Continuum models for materials with microstructure

Continuum models for materials with microstructure

Book reviews 887 lished a common language and notation for communication in this field. Previously, sources in this area have suffered from a lack o...

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Book reviews

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lished a common language and notation for communication in this field. Previously, sources in this area have suffered from a lack of standardization regarding notation and units. The book can thus be described as a unique contribution in the field of hydraulic fracture mechanics, with a worldwide market and is very good value for money. Whilst it is aimed primarily at the petroleum engineering field, the coherent description of fracture mechanics and propagation is applicable in numerous other engineering fields; thus this text will also be of interest to other engineering disciplines.

M. A. Tuck Vibration testing: theory and practice Kenneth G. McConnell, WileyInterscience, New York, 1995, 606 pp., £65.00/US$100.00, ISBN 0-4 71-30435-2 Engineers in many disciplines will from time to time need to assess the vibration performance of an item of equipment or a structure, for example to verify that a specification has been met or for troubleshooting purposes. This will usually involve experimental testing. Such tests are all too frequently performed poorly, so that the results are incomplete, misleading or just plain wrong. What Professor McConnell in this book describes as the 'art and science' of vibration testing is a skill which must be cultivated, and anyone with vibration tests to carry out or to supervize, and who is not an expert in the field, would do well to scan this book first. The author covers the necessary theory of vibration, and then gives extensive discussion of the instrumentation, practical techniques and signal processing required to carry out a good test and to interpret the results correctly. This material is not readily available in print, and this book could find a place on many people's shelves. The book is not rea]!ly one for the specialist or researcher in vibration (although new graduate students in that discipline might find it helpful). Neither is it aimed primarily at undergraduate stud e n t s - w h i l e it is clear that the author teaches this material extensively (he draws many of his illustrative examples from student projects), it is not common for university courses to devote so much time to experimental methods of this kind. Presumably the main target audience is the community of practising engineers. The book would be appropriate for any English-speaking engineer in the world. The presentation is clear, at a level and pace which should suit the nonspecialist well. The presentational style is, at the same time, the source of my only real criticisms

of the book. The easy-paced, rather anecdotal approach adds significantly to the length and can at times be irritating. I was also a little disappointed at the narrow focus of the book. In a book of this length, it seems surprising that the index offers no entries for such topics as laser vibrometers, or spectrogram and wavelet analysis. These are examples of somewhat new ideas which are now finding regular use in vibration testing, and all are capable of the kind of misuse that the author discusses so thoroughly in the more traditional context of the determination of transfer functions using accelerometers for sensing. Even the topic of experimental modal testing is not treated very seriously--all the index references to 'modes' are to theoretical discussions, and the reader wanting to know more about modal testing is referred to the standard text by Ewins. In all, this is a most valuable book on the ground it sets out to cover, but with a decidedly traditional, some would say oldfashioned, style and scope.

J. Woodhouse Continuum models for materials with microstructure Editor H-B MOhlhaus Wiley, Chichester, UK 1995 The classical theories of continuum mechanics, for example the theories of elasticity, plasticity and Newtonian fluids, contain no characteristic length scales, and hence predict no size effects except those which are introduced through the boundary conditions of specific problems. In the vast majority of engineering situations these classical theories are perfectly adequate. However, there is a much smaller but interesting class of problems in which the scale of the microstructure of the material is comparable to the macroscopic dimensions, and so cannot be ignored. Examples occur in the mechanics of granular materials and of composite materials, and in biological applications of mechanics. This volume consists of 13 articles by different authors, each dealing with a different aspect of the title topic. The chapter running heads give a good idea of the scope of the volume: Chap. (1) Experimental methods for study of Cosserat elastic solids (R. Lakes), Chap. (2) Micromechanics-based continuum theory (Y. Okui and H. Horii), Chap. (3) Equilibrium bifurcations in dipole asymptotics model (A. V. Dyskin), Chap. (4) Non-local damage (G. PijaudierCabot), Chap (5) Gradient-dependent elastic model for granular materials (F. Oka), Chap. (6) Computational issues in gradient plasticity (R. de Borst, J. Pamin and L. J. Sluys), Chap. (7) Microstructure and scale effects in granular rocks (J. Sulem, I. Vardoulakis and E. Papamichos), Chap. (8) Constitutive modelling using the disturbed state (C. S. Desai), Chap.

(9)Localization in micropolar continua (K. Willam, A. Dietsche, M.-M. Iordache and P. Steinmann), Chap. (10) Lattice type fracture models for concrete (J. G. M. van Mier, E. Schlangen and A. Vervuurt), Chap. (11) Constitutive modelling for nanostructured materials (W. W. Milligan, S. A. Hackney and E. C. Aifantis), Chap. (12) Spatial coupling and propagative plastic instabilities (Y. Estrin and L. P. Kublin), Chap. (13)Relative gradient model for laminated materials (H.-B. Miihlhaus). A feature of microstructure models is that while it is not too hard to formulate plausible qualitative arguments to justify their introduction, it seems to be very difficult to devise experiments to measure the parameters which characterize the models. Hence it is not surprising, but still disappointing, that only the first chapter deals explicitly with experimental methods, and even there a promised table of published experimental results seems to have been mislaid. Until more hard facts become available it seems probable that nonlocal, micropolar, gradient and other theories, interesting though they are in their own right, will remain rather speculative and academic subjects, and somewhat removed from practical engineering applications. Nevertheless, it remains that this book gives a broad and balanced up-to-date overview of the various approaches to the mechanics of materials with microstructure, and forms an excellent introduction for any reader seeking basic knowledge of the subject.

A. J. M. Spencer Fracture mechanics of concrete: applications of fracture mechanics to concrete, rock and other quasi-brittle materials S. P. Shah, S. E. Swartz and C. Ouyang, Wiley, New York, 1995, xxxi + 552pp., £55.00 The very considerable research activity over the last few years in the field of fracture mechanics applied to the failure of materials has not been matched by similar developments in the teaching of the subject nor, indeed, by its application to engineering practice. The authors see the reason for the latter lack of interest as being due to the unavailability of 'suitable educational materials' (p. xv). It is to fill this void, therefore, that this book was written, it being intended as a 'textbook for graduate students in civil engineering, engineering mechanics and allied disciplines' as well as a 'comprehensive reference w o r k . . , for the practising engineer' (p.xv). The book is divided broadly into two parts. The first of these (Chaps 1-8) presents the fundamentals of fracture mechanics while the second part (Chaps 9-12)