499 results about "Lamb waves" patented technology

A plate wave element includes a piezoelectric body, a comb-shaped electrode disposed on an upper surface of the piezoelectric body, and a medium layer disposed on the upper surface of the piezoelectric body so as to cover the comb-shaped electrode. The comb-shaped electrode excites a Lamb wave as a main wave. The medium layer has a frequency temperature characteristic opposite to that of the piezoelectric body. The plate wave element has a preferable frequency temperature characteristic.

A flow measuring apparatus (300, 500) measures a fluid flow (130) within a conduit (120) including a wall (110). The apparatus (300, 500) includes a transducer arrangement including at least two transducers (100A, 100B) for alternately emitting and receiving ultrasonic radiation through the conduit wall (110) and the flow (130). The apparatus (300, 500) also includes a signal processing arrangement (310) for generating signals to excite the transducer arrangement (100A, 100B) and for processing received signals provided by the transducer arrangement (100A, 100B) for generating output signals from the signal processing arrangement (310) indicative of properties of the flow. The transducer arrangement (100A, 100B) in cooperation with the conduit (120) provides a first path (200) for Lamb-wave ultrasonic radiation coupling directly from a first of the at least two transducers (100A, 100B), to a second of said at least two transducers to generate a first received signal. The transducer arrangement (100A, 100B) in cooperation with the conduit (120) provides at least one second path (210) for ultrasonic propagation along the wall (100) via Lamb waves coupling to at least a portion of the flow (130) from a first of the at least two transducers (100A, 100B) to a second of the at least two transducers (100A, 100B) to generate a second received signal. The signal processing arrangement (310) determines from said first and second received signals ultrasonic radiation propagation time periods through the first path (200) and through the at least one second path (210), and to perform computational operations on the propagation time periods to determine properties of the flow including, but not limited to, at least one of: fluid flow velocity (v) in the conduit (120), a sound velocity (c) through the fluid (130).

A Lamb wave type high frequency device comprises: a piezoelectric substrate; an interdigital transducer (IDT) electrode formed on a first main surface of the piezoelectric substrates a reinforcing substrate connected to a second main surface of the piezoelectric substrate; a space portion formed in one of the piezoelectric substrate and the reinforcing substrate, an area of the space portion being larger than a region in which a Lamb wave is propagated; and a connecting surface formed in a periphery of the space portion.

A bond log device comprising a sonde, an acoustic transducer, and an acoustic receiver. The acoustic transducer is comprised of a magnet combined with a coil, where the coil is energizable by an electrical current source. The acoustic transducer can also be comprised of an electromagnetic acoustic device. The acoustic transducer is capable of producing various waveforms, including compressional waves, shear waves, transversely polarized shear waves, Rayleigh waves, Lamb waves, and combinations thereof.

There is provided a lamb wave device with small variations in frequency, the device including: a piezoelectric thin film; an IDT electrode which is provided on a main surface of the piezoelectric thin film; and a support structure which supports a laminate of the IDT electrode and the piezoelectric thin film, and is formed with a cavity that isolates the laminate, wherein a film thickness h of the piezoelectric thin film and a pitch p of a finger of the IDT electrode are selected such that a lamb wave is excited at a target frequency, the lamb wave making dispersibility of a sonic velocity v with respect to the film thickness h of the piezoelectric thin film small.

A transmitting / receiving filter (filter device) according to one embodiment of the present invention is provided with a transmitting filter, a receiving filter, and a support substrate. The transmitting filter includes a first resonator constituted of a BAW device (FBAR, SMR). The receiving filter includes a second resonator constituted of a Lamb wave device. The support substrate supports both the transmitting filter and the receiving filter. The transmitting filter and the receiving filter are constituted of elastic wave resonators that resonate at different oscillation modes from each other, which allows miniaturization of the support substrate to be realized while preventing oscillation interference between the two filters.

The method and apparatus of the present invention provides for inducing and measuring shear waves within a wellbore casing to facilitate analysis of wellbore casing, cement and formation bonding. An acoustic transducer is provided that is magnetically coupled to the wellbore casing and is comprised of a magnet combined with a coil, where the coil is attached to an electrical current. The acoustic transducer is capable of producing and receiving various waveforms, including compressional waves, shear waves, Rayleigh waves, and Lamb waves as the tool traverses portions of the wellbore casing.

