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The leeds university M.Sc. course in tribology
165
Wear, 38 (1976) 165 - 172 0 Elsevier Sequoia S.A., Lausanne - Printed in the Netherlands
THE LEEDS
UNIVERSITY
D. A. JONES, C. M. TAYLOR Institute of Tribology,
M.Sc. COURSE
IN TRIBOLOGY”
and D. DOWSON
University of Leeds, Leeds (Gt. Britain)
(Received October 9, 1975)
Summary
The twelfth presentation of the Leeds University M.Sc. course in tribology commenced in October, 1975. It is currently the only course of its type in Europe. It was designed to attract students from a variety of disciplines to an area where their diverse backgrounds might be usefully employed. To date 103 people have graduated from the course and a sizable minority do, in fact, hold first degree qualifications in areas other than mechanical engineering. Recruitment to the course continues at a satisfactory level despite a recent fall in the number of students seconded from industry and, indeed, in the number of British graduates opting for advanced study generally.
Introduction
The Leeds University M.Sc. course in tribology is presented within the Institute of Tribology, the latter being an umbrella organization covering tibology teaching, research and industrial liaison within the mechanical engineering department. The Institute has strong links with other departments of our own university and with numerous outside organizations, both academic and industrial. The first presentation of the course commenced in October, 1964. It was then known as the M.Sc course in “Lubrication, Friction, Wear and Bearing Design”. The Jost committee was established in the following December and submitted its report [l] in early 1966. In certain respects at least the Leeds course anticipated the Jost committee findings. In particular, in connection with postgraduate education the working party made the following recommendations. “(i) Postgraduate courses in tribology leading to M.Sc. degrees, diplomas and other higher awards should be made available in three or four centres, placed to meet industrial requirements. These centres should also be capable of offering full-time courses of between 4 and 12 weeks duration. *Paper presented at the 3rd International Tribology Conference Eighties”, Paisley, September 22 - 25, 1975.
“Tribologyfor the
166
(ii) Education for specialists in tribology at postgraduate level should preferably be carried out at centres conducting tribological research.” The Leeds course is suitably centred in the above terms and was designed not only to supply some of the specialist graduates required by industry but also to offer some of the proposed shorter courses. (The dual function was achieved by making use of a component structure for the lecture course.) The course structure Nominally the course occupies a full 12 months. In practice students are involved for approximately 10% months only for administrative reasons. The course involves three main assessable elements, a sequence of lectures, a design project and an experimental project. The course of about 200 lectures builds from a broadly based series on fundamentals to the more practical problems associated with design. An outline of the course content is given in Appendix A. (For a more detailed syllabus see ref. 2.) The greater proportion of the lectures are presented by members of the Institute, although sequences on specific topics are usually rounded-off with one or two lectures given by visitors. In the current session, and typically, ten visiting lecturers are involved. Lectures are presented in the autumn and spring terms. This part of the student’s work is assessed conventionally, through six 3 h examinations which take place at the beginning of the summer term. In the spring term students attempt three or four individual design problems intended to occupy them for approximately 100 h. Their work is assessed on the basis of formally constructed design project reports submitted at the end of the spring term. The tasks allocated in the current session are detailed in Appendix B. Experimental project work begins shortly after students commence their course, in October. Generally speaking, the main data gathering exercises commence with the end of examinations (in May), the earlier period being used for literature survey, planning, equipment modification and so on. Appendix C lists the projects for the current session. Discussion To date approximately 100 men (and one woman) have graduated from the course, a majority having first degrees in mechanical engineering although a sizable minority were trained in other areas. This point reflects the interdisciplinary nature of tribology and makes for an attractive mixture of students; it also imposes certain limitations on timetabling, at least in the early stages since all course members have to have a certain minimum grounding. This is particularly true of a course attracting a significant proportion of overseas students. For example, we find it is necessary to provide extensive instruction in numerical analysis and computer programming, subjects in which in our
167
