EP3850615A1 - Applications furtives d'hyperabsorption acoustique par des cellules en métamatériau acoustiquement sombres - Google Patents

Applications furtives d'hyperabsorption acoustique par des cellules en métamatériau acoustiquement sombres

Info

Publication number
EP3850615A1
EP3850615A1 EP19859064.8A EP19859064A EP3850615A1 EP 3850615 A1 EP3850615 A1 EP 3850615A1 EP 19859064 A EP19859064 A EP 19859064A EP 3850615 A1 EP3850615 A1 EP 3850615A1
Authority
EP
European Patent Office
Prior art keywords
acoustic
cell
cells
fluid
absorption
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19859064.8A
Other languages
German (de)
English (en)
Other versions
EP3850615A4 (fr
Inventor
Dwight W. Swett
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Baker Hughes Holdings LLC
Original Assignee
Baker Hughes Holdings LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Baker Hughes Holdings LLC filed Critical Baker Hughes Holdings LLC
Publication of EP3850615A1 publication Critical patent/EP3850615A1/fr
Publication of EP3850615A4 publication Critical patent/EP3850615A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/162—Selection of materials
    • G10K11/165—Particles in a matrix
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects

Definitions

  • This disclosure relates to an acoustic attenuation system formed from at least one acoustic attenuator comprising a metamaterial matrix and a fluid in which the attenuator is at least partially immersed, and methods of making and using such acoustic attenuators, including in connection with treatments to vessel exteriors for stealth purposes.
  • Submarines can be detected acoustically via two main mechanisms: active detection in which an adversarial acoustic source emits an acoustic wave into the water and an adversarial receiver detects the reflected signal from encountered vessels (reflection signal strength is inversely proportionate to distance), and passive detection (an adversarial receiver detects latent submarine noise emitted into the water).
  • active detection in which an adversarial acoustic source emits an acoustic wave into the water and an adversarial receiver detects the reflected signal from encountered vessels (reflection signal strength is inversely proportionate to distance)
  • passive detection an adversarial receiver detects latent submarine noise emitted into the water.
  • the main acoustic stealth measures to counter detection can also be grouped into two main categories as well, passive (hull treatments) and active (acoustic reflection manipulation).
  • Apparatus may include at least one acoustic attenuator comprising a metamaterial matrix having a plurality of cells and configured, upon at least a partial immersion in a fluid, to form an acoustic attenuation system including at least a portion of the matrix and the fluid, the acoustic attenuation system configured to acoustically attenuate acoustic signals incident on the attenuator from the fluid.
  • At least one cell of the plurality of cells may comprise a plurality of sub-cells azimuthally arrayed about an axis of alignment, with at least one sub-cell of the plurality comprising a plurality of solid cell segments substantially oriented in alignment with a mapping geometry comprising an inversion of a canonical tangent circles mapping.
  • the at least one sub-cell may include a plurality of cell segments with at least a majority of cell segments of the plurality comprising at least one arcuate section and at least one radial finger. At least a majority of cell segments of the plurality may each comprise a plurality of arcuate sections.
  • the at least one radial finger may comprise a resonant fork.
  • the acoustic attenuation system may be configured to acoustically attenuate acoustic signals incident on the attenuator from the fluid by broad-band acoustic attenuation.
  • the canonical tangent circles mapping may provide focusing constant contours of eccentric circles with a common tangent point at the origin of Cartesian coordinates, and the inversion provides defocusing constant contours of the eccentric circles.
  • the matrix may intrinsically damp incident acoustic waves. At least some of the at least one cell may focus incident acoustic waves to a cell interior where energy of the incident acoustic waves is dissipated by absorption. The absorption may be predominantly due to subwavelength wave scattering at metamaterial intracellular boundaries. The absorption may occur over a substantially unbounded attenuation frequency bandwidth.
  • the mapping may relate rectangular [x,y] Cartesian coordinates to [u,v] mapped coordinates by the relations:
  • the inversion may relate rectangular [x,y] Cartesian coordinates to [u,v] mapped coordinates by the relations:
  • At least some cells of the at least one cell may comprise a central elastomeric core. At least a majority of the cells may comprise at least one of: i) metal; ii) plastic; iii) composite.
  • the fluid may be at least one of: i) seawater, ii) freshwater, iii) oil, iv) a hydrocarbon mixture, v) gas.
  • the acoustic attenuation system may be configured to display a substantially unbounded attenuation frequency bandwidth with respect to absorption of incident acoustic energy waves. At least one absorption property of the acoustic attenuation system may be substantially independent of a pressure of the fluid.
  • Apparatus embodiments may include at least one acoustic atenuator comprising a metamaterial matrix having a plurality of cells and configured, upon immersion in a fluid, to form an acoustic attenuation system configured for absorption of incident acoustic signals, wherein the absorption occurs over a substantially unbounded atenuation frequency bandwidth. At least a portion of the absorption may be due to an unbounded hyperbolic spatial frequency dispersion.
