T. Tsukizoe and N. Ohmae
Tribology of the carbon‐fibre‐reinforced plastics has been investigated. The wear‐resistance of carbon‐fibre‐reinforced plastics was found to be much better than those of other…
Abstract
Tribology of the carbon‐fibre‐reinforced plastics has been investigated. The wear‐resistance of carbon‐fibre‐reinforced plastics was found to be much better than those of other plastics reinforced with fibres of glass and stainless steel and was affected by the fibre‐orientation relative to sliding. Law of mixture in the frictional coefficient of composite materials was deduced; a comparison of calculated values with experimental data showed good agreements. Wear‐resistance of the carbon‐fibre‐reinforced plastics against fretting was also examined; good wear‐resistance was obtained when sliding within a region about 30° from the carbon‐fibre axis.
The first part of this paper appeared in our November/December issue and dealt with fretting wear behaviour of mild steel from room temperature to 600°C in air. The general…
Abstract
The first part of this paper appeared in our November/December issue and dealt with fretting wear behaviour of mild steel from room temperature to 600°C in air. The general mechanism for fretting is discussed at all temperatures where normal oxidative processes become involved. The nature of fretting wear is also covered and the effects of temperature are described. In this part of the paper, the discussion is continued to include triboxidation, delamination theory, atmospheric environment, transition temperatures, activitation energy and other factors affecting the influence of temperature on fretting.
ZHI‐HUA ZHONG and JAROSLAV MACKERLE
Contact problems are among the most difficult ones in mechanics. Due to its practical importance, the problem has been receiving extensive research work over the years. The finite…
Abstract
Contact problems are among the most difficult ones in mechanics. Due to its practical importance, the problem has been receiving extensive research work over the years. The finite element method has been widely used to solve contact problems with various grades of complexity. Great progress has been made on both theoretical studies and engineering applications. This paper reviews some of the main developments in contact theories and finite element solution techniques for static contact problems. Classical and variational formulations of the problem are first given and then finite element solution techniques are reviewed. Available constraint methods, friction laws and contact searching algorithms are also briefly described. At the end of the paper, a bibliography is included, listing about seven hundred papers which are related to static contact problems and have been published in various journals and conference proceedings from 1976.
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The tribological behavior of composites varies on matrices materials, the reinforcement material and the direction of reinforcement materials. The purpose of this study is to…
Abstract
Purpose
The tribological behavior of composites varies on matrices materials, the reinforcement material and the direction of reinforcement materials. The purpose of this study is to examine the effects of fiber orientation on the tribological properties of carbon fiber–reinforced epoxy composite.
Design/methodology/approach
The experiments were carried out with a pin-on-ring tribometer. The tests were executed according to three different parameters: load, sliding velocity and direction of reinforcement. Loads measuring 92 N and 150 N were applied at sliding velocities of 1 and 2 m/s, in parallel, antiparallel and normal directions of fiber reinforcements. The frictional force was read every 500 m of sliding distance. To calculate specific wear rate, the mass of the samples was measured before and after each experiment. Moreover, temperature was measured every 1000 m of sliding distance via three-point infrared thermometer, to examine the effect of temperature variations. The sample surfaces were also examined in optic microscope after the experiments. Higher friction coefficient values were obtained in the normal direction-oriented carbon fiber specimen.
Findings
Comparing the friction coefficient values, antiparallel and parallel direction-oriented carbon fiber specimens gave lower friction coefficient values. The increase of sliding velocity and normal load resulted in the increase of surface temperature and this lead to the increase of friction coefficient.
Originality/value
This study shows the effects of fiber orientation on the tribological behavior of carbon fiber–reinforced epoxy composite. According to fiber orientations, relatively moving counter surfaces of this material shows different tribological behaviors.
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Dewan Muhammad Nuruzzaman, Mohammad Asaduzzaman Chowdhury and Mohammad Lutfar Rahaman
The present paper seeks to report the effect of duration of rubbing on friction coefficient for different polymer and composite materials. Variations of friction coefficient and…
Abstract
Purpose
The present paper seeks to report the effect of duration of rubbing on friction coefficient for different polymer and composite materials. Variations of friction coefficient and wear rate with the normal load are also investigated experimentally when stainless steel (SS 304) pin slides on different types of materials such as cloth‐reinforced ebonite (commercially known as gear fiber), glass fiber‐reinforced plastic (glass fiber), nylon and polytetrafluoroethylene (PTFE).