opinion many students receive inadequate tuition in their undergraduate courses. During the 11 years in which the course has been presented many efforts have been made to improve its quality in all aspects. One of the most successful features has been the series of external lectures. This has proved popular with students, accentuates our concern with the needs of industry and enables coverage of areas where permanent staff have no expertise. In addition experiments have been made in other areas: in lecture scheduling, industrial visits, small group teaching [3]. A particular scheme which has proved useful in drawing course members together has been a series of general lectures in which each student has to present to his fellows a discourse on a subject of his choice and to answer questions. This gives experience in gathering data and presenting material. Of course a continuous updating of the lecture material has also been undertaken, this being facilitated by the active research school within the department. Student recruitment has been and continues to be satisfactory, although it becomes ever more difficult to attract British nationals. This is true of postgraduate work in general. There has been a steady flow of candidates for the course from institutions of higher education in the United Kingdom and overseas, with a noticeable growth of students from Europe. The numbers taking the course are approximately twice the national average for master’s courses. Support from industry, at least in terms of staff secondment, has been disappointing of late. In 1970 a statistical review of the course [ 21 indicated that one-third of course members came to us from industry in this way. This proportion has fallen substantially more recently. This is unfortunate since secondment proved mutually beneficial in the past. It certainly requires one to reconsider the r&on d’&re of our scheme of study which was founded at a time when industry seemed to favour the establishment of master’s courses in applied science. Industry has made little use of the five week course component scheme of study. Thus, as Appendix A indicates, the major technical subjects dealt with in the course are divided into five main sections. It was intended that attendance at one of the five components, e.g. bearing selection and design, would be possible. However a substantial short term secondment seems to pose more administrative problems for industry than release for a period of a year. There are also timetabling difficulties in the university so that this scheme has effectively been abandoned although specific requirements in this area can usually be accommodated. No doubt a feature which has limited entry of United Kingdom nationals onto this and like courses has been the modest level of Science Research Council grants, particularly in the recent inflationary times. There would appear to be a case for relating grants not only more directly and frequently to a cost of living index, but also to the national need for such postgraduate training. At first sight it would be expected that master’s courses would have more attraction than Ph.D. research. Industry purports to value the former more highly than the latter [4]. The man who enters industry with a Ph.D.
has little real financial advantage over even a man with only a first degree. However those wishing to undertake research work often do so for other reasons. Such people could often benefit from taking an M.Sc. before commencing research but the Science Research Council limitation on funding to three years postgraduate work makes this unattractive because of the difficulties in completing a research programme in two years. Thus many such men are lost to the master’s degree scheme by examination. Generally M.Sc. course organizers are forced to accept a high proportion of overseas students at the present time and this is causing considerable concern. Each foreign student brings into the country finance of the order of flOO0 per annum, this constituting an invisible export. Fees charged to overseas students are three times those charged to our own nationals, but are still considerably less than the actual cost of the education they receive. Implementation of the suggestion to raise fees for overseas men to an economic level would decimate many postgraduate schools and also abrogate any responsibility we may have to contribute to the progress of underdeveloped countries. In this discussion we have concerned ourselves primarily with administrative and political matters rather than with the technical structure of the course, which has been dealt with more fully elsewhere [ 21. This reflects the need to examine closely the direction in which universities are going at the present time and to reassess values and priorities. Most aspects of university life are under attack: restrictive government financing could possibly be a backdoor-way of implementing a “comprehensive universities” policy (which has not been formally announced); staff career prospects are limited and the consequent low morale must be detrimental to university life; although the quality of the teaching process has probably never been better and is receiving increasing attention there is much adverse comment on courses and the students they,produce; research is widely criticized, particularly by a number of eminent industrialists [ 31. Universities like most institutions have problems and faults, but they do make a valuable contribution to our society. It is to be hoped that a too hasty modification of their functions and aims will not be undertaken without good cause. Conclusion This university department has established, at no small cost, a specific M.Sc. course which meets some of the needs of British industry as expressed in the Jost report. Most of its 100 graduates are now employed in this country and are contributing to the needs of our industry. However, of late there has been a marked reluctance for industry to support this course through staff secondment. Partly for this reason we find it increasingly difficult to attract British students of sufficient quality, resulting in an increase in the proportion of overseas candidates.
