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Structural vibration analysis
Journal of Sound and Vibration (1983) 91(4), 619-621
BOOK
REVIEWS
VIBRATION ANALYSIS 1983 C. F. Beards. Chichester: Ellis Horwood Ltd (distributed by John Wiley & Sons Ltd). 153 pp., price f17.50. ISBN O-85312-325-X (Library Edition) ISBN O-85312-579-1 (Student Edition).
STRUCTURAL
This new book sets out to provide a link between books on basic vibration analysis and those which give comprehensive treatment of general structural dynamics. Its stated aim is to provide understanding of the principles involved in the analysis of structural vibration and to give a theoretical basis for further study. It aims also to give methods of predicting the effects of dynamic loads on structures and to show the effects of structural modifications. This is an ambitious target for the 119 pages of main text. An introductory chapter of seven pages shows how a chimney and a radio-telescope can be represented by lumped-parameter models. It also describes in one page the Diekman criterion for human toler.ance to vibration. Chapter 2 considers, in 35 pages, the single-degree-of-freedom system and covers the simple mass-spring-damper oscillator under free, forced-harmonic and forced transient motion. Three different types of damping are considered. Motion excitation of the base, force transmission through to the base, and general periodic excitation are covered. Rayleigh’s quotient for a beam is briefly introduced. Chapter 3 (27 pages) deals with systems with two or more degrees of freedom. Lumped-mass systems are considered throughout. Matrix methods are briefly introduced, and the calculation of natural frequencies by matrix iteration is described. Lagrange’s equations of motion are introduced and applied, in two pages. The concepts of receptance, mobility and impedance are presented, and applied to mass-spring-damper systems. Chapter 4 (22 pages) deals with the vibration of continuous systems. The free wave equations for longitudinal motion in bars and for flexural motion in beams are derived, and solved for some simple boundary conditions. The end receptances of certain beams are derived, and are used to demonstrate the usefulness of receptances in calculating the natural frequencies of a simple solar array. The natural frequency of a beam with a concentrated mass is studied by Rayleigh’s method and Dunkerley’s method. Finite plate free vibrations are covered in four pages (by using the Rayleigh method) and the finite element method is described in three to four pages. The forced vibrations of continuous systems are not considered explicitly. The final chapter on “Damping in Structures” occupies 28 pages. Of these, four deal with reducing vibration by dealing with the source (suppression and isolation). Seven pages deal with the undamped vibration absorber, and seven deal with the measurement of damping. The remaining pages deal mainly with solid friction damping mechanisms and conclude with a brief note on constrained layer damping. Unconstrained layer damping is not mentioned. The book concludes with 29 pages of problems for the student/reader to solve. Worked examples are included throughout the main text. The author has made a gallant and enthusiastic attempt to squeeze all this material into 149 pages. This can only be done, of course, by some degree of superficiality of treatment. The book does not set out to be a rigorous textbook, but in some places the rigour has been all too freely abandoned and outrageous statements have been made. 619
BOOK REVIEWS
620
The reviewer would like to protect his students from these by stamping “DANGEROUS” across the relevant pages! Provided the book is read in conjunction with a more rigorous text, it will provide a useful addition to the literature on the application of linear vibration theory to structural problems. D. J. MEAD
FUNDAMENTALS OF MECHANICAL VIBRATIONS 1983 M. Hussey. Press. Price f22.00 H/C, 510.00 PPR.
London:
Macmillan
This book covers quite a wide range of vibration and vibration related topics at about second year mechanical engineering degree level. However, the treatment of the material suggests that it is aimed at students who need a basic knowledge of the subject without intending to go any deeper. For example, the coupled oscillator (two degree of freedom system) would normally be used, at this level, to introduce the advanced student in vibration theory to the concepts of orthogonality of the modes, co-ordinate coupling and their influence on the matrix analysis of the problem. These topics are not, however, included. The book does include an initial chapter on Fundamental Mechanical Quantities, including vectors, rigid body dynamics, Hooke’s Law and work and energy. Although these topics would be well covered by other courses for mechanical engineering students, their inclusion in the book is very useful for non-specialists. This also applies to some extent, to the inclusion of Fourier and Laplace theory. The final chapter on human body vibrations is a little out of place in a non-specialist book on vibrations but perhaps the author is really aiming at medical students. In conclusion, this is a useful book for those wishing to have a good but non-specialist knowledge of vibration theory. N. LALOR
83 PROCEEDINGS 1983, edited by R. Lotz. Poughkeepsie, Foundation. 512 pp., price $42.00 within the U.S.A., $57.50
NOISE-CON
Control
New York: overseas.
Noise
Noise-Con is held in odd-numbered years by INCE/USA; its Proceedings hold a place on the noise control engineer’s shelf for reference material along with others such as the related INTER-NOISE annual Proceedings. With the theme in 1983 of controlling noise at source, it is interesting to consider whether the latest proceedings contain material which might also find a place on the shelves of design and development engineers. The editor points out in his Foreword the importance of including consideration of noise from the earliest stages of design rather than finding it necessary to call in the noise specialist at a later, perhaps too late, stage. The reviewer did not attend the Conference, but whilst recognizing the value of attendance and the almost inevitable “Abstract” style of the Proceedings, many readers will be in the same situation. There were ten categorized groups of papers, plus product application workshops and two distinguished lectures concerning flow noise and vibration. It is a disappointment that there are no adequate summaries of these two lectures, nor any references to any related recent work. Eight sessions totalling over 50 papers covered the 10 categorized subject groups: valves and orifices, printers and other mechanisms, structural design and other source quietening, fans and turbomachines, air conditioner fans, motors and transformers, source
BOOK
REVIEWS
VIBRATION ANALYSIS 1983 C. F. Beards. Chichester: Ellis Horwood Ltd (distributed by John Wiley & Sons Ltd). 153 pp., price f17.50. ISBN O-85312-325-X (Library Edition) ISBN O-85312-579-1 (Student Edition).
