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Damage tolerance in advanced composites
Materials
& Design Vol. 17 No 4, pp. 229 - 231, 1996
0 1997 Elsevier Science Ltd printed in Great Britain. AU rights reserved
EL-SEWER
Books and publications Towards the Millenium - A Materials Perspective The Institute of Materials, 1996, f45,406 pp, ISBN: O-901 716-83-9 Also titled the Ray Smallman Symposium, the book is actually the Proceedings of a Meeting held at the University of Birmingham on 27 April 1995 to celebrate Ray Smallman’s 65th year and his 30 years as a Professor at the IJniversity of Birmingham. The preface is a nostalgic profile of a career and achievements that have led to international recognition and respect in the fields of Physical Metallurgy and Materials Engineering. Part I: General Perspective, contains 11 contributions (there is an omission from the list of contents): Population Increases and Technological Change The Future of Materials in the Market Place Power Generation in the 21st Century: The Challenges for Materials Technology Fast Footwork and Quick Wits Commercialising Materials for the 21st Century Materials Technology in the USA Towards 1997 - Materials Research in Hong Kong with China Materials for the New South Africa Successful Materials Research and Technology in Sweden Cost-effective Quality Enhancement of Materials Education Metallurgy - A Digression Ductility, Malleability, Education and Training Part II: Recollections and Revelations, contains 12 contributions: Back to Chemistry in the Theory of Metals Permanent Magnets: Past, Present and Future From the Schrodinger Equation to the Rolling Mill Microstructure: From the Micro-scale to the Nano-scale How Ordered are Intermetallics? Twenty Years of Diffraction Studies on Intermetallic Compounds Electron Microscopy at Birmingham Microscopy Memories The Santa Catharina Meteorite and Low Temperature Ordering in Iron-Nickel Alloys Cast Iron - a Real Advanced Material From Loops to Hips Some Simple Inventions
The general theme of the Symposium is reflected in Part I, where, collectively, the discussion papers consider social requirements, technological challenges, and the scope of global activity with respect to future trends in research, investment and education. In contrast, Part II, although remaining complimentary to the general theme, involves more specific papers on materials science and engineering, mostly considering historical developments through to state-of-the-art technology. The book is well illustrated, containing a plethora of tabular and graphical data, schematic and flow diagrams, photographs and micrographs. Reference lists are given after most papers. As a celebration, the Symposium obviously met its objective, with contributions from ex-postgraduate students and close colleagues. As an historical record, the final and appropriate tribute is given at the end: Professor Ray Smallman - List of Publications Given the circumstances, during the informal atmosphere of the Symposium, the many personal and historical references to Professor Smallman would have expected as an integral part of the proceedings. However, in the published text, references of this nature should have been avoided, as they invariably detract from essential content. Personal tributes could have been summarised separately, thereby enhancing their identity. In the apparent absence of an editorial policy, individual contributors have been given freedom with presentation, style and content, leading to many cases of overdigression and/or overindulgence. The general result is a collection of papers that scarcely arouse and retain interest. Only dedicated readers will stay the full course. Overall, the Proceedings will have a limited appeal to researchers and academics, and the book will no doubt find its place in Libraries for reference. However, as value for money and as a personal purchase, it is not recommended. Dr M. J. Dickson Shefjield Hallam University
Damage Tolerance in Advanced Composites R. L. Sierakowski and G. M. Newaz Technomic Publishing, Pennsylvania, USA, 1995,pp 151 ISBN: I-56676-261 -8 When I saw the title of this book I was
pleased for two reasons. The first, because in many respects the whole area of damage tolerance/representation of composite materials is a major obstacle to their more widespread use and as such remains a major frontier to the composites’ research community. So any book published on the subject should be anticipated with relish. Also, as far as I am aware this is the only book devoted to damage tolerance of composite materials. The other reason is more personal. One of the authors, Sierakowski, co-wrote the excellent Behaviour of Structures Composed of Composite Materials, so again I was looking forward to the read ahead. This book, however, is very different. Although it remains authoritative the style is more formal and as such I found it less enjoyable. The authors introduce it as a monograph that represents the current state-of-the-art methods used by organisations such as NASA and the FAA. As such, the material covers solely that undertaken in the U.S. In some ways the book is no more than a detailed literature review. Of the 68 references more than 40 have been published since 1980; the latest cited was from 1992 and so therefore can claim to be relatively up-todate. The book is split into three chapters. Chapter 1 discusses the classes of advanced materials that are considered, namely continuous fibre lamina construction, as used in the aerospace community. It then introduces the sources of damage that arise in the fabrication and construction of structural components. Discussions of damage tolerance of metallic material/structural systems that include consideration of such defects as flaws and cracks are presented versus advanced composite material defects that include delamination and disbonding as important issues. The basic philosophy of a damage tolerant definition is presented. This includes (1) acceptance that damage will occur, (2) the need for developing an adequate inspection system for damage to be detected, and (3) the requirement that adequate strength will be retained within a damaged structure. Finally, the principal drivers related to the design of primary structures are discussed. Chapter 2 presents a review of analytical developments associated with the importance of impact damage as a primary driver in the damage tolerant design of composites. The analytical approaches are catalogued and predictive capabilities and limitations discussed. The eight different models for evaluating the impact dynamics of composite materials are presented in a logical and easy-to-understand way. A table of the methods highlights the particu-
