著者

Kiyoshi Mabuchi Kensei Tanaka Daichi Uchijima Rina Sakai

出版者

Japanese Society of Tribologists

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.7, no.3, pp.147-151, 2012-09-30 (Released:2012-09-30)

参考文献数

4

被引用文献数

5 12

---

We measured the frictional coefficient under banana skin on floor material. Force transducer with six degrees of freedom was set under a flat panel of linoleum. Both frictional force and vertical force were simultaneously measured during a shoe sole was pushed and rubbed by a foot motion on the panel with banana skin. Measured frictional coefficient was about 0.07. This was much lower than the value on common materials and similar one on well lubricated surfaces. By the microscopic observation, it was estimated that polysaccharide follicular gel played the dominant role in lubricating effect of banana skin after the crush and the change to homogeneous sol.

著者

Motoyuki Murashima Kazuma Aono Noritsugu Umehara Takayuki Tokoroyama Woo-Young Lee

出版者

Japanese Society of Tribologists

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.18, no.6, pp.292-301, 2023-10-31 (Released:2023-10-31)

参考文献数

61

被引用文献数

1

---

With the increasing demand for active friction control, we newly proposed to use dielectrophoresis to change the flow of PG-droplet-containing PAO4 to reduce the friction coefficient. The friction result with a 1-mm roller shows 20% reduction in friction coefficient (from 0.065 to 0.052) at AC 100 V, and in situ observation exhibits that PG tracks are formed over the contact area. On the other hand, at a high bias of 1000 V, the friction coefficient increases to 0.065. In this situation, in situ observation exhibits that PG forms a horseshoe-shaped track covering only the roller edges. Controlled friction tests and FEM analysis using 5-mm rollers revealed a unique behavior; a balanced bias effectively attracts the PG to the roller surface, and surface forces can resist mild dielectrophoretic forces to spread the PG across the roller surface. The present study strongly suggests the importance that the bias strength should be controlled to achieve a balance between surface force and dielectrophoretic force in order to obtain excellent lubrication conditions.

著者

Mabuchi Kiyoshi Tanaka Kensei Uchijima Daichi Sakai Rina

出版者

Japanese Society of Tribologists

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.7, no.3, pp.147-151, 2012

被引用文献数

12

---

We measured the frictional coefficient under banana skin on floor material. Force transducer with six degrees of freedom was set under a flat panel of linoleum. Both frictional force and vertical force were simultaneously measured during a shoe sole was pushed and rubbed by a foot motion on the panel with banana skin. Measured frictional coefficient was about 0.07. This was much lower than the value on common materials and similar one on well lubricated surfaces. By the microscopic observation, it was estimated that polysaccharide follicular gel played the dominant role in lubricating effect of banana skin after the crush and the change to homogeneous sol.

著者

Alan Hase

出版者

Japanese Society of Tribologists

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.18, no.5, pp.202-216, 2023-08-31 (Released:2023-08-31)

参考文献数

19

---

Due to the continuing decrease in the proportion of young people in the population, it is likely to become more difficult to secure the researchers who will lead the next generation. To overcome this problem, it will be necessary to arouse the interest of children and young people in science and engineering. Tribology is the study and application of the principles of friction, lubrication, and wear, and is an interdisciplinary discipline spanning many fields; consequently, the study of tribology can encourage interdisciplinary learning. Furthermore, tribology is an important discipline of itself because it has a direct relationship to issues of energy and the environment. Teaching tribology to young people and helping them to understand it could arouse their interest in a variety of aspects of science and engineering. The key is how to introduce the various academic aspects of tribology, a complex and mysterious discipline, in an engaging manner. The author has energetically striven to promote introductory education to enlighten the next generation about tribology by using a novel educational method that incorporates a problem-solving game. This paper describes the effectiveness of this educational method, the content of the developed teaching materials, and the results in educational practice.

著者

Vilma Ratia Kati Valtonen Anu Kemppainen Veli-Tapani Kuokkala

出版者

(社)日本トライボロジー学会

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.11, no.2, pp.410-416, 2016-04-30 (Released:2016-04-30)

参考文献数

10

被引用文献数

7

---

The role of edge wear was studied in impact-abrasion testing conditions with an impeller-tumbler type test device. Three steels with different mechanical properties were tested at 30° and 90° sample angles using natural granite stone as abrasive particles. The edge and planar (inner) areas were carefully exposed to the same conditions by using tightly fitted two-part samples to obtain relevant information about the differences in their wear behavior. The role of edge-concentrated wear was dominant in all materials, and the edge wear rate was several times higher than the wear rate of the inner parts of the specimens. The difference in wear rate was particularly large in short tests and with the 90° sample angle. However, the dominance of the edge-concentrated wear decreased as the test duration became longer. The wear mechanism was largely microfatigue in all materials, but the samples tested at the 30° sample angle showed more microcutting in comparison to the 90° samples. Moreover, the role of microcutting was higher in the wear of the edge parts than in the inner parts.