  • Method embodiments in accordance with the present disclosure may include methods of reducing an acoustic signature of a vehicle at least partially immersed in a fluid from acoustic investigation.
  • Methods may include positioning at least one acoustic atenuator on an exterior of the vehicle, the at least one acoustic atenuator comprising a metamaterial matrix having a plurality of cells configured for acoustic atenuation; allowing the at least one acoustic atenuator to be at least partially infiltrated with the fluid and thereby forming an acoustic atenuation system; and employing the acoustic atenuation system to mitigate reflected sound from the vehicle by absorbing at least one of: i) acoustic signals from the fluid; and ii) reflections of the acoustic signals from the vehicle.
  • At least one cell of the plurality of cells may comprise a plurality of sub-cells azimuthally arrayed about an axis of alignment, with at least one sub-cell of the plurality comprising a plurality of solid cell segments substantially oriented in alignment with a mapping geometry comprising an inversion of a canonical tangent circles mapping.
  • the vehicle may be a submarine and the acoustic signals may comprise at least one active SONAR transmission.
  • FIG. 1 shows curves representing reflection loss of anechoic tiles over a range of frequencies in accordance with the present disclosure
  • FIGS. 2 A & 2B illustrate the mapping geometry of cells of a metamaterial in accordance with the present disclosure
  • FIGS. 3A-3C illustrate example metamaterial cells with cell segments oriented in alignment with an inversion of a canonical tangent circles mapping for attenuating an acoustic wave in accordance with the present disclosure
  • FIG. 3C & 3D illustrate one example of practical cell design compatible with conventional additive manufacturing technology
  • FIG. 3E & 3F illustrate another example of practical cell design compatible with conventional additive manufacturing technology
  • FIGS. 4 A & 4B illustrate an example metamaterial panel in accordance with embodiments of the present disclosure
  • FIG. 5 illustrates a simulation model and boundary conditions for the metamaterial
  • FIG. 6A shows absorption spectra for an ADM AlSilOMg metamaterial cell for a solid-finger sub-cell design and a resonant-fork sub-cell design
  • FIG. 6B illustrates a harmonic response at 29 kHz for the resonant-fork sub-cell design response
  • FIG. 7A illustrates absorption spectra of two additional ADM materials with a dampening core
  • FIG. 7B illustrates absorption spectra of steel in comparison to PLA plastic material fdled with 36% copper loading in the resonant-fork sub-cell configuration
  • FIG. 7C illustrates absorption characteristics of the metamaterial for frequencies under 5 kHz
  • FIG. 8 illustrates a simulation model and boundary conditions for the metamaterial
  • FIGS. 9 A & 9B illustrate resulting refractive index response spectra
  • FIGS. 10A & 10B illustrate equifrequency contours associated with the metamaterial frequency dispersion for wave propagations at 29 kHz;
  • FIGS. 11A & 11B illustrate an application of the hyperabsorption metamaterial to the reduction of acoustic signatures of naval vessels
  • FIGS. 12 A & 12B shows a graphical illustration of the transient wave propagation response for the reference water case and the metamaterial case in accordance with embodiments of the disclosure
  • FIG. 12C shows a comparison of the reflection frequency spectrum with the incident pulse frequency spectrum in accordance with embodiments of the disclosure
  • FIG. 13 shows an echo reduction coefficient for the metamaterial using three conventional all-metal ADM materials and a copper-filled plastic filament
  • FIGS. 14A & 14B show a transient reflection with and without the metamaterial.
  • aspects of the present disclosure include a broad-band acoustic atenuator comprising a metamaterial defining a plurality of cells.
  • the cells of the metamaterial may intrinsically damp incident acoustic waves.
  • Each cell may focus acoustic waves incident on the cell to an interior of the cell where energy of the acoustic waves is dissipated by absorption.
  • Absorption frequency dispersion may exhibit a hyperbolic response and affect all (spatial) frequencies of propagation.
  • anechoic tiles are composed of elastomeric materials with embedded voids and/or gas-filled cavities that act to absorb incident sound intensity and thereby reduce the strength of the reflected acoustic wave. Reduction of the intensity of the hull acoustic reflection reduces the active sound ranging and the terminal acquisition range of active sonar that may be used, such as, for example, by torpedoes.
  • the technology of anechoic tiles was pioneered by the Kriegsmarine in World War II. The material was nonhomogeneous with embedded air cavities that degraded the reflection of active sonar. The coating reduced acoustic reflection intensity by about 85% in the 10 to 18 kHz range (matching the operating range of the early active sonar used by the Allies).
  • the modem materials for acoustic tiles consist of a number of elastomeric layers embedded with different size gas-filled cavities. Each cavity size may be designed for a specific acoustic frequency range at a range of depths. Some of the most advanced stealth technology tiles include hollow microspheres that are more pressure resistant than the conventional tile technologies. In addition, other materials are sometimes used in different areas of the submarine to better absorb specific frequencies associated with machinery at that location inside the hull. Unfortunately, major problems associated with adhesion and degradation of the acoustic absorption performance with diving depth still remain a challenge for state-of-the-art acoustic tile technologies.