169
References 1 Lubrication (Triboiogy) Education and Research, A Report on the Present Position and Industry’s Needs, HMSO Rep., February, 1966. 2 D. A. Jones, Postgraduate Course in Tribology, Conf. Proc. on Teaching Tribology, Iliffe, London, 1970. 3 C. .M. Taylor, Postgraduate Education and Research in Tribology, Exposition on the Industrial Technologies, Royal Institution, March, 1975. 4 Total Technology, A Report by the Science Research Council, Engineering Board, July, 197 3.
Appendix A A summary of the lecture syllabus on the MSc. (tribology) course at Leeds University General History Bearing classification Lubrication regimes Lubricant properties Numerical analysis Instrumentation Digital computing Surfaces and surface quality
The fundamentals of lubrication Viscous flow Fluid film lubrication Boundary lubrication Lubricant rheology Grease lubrication Lubricant chemistry Lubrication systems Solid lubricants
The fundamentals of dry contact, friction and wear Elasticity Dry contact Dry friction Wear
Analysis of lubricated contacts in machine elements Energy equation Flash temperature Thermal effects in bearings El~tohydrodynamie lubrication Gear lubrication Stresses in elastohydrodynamic contacts Elastohvdrodvnamic lubrication of soft solids Side leakage ” Squeeze film lubrication Fluid seals
170
Bearing selection and design Introduction to bearing design Selection of lubricated bearing materials Rubbing bearings, materials and design Design and performance of hydrodynamic journal bearings Plain bearing manufacture and installation Hydrodynamic thrust bearing design Externally pressurized bearings Dynamically loaded bearings Water lubricated bearings Rolling contact bearings, design and lubrication Compressible flow, gas bearings
Special topics High speed bearings Rotor dynamics Brakes and clutches Piston rings Corrosion Lubrication of human joints
Appendix B Design projects on the M.Sc. (tribology) course at Leeds University in the academic year 1974 - 5 Thrust bearing design problem Design a suitable tilting pad thrust bearing for a steam turbine which carries a maximum thrust load of 0.3 MN at a rotational speed of 60 Hz. The shaft diameter is 0.165 m. The pads are to be “square” with a maximum length not exceeding 0.130 m. A lubricant conforming to the characteristics of Oil 2 in Fig. 4, p. 28, of the Engineering Sciences Data Item 66023, Calculation Methods for Steadily Loaded Pressure Fed Hydrodynamic Journal Bearings, is supplied at a pressure of 0.14 MN me2 and a temperature of 50 “C. Specify the number and dimensions of the thrust pads, the power loss and the minimum film thickness. Estimate the lubricant flow rate and temperature rise and draw attention to the areas ,of uncertainty in your design procedure. The static thrust is 10% of the maximum operating thrust load. What bearing material would you recommend? Is the self-acting hydrodynamic thrust bearing the most suitable bearing form for this application? Discuss the advantages and disadvantages of other forms of thrust bearings. Compare the analytical design performance with that obtained using the Glacier charts, assuming approximately the same number and size of pads. Contrast the predicted performances. Dynamics of a rolling mill bearing design problem The load on a rod rolling mill bearing is fairly static for relatively long periods, but does change level rather suddenly as new rods enter and leave the rolls.