Materials & Design Volume 17 Number 4 1996
229
Books and publications lar conditions that apply so that the reader can readily assess the merits of a particular model for his own purposes. Unfortunately little guidance is given to the reader to assess which models have been used in practice. This is a major criticism because the reader is left thinking that each model is equally important but there is little substance to show how well each model has been accepted by the composites’ community. Indeed all the models, bar one, were published in the academic literature during the 1980s. So it might seem that these models are still too new to be widely accepted. Again no models are presented from outside the States (are there any?). Chapter 3 presents a discussion of techniques needed for assessment of damage tolerance and includes a number of important non-destructive evaluation techniques. Illustrative examples of each of the techniques are given along with limitations and applicability. Also, this chapter presents techniques used to evaluate the residual/retained strength of advanced composites as part of the damage tolerance criterion. The importance of retained strength related to the design of the structure and its service life in the presence of non-visible damage is discussed. Examining the book as a whole I found a particular grievance with the lack of attention to detail. Many of the figures are schematic (even some graphs) and some graphs are missing labels on axes. Occasionally data is presented with no reference and there are some obvious typographic mistakes in the text. If only its proof-reading had been better! On the other hand, tables are clear and concise and are used to summarise the main points. The book (or monograph as the authors like to call it) is intended to be used by the advanced composite materials community on the subject of damage tolerance, its importance, and its role in the design process. As it stands, the book meets this aim but because of the lack of an established knowledge base of how to assess and characterise damage it will probably be most useful to researchers in the field, especially postgraduate students. Designers that want to keep abreast of current developments should find it useful. Maybe one of the models presented can help with their work! The authors state that they want to lay down a challenge to stimulate further discussion and development of the subject. In this respect anybody who reads this account should find it extremely useful. As far as a recommendation goes I shall find it a useful addition to my composites’ books on my bookshelf. On the other hand how long will it be before the ideas presented are outdated? Not knowing the cost of the monograph I can not readily assess its true worth to the personal user. However, a library should find it a welcome addition to their composites’ collection.
Dr Paul Weaver University of Cambridge
230
Mechanisms & Mechanical Devices Sourcebook N. P. Chironis, McGraw-Hill, ISBN: 0-07-010918-4,447pp, (H/B)
1991, f56.95
This book is essentially a large collection of detailed drawings and notes on well known and unusual mechanical devices. The source of the information is mostly derived from American publications. The editor, Nicholas Chironis, is a consulting engineer, having previously held a succession of mechanical engineering positions in industry. He was also associated for a long time with Product Engineering magazine where he was a specialist in mechanical components and design analysis. Presumably this is where the editor has derived a lot of the material for this book. The book has now been in publication for around five years but is still worthy of review. The nature of the information is, in fact, timeless, with some of the more classical mechanisms, such as the Geneva mechanism, having been around for some considerable time. Books like this have been published before, but not so well illustrated, and it is still quite rare to see books devoted entirely to the specialised subject of mechanical mechanisms, linkages and devices. In this book, the information appears to come from a collection of previously published papers and articles in product design and mechanical engineering. The book is aimed at both practising engineers, and teachers and students in engineering and technology subjects. There are several features of this book which make it useful to a prospective reader. Firstly, the book is a single volume which is very convenient as most of the information is normally fragmented and only available in a collection of separate publications. Secondly, the scope is extensive and ranges from simple components to complex machines. Thirdly, the book is large format which allows detailed figures to be presented more clearly at a scale not possible in a normal book. Fourthly, the descriptions are of a practical nature which makes the information easy to understand and amenable to a wide readership. There are, however, several features which let the book down. Firstly, the quality of reproduction is poor in places, particularly the line diagrams with shaded backgrounds and the photographs. Secondly, there is an inconsistent style of presentation which is probably attributed to the different sources of the information, which appear to have been compiled directly. Thirdly, there are not many references and those that are given are mostly incomplete and without dates, which make it difficult to follow up any particular aspects. A list of references at the end of each chapter would have been useful. Fourthly, the index seems quite short for a publication purporting to be a sourcebook, although normal usage of this book is likely to be in the form of browsing. The book
