14 resultados para Sheet-metal -- Study and teaching

em Aston University Research Archive


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In the bulge test, a sheet metal specimen is clamped over a circular hole in a die and formed into a bulge by the hydraulic pressure on one side of the specirnen. As the unsupported part of the specimen is deformed in this way, its area is increased, in other words, the material is generally stretched and its thickness generally decreased. The stresses causing this stretching action are the membrane stresses in the shell generated by the hydraulic pressure, in the same way as the rubber in a toy balloon is stretched by the membrane stresses caused by the air inside it. The bulge test is a widely used sheet metal test, to determine the "formability" of sheet materials. Research on this forming process (2)-(15)* has hitherto been almost exclusively confined to predicting the behaviour of the bulged specimen through the constitutive equations (stresses and strains in relation to displacements and shapes) and empirical work hardening characteristics of the material as determined in the tension test. In the present study the approach is reversed; the stresses and strains in the specimen are measured and determined from the geometry of the deformed shell. Thus, the bulge test can be used for determining the stress-strain relationship in the material under actual conditions in sheet metal forming processes. When sheet materials are formed by fluid pressure, the work-piece assumes an approximately spherical shape, The exact nature and magnitude of the deviation from the perfect sphere can be defined and measured by an index called prolateness. The distribution of prolateness throughout the workpiece at any particular stage of the forming process is of fundamental significance, because it determines the variation of the stress ratio on which the mode of deformation depends. It is found. that, before the process becomes unstable in sheet metal, the workpiece is exactly spherical only at the pole and at an annular ring. Between the pole and this annular ring the workpiece is more pointed than a sphere, and outside this ring, it is flatter than a sphere. In the forming of sheet materials, the stresses and hence the incremental strains, are closely related to the curvatures of the workpiece. This relationship between geometry and state of stress can be formulated quantitatively through prolateness. The determination of the magnitudes of prolateness, however, requires special techniques. The success of the experimental work is due to the technique of measuring the profile inclination of the meridional section very accurately. A travelling microscope, workshop protractor and surface plate are used for measurements of circumferential and meridional tangential strains. The curvatures can be calculated from geometry. If, however, the shape of the workpiece is expressed in terms of the current radial (r) and axial ( L) coordinates, it is very difficult to calculate the curvatures within an adequate degree of accuracy, owing to the double differentiation involved. In this project, a first differentiation is, in effect, by-passed by measuring the profile inclination directly and the second differentiation is performed in a round-about way, as explained in later chapters. The variations of the stresses in the workpiece thus observed have not, to the knowledge of the author, been reported experimentally. The static strength of shells to withstand fluid pressure and their buckling strength under concentrated loads, both depend on the distribution of the thickness. Thickness distribution can be controlled to a limited extent by changing the work hardening characteristics of the work material and by imposing constraints. A technique is provided in this thesis for determining accurately the stress distribution, on which the strains associated with thinning depend. Whether a problem of controlled thickness distribution is tackled by theory, or by experiments, or by both combined, the analysis in this thesis supplies the theoretical framework and some useful experimental techniques for the research applied to particular problems. The improvement of formability by allowing draw-in can also be analysed with the same theoretical and experimental techniques. Results on stress-strain relationships are usually represented by single stress-strain curves plotted either between one stress and one strain (as in the tension or compression tests) or between the effective stress and effective strain, as in tests on tubular specimens under combined tension, torsion and internal pressure. In this study, the triaxial stresses and strains are plotted simultaneously in triangular coordinates. Thus, both stress and strain are represented by vectors and the relationship between them by the relationship between two vector functions. From the results so obtained, conclusions are drawn on both the behaviour and the properties of the material in the bulge test. The stress ratios are generally equal to the strain-rate ratios (stress vectors collinear with incremental strain vectors) and the work-hardening characteristics, which apply only to the particular strain paths are deduced. Plastic instability of the material is generally considered to have been reached when the oil pressure has attained its maximum value so that further deformation occurs under a constant or lower pressure. It is found that the instability regime of deformation has already occurred long before the maximum pressure is attained. Thus, a new concept of instability is proposed, and for this criterion, instability can occur for any type of pressure growth curves.