Design/methodology/approach
A pin on disc apparatus is designed and fabricated. During experiment, the rpm of test samples was kept constant and relative humidity was 70 percent.
Findings
Studies have shown that the values of friction coefficient depend on applied load and duration of rubbing. It is observed that the values of friction coefficient decrease with the increase of normal load for glass fiber, nylon and PTFE. Different trend is observed for gear fiber, i.e. coefficient of friction increases with the increase of normal load. It is also found that wear rate increases with the increase of normal load for all the materials. The magnitudes of friction coefficient and wear rate are different for different materials.
Practical implications
It is expected that the applications of these results will contribute to the design of different mechanical components of these materials.
Originality/value
Within the observed range of applied normal load, the relative friction coefficient and wear rate of gear fiber, glass fiber, nylon and PTFE are experimentally investigated.
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Thomas Ølholm Larsen, Tom Løgstrup Andersen, Bent Thorning and Martin E. Vigild
The purpose of this paper is to describe the construction of a custom‐built pin‐on‐disk (POD) apparatus based on a simple design and on important guidelines.
Abstract
Purpose
The purpose of this paper is to describe the construction of a custom‐built pin‐on‐disk (POD) apparatus based on a simple design and on important guidelines.
Design/methodology/approach
The POD apparatus is built as a part of the main author's PhD project. The apparatus is built at a low cost and is suited for testing polymeric materials under dry‐sliding conditions. The different main parts of the apparatus are described in a way which partly explains the choice of construction and partly makes it possible to produce a similar apparatus. Furthermore, a limited amount of tribological data is presented mainly to exemplify the usefulness of the machine.
Findings
The POD apparatus is successfully applied to measure coefficients of friction, wear rates and disk temperatures at an acceptable level of precision and accuracy. Tribological data obtained with this equipment show the effect of reinforcing an epoxy resin with a plain glass fiber weave.
Research limitations/implications
The data presented in this paper are limited since the main objective is to describe the construction of a POD apparatus.
Practical implications
The paper is intended to be a source of inspiration for industrial or academic laboratories who want to establish their own tailor‐suited tribological test‐equipment, instead of investing in a probably more expensive commercial machine.
Originality/value
The POD apparatus is custom‐built and described in an easily understandable way, which makes this a helpful paper for those who wish to produce a similar apparatus.
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This article contends that the content and scope of “second generation” state reforms in Latin America show a high degree of heterogeneity due to the national contexts and the…
Abstract
This article contends that the content and scope of “second generation” state reforms in Latin America show a high degree of heterogeneity due to the national contexts and the depth of the changes produced by the earlier reforms. The “third generation” reform is rejected as a valid category. There is no clear distinction between premises or values, roles, and instruments of reform. The “first generation” of reforms constituted the easy phase of state transformation. In the second phase, the difficulties are similar to the ones that Latin American countries faced during 70 years of reformist attempts which constituted the prehistory of this process and ended mostly in failure. By means of a critical analysis of the paradigm of the “reinvention of governmentr”, the instrumental challenges implicit in its eventual materialization are reviewed. As an emblematic case, the Argentine experience is used to illustrate the main propositions of this article.
Hao Liu, Yujuan Zhang, Shengmao Zhang, Yanfen Chen, Pingyu Zhang and Zhijun Zhang
The purpose of this paper is synthesis of oil-soluble non-spherical nanoparticles modified with free phosphorus and sulphur modifier and investigation of their tribological…
Abstract
Purpose
The purpose of this paper is synthesis of oil-soluble non-spherical nanoparticles modified with free phosphorus and sulphur modifier and investigation of their tribological properties as environment-friendly lubricating oil additives.
Design/methodology/approach
To study the effect of morphology of nanoparticles on their tribological properties, rice-like CuO nanoparticles were synthesized. To improve the solubility of CuO nanoparticles in organic media, the in-situ surface modification method was used to synthesize these products. The morphology, composition and structure of as-synthesized CuO nanoparticles were investigated by means of transmission electron microscopy, X-ray powder diffraction, thermogravimetric analysis and Fourier transform infrared spectrometry. The tribological properties of as-synthesized CuO nanoparticles as an additive in liquid paraffin (LP) were evaluated with a four-ball tribometer. The morphology and elemental composition of worn steel ball surfaces were analysed by X-ray photoelectron spectroscopy.