171
For a bearing with the parameters listed below, predict the transient motion paths of the journal centre as the “static” load shifts instantaneously between 25 600 N and 128 000 N. (The paths involved are from one equilibrium point to the next.) It is suggested that the solution may be obtained by either the “mobility method” or the “impulse method” based on the ruptured-film (A) short bearing solution. The actual process of solution may be either graphical or numerical, .but final presentation should be graphical. L=
200 mm
I-(
=64x
D=
200 mm
Woumal
=20rads-’
c=
0.1 mm
Hydrostatic
10-3Nsm-2
bearing design problem
It is required to support a machine tool spindle in hydrostatic bearings. The spindle is to allow bars of 60 mm diameter to pass through its centre whilst gripping these in a chuck at one end. The specification is as follows. (1) The radial load due to the cutting tool loading is 6000 N. (2) The axial load due to the cutting forces is 1000 N and can act in either direction. (3) The stiffness of the bearings should be such that at the point of application of the tool (i.e. 200 mm from the main journal bearing) it exceeds 15 x lo6 N m-l. (4) ‘A space limitation is that the entire assembly should be less than 500 mm. (5) The speed is 200 rev min- ’ at these loads. It is required that (1) A bearing assembly be designed to acheive the specification including all the dimensions necessary to manufacture the bearing; (2) the lubricant to be used is specified; (3) the characteristics of the system (stiffness, flow rates, power loss etc.) are indicated; (4) all the auxiliary equipment, pumps, supply lines, reservoir, filters etc., including any compensators or control values used, are listed. All decisions taken should be indicated clearly and all assumptions should be justified. Appendix
C
Experimental the academic
projects on the M.Sc. year 1974 - 75
(tribology)
course at Leeds
University
(1) Variation of pressure in an annulus having an inner wall with axial flow and eccentricity (2) A comparison between soft tissue and articular cartilage lubrication
in
172
(3) Frictional properties of human hip joints (4), (5), (6) Super-laminar flow between eccentric rotating cylinders (three projects) (7) Investigation of a flexible compensator (8) A study of film rupture in journal bearings (9) An experimental study of the thrust capacity of cylindrical roller bearings (10) A study of surface tractions and film thickness in roller bearings (11) Autogeneration of fluid film lubrication in tube drawing
Wear, 38 (1976) 165 - 172 0 Elsevier Sequoia S.A., Lausanne - Printed in the Netherlands
THE LEEDS
UNIVERSITY
D. A. JONES, C. M. TAYLOR Institute of Tribology,
M.Sc. COURSE
IN TRIBOLOGY”
and D. DOWSON
University of Leeds, Leeds (Gt. Britain)
(Received October 9, 1975)
Summary
The twelfth presentation of the Leeds University M.Sc. course in tribology commenced in October, 1975. It is currently the only course of its type in Europe. It was designed to attract students from a variety of disciplines to an area where their diverse backgrounds might be usefully employed. To date 103 people have graduated from the course and a sizable minority do, in fact, hold first degree qualifications in areas other than mechanical engineering. Recruitment to the course continues at a satisfactory level despite a recent fall in the number of students seconded from industry and, indeed, in the number of British graduates opting for advanced study generally.
Introduction
The Leeds University M.Sc. course in tribology is presented within the Institute of Tribology, the latter being an umbrella organization covering tibology teaching, research and industrial liaison within the mechanical engineering department. The Institute has strong links with other departments of our own university and with numerous outside organizations, both academic and industrial. The first presentation of the course commenced in October, 1964. It was then known as the M.Sc course in “Lubrication, Friction, Wear and Bearing Design”. The Jost committee was established in the following December and submitted its report [l] in early 1966. In certain respects at least the Leeds course anticipated the Jost committee findings. In particular, in connection with postgraduate education the working party made the following recommendations. “(i) Postgraduate courses in tribology leading to M.Sc. degrees, diplomas and other higher awards should be made available in three or four centres, placed to meet industrial requirements. These centres should also be capable of offering full-time courses of between 4 and 12 weeks duration. *Paper presented at the 3rd International Tribology Conference Eighties”, Paisley, September 22 - 25, 1975.
