Numerical Simulation of Engagement of Paper Based Wet Clutch Facing

1994 ◽  
Vol 116 (2) ◽  
pp. 232-237 ◽  
Author(s):  
Shinichi Natsumeda ◽  
Tatsuro Miyoshi
Keyword(s):  
Hydrodynamic Lubrication ◽  
Compressive Strain ◽  
Viscosity Reduction ◽  
Frictional Heat ◽  
Asperity Contact ◽  
Wet Clutch ◽  
Engagement Process ◽  
Torque Curve ◽  
The Many ◽  
Made In

Theoretical analysis was carried out on the engagement process of a paper based wet clutch. The annular multidisk clutch in a SAE#2 tester was chosen as an example. The average flow model on partial hydrodynamic lubrication proposed by Patir and Cheng was employed for the analysis of squeeze motion taking the permeability, the compressive strain, and the asperity contact of paper facing into account. Simultaneously, the equations of heat conduction were solved to calculate the viscosity reduction due to frictional heat generation. The theoretical torque curve agreed qualitatively with the experimental one in spite of the many assumptions made in this analysis.

Modeling and experimental research on engaging characteristics of wet clutch

2019 ◽  
Vol 71 (1) ◽  
pp. 94-101 ◽  
Author(s):  
Yanzhong Wang ◽  
Yuan Li ◽  
Yang Liu ◽  
Wei Zhang
Keyword(s):  
Contact Surface ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Lubricating Oil ◽  
Centrifugal Effect ◽  
Element Analysis ◽  
Content Type ◽  
Clutch Engagement ◽  
Wet Clutch ◽  
Engagement Process

PurposeTo gain in-depth understandings of engaging characteristics, the purpose of this paper is to improve the model of wet clutches to predict the transmitted torque during the engagement process.Design/methodology/approachThe model of wet clutch during the engagement process took main factors into account, such as the centrifugal effect of lubricant, permeability of friction material, slippage factor of lubricant on contact surface and roughness of contact surface. Reynolds’ equation was derived to describe the hydrodynamic lubrication characteristics of lubricant film between the friction plate and the separated plate, and an elastic-plastic model of the rough surfaces contact based on the finite element analysis was used to indicate the loading force and friction torque of the contact surface.FindingsThe dynamic characteristics of wet clutch engagement time, relative speed, hydrodynamic lubrication of lubricating oil, rough surface contact load capacity and transfer torque can be obtained by the wet clutch engagement model. And the influence of the groove shape and depth on the engaging characteristics is also analyzed.Originality/valueThe mathematical model of the wet clutch during the engagement process can be used to predict the engaging characteristics of the wet clutch which could be useful to the design of the wet clutch.

Research on the Wet Clutch Engagement Torque

2014 ◽  
Author(s):  
Yingying Zhang ◽  
Changle Xiang
Keyword(s):  
Rough Surface ◽  
Automatic Transmission ◽  
Squeeze Film ◽  
Real Contact Area ◽  
Asperity Contact ◽  
Time Flow ◽  
Clutch Engagement ◽  
Wet Clutch ◽  
Lubrication Oil ◽  
Engagement Process

The driving performance of the vehicle with automatic transmission is influenced by the performance of the wet clutch directly. But at present it is still a challenge to build a reliable predictable model for the torque of the engagement process of the wet clutch. Focusing on the wet clutch of vehicle, this paper starts from mechanism analysis, and a modified Reynolds equation with the consideration of the centrifugal force of the squeeze-film is established. In the model, we can consider the speeds of the friction and separator plates independently. At the same time, flow factors have been used to research the impacts of rough surface on the flow of the lubrication oil. In the three-dimensional solution domain, the circumferential pressure gradient of lubrication oil is considered. The model is solved with the finite volume method. The simulation of the torque of the asperity contact calculates the real contact area changed with the engagement process, and the microscopic texture direction of rough surface is considered. Subsequently, the squeeze-film flow model is combined with the asperity contact model to create an integrated clutch engagement model. Finally, the influence of applied force, viscosity of lubrication oil, friction material, the depth of grooves and the width of the grooves are investigated. Based on the comparison with the experimental data, the performance of the proposed model is found satisfactory. Because in this model more detail properties of material and geometric features of the friction plate are include, the wet clutch model developed in this research can become a baseline model for the prediction of the engagement behavior of a real wet clutch. The present model may become an efficient alternative to laboratory testing and lead to designs that can not be envisioned by other approaches.

