Vibration of Periodic Structures
Vibration of Periodic Structures

Author: Gautam SenGupta

Publisher: Elsevier

Published: 2023-10-27

Total Pages: 268

ISBN-13: 0323990231

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Vibration of Periodic Structures introduces the fundamentals of periodic structure theory by considering the simplest model – wave propagation in an infinitely long periodic spring-mass system. It then shows how the knowledge of the stop and pass bands can be utilized to find the natural frequency distribution in a finite periodic structure. The basic concepts are further extended to wave propagation in infinitely long periodically supported beams and plates; distribution of natural frequencies of a similar structure of finite length; vibration of skin-stringer structures; and structuralacoustic properties of a section of an aircraft fuselage, based on a combination of the finite element method and the periodic structure theory, in a highly cost-effective manner.This book is a valuable resource of information for practicing engineers in various industries, e.g., civil, mechanical, or aerospace engineering, dealing with vibration of structures with periodic properties, including prediction of supersonic flutter characteristics of aerospace structures. It will also prove to be a beneficial reference for researchers involved with wave propagation in metamaterials and phononic devices."Readers who have wanted a clear and connected account of vibration of periodic structures will find this treatment accessible and stimulating and will want to add this volume to their personal or institutional library. – Prof. Earl Dowell, Duke University, Durham, NC, USA - Shows how the periodic structure theory can be combined with the finite element method to model a section of an airplane fuselage to study its structural-acoustic characteristics - Features developing methods for predicting the dynamics of periodic structures in a cost-effective manner - Guides the reader to predict and reduce response of periodically stiffened structures to random excitations

Structural Vibration
Structural Vibration

Author: C. Beards

Publisher: Elsevier

Published: 1996-05-31

Total Pages: 289

ISBN-13: 0080518052

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Many structures suffer from unwanted vibrations and, although careful analysis at the design stage can minimise these, the vibration levels of many structures are excessive. In this book the entire range of methods of control, both by damping and by excitation, is described in a single volume.Clear and concise descriptions are given of the techniques for mathematically modelling real structures so that the equations which describe the motion of such structures can be derived. This approach leads to a comprehensive discussion of the analysis of typical models of vibrating structures excited by a range of periodic and random inputs. Careful consideration is also given to the sources of excitation, both internal and external, and the effects of isolation and transmissability. A major part of the book is devoted to damping of structures and many sources of damping are considered, as are the ways of changing damping using both active and passive methods. The numerous worked examples liberally distributed throughout the text, amplify and clarify the theoretical analysis presented. Particular attention is paid to the meaning and interpretation of results, further enhancing the scope and applications of analysis. Over 80 problems are included with answers and worked solutions to most. This book provides engineering students, designers and professional engineers with a detailed insight into the principles involved in the analysis and damping of structural vibration while presenting a sound theoretical basis for further study.Suitable for students of engineering to first degree level and for designers and practising engineersNumerous worked examplesClear and easy to follow

Wave Propagation Approach for Structural Vibration
Wave Propagation Approach for Structural Vibration

Author: Chongjian Wu

Publisher: Springer Nature

Published: 2020-10-28

Total Pages: 288

ISBN-13: 9811572372

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This book is intended for researchers, graduate students and engineers in the fields of structure-borne sound, structural dynamics, and noise and vibration control. Based on vibration differential equations, it presents equations derived from the exponential function in the time domain, providing a unified framework for structural vibration analysis, which makes it more regular and normalized. This wave propagation approach (WPA) divides structures at “discontinuity points,” and the waves show characteristics of propagation, reflection, attenuation, and waveform conversion. In each segment of the system between two “discontinuity points,” the governing equation and constraint are expressed accurately, allowing the dynamic properties of complex systems to be precisely obtained. Starting with basic structures such as beams and plates, the book then discusses theoretical research on complicated and hybrid dynamical systems, and demonstrates that structural vibration can be analyzed from the perspective of elastic waves by applying WPA.