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This investigation is in two parts, theory and experimental verification. (1) Theoretical Study In this study it is, for obvious reasons, necessary to analyse the concept of formability first. For the purpose of the present investigation it is sufficient to define the four aspects of formability as follows: (a) the formability of the material at a critical section, (b) the formability of the material in general, (c) process efficiency, (d) proportional increase in surface area. A method of quantitative assessment is proposed for each of the four aspects of formability. The theoretical study also includes the distinction between coaxial and non-coaxial strains which occur, respectively, in axisymmetrical and unsymmetrical forming processes and the inadequacy of the circular grid system for the assessment of formability is explained in the light of this distinction. (2) Experimental Study As one of the bases of the experimental work, the determination of the end point of a forming process, which sets the limit to the formability of the work material, is discussed. The effects of three process parameters on draw-in are shown graphically. Then the delay of fracture in sheet metal forming resulting from draw-in is analysed in kinematical terms, namely, through the radial displacements, the radial and the circumferential strains, and the projected thickness of the workpiece. Through the equilibrium equation of the membrane stresses, the effect on the shape of the unsupported region of the workpiece, and hence the position of the critical section is explained. Then, the effect of draw-in on the four aspects of formability is discussed throughout this investigation. The triangular coordinate system is used to present and analyse the triaxial strains involved. This coordinate system has the advantage of showing all the three principal strains in a material simultaneously, as well as representing clearly the many types of strains involved in sheet metal work.

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Once again this publication is produced to celebrate and promote good teaching and learning support and to offer encouragement to those imaginative and innovative staff who continue to wish to challenge students to learn to maximum effect. It is hoped that others will pick up some good ideas from the articles contained in this volume. We have again changed our approach for this 2007/08 edition (our fifth) of the Aston Business School Good Practice Guide. As before, some contributions were selected from those identifying interesting best practice on their Annual Module Reflection Forms in 2006/2007. Brookes? contribution this year is directly from her annual reflection. Other contributors received HELM (Research Centre in Higher Education Learning and Management) small research grants in 2006/2007. Part of the conditions were for them to write an article for this publication. We have also been less tight on the length of the articles this year. Some contributions are, therefore, on the way to being journal articles. HELM will be working with these authors to help develop these for publication. Looking back over the last five years it is brilliant to see how many different people have contributed over the years and, therefore, how much innovative learning and teaching work has been taking place in ABS over this time. In the first edition we were just pleased for people to write a few pages on their teaching. Now things have changed dramatically. The majority of the articles are grounded in empirical research (some funded by HELM small research grants) and Palmer?s article was produced as part of the University?s Postgraduate Certificate in Learning and Teaching. Most encouraging of all, four of this year?s articles have since been developed further and submitted to refereed journals. We await news of publication as we go to press. It is not surprising that how to manage large groups still remains a central theme of the articles, ABS has a large and still growing student body. Essex and Simpson have looked at trying to encourage students to attend taught sessions, on the basis that there is a strong correlation between attendance and higher performance. Their findings are forming the platform of a further study currently being carried out in the Undergraduate Programme. A number of the other articles concentrate on trying to encourage students to engage with study in an innovative way. This is particularly obvious in Shaw?s work. Everyone who has been around campus lately has had evidence that the students on Duncan?s modules have clearly been inspired. I found myself, for example, playing golf in the student dining room as part of this initiative! The articles by Jarzabkowski & Guilietti and Ho involved much larger surveys. This is another first for the Good Practice Guide and marks the first step on what will clearly be larger research efforts for these authors in this area. We look forward to the journal publications which will result from this work. The last articles are the result of HELM?s hosting of the national conference of the Higher Education Academy?s Business, Management, Accounting and Finance (BMAF) Subject Centre Conference in May 2007. Belal and Foster have written about their impressions of the Conference and Andrews has included the paper she gave. The papers on employability and widening participation are the centre of HELM?s current work. In the second volume we mentioned the launch of the School?s Research Centre in Higher Education Learning and Management (HELM). Since then HELM has stimulated a lot of activity across the School (and University) particularly linking research and teaching. A list of the HELM seminars for 2007/2008 is listed as Appendix 1 of this publication. Further details can be obtained from Catherine Foster (c.s.foster@aston.ac.uk), who coordinates the HELM seminars. We have also been working on a list of target journals to guide ABS staff who wish to publish in this area. These are included as Appendix 2 of this publication. May I thank the contributors for taking time out of their busy schedules to write the articles and to Julie Green, the Quality Manager, for putting the varying diverse approaches into a coherent and publishable form and for agreeing to fund the printing of this volume.

