Download or read book Shock Mitigation and Wave Control Using Elastic Metamaterial Structures written by Sagr Mubarak Alamri and published by . This book was released on 2018 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acoustic/Elastic metamaterials have attracted increased attention in recent times. Metamaterials are defined as special materials that exhibit unusual properties not normally found in normal materials. These unusual properties are derived from the specially designed microstructures rather than the chemical composition of the material. Based on the concept of locally resonant metamaterials, these materials are applied in many applications such as impact wave attenuation, blast wave mitigation and wave control and manipulation due to their flexibility and tailoring properties for various needed applications. In this thesis, we present the development of a dissipative elastic metamaterial with multiple Maxwell-type resonators for dynamic load mitigation. Besides the wave attenuation of dynamic loads, we also investigate the asymmetric transmission of elastic waves which has recently been realized by linear structures. We design and propose different diatomic and triatomic elastic metamaterials to obtain large asymmetric elastic wave transmission in multiple low-frequency bands. All these frequency bands can be theoretically predicted to realize one-way wave propagation along different directions of transmission. All proposed models in this research are analytically investigated and numerically verified by both analytical lattice and continuum models. Also, the dynamic responses of the proposed models are explored and analyzed in time and frequency domains. The effect of damping on the proposed models is also investigated for more practical applications. Lastly, experimental verification is further conducted to observe wave asymmetric transmission bands and transient wave responses in time and frequency domains are also explored.
Download or read book Programmable Elastic Metamaterials for Wave Control and Device Applications written by Hui Chen and published by Frontiers Media SA. This book was released on 2023-10-27 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Emerging from electromagnetic waves and fast extending to acoustic and elastic waves, metamaterials that exhibit extraordinary wave control abilities have been gaining soaring attention. Over the past two decades, elastic metamaterials with engineered microstructures have provided a variety of appealing solutions for controlling elastic waves and vibrations. By tailoring their internal microstructures at a subwavelength scale, elastic metamaterials fruitfully distinct themselves from traditional materials or phononic crystals by their striking functions in wave trajectory manipulation, cloaking, nonreciprocal and topological wave control, as well as low-frequency wave/vibration mitigation and absorption.
Download or read book Broadband Reconfigurable and Multifunctional Elastic Wave Control with Smart Metamaterials written by Yangyang Chen and published by . This book was released on 2017 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past two decades, an extensive research effort has been devoted to elastic metamaterials, structured artificial materials at subwavelength scales, for elastic wave manipulations in solids. Due to the extreme values of material parameters, negative and/or positive, they achieved, the applications can range from wave and/or vibration attenuations, wave guiding and imaging, enhanced sensing, to invisible cloaking. However, conventional passive metamaterials have limitations, i.e. they can only be operated in narrow frequency regions and their functions are usually locked into space or with minor tunabilities once fabricated, lacking real time reconfigurabilities. Those limitations strongly hinder them from practical usages. With the rapid development of smart materials and structures, more and more intelligent elements are being introduced into wave propagation, vibration and sound control systems. The piezoelectric shunting technique is one well known method that receives considerable attention. In this dissertation, by leveraging the circuit control concept, both analog and digital, we propose some circuit controlled active/adaptive/hybrid/programmable metamaterials and metasurfaces for unprecedent elastic wave manipulations. Analytical, numerically and experimentally approaches are combined throughout the dissertation to illustrate design concepts, characterize wave propagation properties, and valid the designs. Specifically, active elastic metamaterials with tunable stiffness in local resonators are first designed for tunable wave and/or vibration mitigations. We then extend this concept to achieve super broadband wave attenuations with frequency-dependent stiffness elements. By introducing the variable stiffness elements to the host medium, a hybrid metamaterial is developed for switched ON/OFF wave propagations and broadband negative refractions. Based on a developed approximate transformation method, an active metamaterial is designed and placed on a plate to achieve spatially varying effective mass densities for broadband elastic trajectory control. Finally, a programmable metasurface with ultrathin-thickness is demonstrated for broadband, real-time and multifunctional wavefront manipulations in a plate. The active, adaptive, hybrid, and programmable elastic metamaterials and/or metasurfaces are still in their infant stages. The examples presented in the dissertation are transformable to different length and time scales and could serve as efficient and powerful tools in exploring some unconventional wave phenomenon in solid structures, i.e. by using concepts in quantum mechanics, where passive approaches are significantly limited. The designs could also immediately open new possibilities in elastic wave control devices including, but not limited to structural health monitoring, stealth technology, active noise control, as well as medical instrumentation and imaging.