Investigation for the Analysis of the Vibrations of Quasi-periodic Structures
Investigation for the Analysis of the Vibrations of Quasi-periodic Structures

Author: Safiullah Timorian

Publisher:

Published: 2020

Total Pages: 107

ISBN-13:

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In this thesis, the definition and effects of quasi-periodicity in periodic structure are investigated. More importantly, the presence of irregularity in periodic structures and its significant impact in vibroacoustic responses of elastic systems are analyzed. In the extant literature, it has already shown that a sandwich panel, optimized for vibroacoustic performance with added random properties of the core, can exhibit stop band characteristics in some frequency ranges. Therefore, an additional target can exist in framing the abovementioned property under the Wave Finite Element Method (WFEM) for resulting in some design guideline. In this paper, (1) the numerical stud- ies of the vibrational analysis of 1D finite, periodic, and quasi-periodic beams are presented. The paper's content deals with the finite element models of beams focusing on spectral analysis and the damped forced responses. The quasi-periodicity is defined by invoking the Fibonacci sequence for building the assigned variations (geometry and material) along the span of the finite element model in one direction. Similarly, the same span is used as a super unit cell with WFEM for analyzing the infinite periodic systems. (2) The method of variation with a developed algorithm is also considered to find the most efficient geometrical impedance mismatch behavior of unit cells for vibration control. (3) Numerical studies and experimental measurements on 2D periodic and quasi-periodic lattices are thus performed. Experimental validations are performed by comparing the quasi-periodic lattice simulated by using WFEM modelling, with a prototype manufactured by laser machin- ing. Based on the major findings, and considering both longitudinal and flexural elastic waves in 1D beams, the frequency ranges corresponding to band gaps are investigated. In the 2D structures, the wave characteristics in the quasi-periodic lattice introduce the possibility of designing wider fre- quency stop bands in low frequency ranges, and presents some elements of novelty; moreover, they can be considered for designing structural filters and controlling the properties of elastic waves. The results obtained in this study show that the beam with Fibonacci characteristics and panels with Thue- Morse characteristics can improve performances in terms of attenuation level without weight penalty, which can be an asset for metamaterials.

Analysis of Vibration of 2-D Periodic Cellular Structures
Analysis of Vibration of 2-D Periodic Cellular Structures

Author: Sang Min Jeong

Publisher:

Published: 2005

Total Pages:

ISBN-13:

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The vibration of and wave propagation in periodic cellular structures are analyzed. Cellular structures exhibit a number of desirable multifunctional properties, which make them attractive in a variety of engineering applications. These include ultra-light structures, thermal and acoustic insulators, and impact amelioration systems, among others. Cellular structures with deterministic architecture can be considered as example of periodic structures. Periodic structures feature unique wave propagation characteristics, whereby elastic waves propagate only in specific frequency bands, known as "pass band", while they are attenuated in all other frequency bands, known as "stop bands". Such dynamic properties are here exploited to provide cellular structures with the capability of behaving as directional, pass-band mechanical filters, thus complementing their well documented multifunctional characteristics. This work presents a methodology for the analysis of the dynamic behavior of periodic cellular structures, which allows the evaluation of location and spectral width of propagation and attenuation regions. The filtering characteristics are tested and demonstrated for structures of various geometry and topology, including cylindrical grid-like structures, Kagomé and tetrhedral truss core lattices. Experimental investigations is done on a 2-D lattice manufactured out of aluminum. The complete wave field of the specimen at various frequencies is measured using a Scanning Laser Doppler Vibrometer (SLDV). Experimental results show good agreement with the methodology and computational tools developed in this work. The results demonstrate how wave propagation characteristics are defined by cell geometry and configuration. Numerical and experimental results show the potential of periodic cellular structures as mechanical filters and/or isolators of vibrations.

Vibration of Nearly Periodic Structures and Mistuned Bladed Rotors
Vibration of Nearly Periodic Structures and Mistuned Bladed Rotors

Author: Alok Sinha

Publisher: Cambridge University Press

Published: 2017-06-16

Total Pages: 201

ISBN-13: 1108101348

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This is the first comprehensive volume on nearly periodic structures and mistuned blade vibration. Alok Sinha presents fundamental concepts and state-of-the-art techniques in the analysis of free and forced response of a nearly periodic structure, weaving together his own work (covering thirty-five years of research in this field) with works by other researchers. He also discusses similarities between tools used in bladed rotor analysis and condensed matter physics. Specific subjects covered include the reasons behind mode localization, the reasons behind amplitude amplification of steady-state response, state-of-the-art computational techniques for mistuned bladed rotors including multistage rotors, identification of mistuning from measured response, vibration localization in linear atomic chains, and analysis of two-dimensional periodic structures.