  • FIG. 1 illustrates the endemic degradation in reflection loss with increasing water pressure.
  • FIG. 1 shows curves 101, 102, 103 representing reflection loss of anechoic Expancel ® tiles, designed and fabricated by QinetiQ Ltd, UK, over a range of frequencies. Each curve corresponds to a particular pressure. Curve 101 represents reflection loss at 0.1 Mpa. Curve 102 represents reflection loss at 0.7 Mpa. Curve 103 represents reflection loss at 1.4 Mpa.
  • the parameter‘Reflection Loss’ shown in FIG. 1 includes other dissipative effects such as tile edge scattering and transmission loss through the tile and does not equate to conventional‘Echo Reduction’ experiments extracted from measurements of strictly plane waves with sound hard acoustic waveguide experiments.
  • aspects of the present disclosure include apparatus for enhanced broad-band acoustic attenuation.
  • aspects of the present disclosure include an acoustic metamaterial cell which may be used in bulk production of anechoic materials for undersea acoustic stealth applications.
  • the metamaterial cell may be composed of solid metal material, plastic, or composite that can be easily fabricated from conventional 3D additive manufacturing (ADM) techniques and then attached mechanically to the vessel hull.
  • ADM additive manufacturing
  • additive manufacturing or a combination of manufacturing techniques may be employed to make hull plates or other vehicle structures incorporating metamaterial cells.
  • the metamaterial absorption characteristics may be water pressure independent and remain consistent over a full operational range of diving depths.
  • the metamaterial may intrinsically develop broad-band acoustic echo reduction properties by absorption of incident acoustic energy.
  • Techniques are disclosed herein for acoustic attenuation using a metamaterial comprised of cells comprising a plurality of sub-cells.
  • the metamaterial cell design is investigated analytically herein to with respect to the acoustic absorption characteristics of the material over a broad frequency range (0-100 kHz) of incident acoustic radiation that is of specific interest for military naval stealth applications.
  • the dissipation of the energy of incident acoustic radiation by the metamaterial may be due to macroscopic cell boundary scattering analogous to intrinsic damping in solid metals developed by microscopic grain boundary scattering.
  • the absorption frequency dispersion may exhibit a hyperbolic response and may affect all (spatial) frequencies of propagation.
  • each cell comprises a plurality of sub-cells azimuthally arrayed about an axis of alignment.
  • One example described herein is that of using a canonical tangent circles transformation in which a canonical tangent circles mapping forms the sub-cell geometry. The mapping focuses constant contours of eccentric circles with a common tangent point at the origin of Cartesian coordinates.
  • Each sub-cell comprises a plurality of cell segments with each cell segment of the plurality comprising at least one arcuate section and at least one radial finger, wherein the cell segments of each sub-cell are oriented in alignment with a mapping geometry comprising an inversion of a canonical tangent circles mapping in a plane transverse to the axis of alignment.
  • Cartesian coordinates may be related to the [u,v ⁇ mapped coordinates by the relations:
  • the inversion relates rectangular [x,y ⁇ Cartesian coordinates to ⁇ u v
  • FIG. 1 shows curves 101, 102, 103 representing reflection loss of anechoic tiles over a range of frequencies.
  • FIGS. 2A & 2B illustrate the mapping geometry.
  • FIG. 2A shows tangent circles curvilinear contours.
  • FIG. 2B shows inverted tangent circles curvilinear contours.
  • Eq. (1) develops focusing constant contours of eccentric circles with a common tangent point at the origin of Cartesian coordinates as shown in FIG. 2A.
  • the inversion of this mapping according to the relations of Eq. (2) is used to obtain the defocusing constant contours of eccentric circles, shown in FIG. 2B.
  • the physical cell design is developed with the inversion constant coordinate contours in FIG. 2B as a sub-cell template for octagonal symmetry in the sub-cell geometry.
  • General embodiments include an acoustic metamaterial cell used in metamaterials having“dark” acoustic reflection loss characteristics, e.g., a phenomenon where a material develops broad-band acoustic attenuation characteristics by absorption of incident acoustic energy waves.
  • acoustic metamaterial cell used in metamaterials having“dark” acoustic reflection loss characteristics, e.g., a phenomenon where a material develops broad-band acoustic attenuation characteristics by absorption of incident acoustic energy waves.
  • aspects of the present disclosure include cells comprising a solid material (such as a metal) arrayed in a fluid background resulting from the immersion of the cell in the fluid medium conveying the vehicle.
  • a solid material such as a metal
  • the absorption characteristics may be brought about by energy transfer within the material to dissipate acoustic energy.
  • Both 2D acoustical simulations and frequency dispersion analyses concluded that the attenuation mechanism is related to absorption behavior as opposed to simple reflection.
  • the energy of an incident acoustic wave appears to be focused to the interior of the cell structure and dissipated there by absorption created from macroscopic cell boundary scattering.
  • the absorption frequency dispersion was determined to exhibit a hyperbolic response and affected all (spatial) frequencies of propagation.
  • additive manufacturing processes may be employed to embed the material intrinsically within a tool or tool components with inherent hyperabsorption characteristics. See also, Patent Cooperation Treaty application filed as U.S. Patent Application Ser. No. 2015/044467 to Weisman et al filed August 10, 2014, and published as WO 2016025388 Al.