A method and an apparatus for non-contact and non-invasive characterization of a moving thin sheet and in particular of a paper web on a production line. The method uses a laser for the generation of sonic and ultrasonic waves in the thin sheet and a speckle insensitive interferometric device for the detection of these waves. The generation is performed in conditions to avoid damage impeding further use of the sheet. When the generation and detection spots overlap, the method provides a measurement of the compression modulus. When the generation and detection spots are separated by a known distance and plate waves (Lamb waves) are generated and detected, the method provides a measurement of the in-plane modulus and of the tension applied to the sheet. By detecting waves propagating in various directions, either by rotating the detection sensor head or multiplexing the signals provided by several detection or generation locations, the anisotropy of the in-plane modulus is determined.

A method and apparatus useful to determine the integrity of a cement bond log disposed in the annular space between a casing and a wellbore. The method and apparatus induce a Lamb wave in the casing and into the wellbore. The Lamb wave attenuates upon passage through the cement bond log. The integrity of the cement bond log can be determined through an analysis and evaluation of the attenuation results.

Wireless power transmission to downhole well installations is provided using acoustic guided Lamb waves and a tubular conduit (production tubing, casing) as the power transmission medium. A phased array of acoustic transmitters is present at the transmitting end (surface) and an array of acoustic receivers at the receiving end (downhole). Both transmitter and receiver arrays are coupled to the tubular conduit. Beamforming techniques are used along with power amplifiers to generate directional, high power and low frequency acoustic guided Lamb waves along the wellbore to transmit power over long distances. A downhole multi-channel acoustic energy collecting system receives the transmitted acoustic signal, and generates electrical power and stores the power in downhole electrical power storage. This power is used to operate downhole well equipment including sensing, control and telemetry devices.

There is provided a lamb wave device with small variations in frequency, the device including: a piezoelectric thin film; an IDT electrode which is provided on a main surface of the piezoelectric thin film; and a support structure which supports a laminate of the IDT electrode and the piezoelectric thin film, and is formed with a cavity that isolates the laminate, wherein a film thickness h of the piezoelectric thin film and a pitch p of a finger of the IDT electrode are selected such that a lamb wave is excited at a target frequency, the lamb wave making dispersibility of a sonic velocity v with respect to the film thickness h of the piezoelectric thin film small.

A system, method and computer program product is provided for automated defect detection of corrosion or cracks using synthetic aperture focusing technique (SAFT) processed Lamb wave images. The method comprises processing the first image using a synthetic aperture focusing technique (SAFT) to enhance a resolution and a signal to noise ratio of a first extracted ultrasonic image, applying a systemic background noise suppression algorithm to the first extracted ultrasonic image to render a second extracted ultrasonic image having reduced noise, and applying a deconvolution linear filtering process to the second extracted ultrasonic image to render a third extracted ultrasonic image.

The invention discloses a method of focusing by time reversal for Lamb wave in actively monitoring the engineering structural damage. The method includes the following steps: step one: collecting the damage dispersion signals; step two: carrying out time reversing treatment; and step three: focusing the damage dispersion signals. By sue of the sensor / stimulator array technology, and based on the prior structural damage monitoring equipment, the invention, having no necessity of any other special equipment, adopts the convolution operation to focus the Lamb wave signals in the damage monitoring system, improves the signal to noise ratio of the damage dispersion signals, and simplifies the method of extracting the characteristic parameters, thereby enhancing the accuracy and the stability of the monitoring system.

A very high-Q, low insertion loss resonator can be achieved by storing many overtone cycles of a lateral acoustic wave (i.e., Lamb wave) in a lithographically defined suspended membrane comprising a low damping resonator material, such as silicon carbide. The high-Q resonator can sets up a Fabry-Perot cavity in a low-damping resonator material using high-reflectivity acoustic end mirrors, which can comprise phononic crystals. The lateral overtone acoustic wave resonator can be electrically transduced by piezoelectric couplers. The resonator Q can be increased without increasing the impedance or insertion loss by storing many cycles or wavelengths in the high-Q resonator material, with much lower damping than the piezoelectric transducer material.

