R E B O O K

V I E W S

Elas tohydrodynamics R. Gohar Ellis Horwood Ltd., 1988 320 pp., £45.00/$88.50 ISBN: 0-85312-820-0 (Ellis Horwood Ltd) ISBN: 0-470-21058-3 (Halstead Press)

Elastohydrodynamic lubrication (ehl) is a comparatively recent branch of tribology which only became properly es- tablished in the early 1960's.

It is the mechanism that describes the separation by a lubricant film of two elastic machine elements loaded against each other,, and in relative motion. Its applica- tions in industry include more efficient seals, and improve designs of rolling element bearings and gears.

This book gives an up-to-date account of ehl by explain- ing the subject theoretically and experimentally, as well as presenting a comprehensive account of some of the latest important research findings.

In the introduction, the reader is given an account of the development of ehl and its applications in industry. Chap- ter 2 familiarizes the reader with the material properties of the lubricant and the elastic properties of the bounding surfaces. Chapter 3 discusses the way film surfaces distort under elastostatic normal contact loads. In Chapter 4 the equations needed for ehl theory are derived or presented. Analytical methods are used to describe the lubrication of rigid non-conformal contacts uncoupling elastic and hydro- dynamic equations in Chapter 5. In Chapter 6 all theories of the previous chapters are combined to give a compre- hensive review of the numerical methods which are used to obtain the ehd film thickness and shape. In Chapter 7, the results of numerical solutions of the governing equa- tions are given, compared with experimental results, and formulae for film thicknesses are presented. In Chapter 8 the frictional behavior of ehl contacts is discussed and the assumptions of purely Newtonian behaviour of lubricants is abandoned in favour of mathematical models which at- tempt to correlate theory and experiment. Chapter 9 is devoted to finding the stress distribution within the ma- chine element materials as a consequence of the normal load and friction. Throughout the book, published experi- mental results ate given to support the various theoretical predictions. Chapter 10 is solely concerned with the main techniques used to obtain the various experimental results shown previously. In Chapter 11, some interesting topics related to ehl are summarized, with particular stress given to engineering applications by means of case studies. In Chapter 12 the book is concluded by a short review of fu- ture trends in ehl research and development.

Contents: Introduction; Material properties; Elastostatic contacts; The governing equations; Simple concept of non- conforming contact lubrication; Numerical methods for de- termining oil film thicknesses in elastohydrodynamic lubri- cation (ehl); Film thickness in ehl; Friction in elastohy- drodynamic contacts; Stress and fatigue in elastohydrody- namic contact; Experimental methods in elastohydrody- namics; Various topics related to elastohydrodynamics; Fu- ture trends in elastohydrodynamic lubrication.

Paulo Azevedo Computational Mechanics Institute Southampton, England

In t roduc t ion to Op t imum Design Jasbir S. Arora, University of Iowa, USA McGraw-Hill Book Company, 1989 626 pp., ISBN: 0-07-002460-X

This is a textbook on engineering design and optimization. The emphasis of the book is on the correct formulation of the problem and the basic concept of optimum design. All the methods and theorems described are illustrated with examples, which makes it easy to understand.

The material of the book can be divided into three parts. The first part (Chapters 1-3) presents the basic concepts and definitions of engineering design and opti- mization, which includes an introduction to design, opti- mum design problem formulation and optimum design con- cepts. The second part (Chapters 4-6) focuses on numeri- cal techniques for solving optimization problems. Various approaches from the classical Simplex method, to modern constrained steepest descent methods for constrained opti- mum design are described. The third part (Chapters 7-8) discusses the practical aspects of optimization, iterative al- gorithms and their uses. The appendices contain economic analysis, vector and matrix algebra, a numerical method for nonlinear equations and some computer codes.

Since the book includes all the fundamental concepts and numerical methods with large quantity examples, and the presentation is in a rigorous and simple manner, it is ideal for undergraduates on engineering design. This book could also be useful to graduates and engineers on design optimization.

Zhiye Zhao Computational Mechanics Institute Southampton, England

lO0 Probabilistic Engineering Mechanics, 1990, Vol. 5, No. 2