- Email: [email protected]
Mechanics of textile and laminated composites
Books and publications think about the application of DFX strategically, matching techniques to meet business needs. The core of the book is divided into four main sections: DFX Experience, Design for Life Cycle, Design for Competitiveness, and Trade Off and Integration, containing 22 chapters in total. Each of the sections contains a collection of chapters on different DFX techniques, by mostly academic authors of international origin. There are no local introductions or conclusions to each section, apart from the books preface. There is a large range of techniques and for clarity comments have been maintained at a general level only. It is however worth listing the content of each section by chapter title: DFX Experience. This section contains six chapters on: Design for Manufacture and Assembly; The Boothroyd and Dewhurst Experience; Case Experience with Design for Assembly Methods; Applying DFX Experience in Design for Environment; Design for Competition; The Swedish DFX Experience; Developing DFX Tools; Implementing DFX Tools. This section describes experiences in developing and implementing DFX techniques in practice. Design for Life Cycle. This section contains nine chapters on: GRAI* Approach to Product Development; Design for Dimensional Control; Design for Assembly Cost for Printed Circuit Boards; Design for Inspectability; Design for Effective Material Storage and Distribution; Design for Reliability; Design for Electromagnetic Compatibility; Design for Serviceability; Ease of Disassembly Evaluation in Design for Recycling. This section describes a diverse collection of DFX techniques specific to a life cycle in new product development. Design for Competitiveness. This relatively short section contains four chapters on: Design for Quality; Design for Modularity; Design for Optimal Environmental Impact; Design for Life Cycle; Activity Based Costing and Uncertainty. This section describes DFX techniques for achieving corporate competitiveness. Trade Off and Integration. This is another short section and contains only three chapters on: Design Optimisation for Product Life Cycle; A Meta-Methodology for the Application of DFX Guidelines; Design for Technical Merit. This section describes a few emerging issues. At first sight, the book would appear to offer a comprehensive set of self contained accessible techniques. On further reading each chapter provides good overview of specific techniques, but readers wishing to pursue these beyond the introductory stage will need to follow up the references or contact the authors for further information. References are provided at the end of each chapter and contact details are provided in a list of contributors at the front of the book. However the format allows group-
ings of similar techniques to be directly compared and hence their suitability to produce development. Readers will undoubtedly find that the techniques described are mostly academically based and at a variety of stages of development, ranging from fundamental concepts, through prototype computer implementations, to commercially available software packages. The most famous of the latter case is the established Boothroyd and Dewhurst’s Design for Manufacture and Assembly (DFMA) technique which is widely published, including text books, and available as a computer software package. Disappointingly, the editor has missed an opportunity to put his final stamp on the book with the omission of a general conclusions chapter. Perhaps an expanded version of the penultimate section of the introduction should have more appropriately ended the book as well as a summarised collation of the local summaries that conclude each chapter. The index is also rather short for a book of this type. The text is aimed primarily at practitioners and consultants applying and implementing DFX tools. Postgraduate level research students in engineering design and related fields will also find it useful because of the way it effectively reviews the literature. The depth of coverage on each technique may not be adequate for some although the choice of the most appropriate technique(s) is as important as the application. The choice and application of DFX is also not seen as a process for the amateur, because the use of more than one DFX technique can lead to conflicting and contradictory recommendations if applied simultaneously. A meta-methodology for organising information from DFX techniques is discussed in the book. The book is well illustrated with good quality line diagrams and tables, and the odd monochrome photograph. The quality of presentation throughout is excellent. The technical content of each chapter though is very variable but backed up in the majority of cases with a reasonable number of up to date references. The structure within and between chapters is logical and consistent, a result of careful editorship. This is the first book, to my knowledge, that pulls together such a large collection of difference DFX techniques, normally only found published separately. The book will appeal to a limited readership but represents good value for money.