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This comparative study considers the main causative factors for change in recent years in the teaching of modern languages in England and France and seeks to contribute, in a general sense, to the understanding of change in comparable institutions. In England by 1975 the teaching of modern languages in the comprehensive schools was seen to be inappropriate to the needs of children of the whole ability-range. A combination of the external factor of the Council of Europe initiative in devising a needs-based learning approach for adult learners, and the internal factor of teacher-based initiatives in developing a graded-objectives learning approach for the less-able, has reversed this situation to some extent. The study examines and evaluates this reversal, and, in addition, assesses teachers' attitudes towards, and understanding of, the changes involved. In France the imposition of `la reforme Haby' in 1977 and the creation of `le college unique' were the main external factors for change. The subsequent failure of the reform and the socialist government's support of decentralisation policies returning the initiative for renewal to schools are examined and evaluated, as are the internal factors for changes in language-teaching - `groupes de niveau' and the creation of `equipes pedagogiques'. In both countries changes in the function of examinations at 15/16 plus are examined. The final chapter compared the changes in both education systems.

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A study has been made of the effects of welding and material variables on the occurrence of porosity in tungsten inert gas arc welding of copper. The experiments were based on a statistical design and variables included, welding current, welding speed, arc atmosphere composition, inert gas flow rate, weld preparation, and base material. The extent of weld metal porosity was assessed by density measurement and its morphology by X-ray radiography and metallography. In conjunction with this the copper-steam reaction has been investigated under conditions of controlled atmosphere arc melting. The welding experiments have shown that the extent of steam porosity is increased by increased water vapour content of the arc atmosphere, increased oxygen content of the base material and decreased welding speed. The arc melting experiments have shown that the steam reaction occurs in the body of the weld pool and proceeds to an apparent equi1ibrium state appropriate to to its temperature, the hydrogen and oxygen being supplied by the dissociation of water vapour in the arc atmosphere. It has been shown conclusively that nitrogen porosity can occur in the tungsten inert gas arc welding of copper and that this porosity can be eliminated by using filler wires containing small amounts of aluminum and titanium. Since it has been shown to be much more difficult to produce sound butt welds than melt runs it has been concluded that the porosity associated with joint fit up is due to nitrogen entrained into tho arc atmosphere. Clearly atmospheric entrainment would also, to a much lesser extent, involve water vapour. From a practical welding point of view it has thus been postulated that use of a filler wire containing small amounts of aluminum and/or titanium would eliminate both forms of porosity since these elements are both strongJy deoxidising and denitriding.

