Improving tribological behaviour of piston ring–cylinder liner frictional pair by liner surface texturing

Experiments were carried out on a reciprocating tester. The lubricant was supplied into the inlet side of the contact zone. The construction of tribological tester allows to measure the friction force between specimen and counter-specimen. Tribological behaviours of cylinder liners with and without oil pockets were compared. Specimens were cut from plateau honed cylinder liners made of grey cast iron. Counter-specimens were cut from grey cast iron piston rings. A special tool acted as a hammer to form additional dimples on the liner surfaces. The area density of oil pockets was about 13%. Specimen surfaces had dimples with average depths about 5 μm and diameters in the range 0.15–0.2 mm. Two batches of tribological tests were carried out, in regimes of full and starved lubrication. Friction tests were conducted at three mean sliding speeds: 0.44, 0.66 and 0.88 m/s. Experiments were performed with normal load in the range 50–300 N, starting from the lowest load. Normal load increased in a stepwise manner after 2 min at each load, until the maximum load was reached. Areal surface topographies of specimens and counter-specimens were measured before and after two batches of tests by white light interferometer.     

Effect of additives on a surface textured piston ring–cylinder liner system

ABSTRACT

Laser texturing of the surface is a known approach to improve the tribological performance of mechanical systems. Many studies focused on optimising surface texture parameters for the piston-ring cylinder liner (PRCL) system. However, little attention is given to explore the effect of the textured surface on additive film formation. In the present work, the effect of a laser textured surface on the formation of additives tribochemical films and its impact on the tribological performance of PRCL system is studied. Commercially available steel piston ring and grey cast iron cylinder liner are used as samples to carry out the experiments using linear reciprocating tribometer. Experiments are carried out at 75?N load, 0.1?Hz frequency and 80°C temperature, using polyalphaolefin as base oil mixed with different additives. It is found that dimples are interfering in the formation of tribo-chemical films. However, the hydrodynamic effect of dimples is contributing to the improvement of lubrication performance even in the presence of additives.     

Evaluation of image based Abbott–Firestone curve parameters using machine vision for the characterization of cylinder liner surface topography

In this paper, a method is proposed for the evaluation of image based Abbott–Firestone curve parameters aiming to characterize the cylinder bore surface topography using machine vision. Plateau honing experiments are performed to generate sixteen cylinder liners with different surface topographies and the 2-D and 3-D Abbott–Firestone parameters are measured using a stylus instrument and Coherence Scanning Interferometer (CSI), respectively. The images are captured from the corresponding portions of the cylinder liner surfaces using a Charge Coupled Device (CCD) camera connected with different microscopic attachments. The captured images are filtered using a Butterworth high pass filter followed by the adaptation of the double step Gaussian filtering procedure specified by the ISO 13565-1. An Abbott–Firestone curve is constructed by finding the cumulative of the intensity histogram of the filtered images. Five image based parameters are evaluated from the constructed Abbott curve by adapting the procedures presented in ISO 13565-2. The computed image based Abbott–Firestone curve parameters are observed to bear a statistically significant correlation with the measured 2-D and 3-D Abbott–Firestone curve parameters. An artificial neural network (ANN) is trained and tested to arrive at the actual values of the Abbott–Firestone curve parameters using the computed image based feature parameters. The results indicate that the multiple surface topography parameters of the cylinder bore surface could be estimated/predicted with a reasonable accuracy using machine vision technique coupled with ANN.     

Biomechanics of knee joint – A review

The present paper is to know how the work is carried out in the field of biomechanics of knee. Various model formulations are discussed and further classified into mathematical model, two-dimensional model and three-dimensional model. Knee geometry is a crucial part of human body movement, in which how various views of knee is shown in different planes and how the forces act on tibia and femur are studied. It leads to know the forces acting on the knee joint. Experimental studies of knee geometry and forces acting on knee shown by various researchers have been discussed, and comparisons of results are made. In addition, static and dynamic analysis of knee has been also discussed respectively to some extent.     

表面织构(surface texture)

surface texture,在产品几何量技术规范（GPS）表面结构系列标准中有这词.ISO 4287：1997《产品几何量技术规范（GPS）表面结构：轮廓法 表面结构的术语、定义及参数》中没有给出surface texture的定义.     

Microclamping principles from the perspective of micrometrology – A review

This paper gives an overview of the field of clamping and gripping principles from the viewpoint of sample fixturing for dimensional metrology for microobjects. The requirements for clamping microcomponents that allow dimensional measurements are therefore explained before principles and solutions of microclamps as found in literature are reviewed and evaluated on basis of these requirements. Results show that there is no single superior clamping principle or method of implementation but rather several effective solutions for specific applications. The core value of this paper is the link between requirements for sample fixturing in dimensional micrometrology and the many approaches already investigated in the field of microclamping. A radar chart and a decision tree summarize and visualize the major aspects of this review. Finally, directions of future key research areas are suggested.     