K. L. Edwards Morris Mechanical Handling Loughborough, UK * Groupe de Recherche en Automatisation lntegree
Mechanics of Textile and Laminated Composites A. E. Bogdanovich & C. M. Pastore. Chapman & Hall 1996, ISBN: 0 412 61150 3, S5 Hdbk The level is captured on page 1 where the authors refer to texts on classical elasticity ranging from the rather easy read of Timoshenko and Goodier to the very hard Marsden and Hughes. Love’s book is also frequently mentioned. The present volume is not for the mathematically faint hearted though on closer inspection the level, at least initially, is similar to that of Jones Mechanics of Composite Materials. An example of the forbidding part is perhaps Appendix J where just over four pages are devoted to writing out in detail expressions for the engineering constants obtained by stiffness averaging. The first chapter gives an extensive account of basic mathematical elasticity including variational principles. It also exhibits one of the annoying features of the book - the occasionally overly complex diagram executed in shades of black/grey with insufficient contrast. This makes comprehension even more difficult. It is tendency I have noted elsewhere in the literature; computer generated plots of stress, etc., when multicoloured can be very informative but if the colours are reduced to shades of grey the information is must less obvious. The second chapter considers anisotropy and the effect of axis transformations on stiffness and compliance including cases in which shear stress and strain, for instance, are no longer simply related to one another but depend on normal forces. The presentation is always careful and the reasoning is well explained. Certain, usually minor, points tend to stay in one’s memory. For me one of these is the possibility of getting very large Poisson’s ratios for some composite structures (e.g. -2 for a type of boron/epoxy). This is the sort of topic I would expect to see addressed here, but failed to find. That illustrates, I believe, a weakness of the strictly mathematical approach. If there had been more interaction with practical systems this omission would probably not have occurred. However I do appreciate that this is a matter of personal judgement/preference. The background has now been set and fibre composites are considered in Chapter 3. Eight models are reviewed with the proviso that they should satisfy the basic assumptions, be easy to use for computation and provide a good correlation with experimental data. The assumptions are the standard ones involving fibre and matrix isotropy, perfect bonding, absence of voids, fibre alignment, etc. The models studied include stiffness and compliance averaging through to upper and lower bounds. Differences between expressions for the longitudinal properties are generally very small, but for transverse and shear performance much greater. There is some
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Books and publications discussion of the measurement of composite properties. It is pointed out that different experimental methods give, in some cases, different results for elastic properties (i.e. shear modulus). Strength is not considered as this involves addressing failure mechanisms. The discussion of practical measurements is detailed and the difficulties involved are highlighted. Finally in this chapter predicted and experimental determinations of various properties are compared using a wide range of experimental information, though a limitation is accurate fibre data to feed into the models. Frequently this has to be obtained from a model and the whole process can become somewhat circular. A treatment of textile reinforcement composites (and some textile nomenclature) is given in Chapter 4 together with methods of calculating stiffness and compliance. It is much more difficult to visualise these types of structures geometrically and again the close tones of some of the diagrams do not help matters. It is concluded that the stiffness averaging method provides an excellent model of elastic properties of composites based on these materials. Next is an account of the elasticity of layered, anisotropic, media. The origins of the theories are the iso-strain and stress models of Voigt and Reuss, respectively. Neither is applicable to a layered medium because of the lack of continuity of transverse stresses at interfaces and the lack of perfect bonding between the layers, though the two approaches can be combined to give an approximate solution as is shown in Chapter 5. For a long time, composites users have managed to neglect through thickness properties of laminate structures. Recently, however, interest in measuring and specifying performance in this direction has increased and the present book gives a long and detailed theoretical discussion of this topic. As always the treatment is concise and initially historical starting with the classical theory of plates and shells before delving into much deeper and more mathematical areas at considerable length. Finally there is a short chapter which discusses the analysis of textile composite structures. The advantages of these in terms of better through-thickness properties and damage resistance and the disadvantage of reduced compression properties are mentioned before methods of viewing the geometry of a representative area are evaluated and analysis discussed. The whole treatment is backed by 15 pages of references, many to Russian work, which complement the treatments given by Western authors. This is a meaty, mathematical, book which would repay careful study. Fabrication and strength and damage behaviour of composites are not considered but the mathematically inclined designer would get a great deal of information on the elastic properties of
178
composites from the work. The authors are to be congratulated on the painstaking work which has gone into this volume.
