108 results about "Electromagnetic acoustic transducer" patented technology

A system for evaluating the integrity of a bonded joint in an article includes a laser configured in a laser shock processing arrangement to perform a laser shock processing treatment on the article. A beam delivery system employs an articulated arm assembly to communicate the radiant energy emitted by the laser to a process head proximate the article. The laser shock processing treatment causes the formation of shockwaves that propagate through the article, inducing internal stress wave activity that characteristically interacts with the bonded joint. A sensor detects a stress wave signature emanating from the article, which is indicative of the integrity of the bond. A detector such as a non-contact electromagnetic acoustic transducer provides a measure of the stress wave signature in the form of surface motion measurements.

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.

A combined electromagnetic acoustic transducer (EMAT) is disclosed adapted to generate both SH-type acoustic waves and LAMB-type acoustic waves in a conductive casing, surroundings of which are to be analyzed. The transducer comprises one magnet assembly and two RF coils implemented as multi-layer printed circuit board. Each coil is used to generate or receive acoustic signals of one wave type. Compared to using two single-wave-type transducers the combined EMAT significantly reduces total attraction force to the casing and, correspondingly, simplifies mechanics of the measurement tool. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

The invention pertains to the design, arrangement and fabrication of arrays of electromagnetic acoustic transducers (EMATs) for detection and monitoring of defects in metal components while they are being used in service. Emphasis is placed on printed circuit sensor coil designs that are attached to and covered with thin, flexible and insulating substrates. This laminated construction with additional means for electrical and thermal insulation, radiation heat shielding and simple cooling provides for consistent and reliable EMAT performance in monitoring components at elevated temperatures. The arrays include circular spiral coils, elongated spiral (racetrack) coils and rectangular spiral coils. Also described are arrays of dual-rectangular (butterfly) coils, meander coils and trapezoidal coils. Various assembly designs for the attachment of bias magnets are described.

A method for inspecting welds between welded tubular ends includes arranging a series electromagnetic acoustic transducer (EMAT) assemblies in circumferential direction adjacent to an inner and/or outer surface of at least one of the welded tubular ends and inducing the EMAT assemblies to transmit sequentially or simultaneously acoustic shear wave signals towards the weld and to detect the shear waves reflected by and/or passing through the weld while the EMAT assemblies are maintained in a substantially fixed position relative to the weld such that at least a substantial part of the weld is scanned by the EMAT assemblies instantly after the weld is made.

Apparatus and methods are provided for non-destructive in-line pipeline inspection utilizing electromagnetic acoustic transducer (EMAT) technology wherein the EMATs are arrayed circumferentially in a belt around the body of the tool and wherein the EMAT belt includes a plurality of EMAT clusters, each cluster including a transmitting EMAT essentially sandwiched between a pair of receiving EMATs. The EMAT arrangement enables a single receiving EMAT to monitor both the test signal and the returning reflection from the pipewall defect thus providing each signal with its own internal reference. The number of transducers and their positional relationship limits the generation of interference signals, is conservative in power consumption, and provides a tool having enhanced negotiability through the pipeline.

An EMAT that generates horizontally polarized shear ultrasonic waves is combined with a PZT that generates longitudinal ultrasonic waves to provide simultaneous or sequential inspection of a test component material for improved accuracy in estimating properties of the material or detecting and estimating the dimensions of defects in the material. The transducer combination is constructed so that the EMAT and PZT elements are concentric and therefore interrogate approximately the same volume of the test component material. Nonferromagnetic insulators, such as elastomers, are installed on the bottom surface of PZT component to increase the transmission and reception the ultrasonic waves into the test component. Ferromagnetic, acoustic-absorbing materials are installed on the top surface of the EMAT coil component to minimize generation of ultrasonic waves in the bias magnet.

An electromagnetic acoustic transducer (EMAT) for inspecting an object is provided. The EMAT includes a magnet configured to generate a magnetic field in an object and a radio frequency coil configured to induce eddy currents on a surface of the object. The EMAT further includes a laminated wear plate disposed over the magnet and the radio frequency coil and configured to shield the magnet and the radio frequency coil from damage.

