Ultrasonic arrays for non-destructive evaluation: A review
TL;DR: The use of ultrasonic arrays for non-destructive evaluation has been extensively studied in the literature as mentioned in this paper, where the main advantages of arrays are their increased flexibility over traditional single element transducers, and their ability to produce immediate images of the test structure.
Abstract: An ultrasonic array is a single transducer that contains a number of individually connected elements. Recent years have seen a dramatic increase in the use of ultrasonic arrays for non-destructive evaluation. Arrays offer great potential to increase inspection quality and reduce inspection time. Their main advantages are their increased flexibility over traditional single element transducer methods, meaning that one array can be used to perform a number of different inspections, and their ability to produce immediate images of the test structure. These advantages have led to the rapid uptake of arrays by the engineering industry. These industrial applications are underpinned by a wide range of published research which describes new piezoelectric materials, array geometries, modelling methods and inspection modalities. The aim of this paper is to bring together the most relevant published work on arrays for non-destructive evaluation applications, comment on the state-of the art and discuss future directions. There is also a significant body of published literature referring to use of arrays in the medical and sonar fields and the most relevant papers from these related areas are also reviewed. However, although there is much common ground, the use of arrays in non-destructive evaluation offers some distinctly different challenges to these other disciplines.
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TL;DR: This work introduces monolithic acoustic holograms, which can reconstruct diffraction-limited acoustic pressure fields and thus arbitrary ultrasound beams and is expected to enable new capabilities in beam-steering and the contactless transfer of power, improve medical imaging, and drive new applications of ultrasound.
Abstract: Holograms for sound waves, encoded in a 3D printed plate, are used to shape sound fields that can be used for the contactless manipulation of objects. Sound, especially ultrasound, can be used for contactless manipulation of objects in liquid and air, a phenomenon with applications in medical imaging, non-destructive testing and metrology. Usually, the desired sound field is shaped with arrays of transducers that must be carefully connected and controlled. Here Peer Fischer and colleagues describe a relatively simple technique for creating acoustic holograms and demonstrate their potential for use in matter manipulation. The acoustic holograms are encoded in a polymer plate by 3D printing and then used to shape a sound field that can be used for contactless manipulation of objects. The method can produce complex fields with reconstruction degrees of freedom two orders of magnitude greater than existing approaches. Because the holograms are inexpensive and fast to make, the method could be widely adopted to enable new applications with ultrasound manipulation. Holographic techniques are fundamental to applications such as volumetric displays1, high-density data storage and optical tweezers that require spatial control of intricate optical2 or acoustic fields3,4 within a three-dimensional volume. The basis of holography is spatial storage of the phase and/or amplitude profile of the desired wavefront5,6 in a manner that allows that wavefront to be reconstructed by interference when the hologram is illuminated with a suitable coherent source. Modern computer-generated holography7 skips the process of recording a hologram from a physical scene, and instead calculates the required phase profile before rendering it for reconstruction. In ultrasound applications, the phase profile is typically generated by discrete and independently driven ultrasound sources3,4,8,9,10,11,12; however, these can only be used in small numbers, which limits the complexity or degrees of freedom that can be attained in the wavefront. Here we introduce monolithic acoustic holograms, which can reconstruct diffraction-limited acoustic pressure fields and thus arbitrary ultrasound beams. We use rapid fabrication to craft the holograms and achieve reconstruction degrees of freedom two orders of magnitude higher than commercial phased array sources. The technique is inexpensive, appropriate for both transmission and reflection elements, and scales well to higher information content, larger aperture size and higher power. The complex three-dimensional pressure and phase distributions produced by these acoustic holograms allow us to demonstrate new approaches to controlled ultrasonic manipulation of solids in water, and of liquids and solids in air. We expect that acoustic holograms will enable new capabilities in beam-steering and the contactless transfer of power, improve medical imaging, and drive new applications of ultrasound.
516 citations
TL;DR: In this article, the most studied type of manufacturing defects, voids, form very often in processing of fiber-reinforced composites and have a considerable influence on physical and thermomechanical properties.