  • additive manufacturing powder bed systems such as selective laser melting (SLM), metal 3D printing, laser cusing, electron beam melting (EBM), and direct metal laser sintering (DMLS)
  • powder fed systems such as laser cladding, directed energy deposition, and laser metal deposition
  • Example commercial systems which are suitable for manufacture include the Laser Engineered Net Shaping (LENS) powder delivery system from Optomec, and Studio System+ from Desktop Metal of Burlington, Massachusetts.
  • LENS Laser Engineered Net Shaping
  • Studio System+ from Desktop Metal of Burlington, Massachusetts.
  • filament-based 3D printing techniques such as fused deposition modeling, may be employed in manufacture.
  • 3D printer filaments may include PLA and ABS and may contain metal powder.
  • FIGS. 3A-3C illustrate example metamaterial cells with cell segments oriented in alignment with an inversion of a canonical tangent circles mapping for attenuating an acoustic wave in accordance with the present disclosure.
  • FIG. 3A shows sub-cell inversion of tangents mapping contours.
  • FIG. 3B shows isotropic cell geometry.
  • FIG. 3B illustrates the cell 310.
  • the cell 310 has two opposing planar surfaces that are parallel. As illustrated, the visible planar surface 313 is parallel with the paper. The distance between the two surfaces, or thickness, may be in the range of 1 millimeter to 1000 millimeters. The diameter of a circle enclosing the cell 310 may be in the range of 1 millimeter to 100 millimeters. These dimensions are generally selected to allow phenomena such as resonances to have a measurable influence on the behavior of the cell 310 and affect wave manipulation in the particular frequency ranges of interest.
  • the cells, such as cell 310, of the present disclosure may be made up of a solid, e.g., metals or non-metals. Suitable metals include, but are not limited to, steel, platinum, tungsten, gold, and exotic options such as iridium, with the important material property for acoustic wave attenuation being the mass density of the metal.
  • the cell 310 may be comprised of a plurality of sub-cells 320.
  • the cell 310 includes eight sub-cells 320. Although sub cells are depicted as identical, in some applications, each sub-cell may be unique. In some implementations, one or more sub-cells may depart from the canonical mapping for cost, ease of manufacture, and so on.
  • the curvilinear geometry of the segments 304 of cell 310 may be constructed from the set of sub-cell inversion of tangents mapping contours 301 with [x, y] coordinates located within an eight sub-cell cell of the Cartesian frame such that for each sub-cell the segments 304 align with the set of contours 301.
  • FIG. 3A illustrates the set 391 of contours 301. See P. Moon and D. E. Spencer, Field Theory Handbook, New York: Springer- Verlag, 1971.
  • the cells of the metamaterial intrinsically damp incident acoustic waves. Each cell focuses acoustic waves incident on the cell to an interior of the cell where energy of the acoustic waves is dissipated by absorption. This absorption may be predominantly due to subwavelength wave scattering at metamaterial intracellular boundaries.
  • the dissipation phenomena may display some similarities to damping from grain boundary scattering in conventional metals, except that the metamaterial absorption behaves with a hyperbolic frequency dispersion that develops an almost unbounded ultrasonic attenuation spatial frequency bandwidth; in other words, with“hyperabsorption.”
  • the segments 304 of the plurality may be an arcuate segment
  • the arcuate segments 350 may have offshoot segments, or fingers. These fingers may be radial fingers 351 perpendicular to the tangent of the curve. The fingers may be substantially rectangular, or may also have a curvature, which may also comport with the canonical mapping. Radial fingers 351 and other offshoot segments may also have effects such as chamfering, bullnosing, or the like. The surfaces of the fingers may also be individually curved, textured, split, or the like. Other embodiments may include other types of segments in some or all of the sub-cells, for some or all of the cells, in dependence upon the particular application or design considerations, such as cost, ease of manufacture, and so on.
  • the resonances and anti-resonances within the cell 310 are affected by the interaction of the various structural features.
  • the number, size, shape, and orientation of features influence where and to what extent resonances and anti-resonances occur and how they complement or negate one another in affecting manipulation and control of the incident acoustic wave. Any number of segments may be used. Configuration may be carried out by building the cell - that is, iteratively adding design elements to the mapping.
  • FIG. 3C & 3D illustrate one example of practical cell design compatible with conventional additive manufacturing technology.
  • the cell may be comprised of metallic material and arrayed in a fluid background (e.g., seawater) to produce hyperabsorption characteristics and enhanced reflection loss performance for undersea stealth applications.
  • a fluid background e.g., seawater
  • FIG. 3E & 3F illustrate an example of practical cell design compatible with conventional additive manufacturing technology and including the addition of comer fillet radii 380 and resonant fork fingers 390 that enhance the broadband absorption characteristics of the metamaterial.
  • FIGS. 4 A & 4B illustrate an example metamaterial panel in accordance with embodiments of the present disclosure.
  • the metamaterial panel 400 may comprise a series of connected cells.