著者

Kouki Imai Alan Hase

出版者

Japanese Society of Tribologists

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.17, no.2, pp.86-96, 2022-05-15 (Released:2022-05-15)

参考文献数

15

被引用文献数

2

---

The purpose of this study is to identify tribological phenomena that occur on a machined surface under grinding, using acoustic emission (AE) sensing. The study investigated features exhibited by AE signals due to a change of state of the machined surface during the finish grinding of glass materials. An AE sensor was attached to a glass test piece, and the AE signals generated by using a grinding wheel rotating at high speed were measured. It was found that differences in the grain size of the grinding wheel and the hardness of the test piece changed the amplitude of the AE signal, and that there was a correlation between the amount removed by grinding and the AE mean value. In addition, a frequency analysis of the AE signal waveforms revealed that the AE frequency components generated during friction and during grinding differ. It was also found that a change in grinding ability of the grinding wheel, due to it wearing flat or to abrasive grains falling away, can be established from the change in AE mean value and the peak position in the AE frequency spectrum.

著者

Miho Morita Shodai Tachiyama Ko Onodera Alan Hase

出版者

Japanese Society of Tribologists

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.17, no.2, pp.78-85, 2022-04-30 (Released:2022-04-30)

参考文献数

10

被引用文献数

2

---

Sulfur and phosphorus additives are used in lubricants as extreme-pressure and antiwear agents, which are typically used together to ensure reliability over a wide range of lubrication conditions. However, the working mechanism of the combined additive system has not been clearly defined due to difficulties obtaining information on the material surface where these additives work. This is because this surface is constantly being worn during testing. Therefore, in situ analysis applying an acoustic emission (AE) technique was proposed. AEs are elastic stress waves generated during the deformation and fracture of solids, which can be measured in real-time, providing information with respect to the magnitudes and types of damage. In this paper, an application of the AE helps to clarify how each additive acts on the surface in real-time. The working mechanism to understand improved reliability using both sulfur and phosphorous additives was investigated by the AE technique, along with conventional surface analysis methods. It is concluded that wear reducing properties were improved by the reaction of sulfur additives to remove the protruded parts, followed by the reaction of phosphorous additives to form a protective antiwear film.

著者

Monica Beyer Gareth Brown Michael Gahagan Tomoya Higuchi Gregory Hunt Michael Huston Doug Jayne Chris McFadden Timothy Newcomb Suzanne Patterson Christopher Prengaman Mariam Shamszad

出版者

Japanese Society of Tribologists

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.14, no.5, pp.428-437, 2019-12-15 (Released:2019-12-15)

参考文献数

14

被引用文献数

27

---

It is anticipated that many future electrified vehicle transmissions and axles will incorporate the electric motor within the unit housing. In such an arrangement, the lubricant will be in direct contact with powered motor windings, which raises new concerns regarding its electrical conductivity and its propensity to corrode copper. The heat produced at the motor windings will challenge the lubricant’s heat transfer ability and its thermal stability. Expected high temperature excursions warrant the use of new plastics, which may give rise to new compatibility concerns. In this paper we share our learnings regarding the electrical properties of lubricants and discuss new methods to characterize copper corrosion. We review the factors that affect the heat transfer characteristics of lubricants and illustrate how improving heat transfer will favor the use of lower viscosity lubricants. We also share our early efforts to quantify lubricant compatibility with higher temperature plastics using tensile strength measurements. Finally, we discuss how these new concerns will shift the perception of what is required for lubricants used in different types of electrified transmission hardware.