Download or read book Continuum Modelling and Analysis of a Class of One and Two Dimensional Elastic Metamaterials with Local Rotation written by Antonio J. Schiavone and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The group of materials classified as "metamaterials" have accrued great interest in the scientific community as of late for their potential to revolutionize several multidisciplinary applications. Metamaterials are defined as synthetic/man-made materials which have been engineered to possess a number of desired unusual, and often counterintuitive properties which do not occur naturally. The inception of metamaterials into engineering science was in the field of optics when a material exhibiting an apparent negative index of refraction was designed. Following this, so-called "optical metamaterials" were researched and implemented in the field of electromagnetic cloaking, as well as utilized to design superlenses with sub-wavelength resolution. Recently a subclass of metamaterials known as elastic metamaterials has become of great interest to engineering scientists. This is a large class of materials which exhibits one or more unusual elastic properties such as negative Poisson's ratio, negative effective stiffness, negative shear modulus, and many more. Elastic metamaterials have potential for application in the fields of impact mitigation, shock absorption, wave attenuation, energy shielding, and wave guiding, to name a few.\\ In order to facilitate the use of this new class of materials, it is of paramount importance to possess the ability to predict the behaviour of these materials under specific, as well as sufficiently general loading conditions. There are two main ways to do this; the first of which is experimentally, through trial and error, and the second is analytically by creating a mathematical model capable of predicting both material behaviour and effective properties under specific loading conditions. This thesis will focus on the latter method.\\ There exists a myriad of mathematical techniques for material characterization, some of these techniques include homogenization methods, unit cell design, discrete modelling, and continuum modelling. This thesis will focus on the continuum modelling of a class of elastic metamaterials with local rotational effects. Typically, when local effects need to be considered in the framework of a continuum, the micropolar continuum model is the first avenue people explore. In this thesis it will be shown that this model is incapable of capturing all of the salient features present in both one, and two dimensional elastic metamaterials belonging to this class.\\ In this thesis a series of continuum models are developed with increasing generality. First, in the third chapter, a micropolar-type continuum model is derived for a specific one-dimensional double negative metamaterial capable of exhibiting negative mass and/or negative modulus under certain loading frequencies when subject to harmonic loads. This is done by analyzing a discrete structure, obtaining the equations of motion, and then making a continuous approximation to bring the discrete model to the continuum framework. This model is used to evaluate the transient response of a specific one-dimensional semi-infinite elastic metamaterial when subject to an axial impact. In the fourth chapter, a higher order continuum model is developed in a manner very similar to the methodology presented in the third chapter, but with a higher order derivative of the rotational variable $\theta$. This model is then generalized to an entire class of materials, even though it is developed using a representative discrete structure. Harmonic wave propagation is then studied in the same one-dimensional elastic metamaterial that was modelled in the third chapter using this new model, leading to the determination of the stop and passing bands, as well as the determination of the dispersion relation governing the wave propagation. This new model is then compared to both the model in the third chapter, as well as the discrete model to determine the range of suitability. In the fifth chapter a model for a two-dimensional class of elastic metamaterials with local rotation is developed in a slightly different way than in the previous two chapters. In this chapter a set of constitutive laws for the relevant class of materials is proposed, and then a representative discrete metamaterial is modelled, and approximated as a continuum to prove suitability of the model. This model is then used to study harmonic longitudinal (P) and transverse (S) wave propagation in the material, which covers all cases of general two-dimensional wave propagation. The stop and passing bands, as well as the dispersion relations were determined for both wave propagation schemes and the effect of local rotation was analyzed. The sixth chapter uses the model developed in the fifth chapter to study surface wave propagation in a new continuum with local rotation. The dispersion relation of the surface wave is obtained, as well as expressions for the decay parameters, $b1$ and $b2$. The behaviour of the general dispersion relation, as well as some simplified cases are investigated. It is found that surface waves propagating through a continuum with local rotation are dispersive even when the local rotational effects are small compared to the translational ones. Two parameters governing general wave propagation, $f$ and $g$ are identified. The parameter $f$ controls the height of frequency peaks in the dispersion relation, and the parameter $g$ controls the location of the second peak. Furthermore, for values of $f \approx 1$ or greater, surface waves are found to propagate with wavespeeds significantly lower than $c_R$, a phenomenon unique to this continuum. Finally, the motion of the particles residing on the surface of this continuum is determined to be elliptical when subject to surface wave propagation, similar to classical Rayleigh wave propagation.
