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Aeroelasticity
232
BOOK
AEROELASTICITY,by Raymond L. Bisplinghoff, Holt Ashley and Robert L. Halfman. 860 pages, diagrams, 6 X 9 in. Cambridge, Addison-Wesley Publishing Co., Inc., 1955. Price, $14.50. This book brings forth the “aeroelastician” -and perhaps many new specialists such as the railelastician in the domain of high speed trains. Actually, the first five chapters are an excellent discussion of elastic continuum in vibration systems. It was Rayleigh who formulated the field of continuous elastic structures to vibration analysis and engineers have been reluctant in extending this valuable theoretical background to design applications. Quite logically the authors introduce at the outset generalized structural analysis in terms of reciprocal influence and elastic coefficients, followed by elastic energy methods, minimum worth of Castigliano’s principle as applied to beams and extended structures in airplane wings. From the differential equation of motion of a beam portion, the authors introduce the conception of normal modes associated with finite frequencies, and their orthogonal properties. From this, the beam equation is generalized to normal coordinates. This later is again reviewed from the equation of virtual work through Lagrange’s equation, wherein a more forma1 generalization is given. Obviously the aeroelastician must determine these orthogonal modes for later application with aerodynamic loadings. Computation methods for such are given in Chapter 4. These first four chapters have a real fee1 in the aerodynamic aspect of the subject as well. For instance, Fig. 1-8, which shows a comparison of wing critical speeds, shows the relative zones for divergente speed, bending-torsion flutter and aileron reversal speed, as functions of sweep forward and sweep back wings. The second part of the book, starting with Chapter 5, considers the aerodynamic reactions with emphasis on the analysis of smal1 disturbances. As the authors state quite justly, “Moreover, from the aeroelastician’s standpoint a defect of nearly al1 books on fluid dynamics, is their preoccupation with steady flow phenomena.” Starting with a short review of hydrodynamic principles, the theory is extended to thin airfoils and finite wings treated first in steady motion and then
IJ. F. 1.
REVIEWS
extending to oscillations in incompressible The work then considers steady supersonic flow, followed by wing forms for these conditions. Chapter 6 continues oscillations in both subsonic and supersonic flow. In this phase much detailed consideration is given to slender straight and swept wingy. The last phase of the work covers an extensive discussion on flutter analysis and dynamic response phenomena, as for systems with time dependent external forces. Further discussion on model interpretation and shape simulation, with methods of trsting. is given. While the book appears at first glance to be written for the specialist in aeroelasticity. actually thc hook can be considered as a basic and valuable treatise for the entire field of modern airplane design. It is equally valuablc to engineers interested in applications of similar techniques in other fields.
flow.
RUPEK EKSERMAN ELECTROMAGNETIC WAVES, by G. Toraldo di Francia. 320 pages, diagrams, 6 X 9 in. Xew York, Interscience 1955. Price, $6.00.
Publishers.
Inc..
This is a translation by the author of an Italian text used in the Physics Department of the University of Florence. It considers principally the study of Maxwell’s equations and phenomena relating to the electromagnetic theory of light. In fact, it brings together al1 of the well-known equations and theorems of Fresnel, Fraunhofer, Green, Poisson, Fermat, Malus-Dupin, Hertz, Huygens, Heaviside, to mention a few. Reference is made to the outstanding American texts on electromagnetic theory by Stratton, Schelkunoff, and Slater. In some ways Professor di Francia’s book is like these, but much abbreviated. In this respect there appears to be excessive economy, for the treatment of each subject is pared down to its most concise mathematica1 expression. Few words of explanation are provided, and visualization of the quantities involved in the equations is extremely difficult without prior acquaintance. To prepare the student for the derivations that follow, the author begins with a 40-page introduction to mathematica1 procedures. At several places elsewhere in the book excel-
BOOK
AEROELASTICITY,by Raymond L. Bisplinghoff, Holt Ashley and Robert L. Halfman. 860 pages, diagrams, 6 X 9 in. Cambridge, Addison-Wesley Publishing Co., Inc., 1955. Price, $14.50. This book brings forth the “aeroelastician” -and perhaps many new specialists such as the railelastician in the domain of high speed trains. Actually, the first five chapters are an excellent discussion of elastic continuum in vibration systems. It was Rayleigh who formulated the field of continuous elastic structures to vibration analysis and engineers have been reluctant in extending this valuable theoretical background to design applications. Quite logically the authors introduce at the outset generalized structural analysis in terms of reciprocal influence and elastic coefficients, followed by elastic energy methods, minimum worth of Castigliano’s principle as applied to beams and extended structures in airplane wings. From the differential equation of motion of a beam portion, the authors introduce the conception of normal modes associated with finite frequencies, and their orthogonal properties. From this, the beam equation is generalized to normal coordinates. This later is again reviewed from the equation of virtual work through Lagrange’s equation, wherein a more forma1 generalization is given. Obviously the aeroelastician must determine these orthogonal modes for later application with aerodynamic loadings. Computation methods for such are given in Chapter 4. These first four chapters have a real fee1 in the aerodynamic aspect of the subject as well. For instance, Fig. 1-8, which shows a comparison of wing critical speeds, shows the relative zones for divergente speed, bending-torsion flutter and aileron reversal speed, as functions of sweep forward and sweep back wings. The second part of the book, starting with Chapter 5, considers the aerodynamic reactions with emphasis on the analysis of smal1 disturbances. As the authors state quite justly, “Moreover, from the aeroelastician’s standpoint a defect of nearly al1 books on fluid dynamics, is their preoccupation with steady flow phenomena.” Starting with a short review of hydrodynamic principles, the theory is extended to thin airfoils and finite wings treated first in steady motion and then
IJ. F. 1.
REVIEWS
extending to oscillations in incompressible The work then considers steady supersonic flow, followed by wing forms for these conditions. Chapter 6 continues oscillations in both subsonic and supersonic flow. In this phase much detailed consideration is given to slender straight and swept wingy. The last phase of the work covers an extensive discussion on flutter analysis and dynamic response phenomena, as for systems with time dependent external forces. Further discussion on model interpretation and shape simulation, with methods of trsting. is given. While the book appears at first glance to be written for the specialist in aeroelasticity. actually thc hook can be considered as a basic and valuable treatise for the entire field of modern airplane design. It is equally valuablc to engineers interested in applications of similar techniques in other fields.
flow.
RUPEK EKSERMAN ELECTROMAGNETIC WAVES, by G. Toraldo di Francia. 320 pages, diagrams, 6 X 9 in. Xew York, Interscience 1955. Price, $6.00.
Publishers.
Inc..
This is a translation by the author of an Italian text used in the Physics Department of the University of Florence. It considers principally the study of Maxwell’s equations and phenomena relating to the electromagnetic theory of light. In fact, it brings together al1 of the well-known equations and theorems of Fresnel, Fraunhofer, Green, Poisson, Fermat, Malus-Dupin, Hertz, Huygens, Heaviside, to mention a few. Reference is made to the outstanding American texts on electromagnetic theory by Stratton, Schelkunoff, and Slater. In some ways Professor di Francia’s book is like these, but much abbreviated. In this respect there appears to be excessive economy, for the treatment of each subject is pared down to its most concise mathematica1 expression. Few words of explanation are provided, and visualization of the quantities involved in the equations is extremely difficult without prior acquaintance. To prepare the student for the derivations that follow, the author begins with a 40-page introduction to mathematica1 procedures. At several places elsewhere in the book excel-