties satisfying various demands when supporting buildings, bridges, and industrial facilities. The oscillation period of the bearing, vertical carrying capacity, damping, displacement ability, and ability to receive tensile load can be chosen independently. Dynamic oscillation periods from 1 to 5 s, shifts of up to 1.5 m, high carrying capacity and damping can be provided. Bearings can endure vertical loads of up to 13 500 tons and have minimal construction costs. Data are given on the influence of earthquakes and other force effects on the thermal state and characteristics of frictional pendulum bearings used as seismic isolators on petroleum and gas platforms of the “Sakhalin-2” project.     

PTFE/芳纶织物衬垫自润滑关节轴承性能试验

对比分析研究了同型号国产与进口PTFE/芳纶织物衬垫自润滑关节轴承的粘结质量、摩擦学性能以及承载性能,研究结果表明:进口轴承的剥离强度、摩擦磨损性能以及承载性能均略优于国产同型号的关节轴承;国内自润滑关节轴承的衬垫粘结质量、摩擦学性能以及承载性能需要进一步提高。     

Development of SiO2 nanolubrication system to be used in sliding bearings

New technology using nanoparticles as an additive in lubricants is recently becoming an attractive topic of study. The performance of SiO₂ nanoparticles in the lubrication system is investigated. Tests were conducted for nanolubrication mixing ratios of 0.0, 0.1, 0.2, 0.5, 0.55, 0.6, and 0.8 wt% with plain bearings rotated by a 2,750-rpm high-speed motor. For each mixing ratio, the frictional temperature and wear rate of the rotating sliding bearings were recorded and compared. During surface testing, the surface roughness values of the sliding bearings were compared and the results showed an improvement in surface roughness after the tests. According to the outcome, the optimum tribological performance of nanolubricant was obtained at 0.5 wt% mixing ratio.     

Tribological Behaviors of Self-lubricating Coating Prepared by Electrospark Deposition

Cu/h-BN self-lubricating coating was prepared on AISI1045 steel by electrospark deposition. The friction coefficient and wear rates were measured using the ball-on-disk method, and the tribological behaviors were discussed. Results showed that the friction coefficient decreased with an increase in sliding speed and load. The wear rate decreased with an increase in sliding speed and increased with an increase in load. The self-lubricating coating exhibited much lower friction coefficient and wear rate than the uncoated mild steel under the test condition. SEM micrographs show that the main wear mechanisms of the self-lubricating coating are abrasive wear and fatigue wear.     

织物衬垫自润滑关节轴承的研究现状与展望

针对飞行器等高端设备中广泛使用的免维护织物衬垫自润滑关节轴承,从其基体与自润滑织物衬垫材料、力学仿真与结构分析、性能试验、磨损与寿命分析诸方面介绍了国内、外的研究动态和发展趋势,并在总结现有研究工作的基础上,对织物衬垫自润滑关节轴承的未来发展趋势提出了一些看法.     

Influence of Ultrasonic Oscillation on Static and Sliding Friction

Vibrations of varying frequency and amplitude are used in many technological areas to control and reduce friction. In this study we report the results of systematic high-precision measurements of the static and sliding friction under the influence of ultrasonic oscillations. We investigate the effect of ultrasonic oscillations for in-plane and out-of-plane oscillations in the completely relevant interval of oscillation amplitudes and sliding velocities and for various material pairings. The experimental results are interpreted on the basis of both macroscopic and microscopic models. There are two main effects which are of interest for tribological applications. Firstly, the frictional force typically decreases with increasing oscillation amplitude, with an oscillation amplitude of about 0.1???m typically being sufficient for a significant decrease of frictional force. Secondly, the decrease of force is larger at smaller sliding velocities; therefore, at sufficiently large oscillation amplitudes, the frictional force always increases with sliding velocity. This effect can be used to suppress frictionally induced vibrations.     

Tribological Characteristics of Si3N4-based Self-Lubricating Materials

A new technique for fabrication of self-lubricating ceramic-based composites has been developed. Multi-channel ceramic matrices with a predetermined number, diameter, and distribution of channels are fabricated and then filled with a lubricant such as polytetrafluoroethylene or perfluoropolyether. Friction coefficients of lubricant-filled silicon nitride against 52100 steel were found to be 0.1 to 0.2, in contrast with pure silicon nitride for which values of 0.6 to 0.7 were found. This friction reduction is insensitive to applied load or to sliding speed. The controlled pattern of porosity allows these materials to have lubricant loading of 7.5 to 10 volume percent, instead of 20–25% typical of traditional self-lubricating materials. This configuration permits higher crushing resistance and stiffness in comparison with conventional self-lubricating antifriction materials.     