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The relationship between research and learning and teaching represents what has been described as ‘amongst the most intellectually tangled, managerially complex and politically contentious issues in mass higher education’ (Scott, 2005, p 53). Despite this, arguments that in order to achieve high quality scholarly outcomes, university teachers need to adopt an approach to teaching similar to that of research (i.e. founded upon academic rigour and evidence), has long been discussed in the literature (see for example, Elton, 2005 & Healey, 2000). However, the practicalities of promoting an empirical and evidence-based approach to teaching within a research-led institution makes dealing with the research/learning and teaching nexus a somewhat challenging proposition. Drawing upon the findings of a mixed methodological study, this paper critically analyses the pedagogical, organisational and practical issues encountered by academics and support staff working within a newly established Centre for Learning Innovation and Professional Practice. Comprising an eclectic group of staff drawn from across the five Schools in the University, the Centre is dedicated to enhancing student learning through the development of evidence based teaching practice. Based upon the premise that the promotion of research-led teaching will act to bring teaching and research together, and in doing so enhance students learning experiences (Simmons & Elen 2007), the paper critically analyses the challenges encountered by staff responsible for developing and introducing a new learning & teaching focused organisational strategy (by reflecting on the previous 12 months work). In doing so it makes a significant contribution to current academic theory and debate in the areas of pedagogic practice and organisational management. Focusing specifically on the impact of the new policy on various aspects of university life including, pedagogic practice, student support, staff training, and organisational management, the paper critically addresses the cultural and attitudinal challenges of change management (Kotter, 1996) within a ‘grey-brick’ university. It concludes by arguing that the move towards becoming a more learning-focused university has started to develop an awareness of the positive impact the change initiative is having on the student experience and wider institution; whilst also drawing attention to the organisational challenges ahead.

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Perceptions about the quality of learning and teaching in Higher Education has for many years focused upon the application of market based principles. This includes the notion of students as “customers” of the Higher Education Institutions (HEI) service. We argue that the application of the customer analogy is unhelpful however, as students this approach is likely to affect student expectations about the service and their judgements about its quality. The purpose of this paper is to propose a study consisting of a series of interventions to develop a culture of value co-creation at a UK based HEI. By introducing CCV principles, it is hoped to steer students away from seeing themselves as “customers”, and passive recipients of in the learning and teaching process, to one where they take responsibility for their own learning experience, to be explored and acted upon in partnership with their lecturers and other stakeholders.

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Drawing on an exploratory qualitative study, this article considers the link between business school teaching at graduate level and subsequent work behaviour and experiences of former students. It evaluates the student experience some time after graduation. The findings of the retrospective evaluation point to the value of classroom peer discussion, the testing of ideas against prior work experience and the opportunity to make sense of organisational issues by setting them into broader context. The importance of andragogical approaches to teaching is discussed as well as the implications of the study findings for teaching quality enhancement. © 2009 Taylor & Francis.

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Learning and teaching approaches to engineering are generally perceived to be difficult and academically challenging. Such challenges are reflected in high levels of student attrition and failure. In addressing this issue, a unique approach to engineering education has been developed by the paper authors. This approach, which is suitable for undergraduate and postgraduate levels, brings together pedagogic and engineering epistemologies in an empirically grounded framework. It is underpinned by three distinctive concepts: Relationships, Variety & Synergy. Based upon research, the R + V + S approach to Engineering Education provides a learning and teaching strategy, which in enhancing the student experience, increases retention and positively impacts student success [S2]. Based on the study findings, this paper shows how, by designing engineering education around the concepts of Relationships, Variety and Synergy, the student learning experience becomes one that is academically challenging yet beneficial to both students and engineering educators. The challenge is to widen and test the approach in other areas of engineering education, before going on to investigate the value of the approach in other disciplines.

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Introduction: The research and teaching of French linguistics in UK higher education (HE) institutions have a venerable history; a number of universities have traditionally offered philology or history of the language courses, which complement literary study. A deeper understanding of the way that the phonology, syntax and semantics of the French language have evolved gives students linguistic insights that dovetail with their study of the Roman de Renart, Rabelais, Racine or the nouveau roman. There was, in the past, some coverage of contemporary French phonetics but little on sociolinguistic issues. More recently, new areas of research and teaching have been developed, with a particular focus on contemporary spoken French and on sociolinguistics. Well supported by funding councils, UK researchers are also making an important contribution in other areas: phonetics and phonology, syntax, pragmatics and second-language acquisition. A fair proportion of French linguistics research occurs outside French sections in psychology or applied linguistics departments. In addition, the UK plays a particular role in bringing together European and North American intellectual traditions and methodologies and in promoting the internationalisation of French linguistics research through the strength of its subject associations, and that of the Journal of French Language Studies. The following sections treat each of these areas in turn. History of the French Language There is a long and distinguished tradition in Britain of teaching and research on the history of the French language, particularly, but by no means exclusively, at the universities of Cambridge, Manchester and Oxford.