  • the panel may be coupled to the hull plate 401 of the vessel with an attachment lug 402.
  • the panel may be configured such that when installed on the vessel surface, an axis of alignment 403 for the cells is orthogonal to an incident acoustic wave 405 normal to the surface.
  • the axis of alignment 403 may be normal to the plane formed by cell axes 411 and 413.
  • FIG. 5 illustrates a simulation model and boundary conditions for the metamaterial.
  • the acoustic absorption properties of the proposed metamaterial design are analyzed using an analytical model 500 simulating a perfect waveguide with incident plane wave radiation 502 at the inlet port 501 of the waveguide and a hard sound boundary 590 at the terminal port of the waveguide.
  • the analysis is conducted using the Comsol ® MultiPhysics software package.
  • An array 511 having three solid metamaterial cells 510 along the propagation direction and one cell transverse is placed at the terminal port just inside the hard sound boundary.
  • the fluid background is inviscid water 520.
  • the elastomeric dampening core 599 in both cell designs is a centrally located elliptical geometry having major and minor dimensions of 13 mm and 9 mm, respectively.
  • the absorption analysis may be conducted in the form of a steady-state harmonic frequency response.
  • the absorption spectrum is calculated by first extracting the complex reflection coefficient R at each frequency for the section as denoted for the reflected wave in FIG. 5 :
  • FIG. 6A shows absorption spectra for the ADM AlSilOMg metamaterial cell for the solid-finger sub-cell design, represented by curve 602, and the resonant-fork sub-cell design, represented by curve 601.
  • the introduction of the resonant-fork sub-cell design broadens the high absorption bandwidths over the entire frequency range.
  • FIG. 6B illustrates the harmonic response at 29 kHz for the resonant-fork sub-cell design response.
  • FIG. 7 A illustrates absorption spectra of two additional ADM materials with a dampening core.
  • FIG. 7A shows absorption spectra for steel, represented by curve 701, Ti6Al4V, represented by curve 702, and AlSilOMg, represented by curve 703.
  • the absorption properties of the metamaterial cell design appear to be moderately affected by cell material change, predominantly with respect to local absorption.
  • the AlSilOMg resonant-fork sub-cell design exhibits more absorption generally over the lower frequency (0-20 kHz) of the bandwidth analyzed.
  • the steel cell material has broader absorption bandwidth at 30 kHz than the other all-metal materials considered.
  • FIG. 7B illustrates absorption spectra of steel (represented by curve 711) in comparison to PLA plastic material filled with 36% copper loading (represented by curve 712) in the resonant-fork sub-cell configuration.
  • the material is utilized in 3D additive fabrication machines in the form of a filament and is manufactured under the tradename CopperFill ® .
  • the CopperFill ® material absorption spectrum is much broader bandwidth than any of the all-metal material spectra and exhibits very broadband absorption of almost 100% above 20 kHz.
  • FIG. 7C illustrates absorption characteristics of the metamaterial design for frequencies under 5 kHz.
  • the metamaterial design has also moderate acoustic intensity absorption of energy transmitted to a free fluid medium, such as when internal vessel noise or vibration are transmitted into the water through the vessel hull plate.
  • the frequency content of this type noise and vibration is typically confined below 5 kHz.
  • FIG. 8 illustrates a simulation model and boundary conditions for the metamaterial.
  • the waveguide background material has the acoustic properties of water and the cell material has solid elastic properties of steel.
  • the center core in each cell has solid elastic properties of an elastomeric dampening material as described in Error! Reference source not found..
  • the waveguide longitudinal edges are constrained with Bloch periodic symmetry boundary conditions to simulate the effect of placement in a perfectly reflecting waveguide.
  • An incident harmonic acoustic plane wave propagates from the bohom edge boundary of the waveguide and a perfectly matched layer is placed at the top of the waveguide to eliminate all reflections.
  • the transmission and reflection coefficients are retrieved over a frequency range of 0-100 kHz, and the effective acoustic Pentamode properties are extracted to calculate the effective frequency response spectra.
  • FIGS. 9 A & 9B illustrate resulting refractive index response spectra.
  • the spectra (represented by curves 901, 902, 911, 912) indicate multiple bands of backward propagating sound speed as evidenced by the negative real parts of the refractive indices.
  • the multiple bands of non-zero imaginary part of the indices are an indication of bandwidths containing significant energy absorption.
  • FIGS. 10A & 10B illustrate the equifrequency contours associated with the metamaterial frequency dispersion for wave propagations at 29 kHz. These equifrequency contours show that the imaginary absorptive component of the wavenumber dominates all spatial frequency propagation modes and exhibits a hyperbolic dispersion that continues to increase in the higher spatial frequency modes. This unusual hyperabsorption phenomena is evident for wave propagation in both the cellular‘ 1’ propagation direction as well as the transverse cellular ‘2’ propagation direction. The unusual broadband and significant magnitude of energy absorption shown above can thus be understood as phenomena associated with hyperbolic frequency dispersion affecting all modes of wave propagation through the metamaterial.