Abstract: Voids, the most studied type of manufacturing defects, form very often in processing of fiber-reinforced composites. Due to their considerable influence on physical and thermomechanical properties ...
404 citations
Cites methods from "Ultrasonic arrays for non-destructi..."
...Furthermore, this technique is much faster than the conventional US technique.(182,183) The disadvantage of the phased array US technique is the limitation to thin samples....
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TL;DR: In this article, an acoustic phased array using a metascreen that transmits sound energy from a single source and steers the outgoing wavefront in the desired direction is presented.
Abstract: Manipulating sound waves is key in applications such as ultrasound imaging and nondestructive testing. To this end, the authors present an acoustic phased array using a metascreen that transmits sound energy from a single source and steers the outgoing wavefront in the desired direction. Significantly, this metascreen does not itself contain any source of sound, unlike a conventional phased array with many individual sources. This passive array is therefore notably appealing for its simplicity, low cost, and good acoustic performance.
285 citations
Cites methods from "Ultrasonic arrays for non-destructi..."
...The screen may be used for sound-field shaping in underwater sound arrays [29], nondestructive testing [30], audio presentation [31], and particle manipulation [32]....
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Book•
06 Dec 2012
TL;DR: In this article, acoustic metamaterials have been used for low frequency surface acoustic band gap applications and transformation elastodynamics and active exterior acoustic cloaking with liquid surface waves and plasmonic shells.
Abstract: Preface.- 1 Fundamentals of acoustic metamaterials.- 2 Locally resonant structures for low frequency surface acoustic band gap applications.- 3 Band-gap properties of prestressed structures.- 4 Ultrasound transmission through periodically perforated plates.- 5 Novel Ultrasound Imaging Applications.- 6 Subwavelength focussing in metamaterials using far field time reversal.- 7 Anisotropic metamaterials for transformation acoustics and imaging.- 8 Transformation Acoustics.- 9 Acoustic Cloaking Via Homogenization.- 10 Acoustic Cloaking with Plasmonic Shells.- 11 Cloaking Liquid Surface Waves and Plasmon Polaritons.- 12 Transformation elastodynamics and active exterior acoustic cloaking.
280 citations
Cites background from "Ultrasonic arrays for non-destructi..."
...This effect is well-known in structural engineering [7, 23, 26–28], in two-dimensional boundary-value problems of prestressed solids [3, 4, 9, 11, 13, 14, 31, 37] and finds simple experimental demonstrations, so that for instance prestress plays a chief role in the vibrational behaviour of stringed musical instruments: in the absence of the strong compression induced by ribs a piano soundboard would not vibrate properly....
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...9 (a) Design of an invisibility cloak for bending waves in a thin-elastic plate with concentric rings of homogeneous isotropic materials (here some polymers, see [13]); (b) Civil engineering application for anti-earthquake building foundations (courtesy of Popular Science Magazine)...
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...[11, 13] reported theoretical results in the rigid-solid limit for one- and two-dimensional arrays of square holes, for which they derived the dispersion relation of leaky and non-leaky surface modes....
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...Usually presented as periodic structures with spatially modulated elastic moduli and mass density, the so-called phononic crystals have a number of important features such as the occurrence of frequency band gaps [13, 19]....
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References
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TL;DR: The second edition of this respected text considerably expands the original and reflects the tremendous advances made in the discipline since 1968 as discussed by the authors, with a special emphasis on applications to diffraction, imaging, optical data processing, and holography.
Abstract: The second edition of this respected text considerably expands the original and reflects the tremendous advances made in the discipline since 1968. All material has been thoroughly updated and several new sections explore recent progress in important areas, such as wavelength modulation, analog information processing, and holography. Fourier analysis is a ubiquitous tool with applications in diverse areas of physics and engineering. This book explores these applications in the field of optics with a special emphasis on applications to diffraction, imaging, optical data processing, and holography. This book can be used as a textbook to satisfy the needs of several different types of courses, and it is directed toward both engineers ad physicists. By varying the emphasis on different topics and specific applications, the book can be used successfully in a wide range of basic Fourier Optics or Optical Signal Processing courses.