著者

Vilma Ratia Kati Valtonen Anu Kemppainen Veli-Tapani Kuokkala

出版者

(社)日本トライボロジー学会

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.8, no.2, pp.152-161, 2012-02-15 (Released:2013-02-15)

参考文献数

13

被引用文献数

21

---

Energy can be saved by enhancing the service life of machinery and by designing lighter units. These design changes enable, for example, lower fuel consumption and larger payloads. The implementation of this kind of solutions, however, requires development of better wear resistant materials. In this study, the wear resistance of a structural steel and three grades of wear resistant steel was evaluated with granite abrasive in tests simulating the conditions in heavy machinery in mining and transportation. Two high-stress abrasion and one impact-abrasion wear testing methods were used. In all tests, higher hardness led to decreased mass loss, but in impact-abrasion the hardness dependence was smaller than in the heavy abrasion tests. This may, however, at least partly result from deformation of softer materials over the sample edges, which is not shown as mass loss. Wear surfaces of structural steel samples exhibited the highest degree of plastic deformation due to their lower hardness and higher ductility compared to the wear resistant steels. On the other hand, in harder materials the scratches were more visible, indicating a change in wear mechanism. Both differences and similarities in the behavior and wear mechanisms of the selected steels were observed in the applied conditions.

著者

Alan Hase Masaki Wada Hiroshi Mishina

出版者

(社)日本トライボロジー学会

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.3, no.5, pp.298-303, 2008-10-15 (Released:2008-10-15)

参考文献数

22

被引用文献数

6 16

---

The relationship between acoustic emission (AE) signals and wear phenomena in severe-mild wear transition is discussed on the basis of the results of observations of wear particles and worn surfaces of steel. Each wear mode, severe wear or mild wear, is reproduced for a different sliding velocity. The influence of relative humidity on mild wear is examined. We found a reduction in the true area of contact and the size of wear particles decreases the AE signal level in severe-mild wear transition. In the mild wear mode, an increase in the number of transfer particles lying between the sliding surfaces decreases the AE signal level. Further, a linear relationship is observed between the AE mean value and the specific wear rate, regardless of the wear mode. This is because the AE signals generated by the formation and removal of transfer particles mainly originate under conditions of repeated dry rubbing.

著者

Toshiaki Nishi Atsushi Matsumura Manami Koshida Tatsufumi Matsumoto Takeshi Yamaguchi

出版者

Japanese Society of Tribologists

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.18, no.6, pp.353-364, 2023-10-31 (Released:2023-10-31)

参考文献数

31

被引用文献数

2

---

Sportswear is widely used in various sports and serves multiple functions. A key feature is the ability to absorb sweat during physical activity, which can, however, cause discomfort due to stickiness. This study focuses specifically on the stickiness caused by sweat between sportswear and the skin by objectively evaluating stickiness using specific physical parameters and correlating them with sensory evaluation values. Moreover, there is little research on the adhesion force between sportswear and human skin. Therefore, this study aims to achieve the following objectives: (1) investigate the relationship between the adhesion force between human skin and fabrics and the sensation of stickiness; (2) examine the relationship between the adhesion force between artificial skin and fabric and that between human skin and fabric; and (3) clarify the impact of fabric wettability and geometry on the adhesion force under wet conditions. Experiments reveal that the sensory evaluation value and adhesion force against human skin corresponded. Additionally, a positive correlation was found between the adhesion force against human skin and an artificial skin sheet. These experimental results suggest that fabrics with a lower adhesion force can be achieved by decreasing the load area ratio at 30% Φ0.3 and increasing the contact angle and meniscus height.

著者

Géraldine Theiler Thomas Gradt

出版者

Japanese Society of Tribologists

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.18, no.5, pp.217-231, 2023-08-31 (Released:2023-08-31)

参考文献数

29

被引用文献数

1

---

The development of hydrogen technologies entails high safety requirements in distribution and dispensing infrastructure. Therefore, it is necessary to pursue research on material compatibility in hydrogen, especially for critical parts with tribological issues. The focus of this study is to evaluate the influence of hydrogen on a wider range of commercially available polymer materials. Thereby, the friction and wear behavior of different grades of TPE, POM, PA66, PA12, PPA, PEEK, PPS, PTFE, PAI, PI and PBI were investigated against a rotating steel disk (AISI 304). Filled and unfilled polymers from different suppliers were evaluated at room temperature in air, vacuum temperature, the effect of hydrogen environment on the tribological behavior of neat polymers may be related to lack of moisture, but also to saturated hydrocarbons in gaseous hydrogen. In liquid hydrogen, the best tribological performances were achieved with neat PA polymers as well as PPS and PI composites.