“Tribologyfor the
166
(ii) Education for specialists in tribology at postgraduate level should preferably be carried out at centres conducting tribological research.” The Leeds course is suitably centred in the above terms and was designed not only to supply some of the specialist graduates required by industry but also to offer some of the proposed shorter courses. (The dual function was achieved by making use of a component structure for the lecture course.) The course structure Nominally the course occupies a full 12 months. In practice students are involved for approximately 10% months only for administrative reasons. The course involves three main assessable elements, a sequence of lectures, a design project and an experimental project. The course of about 200 lectures builds from a broadly based series on fundamentals to the more practical problems associated with design. An outline of the course content is given in Appendix A. (For a more detailed syllabus see ref. 2.) The greater proportion of the lectures are presented by members of the Institute, although sequences on specific topics are usually rounded-off with one or two lectures given by visitors. In the current session, and typically, ten visiting lecturers are involved. Lectures are presented in the autumn and spring terms. This part of the student’s work is assessed conventionally, through six 3 h examinations which take place at the beginning of the summer term. In the spring term students attempt three or four individual design problems intended to occupy them for approximately 100 h. Their work is assessed on the basis of formally constructed design project reports submitted at the end of the spring term. The tasks allocated in the current session are detailed in Appendix B. Experimental project work begins shortly after students commence their course, in October. Generally speaking, the main data gathering exercises commence with the end of examinations (in May), the earlier period being used for literature survey, planning, equipment modification and so on. Appendix C lists the projects for the current session. Discussion To date approximately 100 men (and one woman) have graduated from the course, a majority having first degrees in mechanical engineering although a sizable minority were trained in other areas. This point reflects the interdisciplinary nature of tribology and makes for an attractive mixture of students; it also imposes certain limitations on timetabling, at least in the early stages since all course members have to have a certain minimum grounding. This is particularly true of a course attracting a significant proportion of overseas students. For example, we find it is necessary to provide extensive instruction in numerical analysis and computer programming, subjects in which in our
167
opinion many students receive inadequate tuition in their undergraduate courses. During the 11 years in which the course has been presented many efforts have been made to improve its quality in all aspects. One of the most successful features has been the series of external lectures. This has proved popular with students, accentuates our concern with the needs of industry and enables coverage of areas where permanent staff have no expertise. In addition experiments have been made in other areas: in lecture scheduling, industrial visits, small group teaching [3]. A particular scheme which has proved useful in drawing course members together has been a series of general lectures in which each student has to present to his fellows a discourse on a subject of his choice and to answer questions. This gives experience in gathering data and presenting material. Of course a continuous updating of the lecture material has also been undertaken, this being facilitated by the active research school within the department. Student recruitment has been and continues to be satisfactory, although it becomes ever more difficult to attract British nationals. This is true of postgraduate work in general. There has been a steady flow of candidates for the course from institutions of higher education in the United Kingdom and overseas, with a noticeable growth of students from Europe. The numbers taking the course are approximately twice the national average for master’s courses. Support from industry, at least in terms of staff secondment, has been disappointing of late. In 1970 a statistical review of the course [ 21 indicated that one-third of course members came to us from industry in this way. This proportion has fallen substantially more recently. This is unfortunate since secondment proved mutually beneficial in the past. It certainly requires one to reconsider the r&on d’&re of our scheme of study which was founded at a time when industry seemed to favour the establishment of master’s courses in applied science. Industry has made little use of the five week course component scheme of study. Thus, as Appendix A indicates, the major technical subjects dealt with in the course are divided into five main sections. It was intended that attendance at one of the five components, e.g. bearing selection and design, would be possible. However a substantial short term secondment seems to pose more administrative problems for industry than release for a period of a year. There are also timetabling difficulties in the university so that this scheme has effectively been abandoned although specific requirements in this area can usually be accommodated. No doubt a feature which has limited entry of United Kingdom nationals onto this and like courses has been the modest level of Science Research Council grants, particularly in the recent inflationary times. There would appear to be a case for relating grants not only more directly and frequently to a cost of living index, but also to the national need for such postgraduate training. At first sight it would be expected that master’s courses would have more attraction than Ph.D. research. Industry purports to value the former more highly than the latter [4]. The man who enters industry with a Ph.D.