STRUCTURAL
This new book sets out to provide a link between books on basic vibration analysis and those which give comprehensive treatment of general structural dynamics. Its stated aim is to provide understanding of the principles involved in the analysis of structural vibration and to give a theoretical basis for further study. It aims also to give methods of predicting the effects of dynamic loads on structures and to show the effects of structural modifications. This is an ambitious target for the 119 pages of main text. An introductory chapter of seven pages shows how a chimney and a radio-telescope can be represented by lumped-parameter models. It also describes in one page the Diekman criterion for human toler.ance to vibration. Chapter 2 considers, in 35 pages, the single-degree-of-freedom system and covers the simple mass-spring-damper oscillator under free, forced-harmonic and forced transient motion. Three different types of damping are considered. Motion excitation of the base, force transmission through to the base, and general periodic excitation are covered. Rayleigh’s quotient for a beam is briefly introduced. Chapter 3 (27 pages) deals with systems with two or more degrees of freedom. Lumped-mass systems are considered throughout. Matrix methods are briefly introduced, and the calculation of natural frequencies by matrix iteration is described. Lagrange’s equations of motion are introduced and applied, in two pages. The concepts of receptance, mobility and impedance are presented, and applied to mass-spring-damper systems. Chapter 4 (22 pages) deals with the vibration of continuous systems. The free wave equations for longitudinal motion in bars and for flexural motion in beams are derived, and solved for some simple boundary conditions. The end receptances of certain beams are derived, and are used to demonstrate the usefulness of receptances in calculating the natural frequencies of a simple solar array. The natural frequency of a beam with a concentrated mass is studied by Rayleigh’s method and Dunkerley’s method. Finite plate free vibrations are covered in four pages (by using the Rayleigh method) and the finite element method is described in three to four pages. The forced vibrations of continuous systems are not considered explicitly. The final chapter on “Damping in Structures” occupies 28 pages. Of these, four deal with reducing vibration by dealing with the source (suppression and isolation). Seven pages deal with the undamped vibration absorber, and seven deal with the measurement of damping. The remaining pages deal mainly with solid friction damping mechanisms and conclude with a brief note on constrained layer damping. Unconstrained layer damping is not mentioned. The book concludes with 29 pages of problems for the student/reader to solve. Worked examples are included throughout the main text. The author has made a gallant and enthusiastic attempt to squeeze all this material into 149 pages. This can only be done, of course, by some degree of superficiality of treatment. The book does not set out to be a rigorous textbook, but in some places the rigour has been all too freely abandoned and outrageous statements have been made. 619
BOOK REVIEWS
620
The reviewer would like to protect his students from these by stamping “DANGEROUS” across the relevant pages! Provided the book is read in conjunction with a more rigorous text, it will provide a useful addition to the literature on the application of linear vibration theory to structural problems. D. J. MEAD
FUNDAMENTALS OF MECHANICAL VIBRATIONS 1983 M. Hussey. Press. Price f22.00 H/C, 510.00 PPR.
London:
Macmillan
This book covers quite a wide range of vibration and vibration related topics at about second year mechanical engineering degree level. However, the treatment of the material suggests that it is aimed at students who need a basic knowledge of the subject without intending to go any deeper. For example, the coupled oscillator (two degree of freedom system) would normally be used, at this level, to introduce the advanced student in vibration theory to the concepts of orthogonality of the modes, co-ordinate coupling and their influence on the matrix analysis of the problem. These topics are not, however, included. The book does include an initial chapter on Fundamental Mechanical Quantities, including vectors, rigid body dynamics, Hooke’s Law and work and energy. Although these topics would be well covered by other courses for mechanical engineering students, their inclusion in the book is very useful for non-specialists. This also applies to some extent, to the inclusion of Fourier and Laplace theory. The final chapter on human body vibrations is a little out of place in a non-specialist book on vibrations but perhaps the author is really aiming at medical students. In conclusion, this is a useful book for those wishing to have a good but non-specialist knowledge of vibration theory. N. LALOR
83 PROCEEDINGS 1983, edited by R. Lotz. Poughkeepsie, Foundation. 512 pp., price $42.00 within the U.S.A., $57.50
NOISE-CON
Control
New York: overseas.
Noise
Noise-Con is held in odd-numbered years by INCE/USA; its Proceedings hold a place on the noise control engineer’s shelf for reference material along with others such as the related INTER-NOISE annual Proceedings. With the theme in 1983 of controlling noise at source, it is interesting to consider whether the latest proceedings contain material which might also find a place on the shelves of design and development engineers. The editor points out in his Foreword the importance of including consideration of noise from the earliest stages of design rather than finding it necessary to call in the noise specialist at a later, perhaps too late, stage. The reviewer did not attend the Conference, but whilst recognizing the value of attendance and the almost inevitable “Abstract” style of the Proceedings, many readers will be in the same situation. There were ten categorized groups of papers, plus product application workshops and two distinguished lectures concerning flow noise and vibration. It is a disappointment that there are no adequate summaries of these two lectures, nor any references to any related recent work. Eight sessions totalling over 50 papers covered the 10 categorized subject groups: valves and orifices, printers and other mechanisms, structural design and other source quietening, fans and turbomachines, air conditioner fans, motors and transformers, source