The invention relates to a Lamb wave-based autonomous damage identification imaging method in the technical field of detection of mechanical structures, which comprises the following steps of: constructing a sensing network, and correcting time reversal-based damage index DI of each sensing path in the sensing network; then setting 45% of the maximum value in all the corrected damage indexes of all the sensing paths as a threshold, and using the threshold to judge the degree of influences on the sensing paths caused by damages; and finally carrying out weighted distribution treatment on the damage indexes of all the sensing paths, and further obtaining the probability value that the damages emerge at a coordinate point (x, y). By using the method, the flight time for extracting wave signals scattered by defects can be avoided, and the shortcoming of depending on reference signals can be overcome. Not only can the requirements on real-time property and on-line property be satisfied, but also the multiple damages can be accurately identified and positioned, and the autonomous non-destructive testing of a plate-shell structure can be further realized, thus the method has very important practical value in aerospace, buildings and other fields.

A Lamb wave device according to an embodiment of the present invention includes a piezoelectric function member and a supporting member. The piezoelectric function member has a piezoelectric substrate, IDT electrodes, and a cutout portion. The IDT electrodes are disposed on the upper surface of the piezoelectric substrate. The cutout portion is formed in the piezoelectric substrate, and includes a step face provided between the upper surface and the lower surface of the piezoelectric substrate. The supporting member has a supporting surface and a cavity. The supporting surface is bonded to the lower surface of the piezoelectric substrate, and is exposed in the cutout portion toward the upper surface of the piezoelectric substrate. The cavity is formed adjacent to the supporting surface, and faces the IDT electrodes through the piezoelectric substrate.

A filter device that reduces spurious emissions generated in a frequency band 1.2 to 1.4 times greater than a center frequency of a passband of a filter. In one example the filter device includes a first filter connected between a common contact and a first signal contact and having a first passband, and a second filter connected between the common contact and a second signal contact and having a second passband with a center frequency in a range of 1.2 to 1.4 times greater than a center frequency of the first passband. The first filter includes a SAW filter formed on a piezoelectric substrate, a SAW resonator formed on the piezoelectric substrate and connected in series between the common contact and the SAW filter, and a dielectric film covering the SAW filter and SAW resonator, the dielectric film having a reduced thickness in a region corresponding to the SAW resonator.

The invention discloses a monitoring method for time reversal damage to no-datum Lamb wave of an engineering structure. The monitoring method comprises the following steps of: distributing a group of excitation / sensing arrays on a structure to be monitored; building detection channels, and collecting Lamb wave response signals of all excitation / sensing channels; intercepting the response signals, and then conducting time reversal to obtain time reversal structure response signals; loading the time reversal structure response signals onto corresponding excitation, and collecting time reversal focusing structure response signals on the corresponding sensing; and in the time reversal focusing structure response signals of all the detection channels, extracting the occurrence time difference of focusing main wave crest and sidelobe signals, taking the occurrence time difference as a characteristic parameter, calculating to obtain the position and approximate range of the damage by adopting an ellipse positioning method, and analyzing and judging the health condition of the structure to be detected. With the method, the wave packet extension and signal aliasing caused by frequency dispersion can be eliminated, no-datum active positioning and detection to the Lamb wave can be realized, and the healthy monitoring practicalization of the structure can be benefited.

The invention discloses a non-reference Lamb wave damage monitoring method based on a unit doublet piezoelectricity sensor array and time window functions, comprising the steps: arranging the unit doublet piezoelectricity sensor array in the structure; loading Lamb wave narrow band signals onto a piezoelectricity unit; performing further normalization process on the collected structural response signals; separating and obtaining structural impair scattered signals; obtaining structural scatteringin signals; judging structural impair condition. The method realizes separation of the scatteringin signals with direct sense signals, border reflection signals under the drive of initiative Lamb wave; having no use for the structural response signals under healthy condition as the reference signals, monitoring the structure at any time; without changing or increasing the device and the parameter, realizing only through a general hardware system; realizing monitoring without processing or computing impair characteristic parameters at the arrival of the impair scattered signal in the signals.

The invention discloses a method for actively monitoring the damage of an engineering structure excited by adopting a synthesis wave front, comprising the following steps of: collecting Lamb wave standard response signals of all exciting / sensing channels of the structure in a healthy state; collecting Lamb wave standard response signals of all the exciting / sensing channels of the structure in a damaged state; extracting Lamb wave damage scattered signals of all the exciting / sensing channels under the excitation of the synthesis wave front; obtaining the position and the range of damage according to the damage scattered signals so as to analyze and judge the health condition of a detected structure. An arc sensor / exciter array technology is adopted in the method, and an excitation signal in the structure is enhanced by adopting a synthesis wave front method based on the condition of the traditional structure damage monitoring equipment, thus, the energy of the damage scattered signals is increased, and the accuracy and the stability of a monitoring system are improved.