N. L. Hancox
Mechanical Design and Systems Handbook (2nd Edition). International Version Harold A. Rothbart (Editor in chief) McGraw-Hill, 1986, ISBN: 0-07-1002723, f48.95 This book is a major reference work aimed at designers and other engineers employed in a wide variety of mechanical engineering. It is an excellent starting point for the engineer to get ‘into’ a subject new to them. A wide volume, approximately A5 size, it is easy to handle. Sub-titled as an ‘International Edition’, the units used vary widely including lb, in, ‘F, together with kg, m, ‘C and SI. This is not intrusive in a book which does not depend on numeric example and where most of the mathematics is symbolic. In addition, an excellent description of units, and comprehensive units-conversion table is provided near the front. It contains 43 sections written by a total of 53 authors drawn widely from the top echelons of American industry and academia. The section size varies from 16 to 91 pages but each section’s topic is well covered with its own table of contents and a comprehensive list of references, useful both to the newcomer and the more advanced specialist engineer. The sections are grouped together into five parts as shown below; Part Title 1
2 3 4 5
Mechanical Engineering Fundamentals System Analysis and Synthesis Mechanical Design Fundamentals Mechanical Fastener Components Power Contro Components and Sub-systems
Number of sections 7 7 7 6
16
System Analysis and Synthesis covers; dynamics, continuous time and digital control systems, optical and machine systems. Power Control Components covers both hydraulic and pneumatic power transmission. The other parts are mostly selfexplanatory. These ‘parts’ do not figure strongly in the books structure, whilst they are mostly logical groupings, some sections like ‘Properties of Engineering Materials’ and
Materials & Design Volume 17 Number 3 1996
‘CAD/CAM’ have to find a home somewhere and generally a well balanced effect is achieved. The book is laid out with a double page header, the book title is at top left (a little unnecessary I feel, maybe the part title would have been a better choice here) and the section title at the top right. Page numbering is sectionalized with the section number preceding the page number in that section. This is generally no more difficult for the reader to handle but must ease the organization of a book of this size considerably. A single comprehensive 62 alphabetical index is given. Having used the book in earnest I found the subject matter well cross-referenced and the index never led me up ‘blind alleys’ or ‘round in circles’. Also when returning, as one inevitably does, to repeat a search which was not properly documented, it was easy to retrace ones steps and find ‘that page’ again. A wide range of line drawing, charts, graphs and tables are provided. Whilst I did not study them all in detail, they had been redrawn using a consistent and legible format. All are in black and white. A few photographs are reproduced and one or two suffer from loss of grey scale range and tend to lose their impact. Most of the material provided has a fairly long life, and the intervening years have not produced many signs of age. The section on CAD/CAM, whilst covering the range of engineering applications of computers very well, suffers slightly from the move toward distributed computer power, especially in technical applications in the last 10 years. The widespread use of the Internet and the problems of produce data management are not covered. The section on ‘Digital Computers’ contains largely time independent knowledge and does not suffer with age perceptibly but may benefit in due course from including more modem programming techniques as they impact more heavily in engineering. I am thinking here of the ‘object oriented’ approach. Printed largely in an 8pt font, depending on the state of your eyes, it can become tiring. Overall I found this a very useful and satisfying book, containing a truly immense amount of information. Beware though; I was forever being sidetracked by some interesting topic catching my eye whenever I opened it up.
Stephen W. Thorpe School of Engineering Coventry University
ings of similar techniques to be directly compared and hence their suitability to produce development. Readers will undoubtedly find that the techniques described are mostly academically based and at a variety of stages of development, ranging from fundamental concepts, through prototype computer implementations, to commercially available software packages. The most famous of the latter case is the established Boothroyd and Dewhurst’s Design for Manufacture and Assembly (DFMA) technique which is widely published, including text books, and available as a computer software package. Disappointingly, the editor has missed an opportunity to put his final stamp on the book with the omission of a general conclusions chapter. Perhaps an expanded version of the penultimate section of the introduction should have more appropriately ended the book as well as a summarised collation of the local summaries that conclude each chapter. The index is also rather short for a book of this type. The text is aimed primarily at practitioners and consultants applying and implementing DFX tools. Postgraduate level research students in engineering design and related fields will also find it useful because of the way it effectively reviews the literature. The depth of coverage on each technique may not be adequate for some although the choice of the most appropriate technique(s) is as important as the application. The choice and application of DFX is also not seen as a process for the amateur, because the use of more than one DFX technique can lead to conflicting and contradictory recommendations if applied simultaneously. A meta-methodology for organising information from DFX techniques is discussed in the book. The book is well illustrated with good quality line diagrams and tables, and the odd monochrome photograph. The quality of presentation throughout is excellent. The technical content of each chapter though is very variable but backed up in the majority of cases with a reasonable number of up to date references. The structure within and between chapters is logical and consistent, a result of careful editorship. This is the first book, to my knowledge, that pulls together such a large collection of difference DFX techniques, normally only found published separately. The book will appeal to a limited readership but represents good value for money.