Material ratio curve as information on the state of surface topography—A review

This study deals with the analysis and usefulness of the material ratio curve. The parameters obtained from this curve are presented. The most popular of these parameters include two groups that are derived from this curve and provided in the ISO 13565–2 (Rk) and ISO 13565–3 (Rq) standards. They are compared by considering their practical significance and sensitivity to measurement errors. The parameters in the Rk family can easily be calculated but are ambiguous, which leads to errors in their calculation. The Rq group, which is based more on theoretical logic, must be applied with great care because of the problems with the Rpq parameter calculation and approximation of the material ratio probability plot. The methods of obtaining the correct oil capacity and its relation with the transition point between the central and valley surface parts are presented. The application of the material ratio curve in low-wear assessment is discussed.     

Simulation Analysis of a PCB Factory using Factorial Design – A Case Study

This study describes simulation modelling and analysis of a serial production line in a printed circuit board (PCB) factory. Simulation technique is applied to evaluate the performance of the existing manufacturing system, which requires modification to achieve two conflicting objectives, i.e. to maximise the average throughput rate and to minimise the average lead time. Based on a full factorial design, the computer model, which is developed using SIMFACTORY, has been used for finding out the active factors that have a great impact on the current operational problems. Then, a new system design is proposed to enhance the overall performance and is verified using a simulation model. The simulation approach presented here is also applicable to a wide variety of complex operational problems. ID="A1"Correspondance and offprint requests to: Dr F.T.S.Chan, Department of Industrial and Manufacturing Systems Engineering, University of Hong Kong, Pokfulam Road, Hong Kong. E-mail: ftschan@hkucc.hku.hk     

Influence of matrix hardness on honing engine cylinder liner with Cu–Sn–Fe–Ni diamond stones

In this work, three Cu–Sn–Fe–Ni matrices with different hardness were utilized in the diamond honing stones. Structures of the three matrices were investigated by X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy, and the results showed that the Cu–Sn–Fe–Ni matrices were composed of the pure copper, pure iron and (Cu, Ni)₄₁Sn₁₁. The wear properties of the matrices were estimated by a pin-on-disk wear machine under dry conditions at room temperature in the air. The influences of hardness on the honing performances were studied in terms of the honed surface aspect, the honing efficiency and the throughput of cylinder liners. Among the three stones, the stone with matrix B (HRB 71) reaches the self-sharpening range in terms of the three aspects mentioned above. Compared this stone with a commercially available product, the former has better honing efficiency.     

Analysis of environmental organic matters by Ultrahigh-Resolution mass spectrometry—A review on the development of analytical methods

Owing to the increasing environmental and climate changes globally, there is an increasing interest in the molecular-level understanding of environmental organic compound mixtures, that is, the pursuit of complete and detailed knowledge of the chemical compositions and related chemical reactions. Environmental organic molecule mixtures, including those in air, soil, rivers, and oceans, have extremely complex and heterogeneous chemical compositions. For their analyses, ultrahigh-resolution and sub-ppb level mass accuracy, achievable using Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), are important. FT-ICR MS has been successfully used to analyze complex environmental organic molecule mixtures such as natural, soil, particulate, and dissolved organic matter. Despite its success, many limitations still need to be overcome. Sample preparation, ionization, structural identification, chromatographic separation, and data interpretation are some key areas that have been the focus of numerous studies. This review describes key developments in analytical techniques in these areas to aid researchers seeking to start or continue investigations for the molecular-level understanding of environmental organic compound mixtures.     

Monitoring and processing signal applied in machining processes – A review

In machining processes several phenomena occur during material cutting. These phenomena can affect the production through the reduction of quality or accuracy, or by increasing costs (tools, materials, time). Thus, an understanding of machining phenomena is needed not only to define the cutting parameters for maximizing production, but also to ensure worker safety. An easy way to identify these phenomena is by monitoring machining processes, such as the measurement of cutting force, temperature and vibration. The acquired signal can have information about tool life, quality of cutting and defects in the workpiece. This review paper discusses the first steps involved in choosing and defining various techniques that may be used to monitor machining processes. Furthermore, this paper also outlines the techniques to acquire and process the signals of the monitoring processes. Hence, the objective of this paper is to help the reader understand the procedures for monitoring machining processes, and define methods, parameters, targets and other factors involved in doing so.     

Analysis of surface layers and wear products by Mössbauer spectral analysis

The article presents results of Mössbauer analysis conducted in order to identify structural factors which help to increase wear resistance of steel friction pairs. Wear resistance was tested in the regime of dry friction and oxidative wear using an original tribological tester. The device measured wear in conditions of a created and regulated isothermal boundary at a precisely defined distance from contact of rubbing bodies by receiving heat generated by friction. Cleaning elements were also employed to stabilise frictional resistances.Enhanced wear resistance was observed to obtain where temperature of the friction area becomes equal to the specific temperature of a given system.Mössbauer analysis was applied to surfaces of specimens made of C45, 145Cr6 counter specimens, and wear products. Application of Mössbauer analysis helped to identify composition and structures of ferrous compounds generated by friction, including oxidative secondary structures.Factors improving wear resistance in the testing included: presence of greater quantities of FeO and Fe₃O₄ combined with absence of Fe₂O₃ in the friction area of ferrous oxides, transfer of wear particles arising from ferrite, martensite and oxides between co-acting surfaces, enrichment of the specimen surface with martensite from the hard counter specimen and martensite generated in effect of diffusion impacts.     