Findings
It has been found that as-synthesized CuO nanoparticles with rice-like morphology have an average size of 7 and 15 nm along the shorter axle and longer axle, respectively, and can be well-dispersed in LP. Tribological properties evaluation results show that as-synthesized CuO nanoparticles as additives in LP show good friction-reducing, anti-wear and load-carrying capacities, especially under a higher normal load.
Originality/value
Oil-soluble rice-like CuO nanoparticles without phosphorus and sulphur were synthesized and their tribological properties as lubricating oil additives were also investigated in this paper. These results could be very helpful for application of CuO nanoparticles as environment-friendly lubricating oil additives, owing to their free phosphorus and sulphur elements characteristics.
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Sheri Kurgin, Jean M. Dasch, Daniel L. Simon, Gary C. Barber and Qian Zou
The purpose of this paper is to evaluate the cooling ability of minimum quantity lubrication (MQL) cutting fluid.
Abstract
Purpose
The purpose of this paper is to evaluate the cooling ability of minimum quantity lubrication (MQL) cutting fluid.
Design/methodology/approach
An experimental system is devised to find the heat transfer coefficient of MQL under simulated reaming conditions. Cooling rate of the specimen is measured with an infrared camera. The effect of air pressure and oil volume on cooling rate is tested. Metal cutting tests are performed to evaluate the effect of heat transfer coefficient on workpiece temperature.
Findings
Convective heat transfer coefficient for MQL increases with increasing air pressure. Oil volume has an indeterminate effect on the heat transfer coefficient; however, it is a dominant factor for controlling temperature during reaming.
Practical implications
The results of the study can provide guidance to optimize the temperature controlling ability of MQL for production.
Originality/value
There is limited information available in literature regarding the heat transfer coefficient of metal working fluids, particularly for MQL. In particular, experiments designed to investigate the effect of air pressure and oil volume on the heat transfer coefficient of the mist have not been previously documented. This information may be used to improve the overall cooling ability of MQL mist, thus increasing its effectiveness at controlling tool wear and maintaining part quality. The other major contribution of this work is to separate the role of the cooling and lubrication for controlling temperature while reaming aluminum. Prior to this study, there has been relatively little research performed for the reaming metal cutting operation, and still less for reaming with MQL. The nature of how metal working fluids control temperature is not fully understood, and this work provides insight as to whether cooling or lubrication plays the dominant role for reaming.
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Bin Shi, Jian Hua Guo, Xing An Cao, En Zhu Hu and Kun Hong Hu
This paper aims to explore the effects of mineral diesel fuel carbon soot (MCS) and biodiesel carbon soot (BCS) on the lubrication of polyalphaolefin (PAO) and diesel fuels.
Abstract
Purpose
This paper aims to explore the effects of mineral diesel fuel carbon soot (MCS) and biodiesel carbon soot (BCS) on the lubrication of polyalphaolefin (PAO) and diesel fuels.
Design/methodology/approach
Two styles of carbon soot were prepared from the natural combustion of mineral diesel fuel oil (MDO) and biodiesel oil (BDO). Tribological tests were conducted on a high-frequency reciprocating rig. Friction surfaces were characterized using three-dimensional laser scanning confocal microscopy and Raman spectroscopy.
Findings
The addition of MCS and BCS to PAO could reduce friction in most cases. MCS had a negligible effect on the wear for contents not exceeding 1.0 per cent. By contrast, BCS exhibited a considerable negative influence on the wear resistance even at low contents. For diesel fuels, MCS reduced both friction and wear, whereas BCS substantially deteriorated the lubrication of BDO. MCS formed a Fe3O4/C composite lubricating film on the friction surface. BCS also entered the contact region, but it did not form an effective Fe3O4/C composite lubricating film.
Originality/value
This work compared MDO and BDO from a different perspective, i.e. the effects of their combustion carbon soot on the lubrication of lubricating oil and fuel oil. The significant negative effect of BCS on the lubrication of lubricating oil and BDO is a problem that could occur in the industrial application of BDO.