Download or read book Shock Waves in Solid State Physics written by G.I. Kanel' and published by CRC Press. This book was released on 2019-04-30 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: Methods and the latest results of experimental studies of the strength properties, polymorphism and metastable states of materials and substances with extremely short durations of shock-wave action are presented. The author provides a comprehensive and theoretical description of specific features of the dynamics of elastoplastic shock compression waves in relaxing media. The presentation is preceded by a detailed description of the theoretical foundations of the method and a brief discussion of the basic methods of generating and diagnosing shock waves in solids. Key Selling Features: Addresses dynamic elastic-plastic response, spallation, and shock-induced phase transformation. Provides a centralized presentation of topics of interest to the shock physics community Presents new data on the mechanism and basic patterns of sub-microsecond polymorphic transformations and phase transitions. Investigates destruction waves in shock-compressed glasses. Analyzes the behavior of highly hard brittle materials under shock-wave loading and ways to diagnose fracture.
Download or read book Blast Mitigation Strategies in Marine Composite and Sandwich Structures written by Srinivasan Gopalakrishnan and published by Springer. This book was released on 2017-12-14 with total page 477 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book primarily focuses on methodologies to enable marine structures to resist high velocity impact loadings. It is based on invited talks presented at the recent India–USA workshop on “Recent Advances in Blast Mitigation Strategies in Civil and Marine Composite Structures” The book comprises content from top researchers from India and the USA and covers various aspects of the topic, including modeling and simulation, design aspects, experimentation and various challenges. These failure modes significantly reduce the structural integrity of the marine structures unless they are designed to resist such harsh loadings. Understanding the mechanics of these structures under harsh loadings is still an open area of research, and the behavior of these structures is not fully understood. The book highlights efforts to reduce the effects of blast loadings on marine composite structures. Intended for researchers/scientists and practicing engineers, the book focuses not only the design and analysis challenges of marine composite structures under such harsh loading conditions, but also provides new design guidelines.
Download or read book Acoustical Imaging written by Woon Siong Gan and published by John Wiley & Sons. This book was released on 2012-05-11 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: The technology of acoustical imaging has advanced rapidly over the last sixty years, and now represents a sophisticated technique applied to a wide range of fields including non-destructive testing, medical imaging, underwater imaging and SONAR, and geophysical exploration. Acoustical Imaging: Techniques and Applications for Engineers introduces the basic physics of acoustics and acoustical imaging, before progressing to more advanced topics such as 3D and 4D imaging, elasticity theory, gauge invariance property of acoustic equation of motion and acoustic metamaterials. The author draws together the different technologies in sonar, seismic and ultrasound imaging, highlighting the similarities between topic areas and their common underlying theory. Key features: Comprehensively covers all of the important applications of acoustical imaging. Introduces the gauge invariance property of acoustic equation of motion, with applications in the elastic constants of isotropic solids, time reversal acoustics, negative refraction, double negative acoustical metamaterial and acoustical cloaking. Contains up to date treatments on latest theories of sound propagation in random media, including statistical treatment and chaos theory. Includes a chapter devoted to new acoustics based on metamaterials, a field founded by the author, including a new theory of elasticity and new theory of sound propagation in solids and fluids and tremendous potential in several novel applications. Covers the hot topics on acoustical imaging including time reversal acoustics, negative refraction and acoustical cloaking. Acoustical Imaging: Techniques and Applications for Engineers is a comprehensive reference on acoustical imaging and forms a valuable resource for engineers, researchers, senior undergraduate and graduate students.
