- Email: [email protected]
Plane strain slip line fields for metal deformation processes
Journal of Mechanical Working Technology, 9 (1984) 101-111 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands
101
Book Reviews
System Components: Design and Safety, by Rudolf Limper& WileyInterscience, New York and Toronto, 1982. ISBN o-471-08133-7, xii + 144 pages, 33 illustrations, hard cover 625.00.
Vehicle
Public concern about safety and in particular public demand for better protection against injury from vehicles undergoing collision, has become increasingly vocal in recent years. Mitigating or reducing collision damage and redressing its consequences is now a matter of widespread interest in its legal, commercial and insurance aspects. The development and detail design of mechanical devices for dissipating kinetic energy in a controlled manner or at a predetermined rate has become increasingly more important to the engineer. Advances in technology have led to higher speeds and more massive vehicles which can cause more serious damage to people, to the environment, and to the costly structures themselves. The book by Limpert follows more or less these lines, dealing with safetyoriented design analysis for motor vehicles. It is a relatively short text with eight chapters. A very brief overview of accident reconstruction is given in Chapter 1, whilst general design aspects for vehicles are listed in Chapter 2. Design details of the tire-rim assembly and of the brake system are discussed in Chapters 3 and 4 respectively. The suspension systems are examined in Chapter 5, and in Chapter 6 basic design considerations and defects of the steering systems are outlined. Chapter 7, under the heading of overall vehicle design, very briefly deals with crashworthiness. Finally, U.S. safety standards related to crash avoidance and injury reduction are reviewed in Chapter 8. Although some of the aspects of vehicle design considered would have to be given more emphasis and a more concise view of the field provided, the book, as a practical introductory guide to vehicle design, could be of interest and use to the automotive engineer. A.G. MAMALIS
Plane Strain Slip Line Fields for Metal Deformation Processes, by W. Johnson, R. Sowerby and R.D. Ventner, Pergamon Press, Oxford, 1982. ISBN O-08. 025452-7, xi + 364 pages, 140 illustrations, 850 literature references, hard cover 122.5O/US$45.00. This new monograph is much more than merely an updated version of the 1970 source book and bibliography with a similar title written by Johnson, Sowerby and Haddow. In addition to bringing the references up-to-date and revising the presentation of parts of the 1970 text, many new topics are dis-
102
cussed. In particular, a b o u t a third of the new b o o k is devoted to modern c o m p u t e r techniques of constructing slip line fields employing the matrix operator m e t h o d derived from the work of Hill, Ewing, Collins, Dewhurst and others which has been the principal advance since the earlier b o o k was published. Also the final chapter, entitled "plasticity problems for other than plane strains conditions", concerns a wide variety of topics n o t anticipated from the chapter title, such as anisotropy, sheet forming, limit diagrams, minimum weight frames, plate bending and the powerful (but, it seems, little used) technique of force-plane diagrams for plane strain slip line fields. Indeed, perhaps the new b o o k should have had the sort of title page found in 18th century publications "...Plane Strip Slip Line Fields etc. with observations on Divers T o p i c s . . . etc." Although a comprehensive bibliography and reference book, each chapter has an excellent expository background to the topic being considered and therefore makes the work into a textbook. Thus the section on matrix operator methods is extremely valuable and stands in its own right as do many other parts of the book. Even where one or t w o of the early chapters on basic theory remain essentially the same as in the 1970 book, the figures have been redrawn in some cases and, importantly, the number of end-of~hapter references is greater. In other cases the text of the earlier publication has been rewritten and incorporates important clarifications and new lines of attack to problems (for example in Chapter 5, an alternative procedure for constructing orthogonal slf nets and their construction using Ringleb's theorem). In the important chapter on applications to specific processes, there are over 100 new references -- an increase of 25% -- classified according to the individual processes such as Indenting, Drawing, Extrusion and so on. There is a new section for pressure vessels. N o t all the references are necessarily devoted to slf analysis per se, b u t deal with the foundations of plasticity theory, observations of material flow, or associated forming processes. This is a bonus. There are one or t w o inconsequential hiccups in the retyped text, for example on page 67, line 1, the Appendix number should be 7 n o t 3 (it was 3 in the earlier book); later on the same page it is correctly identified. In the particular Appendix in question (concerning the nodal points for an equiangular 5° net in the extension of t w o centred fan fields, Fig. 5.3) the ratio of fan radii should be r/p, b u t lower case p has been t y p e d throughout for p. Also in the rewritten text on the plastic potential and the flow rule, and on representative stress and representative plastic strain increment, the equation concerning b-referenced at the b o t t o m o f page 25 should, I think, be 2.17 n o t 2.21. But these are picayune matters. The b o o k has been produced using camera-ready manuscript to keep down costs. The appearance of the b o o k is inevitably less satisfactory than before, but if the publishers have to do this, it would be preferable to employ a better typeface. Whatever happened to typewriters with proportional spacing? Of course this is a personal view and nothing to do with the text
103
and what the authors have achieved. There is no doubt that the book is a good buy and will be a valuable aid to those involved in problems of plastic flow. Ad.