Materials & Design Volume 17 Number 4 1996
is also essentially a large collection of articles from different sources, therefore locating specific information is potentially difficult without a good index. Fifthly, the book would have benefited from a general introduction. The main contents of the book are logically arranged with the chapters divided by mechanism class, or in some cases as a group of similar mechanisms, as follows: 1. Parts handling mechanisms 2. Reciprocating and general purpose mechanisms 3. Special purpose mechanisms 4. Spring, bellow, flexure, screw and ball devices 5. Cam, toggle, chain and belt mechanisms 6. Geared systems and variable-speed mechanisms 7. Coupling, clutching and braking devices 8. Torque-limiting, tensioning and governing devices 9. Non-mechanical methods of machine and mechanism control 10. Fastening, latching, clamping and chucking devices 11. Key equations and charts for designing mechanisms The arrangement of topics (or articles) within each of the chapters has been carefully ordered. Chapters 1 through 10 provide a comprehensive coverage of the various types of practical mechanism available, some of which are purported to be new, although it is not clear which if any may be just theoretical or experimental. The descriptions of individual mechanisms is sufficiently detailed in most cases to permit possible direct application in the solution of design problems, particularly at conceptual and early embodiment phases. Chapter 11 deals specifically with design analysis but seems a bit of an attachment to the rest of the book, and arguably design is a common theme throughout the book, the topics of the last chapter could have been integrated within the other relevant chapters. The price of the book is considered prohibitively expensive for the individual, but as a reference book for an engineering group or department, in industry or academia it is seriously worth considering. The general and practical treatment, and breadth of subject matter makes this an invaluable source of ideas for mechanical design problems.
K. L. Edwards Morris Mechanical Handling Loughborough
& Design Vol. 17 No 4, pp. 229 - 231, 1996
0 1997 Elsevier Science Ltd printed in Great Britain. AU rights reserved
EL-SEWER
Books and publications Towards the Millenium - A Materials Perspective The Institute of Materials, 1996, f45,406 pp, ISBN: O-901 716-83-9 Also titled the Ray Smallman Symposium, the book is actually the Proceedings of a Meeting held at the University of Birmingham on 27 April 1995 to celebrate Ray Smallman’s 65th year and his 30 years as a Professor at the IJniversity of Birmingham. The preface is a nostalgic profile of a career and achievements that have led to international recognition and respect in the fields of Physical Metallurgy and Materials Engineering. Part I: General Perspective, contains 11 contributions (there is an omission from the list of contents): Population Increases and Technological Change The Future of Materials in the Market Place Power Generation in the 21st Century: The Challenges for Materials Technology Fast Footwork and Quick Wits Commercialising Materials for the 21st Century Materials Technology in the USA Towards 1997 - Materials Research in Hong Kong with China Materials for the New South Africa Successful Materials Research and Technology in Sweden Cost-effective Quality Enhancement of Materials Education Metallurgy - A Digression Ductility, Malleability, Education and Training Part II: Recollections and Revelations, contains 12 contributions: Back to Chemistry in the Theory of Metals Permanent Magnets: Past, Present and Future From the Schrodinger Equation to the Rolling Mill Microstructure: From the Micro-scale to the Nano-scale How Ordered are Intermetallics? Twenty Years of Diffraction Studies on Intermetallic Compounds Electron Microscopy at Birmingham Microscopy Memories The Santa Catharina Meteorite and Low Temperature Ordering in Iron-Nickel Alloys Cast Iron - a Real Advanced Material From Loops to Hips Some Simple Inventions
The general theme of the Symposium is reflected in Part I, where, collectively, the discussion papers consider social requirements, technological challenges, and the scope of global activity with respect to future trends in research, investment and education. In contrast, Part II, although remaining complimentary to the general theme, involves more specific papers on materials science and engineering, mostly considering historical developments through to state-of-the-art technology. The book is well illustrated, containing a plethora of tabular and graphical data, schematic and flow diagrams, photographs and micrographs. Reference lists are given after most papers. As a celebration, the Symposium obviously met its objective, with contributions from ex-postgraduate students and close colleagues. As an historical record, the final and appropriate tribute is given at the end: Professor Ray Smallman - List of Publications Given the circumstances, during the informal atmosphere of the Symposium, the many personal and historical references to Professor Smallman would have expected as an integral part of the proceedings. However, in the published text, references of this nature should have been avoided, as they invariably detract from essential content. Personal tributes could have been summarised separately, thereby enhancing their identity. In the apparent absence of an editorial policy, individual contributors have been given freedom with presentation, style and content, leading to many cases of overdigression and/or overindulgence. The general result is a collection of papers that scarcely arouse and retain interest. Only dedicated readers will stay the full course. Overall, the Proceedings will have a limited appeal to researchers and academics, and the book will no doubt find its place in Libraries for reference. However, as value for money and as a personal purchase, it is not recommended. Dr M. J. Dickson Shefjield Hallam University