Coupling of components at plane–cylinder surfaces

The mating of components at plane–cylinder surfaces is studied, by simulation. The influence of the shape and positional precision of the coupled surfaces on the relative position of the components is analyzed.     

Speed/position sensor fault tolerant control in adjustable speed drives – A review

The position sensor is one of the most used devices in Adjustable Speed Drives (ASDs). Its use is mandatory in electric machines vector control. In this paper, an interest was addressed to this field. Indeed, a bibliographical review, about Fault Detection and Isolation (FDI) and Fault Tolerant Control (FTC) in ASDs, is presented. Thus, the paper deals with position sensor FDI and sensorless control-based FTC in ASDs. Moreover, this issue is mainly addressed to position sensor faults in ASDs. This paper is based on a wide literature review referring to scientific papers and manufacturer׳s technical documents. In total, 186 references in the open literature, dating back to 1981, have been investigated in order to perform this study.     

Erratum to “Analysis of optical and wetting properties of a biomimetic antireflective surface for practical application”

Journal of Mechanical Science and Technology -     

A study of a nano-sized water droplet’s transition from a flat surface to a pillared surface

The ability to control the hydrophobicity of a surface is of importance to many industries. The dynamic behavior of nano-sized water droplets moving from a flat surface to a pillared surface using molecular dynamics simulations was investigated. Simulations were carried out in two steps. In the first computational step, the initial group of water molecules reached equilibrium on a flat graphite surface. In the second computational step, a constant force was applied to the water droplet and the motion of the water droplet was evaluated as it moved from the flat surface to the pillar-type surface. The movement of the water droplet could be grouped into three different categories and depended on the pillar height and the magnitude of the applied force. The results showed the strongest body force with a pillar height of 6 graphite layers allowed most of the water molecules to move along the top of the pillars. In conclusion, a strong force and pillar height approximately half of the droplet height displayed the best transition from a flat surface to a pillared surface.

     

A new numerical analysis for piston skirt–liner system lubrication considering the effects of connecting rod inertia

A new numerical analysis for the piston skirt is conducted to consider the effects of the connecting rod inertia on the piston skirt–liner system lubrication. The piston dynamics, the oil film and the friction loss of the system are analyzed and compared with one earlier model that has been adopted widely. The results on a gasoline engine show that the connecting rod inertia does have some influence on the system lubrication as well as the piston dynamics, especially when engine runs at high speeds.     

“Multimode vibration cutting” – A new vibration cutting for highly-efficient and highly-flexible surface texturing

This paper proposes a new vibration cutting method named “multimode vibration cutting” for precision surface texturing. The proposed cutting method utilizes multiple unidirectional vibration modes mainly in the depth-of-cut direction. The vibrations at multiple frequencies induced to the tool tip can generate not only sinusoidal but also highly-flexible trajectories such as trapezoidal, triangular, and distorted triangular waves. Notably, only a sinusoidal vibration can be induced when a single resonant vibration is applied to the tool tip. Compared to conventional highly-flexible cutting methods for surface texturing, such as the utilization of fast tool servo and amplitude control of ultrasonic elliptical vibration cutting, the proposed method is highly-efficient because of its direct usage of high resonant frequencies. Compared to conventional highly-efficient cutting methods for surface texturing, such as linear and elliptical vibration cutting which mainly utilizes the vibration component in the depth-of-cut direction, the proposed method can generate highly-flexible trajectories for various micro texture profiles. In this study, an ultrasonic multimode vibration device is developed, and the mechanics of generating multimode vibrations are demonstrated. Turning experiments with several texture profiles are performed to confirm the validity of the proposed method for highly-efficient and highly-flexible micro/nano surface texturing.     

A review on Pitot tube icing in aeronautics: Research- design and characterization – future trends

The correct measurement of airspeed is a crucial task since a lot of algorithms for the autopilot are based on it and even human pilots depend completely on this reading to take corrective and non-corrective actions to control the aircraft. This work presents a detailed review concerning an important aspect of aeronautical safety, i.e., Pitot tube (PT) icing. The topics covered include first the risks present in flight, relating meteorological conditions, and antecedents of air accidents related to the icing of the PT. Then, the principles of operation of the PT, its conventional design, how such design is currently regulated, as well as unique guidance for experimentation of PT. Also discussed are the principal modelling considerations for the numerical analysis of PTs including the proper selection of geometry, governing equations, turbulence models, and boundary conditions for the simulation of different flight circumstances. This guidance for both experimental and numerical analysis is enriched with a well-selected state the art research. Finally, a summary of the most recent advances and future trends is offered. The outcomes of this review exhibit several interesting ideas showing promising results, such as microwave heating of the pitot surroundings, phase change materials that delay ice formation, and even mechanical internal arrangement of bulkheads to prevent the ice to travel through the throat of the probe. The combined research efforts on novel safety measures and new designs for aeronautical PT represent a remarkable potential to improve flight security.