ATKINS
Virtual Work in Structural Analysis, by G.A.O. Davies, Wiley, Chichester, 1982. xvi + 325 pages, illustrated, ISBN O-471-10112-5, cloth $19.50/ $44.60; ISBN 0471-10113-5, paper $9.96. This book highlights the practicability and simplicity of the principle of virtual work and demonstrates clearly how the essential link between the equations of equilibrium and compatibility is obtained. The presentation of the subject matter is clear and systematic resulting in a well laid-out text. In the first chapter the principle of virtual work is introduced, and how it can be applied to both pin-jointed frameworks and for a continuum is shown. This is followed in Chapters 2 and 3 by a discussion of the two principles of virtual displacements and virtual forces; their duality and differences are emphasized. In Chapter 2 it is shown that the assembly of a stiffness matrix for a large framework can be simplified and systematised by imposing a single displacement on an element of the structure. In Chapter 3 many examples are given of the application of the principle of virtual forces to discrete and continuous structures. The application of virtual work when using approximate methods of structural analysis is reviewed in detail in Chapter 4. The principles of virtual displacements and virtual forces are used to solve various problems in one-, two- and three-dimensional geometries, and the technique is generalised to the mixed method, i.e. assumed displacement and stress fields. The approximate solutions obtained from the application of the principles of virtual displacements and virtual forces are compared, and it is concluded that a combination of the two - the mixed method - could produce an approximate solution which is better than given by either the virtual displacements or the virtual forces methods. In Chapters 5 and 6 the limitations imposed by geometrically complex structures are recognised, and the use of finiteelement idealization is developed. This method is employed, using concise matrix notation, to obtain the internal and external virtual work for an element in terms of local forces and displacements. By summing the expressions for all elements over the entire structure a global relationship between forces and displacements is formed. Although the concise matrix notation is a convenient shorthand to demonstrate the principles and methods, the main purpose should be to set up a formal procedure which can form the basis of a computer program. The detailed design and programming of sub-routines for carrying out standard
101
Book Reviews
System Components: Design and Safety, by Rudolf Limper& WileyInterscience, New York and Toronto, 1982. ISBN o-471-08133-7, xii + 144 pages, 33 illustrations, hard cover 625.00.
Vehicle
Public concern about safety and in particular public demand for better protection against injury from vehicles undergoing collision, has become increasingly vocal in recent years. Mitigating or reducing collision damage and redressing its consequences is now a matter of widespread interest in its legal, commercial and insurance aspects. The development and detail design of mechanical devices for dissipating kinetic energy in a controlled manner or at a predetermined rate has become increasingly more important to the engineer. Advances in technology have led to higher speeds and more massive vehicles which can cause more serious damage to people, to the environment, and to the costly structures themselves. The book by Limpert follows more or less these lines, dealing with safetyoriented design analysis for motor vehicles. It is a relatively short text with eight chapters. A very brief overview of accident reconstruction is given in Chapter 1, whilst general design aspects for vehicles are listed in Chapter 2. Design details of the tire-rim assembly and of the brake system are discussed in Chapters 3 and 4 respectively. The suspension systems are examined in Chapter 5, and in Chapter 6 basic design considerations and defects of the steering systems are outlined. Chapter 7, under the heading of overall vehicle design, very briefly deals with crashworthiness. Finally, U.S. safety standards related to crash avoidance and injury reduction are reviewed in Chapter 8. Although some of the aspects of vehicle design considered would have to be given more emphasis and a more concise view of the field provided, the book, as a practical introductory guide to vehicle design, could be of interest and use to the automotive engineer. A.G. MAMALIS
Plane Strain Slip Line Fields for Metal Deformation Processes, by W. Johnson, R. Sowerby and R.D. Ventner, Pergamon Press, Oxford, 1982. ISBN O-08. 025452-7, xi + 364 pages, 140 illustrations, 850 literature references, hard cover 122.5O/US$45.00. This new monograph is much more than merely an updated version of the 1970 source book and bibliography with a similar title written by Johnson, Sowerby and Haddow. In addition to bringing the references up-to-date and revising the presentation of parts of the 1970 text, many new topics are dis-
102