An improved high temperature electromagnetic acoustic transducer (EMAT) for conducting inspections of materials with elevated temperatures, which has cooling means using gas cooling, such as air or nitrogen, for cooling the transducer RF coil, the onboard circuitry and magnets, while also providing for the easy removal of the coil and onboard circuitry. Prior art EMAT's are susceptible to failure since high temperatures reduces the signal quality of the electronics components, degrades the insulation of the RF coils, and permanent magnets can loose field strength.

Electronic circuitry for high-power, high-frequency excitation of electromagnetic acoustic transducers (EMAT) without the use of a matching transformer is described. This circuit contains a least 4 switching devices such as power Mosfet transistors, arranged in an H-Bridge configuration that are designed to drive various EMATs over a wide range of frequencies. The switching devices can be connected in parallel with respect to the H-Bridge and switched in sequence for greater power output and variety of wave forms. This circuit configuration can provide a many excitation waveforms including, Churp, Hemming window tone burst, rectangular tone burst and Barker Code wave forms.

An improved electronic pulser circuit based on the H-bridge topology is designed for driving the sensor coils of an electromagnetic acoustic transducer (EMAT) to correct the disadvantages of conventional H-bridge pulsers and pulsers that require the use of an output transformer. A plurality of switching devices, primarily power Mosfets, are connected in parallel and augmented with support circuitry to provide improved performance in terms of increased power output, stability, reduced noise and complex output wave forms. This improved design provides for the application of modulated pulses such as multi-pulse, multi-frequency tone bursts of peak power outputs in excess of 20 thousand watts and frequencies in excess of 10 thousand Hertz.

An electromagnetic acoustic transducer for inducing and sensing vibrations in a cylindrical object and methods of using an electromagnetic acoustic transducer to determine resonant frequencies and physical properties of cylindrical objects. The electromagnetic acoustic transducers produce specific modes of vibration in cylindrical objects including axial shear vibrations. The electromagnetic acoustic transducers are used to determine the temperature, dimensions, elastic constants, and damping coefficients of cylindrical objects, the magnitude of a load applied to a cylindrical object, or the texture or grain orientation of the material forming a cylindrical object.

An ultrasound system for inspecting an object is provided. The ultrasound system includes an electromagnetic acoustic transducer (EMAT) and a pulser-receiver system. The EMAT is configured to generate acoustic signals representative of the area being inspected and comprises a flux concentrating non-conductive pole piece separating a radio frequency (RF) coil and a magnet. The pulser-receiver system is coupled to the EMAT and configured to receive the acoustic signals and convert the acoustic signal to electrical signals.

Disclosed are systems and methods that permit both real-time, and off-line, measurement of weld penetration depth. Exemplary systems and methods comprise an ultrasound source, such as a pulsed Nd:Yag laser, that simultaneously generates longitudinal and shear waves that radiate adjacent one side of a weld joining two specimens. An ultrasonic sensor, such as an electro-magnetic acoustic transducer or a piezo-electric transducer, capable of detecting shear and/or longitudinal waves, is disposed on an opposite side of the weld from the source. A signal processor is coupled to the sensor that processes time of flight signals for selected longitudinal or shear waves transmitted across the weld seam. The signal processor implements an algorithm that computes the weld penetration depth from the time of flight signals.

The invention belongs to the field of electromagnetic ultrasonic nondestructive inspection and discloses an impulse electromagnet for an electromagnetic acoustic transducer, which is capable of improving the performance of the EMAT and reducing the volume and power consumption of the probe of the EMAT. The invention aims to solve various problems aroused by a magnet in the traditional electromagnetic acoustic transducer and reduce probe volume. The impulse electromagnet for the electromagnetic acoustic transducer consists of an impulse electromagnet and an impulse electromagnet driving circuit, wherein the impulse electromagnet consists of a framework and a coil; and the impulse electromagnet driving circuit consists of a power pulse forming circuit, a power driving circuit, a control main machine and a booster circuit. The impulse electromagnet for the electromagnetic acoustic transducer can build a strong magnetic field in a very short period before the EMAT starts to operate to meet the working needs of the EMAT; and after the EMAT stops operating, the magnetic field disappears quickly. The impulse electromagnet is short in operation time, small in power consumption and small in volume and can be used in on-line detection of low-power consumption and portable ferromagnetic test pieces, and the like.