Experimental Study and Numerical Simulation of the Large-Scale Testing of Polymeric Composite Journal Bearings: Two-Dimensional Modeling and Validation

The self-lubricating properties of some polymeric materials make them very valuable in bearing applications, where the lubrication is difficult or impossible. Composite bearings combine the self-lubricating properties of polymeric materials with better mechanical and thermal properties of the fibers. At present, there are few studies about these bearings and their design is mainly based on manufacturers’ experiences. This study includes an experimental and numerical study of the large-scale testing of fiber-reinforced polymeric composite bearings. In the first part of this article, a new tribological test setup for large composite bearings is demonstrated. Besides, a two-dimensional finite-element model is developed in order to study the stress distribution in the composite bearing and kinematics of the test setup. A mixed Lagrangian–Eulerian formulation is used to simulate the rotation of the shaft and the contact between the composite bearing and the shaft. Simulation results correspond closely to the experimental data, and provide careful investigation of the stress distribution in the bearing. In the second part of this article, three-dimensional quasi-static and two-dimensional dynamic models are studied.     

Formation of Friction Layers in Graphene-Reinforced TiAl Matrix Self-Lubricating Composites

The friction layer structure has been proved to be formed during severe plastic deformation and markedly improves the tribological properties of material. The dry friction and wear performance of graphene-reinforced TiAl matrix self-lubricating composites (GTMSC) at different sliding velocities are systematically researched. GTMSC show the best tribological properties and special friction layer structure containing a wear-induced layer and a grain refinement layer with a nanocrystalline (NC) structure under surface after sliding at a sliding speed of 1.1 m/s. Nanoindentation results show that the grain refinement layer has a higher hardness and elastic modulus than the wear-induced layer. This special microstructure of friction layers beneath the surface after sliding leads to a low coefficient of friction and high wear resistance of GTMSC. Moreover, it is deduced that the appearance of an NC structure results in hardening of the material. The formation mechanisms of friction layers are researched in detail. It can be concluded that the formation of a wear-induced layer results from frictional heat and fracture of the counterpart. The formation of a grain refinement layer is due to severe plastic deformation and dynamic recrystallization. Severe plastic deformation results in the formation of an NC structure and dynamic recrystallization leads to grain refinement.     

Application of frictional pendulum sliding bearings for seismic insulation

The sea platforms Lun-A and PA-B of the Sakhalin-2 project erected off the northwestern coast of Sakhalin have been designed and constructed taking into account the severe regional seismicity in which they are used. Their design, which incorporates an effective frictional pendulum bearing (FPBs are capable of running damage- and failure-free when exposed to loads created by earthquakes, which occur once every 200 years, and should stay undamaged in the case of a rare earthquake, which occurs once every 2000 years [1–3]. When the Arkutun-Dagi deposit was put to use, the seismic reliability of oil producing Sakhalin-2 project was designed for use on the previously tested platforms at the Lun and Piltun-Astokh deposits. The Sakhalin-2 project was seismically protected and have been successfully and safely used since 2007. These works used experimental calculation techniques to estimate the life of the seismic insulating pendulum sliding bearing in order to determine its wear rate. The dependences of determining the wear rate are presented in summarized variables and the coefficient of friction and temperature assessments to establish the temperature condition of the FPB [4, 6].     

Experimental Study on the Friction Characteristics of Textured Steel Surface with Ring-Shaped Pits under Lubricated Sliding Conditions

Surface texturing has been recognized to be an effective approach to modify the tribological performances of sliding surfaces. A ring-shaped texture has been fabricated on the surface of AISI1045 steel using a pulse laser, and reciprocating sliding tests were performed on a variable load tribometer (VLT). Frictional force of the textured surfaces was investigated under various geometrical parameters (inner radius, external radius, pitch, and offset ratio of texture units) and operating conditions (velocity and load). The results show that the width of the ring-shaped texture has a significant influence on antifriction, an optimum width for minimum friction is about 200 µm, and the staggered array of texture units is an effective way of reducing frictional force and wear.