Damage Tolerance in Advanced Composites R. L. Sierakowski and G. M. Newaz Technomic Publishing, Pennsylvania, USA, 1995,pp 151 ISBN: I-56676-261 -8 When I saw the title of this book I was
pleased for two reasons. The first, because in many respects the whole area of damage tolerance/representation of composite materials is a major obstacle to their more widespread use and as such remains a major frontier to the composites’ research community. So any book published on the subject should be anticipated with relish. Also, as far as I am aware this is the only book devoted to damage tolerance of composite materials. The other reason is more personal. One of the authors, Sierakowski, co-wrote the excellent Behaviour of Structures Composed of Composite Materials, so again I was looking forward to the read ahead. This book, however, is very different. Although it remains authoritative the style is more formal and as such I found it less enjoyable. The authors introduce it as a monograph that represents the current state-of-the-art methods used by organisations such as NASA and the FAA. As such, the material covers solely that undertaken in the U.S. In some ways the book is no more than a detailed literature review. Of the 68 references more than 40 have been published since 1980; the latest cited was from 1992 and so therefore can claim to be relatively up-todate. The book is split into three chapters. Chapter 1 discusses the classes of advanced materials that are considered, namely continuous fibre lamina construction, as used in the aerospace community. It then introduces the sources of damage that arise in the fabrication and construction of structural components. Discussions of damage tolerance of metallic material/structural systems that include consideration of such defects as flaws and cracks are presented versus advanced composite material defects that include delamination and disbonding as important issues. The basic philosophy of a damage tolerant definition is presented. This includes (1) acceptance that damage will occur, (2) the need for developing an adequate inspection system for damage to be detected, and (3) the requirement that adequate strength will be retained within a damaged structure. Finally, the principal drivers related to the design of primary structures are discussed. Chapter 2 presents a review of analytical developments associated with the importance of impact damage as a primary driver in the damage tolerant design of composites. The analytical approaches are catalogued and predictive capabilities and limitations discussed. The eight different models for evaluating the impact dynamics of composite materials are presented in a logical and easy-to-understand way. A table of the methods highlights the particu-
Materials & Design Volume 17 Number 4 1996
229
Books and publications lar conditions that apply so that the reader can readily assess the merits of a particular model for his own purposes. Unfortunately little guidance is given to the reader to assess which models have been used in practice. This is a major criticism because the reader is left thinking that each model is equally important but there is little substance to show how well each model has been accepted by the composites’ community. Indeed all the models, bar one, were published in the academic literature during the 1980s. So it might seem that these models are still too new to be widely accepted. Again no models are presented from outside the States (are there any?). Chapter 3 presents a discussion of techniques needed for assessment of damage tolerance and includes a number of important non-destructive evaluation techniques. Illustrative examples of each of the techniques are given along with limitations and applicability. Also, this chapter presents techniques used to evaluate the residual/retained strength of advanced composites as part of the damage tolerance criterion. The importance of retained strength related to the design of the structure and its service life in the presence of non-visible damage is discussed. Examining the book as a whole I found a particular grievance with the lack of attention to detail. Many of the figures are schematic (even some graphs) and some graphs are missing labels on axes. Occasionally data is presented with no reference and there are some obvious typographic mistakes in the text. If only its proof-reading had been better! On the other hand, tables are clear and concise and are used to summarise the main points. The book (or monograph as the authors like to call it) is intended to be used by the advanced composite materials community on the subject of damage tolerance, its importance, and its role in the design process. As it stands, the book meets this aim but because of the lack of an established knowledge base of how to assess and characterise damage it will probably be most useful to researchers in the field, especially postgraduate students. Designers that want to keep abreast of current developments should find it useful. Maybe one of the models presented can help with their work! The authors state that they want to lay down a challenge to stimulate further discussion and development of the subject. In this respect anybody who reads this account should find it extremely useful. As far as a recommendation goes I shall find it a useful addition to my composites’ books on my bookshelf. On the other hand how long will it be before the ideas presented are outdated? Not knowing the cost of the monograph I can not readily assess its true worth to the personal user. However, a library should find it a welcome addition to their composites’ collection.