K. L. Edwards Morris Mechanical Handling Loughborough, UK * Groupe de Recherche en Automatisation lntegree
Mechanics of Textile and Laminated Composites A. E. Bogdanovich & C. M. Pastore. Chapman & Hall 1996, ISBN: 0 412 61150 3, S5 Hdbk The level is captured on page 1 where the authors refer to texts on classical elasticity ranging from the rather easy read of Timoshenko and Goodier to the very hard Marsden and Hughes. Love’s book is also frequently mentioned. The present volume is not for the mathematically faint hearted though on closer inspection the level, at least initially, is similar to that of Jones Mechanics of Composite Materials. An example of the forbidding part is perhaps Appendix J where just over four pages are devoted to writing out in detail expressions for the engineering constants obtained by stiffness averaging. The first chapter gives an extensive account of basic mathematical elasticity including variational principles. It also exhibits one of the annoying features of the book - the occasionally overly complex diagram executed in shades of black/grey with insufficient contrast. This makes comprehension even more difficult. It is tendency I have noted elsewhere in the literature; computer generated plots of stress, etc., when multicoloured can be very informative but if the colours are reduced to shades of grey the information is must less obvious. The second chapter considers anisotropy and the effect of axis transformations on stiffness and compliance including cases in which shear stress and strain, for instance, are no longer simply related to one another but depend on normal forces. The presentation is always careful and the reasoning is well explained. Certain, usually minor, points tend to stay in one’s memory. For me one of these is the possibility of getting very large Poisson’s ratios for some composite structures (e.g. -2 for a type of boron/epoxy). This is the sort of topic I would expect to see addressed here, but failed to find. That illustrates, I believe, a weakness of the strictly mathematical approach. If there had been more interaction with practical systems this omission would probably not have occurred. However I do appreciate that this is a matter of personal judgement/preference. The background has now been set and fibre composites are considered in Chapter 3. Eight models are reviewed with the proviso that they should satisfy the basic assumptions, be easy to use for computation and provide a good correlation with experimental data. The assumptions are the standard ones involving fibre and matrix isotropy, perfect bonding, absence of voids, fibre alignment, etc. The models studied include stiffness and compliance averaging through to upper and lower bounds. Differences between expressions for the longitudinal properties are generally very small, but for transverse and shear performance much greater. There is some
Materials & Design Volume 17 Number 3 1996
177
Books and publications discussion of the measurement of composite properties. It is pointed out that different experimental methods give, in some cases, different results for elastic properties (i.e. shear modulus). Strength is not considered as this involves addressing failure mechanisms. The discussion of practical measurements is detailed and the difficulties involved are highlighted. Finally in this chapter predicted and experimental determinations of various properties are compared using a wide range of experimental information, though a limitation is accurate fibre data to feed into the models. Frequently this has to be obtained from a model and the whole process can become somewhat circular. A treatment of textile reinforcement composites (and some textile nomenclature) is given in Chapter 4 together with methods of calculating stiffness and compliance. It is much more difficult to visualise these types of structures geometrically and again the close tones of some of the diagrams do not help matters. It is concluded that the stiffness averaging method provides an excellent model of elastic properties of composites based on these materials. Next is an account of the elasticity of layered, anisotropic, media. The origins of the theories are the iso-strain and stress models of Voigt and Reuss, respectively. Neither is applicable to a layered medium because of the lack of continuity of transverse stresses at interfaces and the lack of perfect bonding between the layers, though the two approaches can be combined to give an approximate solution as is shown in Chapter 5. For a long time, composites users have managed to neglect through thickness properties of laminate structures. Recently, however, interest in measuring and specifying performance in this direction has increased and the present book gives a long and detailed theoretical discussion of this topic. As always the treatment is concise and initially historical starting with the classical theory of plates and shells before delving into much deeper and more mathematical areas at considerable length. Finally there is a short chapter which discusses the analysis of textile composite structures. The advantages of these in terms of better through-thickness properties and damage resistance and the disadvantage of reduced compression properties are mentioned before methods of viewing the geometry of a representative area are evaluated and analysis discussed. The whole treatment is backed by 15 pages of references, many to Russian work, which complement the treatments given by Western authors. This is a meaty, mathematical, book which would repay careful study. Fabrication and strength and damage behaviour of composites are not considered but the mathematically inclined designer would get a great deal of information on the elastic properties of
178
composites from the work. The authors are to be congratulated on the painstaking work which has gone into this volume.