Parametric analysis of wear factors of a wet clutch friction material with different groove patterns

2017 ◽  
Vol 231 (8) ◽  
pp. 1056-1067 ◽  
Author(s):  
M Li ◽  
MM Khonsari ◽  
DMC McCarthy ◽  
Joakim Lundin
Keyword(s):  
Temperature Field ◽  
Material Properties ◽  
Parametric Analysis ◽  
Wear Test ◽  
Friction Material ◽  
Asperity Contact ◽  
Wet Clutch ◽  
Engagement Process ◽  
Insight Into ◽  
Friction Lining

The experimentally observed, two-stage wear in the wet clutch friction material is directly related to temperature and engagement load. To gain insight into the durability of the friction lining, an extensive parametric analysis of the factors is performed that takes into account different groove patterns (waffle shape, radial, and spiral), internal structure and material properties. The temperature field is predicted using a thermohydrodynamic analysis with the consideration of the asperity contact stress during the engagement process. The results should be useful to facilitate the industrial design of friction lining by avoiding costly wear test.

A Handbook to Eddic Poetry: Myths and Legends of Early Scandinavia, ed. Carolyne Larrington, Judy Quinn, and Brittany Schorn. Cambridge: Cambridge University Press, 2016, xii, 413 pp., 12 b/w ill.

Mediaevistik ◽  
2018 ◽  
Vol 31 (1) ◽  
pp. 366-366
Author(s):  
Albrecht Classen
Keyword(s):  
Old Norse ◽  
Entire Volume ◽  
Cambridge University ◽  
Critical Studies ◽  
Individual Contributions ◽  
The Many ◽  
The Individual ◽  
Made In ◽  
Scandinavian Literature

Eddic poetry constitutes one of the most important genres in Old Norse or Scandinavian literature and has been studied since the earliest time of modern-day philology. The progress we have made in that field is impressive, considering the many excellent editions and translations, not to mention the countless critical studies in monographs and articles. Nevertheless, there is always a great need to revisit, to summarize, to review, and to digest the knowledge gained so far. The present handbook intends to address all those goals and does so, to spell it out right away, exceedingly well. But in contrast to traditional concepts, the individual contributions constitute fully developed critical article, each with a specialized topic elucidating it as comprehensively as possible, and concluding with a section of notes. Those are kept very brief, but the volume rounds it all off with an inclusive, comprehensive bibliography. And there is also a very useful index at the end. At the beginning, we find, following the table of contents, a list of the contributors, unfortunately without emails, a list of translations and abbreviations of the titles of Eddic poems in the Codex Regius and then elsewhere, and a very insightful and pleasant introduction by Carolyne Larrington. She briefly introduces the genre and then summarizes the essential points made by the individual authors. The entire volume is based on the Eddic Network established by the three editors in 2012, and on two workshops held at St. John’s College, Oxford in 2013 and 2014.

Evidence-based Assessment

2010 ◽  
pp. 76-98
Author(s):  
John Hunsley ◽  
Eric J. Mash
Keyword(s):  
Decision Making ◽  
Clinical Assessment ◽  
Assessment Process ◽  
Evidence Based ◽  
The Past ◽  
Specific Assessment ◽  
The Many ◽  
Selection Of ◽  
Made In

Evidence-based assessment relies on research and theory to inform the selection of constructs to be assessed for a specific assessment purpose, the methods and measures to be used in the assessment, and the manner in which the assessment process unfolds. An evidence-based approach to clinical assessment necessitates the recognition that, even when evidence-based instruments are used, the assessment process is a decision-making task in which hypotheses must be iteratively formulated and tested. In this chapter, we review (a) the progress that has been made in developing an evidence-based approach to clinical assessment in the past decade and (b) the many challenges that lie ahead if clinical assessment is to be truly evidence-based.

Effect of shape/size and distribution of microgeometries of textures on tribo-performance of crankpin bearing

2021 ◽  
pp. 135065012110105
Author(s):  
Nguyen Van Liem ◽  
Wu Zhenpeng ◽  
Jiao Renqiang
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Contact Force ◽  
Distribution Density ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Asperity Contact ◽  
Combined Model ◽  
Obvious Effect ◽  
Area Density

The effect of the shape/size and distribution of microgeometries of textures on improving the tribo-performance of crankpin bearing is proposed. Based on a combined model of the slider-crank mechanism dynamic and hydrodynamic lubrication, the distribution density, area density, and shape of spherical textures, square-cylindrical textures, wedge-shaped textures, and a hybrid between spherical texture and square-cylindrical texture on the crankpin bearing's tribo-performance are investigated under different operating conditions of the engine. The tribological characteristic of the crankpin bearing is then evaluated via the indexes of the oil film pressure p, asperity contact force, friction force, and friction coefficient of the crankpin bearing. The research results show that the distribution density with n = 12 and m = 6, and area density with α = 30% of various microtextures have an obvious effect on ameliorating the crankpin bearings tribo-performance. Concurrently, at the mixed lubrication region, the shape of the square-cylindrical texture on improving the tribo-performance is better than the other shapes of the spherical texture, wedge-shaped texture, and spherical and square-cylindrical texture. Particularly, all the average values of the asperity contact force, friction force, and friction coefficient with a square-cylindrical texture are significantly reduced by 14.6%, 19.5%, and 34.5%, respectively, in comparison without microtextures. Therefore, the microtextures of the spherical texture applied on the bearing surface can contribute to enhance the durability and decrease the friction power loss of the engine.