Embodiments of the present invention beneficially provide an ultrasound communication system and methods of ultrasound communication for diagnostics and prognostics of structures. For example, ultrasound transmitters are connected to a metal or composite structure and modulated to produce Lamb waves that travel to an ultrasound receiver. The ultrasound transmitters can use frequency-hopped signals to digitally encode transducer information among different transmitters. The transmitters can be operated asynchronously. The receiver can use a channel equalizer to reduce the effects of signal multipath and a decoder to decode the transducer information from the ultrasound transmitters.

The invention relates to a method for detecting guide waves of a steel storage tank bottom plate, comprising the following steps in sequence; (1) selecting the number of ultrasonic probe arrays (5), and symmetrically distributing the ultrasonic probe arrays (5) along the steel storage tank bottom plate (3); (2) arranging two signal processing devices (4) on each ultrasound probe array (5), and arranging the ultrasound probe array (5) on the steel storage tank bottom plate (3) through a wedge block in a coupling way; (3) selecting a ultrasonic wave length which corresponds to the thickness of the steel storage tank bottom plate (3) and selecting a method for exciting Lamb waves; (4) transforming a travel time matrix with Radon algorithmic function to generate Lamb wave travel time projections of different incidence angles, which are used as the projection data for the subsequent tomography reconstruction; (5) reconstructing a tomography in the projection data with the filtered back projection algorithm; (6) analyzing the tomography to find the position of the defect and grade the defect level; and (7) if the defect existing, changing the positions of ultrasonic probes clockwise, repeating the steps (1), (2), (3), (4), (5) and (6), comparing the repeated detection and tomography reconstruction results, and eliminating the effect of noise and other factors if the position of the defect and the morphology existing.

Embodiments of the present invention beneficially provide an ultrasound communication system and methods of ultrasound communication for diagnostics and prognostics of structures. For example, ultrasound transmitters are connected to a metal or composite structure and modulated to produce Lamb waves that travel to an ultrasound receiver. The ultrasound transmitters can use frequency-hopped signals to digitally encode transducer information among different transmitters. The transmitters can be operated asynchronously. The receiver can use a channel equalizer to reduce the effects of signal multipath and a decoder to decode the transducer information from the ultrasound transmitters.

A transmitting / receiving filter (filter device) according to one embodiment of the present invention is provided with a transmitting filter, a receiving filter, and a support substrate. The transmitting filter includes a first resonator constituted of a BAW device (FBAR, SMR). The receiving filter includes a second resonator constituted of a Lamb wave device. The support substrate supports both the transmitting filter and the receiving filter. The transmitting filter and the receiving filter are constituted of elastic wave resonators that resonate at different oscillation modes from each other, which allows miniaturization of the support substrate to be realized while preventing oscillation interference between the two filters.

The invention discloses an improved Lamb wave engineering structure crack damage monitoring and estimating tomographic imaging method. The method comprises the steps of arranging an excitation / sensing circular array on a to-be-detected structure, establishing a detection passage, acquiring Lamb wave response signals of all excitation / sensing passages, and calculating an SDC value of each excitation / sensing passage; grouping the Lamb wave response signals, selecting a maximum SDC value in each group, and determining the direction of a crack according to two minimum values in all maximum SDC values; correcting the SDC value in the direction of the crack, and reconfiguring a damage image of the crack by adopting an RAPID algorithm; drawing an SDC distribution diagram of a receiving end, damaging a sensing route with the SDC value being greater than a set threshold value, and calculating the length of the crack according to a mathematic geometric relation. By adopting the method, the influence on the signal analysis caused by complicated multi-mode propagation characteristics of the Lamb wave can be overcome, the image reconfiguration of the crack damage is realized by utilizing the improved RAPID algorithm to correct the SDC value in the direction of the crack, and the length of the crack is evaluated by virtue of the SDC distribution diagram on the receiving end.

A method, apparatus and computer-readable medium for identifying a micro-annulus outside a casing in a cemented wellbore. The attenuation of a Lamb wave and a compressional wave is used to determine a presence of a micro-annulus between the casing and the cement.