N. L. Hancox
Mechanical Design and Systems Handbook (2nd Edition). International Version Harold A. Rothbart (Editor in chief) McGraw-Hill, 1986, ISBN: 0-07-1002723, f48.95 This book is a major reference work aimed at designers and other engineers employed in a wide variety of mechanical engineering. It is an excellent starting point for the engineer to get ‘into’ a subject new to them. A wide volume, approximately A5 size, it is easy to handle. Sub-titled as an ‘International Edition’, the units used vary widely including lb, in, ‘F, together with kg, m, ‘C and SI. This is not intrusive in a book which does not depend on numeric example and where most of the mathematics is symbolic. In addition, an excellent description of units, and comprehensive units-conversion table is provided near the front. It contains 43 sections written by a total of 53 authors drawn widely from the top echelons of American industry and academia. The section size varies from 16 to 91 pages but each section’s topic is well covered with its own table of contents and a comprehensive list of references, useful both to the newcomer and the more advanced specialist engineer. The sections are grouped together into five parts as shown below; Part Title 1
2 3 4 5
Mechanical Engineering Fundamentals System Analysis and Synthesis Mechanical Design Fundamentals Mechanical Fastener Components Power Contro Components and Sub-systems
Number of sections 7 7 7 6
16
System Analysis and Synthesis covers; dynamics, continuous time and digital control systems, optical and machine systems. Power Control Components covers both hydraulic and pneumatic power transmission. The other parts are mostly selfexplanatory. These ‘parts’ do not figure strongly in the books structure, whilst they are mostly logical groupings, some sections like ‘Properties of Engineering Materials’ and
Materials & Design Volume 17 Number 3 1996
‘CAD/CAM’ have to find a home somewhere and generally a well balanced effect is achieved. The book is laid out with a double page header, the book title is at top left (a little unnecessary I feel, maybe the part title would have been a better choice here) and the section title at the top right. Page numbering is sectionalized with the section number preceding the page number in that section. This is generally no more difficult for the reader to handle but must ease the organization of a book of this size considerably. A single comprehensive 62 alphabetical index is given. Having used the book in earnest I found the subject matter well cross-referenced and the index never led me up ‘blind alleys’ or ‘round in circles’. Also when returning, as one inevitably does, to repeat a search which was not properly documented, it was easy to retrace ones steps and find ‘that page’ again. A wide range of line drawing, charts, graphs and tables are provided. Whilst I did not study them all in detail, they had been redrawn using a consistent and legible format. All are in black and white. A few photographs are reproduced and one or two suffer from loss of grey scale range and tend to lose their impact. Most of the material provided has a fairly long life, and the intervening years have not produced many signs of age. The section on CAD/CAM, whilst covering the range of engineering applications of computers very well, suffers slightly from the move toward distributed computer power, especially in technical applications in the last 10 years. The widespread use of the Internet and the problems of produce data management are not covered. The section on ‘Digital Computers’ contains largely time independent knowledge and does not suffer with age perceptibly but may benefit in due course from including more modem programming techniques as they impact more heavily in engineering. I am thinking here of the ‘object oriented’ approach. Printed largely in an 8pt font, depending on the state of your eyes, it can become tiring. Overall I found this a very useful and satisfying book, containing a truly immense amount of information. Beware though; I was forever being sidetracked by some interesting topic catching my eye whenever I opened it up.
Stephen W. Thorpe School of Engineering Coventry University