The invention relates to a variable-wavelength low-order shear-horizontal-wave electromagnetic acoustic transducer which can be used for ultrasonic flaw inspection for conductor materials, and belongs to the technical field of nondestructive inspection. An array-magnet equidistant change driving system mainly functions in providing a bias magnetic field with variable magnet spacing, namely variable wavelength, to an electrical system of the transducer. The SH (shear horizontal) modal magnet array type EMAT (electromagnetic acoustic transducer) can better meet inspection requirements by changing wavelength and changing excitation frequency at the same time, and the transducer can be adjusted according to actual inspection requirements. Therefore, the EMAT has higher adaptability and flexibility.

The invention relates to a method for detecting the thickness of industrial boiler scale by utilizing an SH (Shear) wave which is sensitive to an attachment on the surface of a plate layer, belonging to the field of nondestructive inspection of ultrasonic guided waves. In the method, firstly, a dispersion curve with different scale thicknesses is drawn by utilizing a dispersion equation for SH wave propagation in a double-layer structure to obtain a variation curve of SH0 modal group velocity changing along with the increase of the thickness of the scale, and then a high detection frequency and a low detection frequency respectively corresponding to thinner scales and thicker scales are further obtained. A detection system is shown as the drawing and comprises a function generator (1), a power amplifier (2), a change-over switch (3), an EMAT (Electromagnetic-Acoustic Transducer) sensor (4), an oscillometer (5) and a computer (6). The group velocity of an SH0 modal in a structure formed by a boiler and scales can be measured by the system, and the thickness of the scale can be obtained according to the corresponding curve of the group velocity and the scale thickness by the calculation, thereby the online and nondestructive testing on the thickness of the industrial boiler scale is realized.

An electromagnetic acoustic transducer (4) includes a flux guide (8) surrounded by one or more permanent magnets (10) abutting side faces of the flux guide (8). The magnetic field from the permanent magnets (10) enters the flux guide (8) where repulsion between the magnetic fields directs at least a portion of the magnetic fields toward a test face abutting a test object (2). The flux density at the test face is greater than the flux density within the originating permanent magnets (10). An active portion of a coil (12) disposed between the flux guide (8) and the test object contains conductors that are substantially straight, parallel and carry current in the same direction in order to provide substantially mode pure and uni-directionally polarised excitation of shear waves within the test object.

A method and apparatus for non-destructive testing. An embodiment of the present disclosure provides a non-destructive inspection system comprising a capacitive electromagnetic acoustic transducer and a control unit connected to the capacitive electromagnetic transducer.

The invention discloses a low-order torsional mode electromagnetic acoustic array transducer which is characterized by comprising a plurality of PPM (Pulse Position Modulation) electromagnetic acoustic transducers, wherein each PPM electromagnetic acoustic transducer comprises a rubidium ferrum boron magnet array (A) and at least one runway type coil (B) in a flexible printed circuit board; the PPM electromagnetic acoustic transducers are uniformly distributed at the periphery of a ring pipe structure; adjacent magnets in the rubidium ferrum boron magnet arrays (A) generate static magnetic fields in opposite directions; the width of each magnet is equal to half of the T (0,1) mode wavelength at excitation frequency; the magnets are the same in shape, are in strip-type arc shapes, and are placed together tightly to form a tile shape; the centers of the rubidium ferrum boron magnet arrays (A) are coincided with those of the runway type coils (B); the runway type coils (B) are concentrated on one flexible printed circuit board (D); and the runway type coils (B) are connected in parallel. The low-order torsional mode electromagnetic acoustic array transducer can effectively excite and receive T (0,1) mode ultrasonic guided waves; when the transducer is mounted, the surface of a pipeline is not required to be treated; the accuracy of a result is high; the repeatability is good; and a detection process is convenient and quick.