  • FIGS. 11 A & 11B illustrate an application of the hyperabsorption metamaterial to the reduction of acoustic signatures of naval vessels. The implications are to reduce the targeting range of undersea and surface vessels by enemy active sonar systems through the enhancement of the acoustic echo reduction characteristics of the vessel hull.
  • FIG. 11 A illustrates a 2D acoustic waveguide Comsol ® Multiphysics simulation model of an array of the metamaterial cells in a water medium used to evaluate the transient echo properties of the metamaterial.
  • FIG. 11B illustrates an incident pressure pulse.
  • the Multiphysics simulation model includes waveguide boundary conditions that develop Bloch periodicity in the finite dimension metamaterial array to approximate a large extent cellular array in the geometry directions lateral to the waveguide propagation direction.
  • the terminal wall of the waveguide behind the metamaterial array is modeled as a perfect reflector so that any reduction in reflection would be known to be attributable to the hyperabsorption properties of the metamaterial.
  • the simulation is conducted by applying a plane wave incident pressure pulse at the entry port of the waveguide propagating towards the metamaterial array.
  • the transient pressure pulse is a short
  • the waveguide transient simulations were conducted using pure water. To determine the echo reduction properties, spectral characteristics of the transient reflection waveforms are calculated using the FFT algorithm with no zero padding and 1500 microsecond transient response windows. The echo reduction coefficient is calculated in the frequency domain as:
  • FIGS. 12A & 12B illustrates a graphical illustration of the transient wave propagation response for the reference water case and the metamaterial case.
  • the reflected wave is shown in two dimensions as lighter with increasing amplitude.
  • FIG. 12C shows a comparison of the reflection frequency spectrum (1202) with the incident pulse frequency spectrum (1201). As can be seen, pressure is drastically reduced over entire range of frequencies, so that very little acoustic signature remains.
  • FIG. 13 shows the echo reduction coefficient for the metamaterial using three conventional all-metal ADM materials (Steel, Ti6Al4V, and AlSilOMg) and the copper-filled plastic filament, each with a dampening core.
  • the curve 1301 represents echo reduction for cells manufactured using copper-filled plastic filament.
  • the curve 1302 represents echo reduction for cells manufactured using steel.
  • the curve 1303 represents echo reduction for cells manufactured using AlSilOMg.
  • the curve 1304 represents echo reduction for cells manufactured using Ti6Al4V.
  • Narrow band amplifications in echo reduction vary among the all-metal cell material options, with the overall echo reduction spectra extending from about 20 dB below 1 kHz and increasing asymptotically to about 26 dB above 15 kHz.
  • the echo reduction spectrum for the CopperFill ® is similar over the lower frequency range below 15 kHz but exhibits more extensive narrowband attenuation regions than the all-metal spectra.
  • FIGS. 14 A & 14B show a transient reflection with and without the metamaterial.
  • FIGS. 14 A & 14B illustrate that a reflection of the incident pressure pulse from the metamaterial is not only significantly reduced in amplitude but the incident signature is distorted in the reflection as well.
  • the degree of distortion in the echo returned from the metamaterial decreases the signature correlation with the incident waveform thus increasing the difficulty in detection by devices such as comparative receivers.
  • the CopperFill ® filament may be preferable for the cell material due to the more significant energy absorption properties and the resulting lightweight metamaterial (0.933 g/cc anechoic panel).
  • materials may be suitable for individual applications, in dependence upon a variety of factors, such as cost, durability, availability, detectability via non acoustic means, ease of manufacture, and so on. Materials and overall design may be tailored to different types of vehicles, or vehicles used for different purposes.
  • combinations of materials may be used for an individual panel, for cells in a panel, sub-cells in a cell, segments in a sub-cell, and so on. Subsequent panels, cells, sub-cells, and/or segments of an installation may be made of different materials or combinations of materials, or with different configurations, such as, for example, alternating cell size, segment design, mapping, and the like.
  • the cell design of a panel may be layered, or panels themselves may be installed in layers, or different portions of the vehicle may correspond with panels having a different configuration.
  • a panel, or other form of the metamaterial may be manufactured integral with vessel structures, such as, for example, hull plates, such that integrated structure in its entirety comprises the acoustic attenuator.
  • An acoustic attenuator may also be manufactured or assembled to include structural components, including fastening, welding, adhering, or otherwise coupling the matrix to one or more components.
  • a metamaterial is a material engineered to have a property that is not found in nature.
  • “Conformal mapping geometry,” as used herein, refers to an arrangement of cell segments within the cell such that the contour lines from a non-Cartesian coordinate system are mapped onto a surface.
  • the surface may be a flat base from which each cell projects in a cantilever fashion.
  • “Unbounded” as used herein describes a frequency range including normal operating frequencies for downhole ultrasonic (e.g., less than lMHz).
  • Non-solid as defined herein refers to a liquid, gas, vacuum, dissolved and/or suspended particulate matter, mixtures, solutions, emulsions, suspensions, or combinations of these.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)