著者

Kaisei Sato Hikaru Okubo Shouhei Kawada Seiya Watanabe Shinya Sasaki

出版者

Japanese Society of Tribologists

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.16, no.3, pp.178-191, 2021-09-30 (Released:2021-09-30)

参考文献数

66

被引用文献数

5

---

Ionic liquids (ILs) are being considered as novel lubricant additives to improve the friction and anti-wear characteristics of sliding surfaces. Because ILs consist of only cations and anions, their physical and chemical properties can be easily tailored by modifying their combination. These features enable to design of specific ILs for a given tribological system. However, there are few reports on the effect of ILs used as lubricant additives on the friction and anti-wear characteristics of sliding surfaces. Moreover, it is necessary to investigate the synergism between ILs and other lubricant additives to achieve high practical efficiency. Therefore, in this study, two ILs with different cations but similar anions were used in combination with an anti-wear additive, zinc dialkyldithiophosphate (ZDDP), and the resultant wear and friction characteristics of the worn surfaces were analyzed. We found that the tribological performance under steel/steel sliding conditions was dependent on the chemical composition of the ILs. In addition, mixed ZDDP and IL solutions exhibited lower friction and wear when compared to ZDDP alone. It is considered that the excellent lubrication and frictional performance observed with the mixed lubricant solutions is due to the formation of tribofilms comprising of ZDDP and IL on the sliding surface.

著者

Krapfl Thilo Shakhvorostov Dmitriy Langston Justin Eisenberg Boris Debus Daniel Miklozic Ksenija Topolovec Miklozic Gvido

出版者

Japanese Society of Tribologists

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.7, no.3, pp.132-138, 2012

被引用文献数

2

---

Driven by diminishing fossil fuel resources, global warming and subsequently rigid legislation on CO₂ emission, fuel economy is a major challenge for the automotive industry. Each element of the powertrain has been optimized or newly designed to increase efficiency. In this optimization process the engine oils and transmission fluids are important design elements and their contribution to improved efficiency is significant. Polyalkylmethacrylates (PAMAs) are widely used as viscosity index improvers in engine, transmission and hydraulic oils. They have been shown to adsorb from oil solution onto metal surfaces to produce thick and viscous boundary films. These films are maintained even in low speed and high temperature conditions and thus produce a reduction of friction and wear. It was found that specifically designed film-forming PAMAs can improve pitting performance of lubricant formulations. The paper describes the impact of tailor-made functionalized PAMAs on boundary film formation and explores their ability to increase the fatigue life of lubricants.

著者

Uzuhiko Tsuboi

出版者

(社)日本トライボロジー学会

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.6, no.3, pp.160-167, 2011-01-31 (Released:2011-01-31)

参考文献数

10

被引用文献数

2

---

It is inspiring to discover technology related to tribology throughout the history of mankind. This paper describes sketches produced by da Vinci in the 15th century corresponding to modern bearings and notable tribological achievements in Japan from ancient times. Explained herein are a project to construct bearing models based on da Vinci’s sketches, a fire-making device used in Japan since ancient times, shura sleds that were widely used in Japan, investigations of the revolving stage mechanisms of Japan’s oldest surviving theater, and ingenious automated doll devices of Japan’s Edo period that paved the way to the creation of modern humanoid robots. Lastly, this paper touches on how these technologies led to the development of Japan’s bearing industry.

著者

Kanao Fukuda Joichi Sugimura

出版者

(社)日本トライボロジー学会

雑誌

Tribology Online (ISSN:18812198)

巻号頁・発行日

vol.8, no.1, pp.22-27, 2013-01-31 (Released:2013-01-31)

参考文献数

14

被引用文献数

1 14

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The authors have clarified that trace impurities such as water and oxygen inevitably contained in a hydrogen environment influence friction and wear of metallic materials substantially and even often govern them. In this study, an experimental technique was devised to enable sliding tests in a hydrogen environment which contains controlled concentration of water and virtually no oxygen as impurities. By comparing data of Fe sliding tests between this study and our previous studies, the influences of water and oxygen were understood separately. Water without oxygen as impurity in a hydrogen environment decreased wear of pure Fe while oxygen in additional to water increased the wear. Sliding of pure Fe consumed water when a hydrogen environment contained only water while it produced water and consumed oxygen when the environment contained both water and oxygen. The number of water molecules consumed by sliding in a hydrogen environment with water more than 5,000 ppb and without oxygen was larger than the estimated number of nascent Fe atoms by sliding. This suggests that multi-layer adsorption of water molecules decreased the wear of pure Fe.