Download or read book Optical Systems and Processes written by Joseph Shamir and published by SPIE Press. This book was released on 1999 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: A concise, comprehensive reference text covering electro-optical systems, optical system design, optical physics, holography, Fourier optics, and optical metrology. It emphasizes physical insight aimed at engineering applications. This book is suitable as an advanced undergraduate or graduate level text; problems and solutions are included.
Download or read book Stress Waves in Solids written by Herbert Kolsky and published by Courier Corporation. This book was released on 1963-01-01 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most readable survey of the theoretical core of current knowledge available. The author gives a concise account of the classical theory necessary to an understanding of the subject and considers how this theory has been extended to solids.
Download or read book Auxetic Materials and Structures written by Teik-Cheng Lim and published by Springer. This book was released on 2014-12-27 with total page 591 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book lays down the foundation on the mechanics and design of auxetic solids and structures, solids that possess negative Poisson’s ratio. It will benefit two groups of readers: (a) industry practitioners, such as product and structural designers, who need to control mechanical stress distributions using auxetic materials, and (b) academic researchers and students who intend to produce unique mechanical and other physical properties of structures using auxetic materials.
Download or read book Computational Techniques for Structural Health Monitoring written by Srinivasan Gopalakrishnan and published by Springer Science & Business Media. This book was released on 2011-08-01 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increased level of activity on structural health monitoring (SHM) in various universities and research labs has resulted in the development of new methodologies for both identifying the existing damage in structures and predicting the onset of damage that may occur during service. Designers often have to consult a variety of textbooks, journal papers and reports, because many of these methodologies require advanced knowledge of mechanics, dynamics, wave propagation, and material science. Computational Techniques for Structural Health Monitoring gives a one-volume, in-depth introduction to the different computational methodologies available for rapid detection of flaws in structures. Techniques, algorithms and results are presented in a way that allows their direct application. A number of case studies are included to highlight further the practical aspects of the selected topics. Computational Techniques for Structural Health Monitoring also provides the reader with numerical simulation tools that are essential to the development of novel algorithms for the interpretation of experimental measurements, and for the identification of damage and its characterization. Upon reading Computational Techniques for Structural Health Monitoring, graduate students will be able to begin research-level work in the area of structural health monitoring. The level of detail in the description of formulation and implementation also allows engineers to apply the concepts directly in their research.
Download or read book Vibrations and Waves in Continuous Mechanical Systems written by Peter Hagedorn and published by John Wiley & Sons. This book was released on 2007-10-22 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: The subject of vibrations is of fundamental importance in engineering and technology. Discrete modelling is sufficient to understand the dynamics of many vibrating systems; however a large number of vibration phenomena are far more easily understood when modelled as continuous systems. The theory of vibrations in continuous systems is crucial to the understanding of engineering problems in areas as diverse as automotive brakes, overhead transmission lines, liquid filled tanks, ultrasonic testing or room acoustics. Starting from an elementary level, Vibrations and Waves in Continuous Mechanical Systems helps develop a comprehensive understanding of the theory of these systems and the tools with which to analyse them, before progressing to more advanced topics. Presents dynamics and analysis techniques for a wide range of continuous systems including strings, bars, beams, membranes, plates, fluids and elastic bodies in one, two and three dimensions. Covers special topics such as the interaction of discrete and continuous systems, vibrations in translating media, and sound emission from vibrating surfaces, among others. Develops the reader’s understanding by progressing from very simple results to more complex analysis without skipping the key steps in the derivations. Offers a number of new topics and exercises that form essential steppingstones to the present level of research in the field. Includes exercises at the end of the chapters based on both the academic and practical experience of the authors. Vibrations and Waves in Continuous Mechanical Systems provides a first course on the vibrations of continuous systems that will be suitable for students of continuous system dynamics, at senior undergraduate and graduate levels, in mechanical, civil and aerospace engineering. It will also appeal to researchers developing theory and analysis within the field.