has little real financial advantage over even a man with only a first degree. However those wishing to undertake research work often do so for other reasons. Such people could often benefit from taking an M.Sc. before commencing research but the Science Research Council limitation on funding to three years postgraduate work makes this unattractive because of the difficulties in completing a research programme in two years. Thus many such men are lost to the master’s degree scheme by examination. Generally M.Sc. course organizers are forced to accept a high proportion of overseas students at the present time and this is causing considerable concern. Each foreign student brings into the country finance of the order of flOO0 per annum, this constituting an invisible export. Fees charged to overseas students are three times those charged to our own nationals, but are still considerably less than the actual cost of the education they receive. Implementation of the suggestion to raise fees for overseas men to an economic level would decimate many postgraduate schools and also abrogate any responsibility we may have to contribute to the progress of underdeveloped countries. In this discussion we have concerned ourselves primarily with administrative and political matters rather than with the technical structure of the course, which has been dealt with more fully elsewhere [ 21. This reflects the need to examine closely the direction in which universities are going at the present time and to reassess values and priorities. Most aspects of university life are under attack: restrictive government financing could possibly be a backdoor-way of implementing a “comprehensive universities” policy (which has not been formally announced); staff career prospects are limited and the consequent low morale must be detrimental to university life; although the quality of the teaching process has probably never been better and is receiving increasing attention there is much adverse comment on courses and the students they,produce; research is widely criticized, particularly by a number of eminent industrialists [ 31. Universities like most institutions have problems and faults, but they do make a valuable contribution to our society. It is to be hoped that a too hasty modification of their functions and aims will not be undertaken without good cause. Conclusion This university department has established, at no small cost, a specific M.Sc. course which meets some of the needs of British industry as expressed in the Jost report. Most of its 100 graduates are now employed in this country and are contributing to the needs of our industry. However, of late there has been a marked reluctance for industry to support this course through staff secondment. Partly for this reason we find it increasingly difficult to attract British students of sufficient quality, resulting in an increase in the proportion of overseas candidates.
169
References 1 Lubrication (Triboiogy) Education and Research, A Report on the Present Position and Industry’s Needs, HMSO Rep., February, 1966. 2 D. A. Jones, Postgraduate Course in Tribology, Conf. Proc. on Teaching Tribology, Iliffe, London, 1970. 3 C. .M. Taylor, Postgraduate Education and Research in Tribology, Exposition on the Industrial Technologies, Royal Institution, March, 1975. 4 Total Technology, A Report by the Science Research Council, Engineering Board, July, 197 3.