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Once again this publication is produced to celebrate and promote good teaching and learning support and to offer encouragement to those imaginative and innovative staff who continue to wish to challenge students to learn to maximum effect. It is hoped that others will pick up some good ideas from the articles contained in this volume. We have again changed our approach for this 2006/07 edition (our fourth) of the Aston Business School Good Practice Guide. As before, some contributions were selected from those identifying interesting best practice on their Annual Module reflection forms in 2005/2006. Other contributors received HELM (Research Centre in Higher Education Learning and Management) small research grants in 2005/2006. Part of the conditions were for them to write an article for this publication. We have also been less tight on the length of the articles this year. Some contributions are, therefore, on the way to being journal articles. HELM will be working with these authors to help develop these for publication. The themes covered in this year?s articles are all central to the issues faced by those providing HE teaching and learning opportunities in the 21st Century. Specifically this is providing support and feedback to students in large classes, embracing new uses of technology to encourage active learning and addressing cultural issues in a diverse student population. Michael Grojean and Yves Guillaume used Blackboard™ to give a more interactive learning experience and improve feedback to students. It would be easy for other staff to adopt this approach. Patrick Tissington and Qin Zhou (HELM small research grant holders) were keen to improve the efficiency of student support, as does Roger McDermott. Celine Chew shares her action learning project, completed as part of the Aston University PG Certificate in Teaching and Learning. Her use of Blackboard™ puts emphasis on the learner having to do something to help them meet the learning outcomes. This is what learning should be like, but many of our students seem used to a more passive learning experience, so much needs to be done on changing expectations and cultures about learning. Regina Herzfeldt also looks at cultures. She was awarded a HELM small research grant and carried out some significant new research on cultural diversity in ABS and what it means for developing teaching methods. Her results fit in with what many of us are experiencing in practice. Gina leaves us with some challenges for the future. Her paper certainly needs to be published. This volume finishes with Stuart Cooper and Matt Davies reflecting on how to keep students busy in lectures and Pavel Albores working with students on podcasting. Pavel?s work, which was the result of another HELM small research grant, will also be prepared for publication as a journal article. The students learnt more from this work that any formal lecture and Pavel will be using the approach again this year. Some staff have been awarded HELM small research grants in 2006/07 and these will be published in the next Good Practice Guide. In the second volume we mentioned the launch of the School?s Research Centre in Higher Education Learning and Management (HELM). Since then HELM has stimulated a lot of activity across the School (and University) particularly linking research and teaching. A list of the HELM seminars for 2006/2007 is listed as Appendix 1 of this publication. Further details can be obtained from Catherine Foster (c.s.foster@aston.ac.uk), who coordinates the HELM seminars. For 2006 and 2005 HELM listed, 20 refereed journal articles, 7 book chapters, 1 published conference papers, 20 conference presentations, two official reports, nine working papers and £71,535 of grant money produced in this research area across the School. I hope that this shows that reflection on learning is alive and well in ABS. We have also been working on a list of target journals to guide ABS staff who wish to publish in this area. These are included as Appendix 2 of this publication. May I thank the contributors for taking time out of their busy schedules to write the articles and to Julie Green, the Quality Manager, for putting the varying diverse approaches into a coherent and publishable form and for agreeing to fund the printing of this volume.