12,159 citations
Book•
01 Jan 1968
TL;DR: The second edition of this respected text considerably expands the original and reflects the tremendous advances made in the discipline since 1968 as discussed by the authors, with a special emphasis on applications to diffraction, imaging, optical data processing, and holography.
Abstract: The second edition of this respected text considerably expands the original and reflects the tremendous advances made in the discipline since 1968. All material has been thoroughly updated and several new sections explore recent progress in important areas, such as wavelength modulation, analog information processing, and holography. Fourier analysis is a ubiquitous tool with applications in diverse areas of physics and engineering. This book explores these applications in the field of optics with a special emphasis on applications to diffraction, imaging, optical data processing, and holography. This book can be used as a textbook to satisfy the needs of several different types of courses, and it is directed toward both engineers ad physicists. By varying the emphasis on different topics and specific applications, the book can be used successfully in a wide range of basic Fourier Optics or Optical Signal Processing courses.
9,800 citations
TL;DR: A simple physical model of 1-3 composite piezoelectrics is advanced for the material properties that are relevant to thickness-mode oscillations, revealing that the composite's material properties cannot be optimized simultaneously; tradeoffs must be made.
Abstract: A simple physical model of 1-3 composite piezoelectrics is advanced for the material properties that are relevant to thickness-mode oscillations. This model is valid when the lateral spatial scale of the composite is sufficiently fine that the composite can be treated as an effective homogeneous medium. Expressions for the composite's material parameters in terms of the volume fraction of piezoelectric ceramic and the properties of the constituent piezoelectric ceramic and passive polymer are derived. A number of examples illustrate the implications of using piezocomposites in medical ultrasonic imaging transducers. While most material properties of the composite roughly interpolate between their values for pure polymer and pure ceramic, the composite's thickness-mode electromechanical coupling can exceed that of the component ceramic. This enhanced electromechanical coupling stems from partially freeing the lateral clamping of the ceramic in the composite structure. Their higher coupling and lower acoustic impedance recommend composites for medical ultrasonic imaging transducers. The model also reveals that the composite's material properties cannot be optimized simultaneously; tradeoffs must be made. Of most significance is the tradeoff between the desired lower acoustic impedance and the undesired smaller electromechanical coupling that occurs as the volume fraction of piezoceramic is reduced. >
773 citations
TL;DR: This paper describes an alternative approach in which the full matrix of time domain signals from every transmitter–receiver pair is captured and post-processed and shown to offer significant performance advantages for NDE.
Abstract: Processing of ultrasonic array data is traditionally based on having parallel transmission circuits that enable staggered firing of transmitter elements to produce the desired wavefront. This paper describes an alternative approach in which the full matrix of time domain signals from every transmitter–receiver pair is captured and post-processed. Various post-processing approaches are modelled and assessed in terms of their ability to image a point-like reflector. Experimental results are then presented which show good quantitative agreement with the modelled results. An advanced processing algorithm is also implemented which allows the array to be focused at every point in the target region in both transmission and reception. This approach is shown to offer significant performance advantages for NDE.
747 citations
TL;DR: A method for the analysis of piezoelectric media based on finite-element calculations is presented, which provides deeper insight into the physical mechanisms of acoustic wave propagation in piezoeselastic media.
Abstract: A method for the analysis of piezoelectric media based on finite-element calculations is presented in which the fundamental electroelastic equations governing piezoelectric media are solved numerically The results obtained by this finite-element calculation scheme agree with theoretical and experimental data given in the literature The method is applied to the vibrational analysis of piezoelectric sensors and actuators with arbitrary structure Natural frequencies with related eigenmodes of those devices as well as their responses to various time-dependent mechanical or electrical excitations are computed The theoretically calculated mode shapes of piezoelectric transducers and their electrical impedances agree quantitatively with interferometric and electric measurements The simulations are used to optimize piezoelectric devices such as ultrasonic transducers for medical imaging The method also provides deeper insight into the physical mechanisms of acoustic wave propagation in piezoelectric media >
524 citations