Dr Paul Weaver University of Cambridge
230
Mechanisms & Mechanical Devices Sourcebook N. P. Chironis, McGraw-Hill, ISBN: 0-07-010918-4,447pp, (H/B)
1991, f56.95
This book is essentially a large collection of detailed drawings and notes on well known and unusual mechanical devices. The source of the information is mostly derived from American publications. The editor, Nicholas Chironis, is a consulting engineer, having previously held a succession of mechanical engineering positions in industry. He was also associated for a long time with Product Engineering magazine where he was a specialist in mechanical components and design analysis. Presumably this is where the editor has derived a lot of the material for this book. The book has now been in publication for around five years but is still worthy of review. The nature of the information is, in fact, timeless, with some of the more classical mechanisms, such as the Geneva mechanism, having been around for some considerable time. Books like this have been published before, but not so well illustrated, and it is still quite rare to see books devoted entirely to the specialised subject of mechanical mechanisms, linkages and devices. In this book, the information appears to come from a collection of previously published papers and articles in product design and mechanical engineering. The book is aimed at both practising engineers, and teachers and students in engineering and technology subjects. There are several features of this book which make it useful to a prospective reader. Firstly, the book is a single volume which is very convenient as most of the information is normally fragmented and only available in a collection of separate publications. Secondly, the scope is extensive and ranges from simple components to complex machines. Thirdly, the book is large format which allows detailed figures to be presented more clearly at a scale not possible in a normal book. Fourthly, the descriptions are of a practical nature which makes the information easy to understand and amenable to a wide readership. There are, however, several features which let the book down. Firstly, the quality of reproduction is poor in places, particularly the line diagrams with shaded backgrounds and the photographs. Secondly, there is an inconsistent style of presentation which is probably attributed to the different sources of the information, which appear to have been compiled directly. Thirdly, there are not many references and those that are given are mostly incomplete and without dates, which make it difficult to follow up any particular aspects. A list of references at the end of each chapter would have been useful. Fourthly, the index seems quite short for a publication purporting to be a sourcebook, although normal usage of this book is likely to be in the form of browsing. The book
Materials & Design Volume 17 Number 4 1996
is also essentially a large collection of articles from different sources, therefore locating specific information is potentially difficult without a good index. Fifthly, the book would have benefited from a general introduction. The main contents of the book are logically arranged with the chapters divided by mechanism class, or in some cases as a group of similar mechanisms, as follows: 1. Parts handling mechanisms 2. Reciprocating and general purpose mechanisms 3. Special purpose mechanisms 4. Spring, bellow, flexure, screw and ball devices 5. Cam, toggle, chain and belt mechanisms 6. Geared systems and variable-speed mechanisms 7. Coupling, clutching and braking devices 8. Torque-limiting, tensioning and governing devices 9. Non-mechanical methods of machine and mechanism control 10. Fastening, latching, clamping and chucking devices 11. Key equations and charts for designing mechanisms The arrangement of topics (or articles) within each of the chapters has been carefully ordered. Chapters 1 through 10 provide a comprehensive coverage of the various types of practical mechanism available, some of which are purported to be new, although it is not clear which if any may be just theoretical or experimental. The descriptions of individual mechanisms is sufficiently detailed in most cases to permit possible direct application in the solution of design problems, particularly at conceptual and early embodiment phases. Chapter 11 deals specifically with design analysis but seems a bit of an attachment to the rest of the book, and arguably design is a common theme throughout the book, the topics of the last chapter could have been integrated within the other relevant chapters. The price of the book is considered prohibitively expensive for the individual, but as a reference book for an engineering group or department, in industry or academia it is seriously worth considering. The general and practical treatment, and breadth of subject matter makes this an invaluable source of ideas for mechanical design problems.
K. L. Edwards Morris Mechanical Handling Loughborough