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Once again this publication is produced to celebrate and promote good teaching and learning support and to offer encouragement to those imaginative and innovative staff who continue to wish to challenge students to learn to maximum effect. It is hoped that others will pick up some good ideas from the articles contained in this volume. We had changed our editorial approach in drawing together the articles for this 2005/6 edition (our third) of the ABS Good Practice Guide. Firstly we have expanded our contributors beyond ABS academics. This year?s articles have also been written by staff from other areas of the University, a PhD student, a post-doctoral researcher and staff working in learning support. We see this as an acknowledgement that the learning environment involves a range of people in the process of student support. We have also expanded the maximum length of the articles from two to five pages, in order to allow greater reflection on the issues. The themes of the papers cluster around issues relating to diversity (widening participation and internationalisation of the student body), imaginative use of new technology (electronic reading on BlackboardTM ) and reflective practitioners, (reflection on rigour and relevance; on how best to train students in research ethics, relevance in the curriculum and the creativity of the teaching process) Discussion of efforts to train the HE teachers of the future looks forward to the next academic year when the Higher Education Academy?s professional standards will be introduced across the sector. In the last volume we mentioned the launch of the School?s Research Centre in Higher Education Learning and Management (HELM). Since then HELM has stimulated a lot of activity across the School (and University) particularly linking research and teaching. A list of the HELM seminars is listed as an appendix to this publication. Further details can be obtained from Catherine Foster (c.s.foster@aston.ac.uk) who coordinates the HELM seminars. HELM has also won its first independent grant from the EU Leonardo programme to look at the effect of business education on employment. In its annual report to the ABS Research Committee HELM listed for 2004 and 2005, 11 refereed journal articles, 4 book chapters, 3 published conference papers, 18 conference papers, one official reports and £72,500 of grant money produced in this research area across the School. I hope that this shows that reflection on learning is live and well in ABS. May I thank the contributors for taking time out of their busy schedules to write the articles and to Julie Green, the Quality Manager, for putting our diverse approaches into a coherent and publishable form.

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This is the second edition of our Aston Business School (ABS) Good Practice Guide and the enthusiasm of the contributors appears undiminished. I am again reminded that I work with a group of very committed, dedicated and professional colleagues. Once again this publication is produced to celebrate and promote good teaching across the School and to offer encouragement to those imaginative and innovative staff who continue to wish to challenge students to learn to maximum effect. It is hoped that others will pick up some good ideas from the articles contained in this volume. Contributors to this Guide were not chosen because they are the best teachers in the School, although they are undoubtedly all amongst my colleagues who are exponents of enthusiastic and inspiring approaches to learning. The Quality Unit approached these individuals because they declared on their Annual Module Reflection Forms that they were doing something interesting and worthwhile which they thought others might find useful. Amongst those reading the Guide I am sure that there are many other individuals who are trying to operate similar examples of good practice in their teaching, learning and assessment methods. I hope that this publication will provoke these people into providing comments and articles of their own and that these will form the basis of next year’s Guide. It may also provoke some people to try these methods in their own teaching. The themes of the articles this year can be divided into two groups. The first theme is the quest to help students to help themselves to learn via student-run tutorials, surprise tests and mock examinations linked with individual tutorials. The second theme is making learning come to life in exciting practical ways by, for example, hands-on workshops and simulations, story telling, rhetorical questioning and discussion groups. A common theme is one of enthusiasm, reflection and commitment on behalf of the lecturers concerned. None of the approaches discussed in this publication are low effort activities on the part of the facilitator, but this effort is regarded as worthwhile as a means of creating greater student engagement. As Biggs (2003)[1] says, in his similarly inspiring way, students learn more the less passive they are in their learning. (Ref). The articles in this publication bear witness of this and much more. Since last year Aston Business School has launched its Research Centre in Higher Education Learning and Management (HELM) which is another initiative to promote excellent learning and teaching. Even before this institution has become fully operational, at least one of the articles in this publication has seen the light of day in the research arena and at least two others are ripe for dissemination to a wider audience via journal publication. More news of our successes in this activity will appear in next year’s edition. May I thank the contributors for taking time out of their busy schedules to write the articles this summer, and to Julie Green who runs the ABS Quality Unit, for putting our diverse approaches into a coherent and publishable form and for chasing us when we have needed it! I would also like to thank Ann Morton and her colleagues in the Centre for Staff Development who have supported this publication. During the last year the Centre has further stimulated the learning and teaching life of the School (and the wider University) via their Learning and Teaching Week and sponsorship of Teaching Quality Enhancement Fund (TQEF) projects. Pedagogic excellence is in better health at Aston than ever before – long may this be because this is what life in HE should be about.