Download or read book Coherent Structures in Granular Crystals written by Christopher Chong and published by Springer. This book was released on 2018-03-29 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes a number of fundamental developments at the interface of granular crystals and the mathematical and computational analysis of some of their key localized nonlinear wave solutions. The subject presents a blend of the appeal of granular crystals as a prototypical engineering tested for a variety of diverse applications, the novelty in the nonlinear physics of its coherent structures, and the tractability of a series of mathematical and computational techniques to analyse them. While the focus is on principal one-dimensional solutions such as shock waves, traveling waves, and discrete breathers, numerous extensions of the discussed patterns, e.g., in two dimensions, chains with defects, heterogeneous settings, and other recent developments are discussed. The emphasis on the subject was motivated by models in condensed matter physics, ferroelectrics, high energy physics, and statistical mechanics, leading to developments in mathematical analysis, numerical computation and insights on the physical aspects of the model. The book appeals to researchers in the field, as well as for graduate and advanced undergraduate students. It will be of interest to mathematicians, physicists and engineers alike.
Download or read book Kernel Smoothing written by M.P. Wand and published by CRC Press. This book was released on 1994-12-01 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: Kernel smoothing refers to a general methodology for recovery of underlying structure in data sets. The basic principle is that local averaging or smoothing is performed with respect to a kernel function. This book provides uninitiated readers with a feeling for the principles, applications, and analysis of kernel smoothers. This is facilita
Download or read book Geotechnical Earthquake Engineering written by Ikuo Towhata and published by Springer Science & Business Media. This book was released on 2008-12-19 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt: This fascinating new book examines the issues of earthquake geotechnical engineering in a comprehensive way. It summarizes the present knowledge on earthquake hazards and their causative mechanisms as well as a number of other relevant topics. Information obtained from earthquake damage investigation (such as ground motion, landslides, earth pressure, fault action, or liquefaction) as well as data from laboratory tests and field investigation is supplied, together with exercises/questions.
Download or read book Shock Induced Transitions and Phase Structures in General Media written by J.E. Dunn and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: This IMA Volume in Mathematics and its Applications SHOCK INDUCED TRANSITIONS AND PHASE STRUCTURES IN GENERAL MEDIA is based on the proceedings of a workshop that was an integral part of the 1990-91 IMA program on "Phase Transitions and Free Boundaries." The workshop focused on the thermodynamics and mechanics of dynamic phase transitions that are mainly inertially driven and brought together physicists, metallurgists, mathematicians, engineers, and molecular dynamicists with interests in these problems. Financial support of the National Science Foundation made the meeting pos sible. We are grateful to J .E. Dunn, Roger Fosdick, and Marshall Slemrod for organizing the meeting and editing the proceedings. A vner Friedman Willard Miller, .Jr. PREFACE When a body is subjected to a strong shock the material may suffer severe local structural changes. Rapid solidification, liquification, or vaporization can oc cur, and, moreover, complex structural heterogeneity is often left in the wake of the passing wave. Thus, inertially driven shock waves raise fundamental questions involving experiment, theory, and mathematics which bear on phase stability and metastability, as well as on reaction kinetics and appropriate measures of phase structure.
Download or read book Wave Propagation in Linear and Nonlinear Periodic Media written by Francesco Romeo and published by Springer Science & Business Media. This book was released on 2013-07-30 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: Waves and defect modes in structures media.- Piezoelectric superlattices and shunted periodic arrays as tunable periodic structures and metamaterials.- Topology optimization.- Map-based approaches for periodic structures.- Methodologies for nonlinear periodic media. The contributions in this volume present both the theoretical background and an overview of the state-of-the art in wave propagation in linear and nonlinear periodic media in a consistent format. They combine the material issued from a variety of engineering applications, spanning a wide range of length scale, characterized by structures and materials, both man-made and naturally occurring, featuring geometry, micro-structural and/or materials properties that vary periodically in space, including periodically stiffened plates, shells and beam-like as well as bladed disc assemblies, phononic metamaterials, photonic crystals and ordered granular media. Along with linear models and applications, analytical methodologies for analyzing and exploiting complex dynamical phenomena arising in nonlinear periodic systems are also presented.
