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only with essentially the electrochemistry of corrosion, and not mention the particular inputs that the designer himself can bring to bear on this problem? Materials usage and engineering design are interdependent, not independent, aspects of technology and if we are to reduce the number of instances in which design and materials selection are dealt with in isolation, thereby hopefully reducing the chances of failure, perhaps we need to revise our ap- proach to teaching at this interface.

However, to return to my opening sentence, this reviewer has not written a text book and finds criticism easier than doing so. Dr. Pascoe has and, within the boundaries of his selected approach, appears to have done so with success. Perhaps when a further edition is required, he may consider more widely the influence that the engineering designer can have upon the service of materials, as opposed to those limits inherent in the materials available.

R.N. PARKINS

Engineering Plasticity: Theory of Metal Forming Processes, CISM Internatio- nal Centre for Mechanical Sciences, Courses and Lectures No. 139, edited by H. Lippmann, Springer-Verlag, Vienna, 1977. ISBN 3-211-81429-9. Vol. I: vii + 236 pp., 68 figs. Vol. II: v + 323 pp., 109 figs. Soft-cover, Austrian S 642.00, DM 93.00, US$ 46.50.

In 1975, a course on metal forming plasticity was presented at Udine by six of the most eminent people in this field, namely W. Johnson of Cambridge, S. Kobayashi of Berkeley, E.H. Lee of Stanford, H. Lippmann of Munich, P. MeUor of Bradford and W. Szczepinski of Warsaw. With the re- grettable exception of Szczepinski's lectures because of copyright difficul- ties, the course material has been collected and edited by Lippmann and is now published in two convenient soft-cover volumes. There are very many good things about this book. There are a few bad things too, but it could become a widely used source for people working in this field. It contains much of the basic theory which is clearly set out and well presented; it con- tains some new ideas and important philosophical statements and it also in- cludes useful bibliography. It should be stated however that the scope is strictly confined to the mathematical theory of plasticity and its application in the analysis of metal forming processes. It does not discuss why materials are formed in the way they are, what is the structure and behaviour of met- als during deformat ion nor does it deal with the equipment used to form metals. Accepting this limitation, the topics are well chosen and wor thy of brief description in this review.

Professor Lippmann has three contributions. The first is a brief summary of the important plasticity relations used in metal forming analysis. The sec- ond is a fascinating description of the origins of the "slab theory" of analysis of forging, drawing and rolling. This approach employs arbitrary assumPtions about the mode of deformation but as the author shows, it is capable of

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producing excellent results. Although not mentioned, this approach is being increasingly used in North America in computer-aided process design sys- tems. It is desirable that these systems should be interactive so that the engi- neer can see quickly the result of changes in tool shape or material parame- ters. It has been found that other techniques such as the finite element ap- proach are too cumbersome for these applications. In another contribution, Lippmann discusses a simplified yield law of the Tresca type which was suggested by Sawczuk; this approach is probably not so widely known and appears to be very practical.

Kobayashi deals with the application of the variational principle in three sections. The first is on Hill's approximation method, the second on the finite-element method and the third on the application of the extremum principle to a process which is not fully constrained such as in "spread" in rolling. This whole section by Kobayashi is comprehensive and well written; the author has had a lot of experience in this field and he has presented a valuable survey.

Professor Lee gives a clear discussion of the simplifying assumptions which must be employed in analysing forming processes and the consequent limita- tions of the solution. He deals with the finite-element approach which he considers to offer the most promise and in particular discusses the errors which may arise in not taking the appropriate derivatives in determining the stress rate. This serves as a timely warning to those who might be tempted to use existing numerical techniques without fully understanding their formula- tion.

Analysis of processes in which the material exhibits significant anisotropy is discussed by Professor Mellor. In the second part of his contribution he describes clearly the discrepancies observed in the macroscopic anisotropy model generally attributed to Hill. It is unfortunate that Professor Mellor did not heed his own advice because the value of the first part which is based en- tirely on this model is seriously diminished by developments which have oc- curred recently in anisotropy models, particularly the work of Hosford. The processes considered by Mellor are deep drawing and stretch forming. The latter deals extensively with the Marciniak hypothesis of local necking. The problem of strain localization in sheet metal forming would certainly war- rant a special chapter if the course was given in 1979 and the 1975 contribu- tion does not really anticipate the major directions in which developments have taken place in this area in recent years.

The second volume contains the lectures by W. Johnson and are written with A.G. Mamalis as co-author. About seventy pages are devoted to a litera- ture survey of some interesting processes including high speed forming. The greater part of the volume deals with load bounding and slip line field anal- ysis of plane strain processes. Much of this is to be found in familiar texts although the authors do introduce the force polygon technique and discuss computer generated slip line fields. The final chapter is very short but it is an excellent idea. It contains a number of hints and techniques about experi-

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mental studies relating to metal flow. The approach is quite deliberately that of a "cook book" but it is a very useful cook book and it is to be hoped that many will use it to aid their own observations of metal flow, even where ex- tensive laboratory facilities are not available.

The preceding paragraphs describe briefly what the book contains. What are the things which have been left out? Sheet metal forming processes are the most notable omission. There is a section on cylindrical deep drawing, but in general the field is neglected. Another area which could well have re- ceived more t reatment relates to instability, necking and strain localization in both tensile and compressive processes; these are topics which coulde have been treated in the same way as others in this book. Apart from these omis- sions, one wonders whether the basic viewpoint of the lecturers, which is sur- prisingly unanimous, is entirely appropriate. They see the theory of metal forming processes as being entirely the application of the mathematical theo- ries of elasticity and plasticity to the shaping of metals. There is not a single illustration of a metal forming machine or a formed part in the whole two volumes although there are some schematic drawings of idealized parts. There are no micrographs or discussion of plastic deformation at the micro- scopic level and, with a few exceptions, the processes are viewed as being quasi-static and isothermal.

It is worth pointing out that in certain countries there is a discernable shift amongst those who could consider themselves as physical metallurgists into the area of the mechanics of metal forming processes. They realize that some of the basic methods of analyzing plastic deformation are really quite simple and that a person who combines an understanding of material behav- iour with a modest apti tude for mechanics can contribute enormously to the development of metal forming processes. Having said this however, and having allowed for the necessity for taking a concise view of the field in any course of this nature, one would recommend this book as a valuable refer- ence source and for its clear exposition of many important topics.

J.L. DUNCAN

Aluminium Workshop Practice, by W. Hegmann, Translated from the German by E.J. Groom, English edition edited and revised by A.W. Brace, Techni- copy Limited, Stonehouse, Glos., U.K., 1978. 256 + xii pages, hardback, £16.00/US$35.00, ISBN 0-905228-04-9.

Wherever light weight is called for, where easy maintenance is required, or simply when an attractive finish is needed, we are likely to find the ubiqui- tous aluminium and its alloys. The increasing usage of this metal has meant tha t workshops are more frequently faced with the task of bending, machin- ing, joining etc. different kinds of aluminium sections, rod or sheet. Although many of the standard techniques can be used for some of these operations, to get the best results, and, sometimes to avoid expensive mistakes, special