Abstract

Des aspects de la présente invention concernent des systèmes et des procédés pour améliorer les capacités de furtivité passive. L'appareil peut comprendre au moins un atténuateur acoustique comprenant une matrice de métamatériau ayant une pluralité de cellules et configuré, lors d'au moins une immersion partielle dans un fluide, pour former un système d'atténuation acoustique comprenant au moins une partie de la matrice et du fluide, le système d'atténuation acoustique étant configuré pour atténuer acoustiquement des signaux acoustiques incidents sur l'atténuateur avec le fluide. Au moins une cellule de la pluralité de cellules peut comprendre une pluralité de sous-cellules agencées de manière azimutale en réseau autour d'un axe d'alignement, avec au moins une sous-cellule de la pluralité comprenant une pluralité de segments de cellules solides sensiblement orientés en alignement avec une géométrie de mappage comprenant une inversion d'un mappage canonique de cercles tangents.
EP19859064.8A 2018-09-15 2019-09-13 Applications furtives d'hyperabsorption acoustique par des cellules en métamatériau acoustiquement sombres Withdrawn EP3850615A4 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201816132402A 2018-09-15 2018-09-15
PCT/US2019/051127 WO2020056337A1 (fr) 2018-09-15 2019-09-13 Applications furtives d'hyperabsorption acoustique par des cellules en métamatériau acoustiquement sombres

Publications (2)

Publication Number Publication Date
EP3850615A1 true EP3850615A1 (fr) 2021-07-21
EP3850615A4 EP3850615A4 (fr) 2022-06-15