The Technique of the Boyne Carvings

1956 ◽  
Vol 21 ◽  
pp. 156-159
Author(s):  
O. G. S. Crawford
Keyword(s):  
Presidential Address ◽  
Time And Space ◽  
East Anglia ◽  
Actual Design ◽  
The Many ◽  
To Receive ◽  
Vast Range ◽  
Made In

The prudent contributor to a Festschrift will select some subject about which he thinks he knows as much as the professor who is to receive it. That is peculiarly difficult here because of the vast range of Professor Childe's knowledge, both in time and space, far exceeding the present contributor's. This Note is offered as a grateful tribute from one of the many who have been intellectually enriched by his writings and encouraged by his devotion to scholarship. It is little more than an amplification and criticism of the Abbé Breuil's classic Presidential Address to the Prehistoric Society of East Anglia, delivered in 1934; but on the strength of observations made in August and September, 1955, I have come to different conclusions.The Abbé Breuil detected five successive techniques, all of them found on the stones of the Boyne Tombs:(1) Incised thin lines (pl. XIX, B).(2) Picked grooves left rough (pl. XVIII).(3, a) Picked grooves afterwards rubbed smooth; in this and the preceding group ‘it is invariably the line (groove) itself on which the pattern depends, which gives and is the design’.(3, b) Picked areas which ‘only define the limits of the pattern, the surface, left in relief by the cutting down of the background, constituting the actual design’ (pl. xx, B).(4) Rectilinear patterns where also the pattern is residual, consisting of raised ribs, forming triangles or lozenges, left standing by picking away the surrounding surface (pl. xx, A).

Closing Remarks

2019 ◽  
Vol 15 (S367) ◽  
pp. 515-517
Author(s):  
Debra Meloy Elmegreen
Keyword(s):  
Big Data ◽  
Education Research ◽  
Strategic Plan ◽  
Astronomy Education ◽  
The Public ◽  
The Many ◽  
Collaborative Efforts ◽  
Made In

AbstractThis symposium has highlighted key first steps made in addressing many goals of the IAU Strategic Plan for 2020–2030. Presentations on initiatives regarding education, with applications to development, outreach, equity, inclusion, big data, and heritage, are briefly summarized here. The many projects underway for the public, for students, for teachers, and for astronomers doing astronomy education research provide a foundation for future collaborative efforts, both regionally and globally.

Legislation as Vulnerability Factor

2006 ◽  
Vol 31 (1) ◽  
pp. 84-89
Author(s):  
Jorge Gavidia ◽  
Annalisa Crivellari
Keyword(s):  
Dominican Republic ◽  
Central America ◽  
Disaster Management ◽  
Good Practice ◽  
Hurricane Mitch ◽  
Normative Framework ◽  
The Many ◽  
Civil Defence ◽  
Interconnected Structure ◽  
Made In

A study conducted in Central America in 2003 shows that in the aftermath of Hurricane Mitch noticeable progress was made in introducing new legislation for disaster management, understood as covering the whole cycle from prevention, preparedness and relief, to reconstruction. The new legislation includes civil defence or disaster management laws and regulations to improve their effectiveness in responding to the threat of natural disasters. A similar situation can be observed in other countries like Cuba and the Dominican Republic. The study looks into existing urban and municipal laws, regulations and planning guidelines to assess the extent to which they respond to vulnerability reduction criteria. This paper focuses on aspects of prevention and risk reduction. An attempt was made to look into the complementarities and gaps between the two sets of regulations for disaster management and for municipal/urban management. It is found that despite the many elements of good practice included in them, the links between these instruments are weak or absent on issues ranging from planning to the actual supervision of interventions on the built environment. Thus, the main elements of the edifice were there, but they did not constitute a solid, interconnected, structure, therefore, bound to fail under the loads imposed by rapid urbanisation, speculation, emergencies and weak governance structures. Institutions are often left to fend themselves in discharging their tasks. Without a coherent normative framework, and the capacity to apply it, their work is primarily driven by institutional initiative, leading to problems of underperformance, overlaps, gaps, and non-constructive competition. Thus, the institutional setup and normative framework become important factors in increasing vulnerability, as real as a building with the wrong foundations. The article reviews the mentioned aspects drawing from the experience in Central America, Cuba and Dominican Republic.

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