Appendix A A summary of the lecture syllabus on the MSc. (tribology) course at Leeds University General History Bearing classification Lubrication regimes Lubricant properties Numerical analysis Instrumentation Digital computing Surfaces and surface quality
The fundamentals of lubrication Viscous flow Fluid film lubrication Boundary lubrication Lubricant rheology Grease lubrication Lubricant chemistry Lubrication systems Solid lubricants
The fundamentals of dry contact, friction and wear Elasticity Dry contact Dry friction Wear
Analysis of lubricated contacts in machine elements Energy equation Flash temperature Thermal effects in bearings El~tohydrodynamie lubrication Gear lubrication Stresses in elastohydrodynamic contacts Elastohvdrodvnamic lubrication of soft solids Side leakage ” Squeeze film lubrication Fluid seals
170
Bearing selection and design Introduction to bearing design Selection of lubricated bearing materials Rubbing bearings, materials and design Design and performance of hydrodynamic journal bearings Plain bearing manufacture and installation Hydrodynamic thrust bearing design Externally pressurized bearings Dynamically loaded bearings Water lubricated bearings Rolling contact bearings, design and lubrication Compressible flow, gas bearings
Special topics High speed bearings Rotor dynamics Brakes and clutches Piston rings Corrosion Lubrication of human joints
Appendix B Design projects on the M.Sc. (tribology) course at Leeds University in the academic year 1974 - 5 Thrust bearing design problem Design a suitable tilting pad thrust bearing for a steam turbine which carries a maximum thrust load of 0.3 MN at a rotational speed of 60 Hz. The shaft diameter is 0.165 m. The pads are to be “square” with a maximum length not exceeding 0.130 m. A lubricant conforming to the characteristics of Oil 2 in Fig. 4, p. 28, of the Engineering Sciences Data Item 66023, Calculation Methods for Steadily Loaded Pressure Fed Hydrodynamic Journal Bearings, is supplied at a pressure of 0.14 MN me2 and a temperature of 50 “C. Specify the number and dimensions of the thrust pads, the power loss and the minimum film thickness. Estimate the lubricant flow rate and temperature rise and draw attention to the areas ,of uncertainty in your design procedure. The static thrust is 10% of the maximum operating thrust load. What bearing material would you recommend? Is the self-acting hydrodynamic thrust bearing the most suitable bearing form for this application? Discuss the advantages and disadvantages of other forms of thrust bearings. Compare the analytical design performance with that obtained using the Glacier charts, assuming approximately the same number and size of pads. Contrast the predicted performances. Dynamics of a rolling mill bearing design problem The load on a rod rolling mill bearing is fairly static for relatively long periods, but does change level rather suddenly as new rods enter and leave the rolls.
171
For a bearing with the parameters listed below, predict the transient motion paths of the journal centre as the “static” load shifts instantaneously between 25 600 N and 128 000 N. (The paths involved are from one equilibrium point to the next.) It is suggested that the solution may be obtained by either the “mobility method” or the “impulse method” based on the ruptured-film (A) short bearing solution. The actual process of solution may be either graphical or numerical, .but final presentation should be graphical. L=
200 mm
I-(
=64x
D=
200 mm
Woumal
=20rads-’
c=
0.1 mm
Hydrostatic
10-3Nsm-2
bearing design problem
It is required to support a machine tool spindle in hydrostatic bearings. The spindle is to allow bars of 60 mm diameter to pass through its centre whilst gripping these in a chuck at one end. The specification is as follows. (1) The radial load due to the cutting tool loading is 6000 N. (2) The axial load due to the cutting forces is 1000 N and can act in either direction. (3) The stiffness of the bearings should be such that at the point of application of the tool (i.e. 200 mm from the main journal bearing) it exceeds 15 x lo6 N m-l. (4) ‘A space limitation is that the entire assembly should be less than 500 mm. (5) The speed is 200 rev min- ’ at these loads. It is required that (1) A bearing assembly be designed to acheive the specification including all the dimensions necessary to manufacture the bearing; (2) the lubricant to be used is specified; (3) the characteristics of the system (stiffness, flow rates, power loss etc.) are indicated; (4) all the auxiliary equipment, pumps, supply lines, reservoir, filters etc., including any compensators or control values used, are listed. All decisions taken should be indicated clearly and all assumptions should be justified. Appendix
C
Experimental the academic
projects on the M.Sc. year 1974 - 75
(tribology)
course at Leeds
University
(1) Variation of pressure in an annulus having an inner wall with axial flow and eccentricity (2) A comparison between soft tissue and articular cartilage lubrication
in
172
(3) Frictional properties of human hip joints (4), (5), (6) Super-laminar flow between eccentric rotating cylinders (three projects) (7) Investigation of a flexible compensator (8) A study of film rupture in journal bearings (9) An experimental study of the thrust capacity of cylindrical roller bearings (10) A study of surface tractions and film thickness in roller bearings (11) Autogeneration of fluid film lubrication in tube drawing