Abstract: An automatic impedance matching system that can read the input impedance of an EMAT electrical circuit and automatically select the appropriate impedance matching by combining components from a built-in selection of matching circuitry. A Vector Network Analyzer or similar impedance measuring circuit is connected to the EMAT electrical circuit and measures the impedance of the EMAT RF coil, coil cable, and conductive material to be inspected at a given material lift-off, and relies on the information to the system processor. The processor uses this information to adjust the overall impedance by selecting appropriate capacitors and transformer taps on a programmable impedance matching circuit connected between the system pulser/receiver and the RF coil cable. The system can work in either pulse-echo (same transmitter and receiver) or pitch-catch (different transmitter and receiver).

Abstract: A system and method for sizing defects in solid structures using guided waves. The system includes a magnetostrictive-strip EMAT transducer comprising at least one biasing static magnetic field, at least one RF coil for fixed-wavelength measurements, at least one RF coil for variable-wavelength measurements, and a strip of highly magnetostrictive material that is coupled with the structure. The fixed-wavelength RF coil permits obtaining measurements of amplitude and frequency content of signals reflected and/or attenuated when traveling through the structure which are used to estimate the size and geometry of any defects in this structure. The variable-wavelength RF coil permits recording the frequencies that are cut off or pass through the structure to also estimate the size of any defects in the structure. The fixed-wavelength sizing and geometry assessment is used to determine whether the variable-wavelength estimate is valid.

Abstract: This disclosure relates to the inspection of train wheels while mounted on a train that is moving on a railroad track. A magnetostrictive EMAT transducer is built using an RF Coil, a static biasing magnetic field, and a strip of highly magnetostrictive material. This magnetostrictive EMAT transducer is subsequently attached to a rail on the track so the wheel tread of the moving train can contact and apply downward pressure on the magnetostrictive EMAT transducer. A mechanism under the transducer provides enough counterforce to pressure-couple the transducer with the tread of the wheel. Once the transducer is ultrasonically coupled with the wheel, an ultrasonic instrument sends a pulse to the transducer generating a Shear Horizontal wave that travels circumferentially following the tread body. The Shear Horizontal wave generated with this magnetostrictive strip EMAT transducer penetrates deep into the wheel tread and permits detection of both surface and internal defects.

Abstract: A system comprising a motorized scanner, a magnetostrictive EMAT sensor, and a mechanism to pressure-couple the sensor against the structure that is going to be ultrasonically inspected. The magnetostrictive EMAT sensor includes a magnet or magnets to provide a biasing field, an EMAT RF coil or coils to generate the RF field, a magnetostrictive strip under the coil or coils where the ultrasound is generated. Different magnet and coil configurations can be used to generate guided waves, such as shear horizontal and lamb waves, or bulk waves at different angles. The motorized scanner moves the sensor on the structure and stops at the desired inspection locations based on position readings. Once in position, a built-in device applies downward pressure on the sensor to pressure couple the magnetostrictive strip against the structure so the ultrasound can propagate within this structure and ultrasonic readings can be taken.

Abstract: A system for non-destructive inspection that generates Shear Horizontal waves in phased array configuration using an Electro Magnetic Acoustic Transducer (EMAT). The system includes an EMAT transducer with a plurality of elements made of individually wound elements under a single magnetic field, and an instrument to pulse, receive and record the signals from each element separately. Each wired element in the array generates shear waves perpendicularly to the coil windings which radiate around the elements' long axis. By phasing the pulsing and receiving of the individual elements, the beam can be electronically focused at different angles in the component from 0° to +/?90°. The compact distribution of the array permit using relatively high frequencies without generating deleterious grating lobes.

Abstract: A system comprising a motorized scanner, a magnetostrictive EMAT sensor, and a mechanism to pressure-couple the sensor against the structure that is going to be ultrasonically inspected. The magnetostrictive EMAT sensor includes a magnet or magnets to provide a biasing field, an EMAT RF coil or coils to generate the RF field, a magnetostrictive strip under the coil or coils where the ultrasound is generated. Different magnet and coil configurations can be used to generate guided waves, such as shear horizontal and lamb waves, or bulk waves at different angles. The motorized scanner moves the sensor on the structure and stops at the desired inspection locations based on position readings. Once in position, a built-in device applies downward pressure on the sensor to pressure couple the magnetostrictive strip against the structure so the ultrasound can propagate within this structure and ultrasonic readings can be taken.

Abstract: An EMAT ultrasonic system for non-destructive testing that comprises a layer of magnetostrictive material with low magnetocrystalline anisotropy bonded to the surface of the component where the ultrasound is being generated, an EMAT transducer capable of radiating a shear horizontal wave orthogonally to the entry plane on this magnetostrictive layer, and an instrument connected to the transducer capable of transmitting and receiving EMAT signals and provide measurements of time, amplitude and frequency response. The transducer is designed to generate shear horizontal waves that radiate normal to the surface, and can be deployed as a single element or in phased array. The transducer can work in either pulse-echo (same transmitter and receiver) or pitch-catch (different transmitter and receiver).

Abstract: 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.

Abstract: 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.

Abstract: 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.