Family

ID=69778550

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19859064.8A Withdrawn EP3850615A4 (fr) 2018-09-15 2019-09-13 Applications furtives d'hyperabsorption acoustique par des cellules en métamatériau acoustiquement sombres

Country Status (2)

Country Link
EP (1) EP3850615A4 (fr)
WO (1) WO2020056337A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021116923A1 (fr) 2019-12-10 2021-06-17 Saudi Arabian Oil Company Cellules de métamatériaux électromagnétiques, détecteurs les comprenant, et leurs procédés d'utilisation
KR102387310B1 (ko) * 2020-04-06 2022-04-18 한국표준과학연구원 매끈한 일면이 노출되는 메타표면 및 이의 설계 방법
CN113450751B (zh) * 2021-05-11 2024-05-31 科大讯飞股份有限公司 声学包控制方法、装置和计算机可读存储介质

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2442301A1 (fr) * 2007-12-21 2012-04-18 3m Innovative Properties Company Cristal photonique visco-élastique
US11037543B2 (en) * 2015-10-30 2021-06-15 Massachusetts Institute Of Technology Subwavelength acoustic metamaterial with tunable acoustic absorption
US10054707B2 (en) * 2016-04-15 2018-08-21 Baker Hughes, A Ge Company, Llc Bipolar acoustic hyperlens for dual-string thru-casing ultrasonic sensors
US9952343B2 (en) * 2016-07-20 2018-04-24 Baker Hughes, A Ge Company, Llc Rhodonea cell acoustic hyperlens for thru-casing ultrasonic sensors

Also Published As

Publication number Publication date
WO2020056337A1 (fr) 2020-03-19
EP3850615A4 (fr) 2022-06-15

Similar Documents

Publication Publication Date Title
WO2020056337A1 (fr) Applications furtives d'hyperabsorption acoustique par des cellules en métamatériau acoustiquement sombres
CN108133700B (zh) 一种声学黑洞减振降噪装置
Lin et al. Three-dimensional sound propagation models using the parabolic-equation approximation and the split-step Fourier method
Gaunaurd et al. Acoustic resonance scattering by submerged elastic shells
Zhang et al. Review and perspective on acoustic metamaterials: From fundamentals to applications
CN109741726A (zh) 一种协同耦合双层薄板型声学超表面装置
US11817075B2 (en) Acoustic metamaterial structures and geometry for sound amplification and/or cancellation
CN110880312A (zh) 一种水下亚波长局域共振型声学超材料
Sastry et al. A transfer matrix approach for evaluation of the response of a multi-layer infinite plate to a two-dimensional pressure excitation
Zhang et al. Recent study progress of underwater sound absorption coating
CN113808563B (zh) 一种含有参数呈梯度变化圆柱形散射体的低频吸声覆盖层
US4669573A (en) Underwater acoustic baffle enhancer
Audoly Acoustic metamaterials and underwater acoustics applications
Gaafer Perfect absorption for modulus-near-zero acoustic metamaterial in air or underwater at low-frequency
Li et al. Piezoelectric transducer design for a miniaturized injectable acoustic transmitter
Audoly Perspectives of metamaterials for acoustic performances of submerged platforms and systems
CN110880311A (zh) 一种水下亚波长空间盘绕型声学超材料
Wang et al. Topology optimization of chiral metamaterials with application to underwater sound insulation
CN112729532B (zh) 浅海运动声源近场传递函数获取方法、装置、设备及介质
Ko et al. Structure-borne noise reduction for an infinite, elastic cylindrical shell
KR20220076749A (ko) 차음 배플 구조체
Bonomo et al. Modeling the acoustic scattering from axially symmetric fluid, elastic, and poroelastic objects due to nonsymmetric forcing using COMSOL Multiphysics
Partridge Acoustic scattering from viscoelastically coated bodies
Greenspon Structural acoustics: Deterministic and random phenomena
Guolong et al. Acoustic characteristics of underwater composite materials at oblique incidence of sound wave

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20210331

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)
A4 Supplementary search report drawn up and despatched

Effective date: 20220513

RIC1 Information provided on ipc code assigned before grant

Ipc: G10K 11/165 20060101ALI20220509BHEP

Ipc: G10K 11/36 20060101ALI20220509BHEP

Ipc: G10K 11/30 20060101ALI20220509BHEP

Ipc: G10K 11/172 20060101ALI20220509BHEP

Ipc: G10K 11/162 20060101ALI20220509BHEP

Ipc: G10K 11/16 20060101AFI20220509BHEP

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20221213