cussed. In particular, a b o u t a third of the new b o o k is devoted to modern c o m p u t e r techniques of constructing slip line fields employing the matrix operator m e t h o d derived from the work of Hill, Ewing, Collins, Dewhurst and others which has been the principal advance since the earlier b o o k was published. Also the final chapter, entitled "plasticity problems for other than plane strains conditions", concerns a wide variety of topics n o t anticipated from the chapter title, such as anisotropy, sheet forming, limit diagrams, minimum weight frames, plate bending and the powerful (but, it seems, little used) technique of force-plane diagrams for plane strain slip line fields. Indeed, perhaps the new b o o k should have had the sort of title page found in 18th century publications "...Plane Strip Slip Line Fields etc. with observations on Divers T o p i c s . . . etc." Although a comprehensive bibliography and reference book, each chapter has an excellent expository background to the topic being considered and therefore makes the work into a textbook. Thus the section on matrix operator methods is extremely valuable and stands in its own right as do many other parts of the book. Even where one or t w o of the early chapters on basic theory remain essentially the same as in the 1970 book, the figures have been redrawn in some cases and, importantly, the number of end-of~hapter references is greater. In other cases the text of the earlier publication has been rewritten and incorporates important clarifications and new lines of attack to problems (for example in Chapter 5, an alternative procedure for constructing orthogonal slf nets and their construction using Ringleb's theorem). In the important chapter on applications to specific processes, there are over 100 new references -- an increase of 25% -- classified according to the individual processes such as Indenting, Drawing, Extrusion and so on. There is a new section for pressure vessels. N o t all the references are necessarily devoted to slf analysis per se, b u t deal with the foundations of plasticity theory, observations of material flow, or associated forming processes. This is a bonus. There are one or t w o inconsequential hiccups in the retyped text, for example on page 67, line 1, the Appendix number should be 7 n o t 3 (it was 3 in the earlier book); later on the same page it is correctly identified. In the particular Appendix in question (concerning the nodal points for an equiangular 5° net in the extension of t w o centred fan fields, Fig. 5.3) the ratio of fan radii should be r/p, b u t lower case p has been t y p e d throughout for p. Also in the rewritten text on the plastic potential and the flow rule, and on representative stress and representative plastic strain increment, the equation concerning b-referenced at the b o t t o m o f page 25 should, I think, be 2.17 n o t 2.21. But these are picayune matters. The b o o k has been produced using camera-ready manuscript to keep down costs. The appearance of the b o o k is inevitably less satisfactory than before, but if the publishers have to do this, it would be preferable to employ a better typeface. Whatever happened to typewriters with proportional spacing? Of course this is a personal view and nothing to do with the text
103
and what the authors have achieved. There is no doubt that the book is a good buy and will be a valuable aid to those involved in problems of plastic flow. Ad.
ATKINS
Virtual Work in Structural Analysis, by G.A.O. Davies, Wiley, Chichester, 1982. xvi + 325 pages, illustrated, ISBN O-471-10112-5, cloth $19.50/ $44.60; ISBN 0471-10113-5, paper $9.96. This book highlights the practicability and simplicity of the principle of virtual work and demonstrates clearly how the essential link between the equations of equilibrium and compatibility is obtained. The presentation of the subject matter is clear and systematic resulting in a well laid-out text. In the first chapter the principle of virtual work is introduced, and how it can be applied to both pin-jointed frameworks and for a continuum is shown. This is followed in Chapters 2 and 3 by a discussion of the two principles of virtual displacements and virtual forces; their duality and differences are emphasized. In Chapter 2 it is shown that the assembly of a stiffness matrix for a large framework can be simplified and systematised by imposing a single displacement on an element of the structure. In Chapter 3 many examples are given of the application of the principle of virtual forces to discrete and continuous structures. The application of virtual work when using approximate methods of structural analysis is reviewed in detail in Chapter 4. The principles of virtual displacements and virtual forces are used to solve various problems in one-, two- and three-dimensional geometries, and the technique is generalised to the mixed method, i.e. assumed displacement and stress fields. The approximate solutions obtained from the application of the principles of virtual displacements and virtual forces are compared, and it is concluded that a combination of the two - the mixed method - could produce an approximate solution which is better than given by either the virtual displacements or the virtual forces methods. In Chapters 5 and 6 the limitations imposed by geometrically complex structures are recognised, and the use of finiteelement idealization is developed. This method is employed, using concise matrix notation, to obtain the internal and external virtual work for an element in terms of local forces and displacements. By summing the expressions for all elements over the entire structure a global relationship between forces and displacements is formed. Although the concise matrix notation is a convenient shorthand to demonstrate the principles and methods, the main purpose should be to set up a formal procedure which can form the basis of a computer program. The detailed design and programming of sub-routines for carrying out standard