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: A high-voltage pulser circuit for Electromagnetic Acoustic Transducer (EMAT) coils using a Capacitive Discharge push-pull converter. The present invention relates in particular to the operation of the converter into an Electromagnetic Acoustic Transducer (EMAT) differential coil. The present invention reduces ringing of the coil current resulting in a smaller blind zone and a well-defined broadband ultrasonic wave from the coil. The pulser can be used to generate one or more cycles and work in either pulse-echo (same transmitter and receiver) or pitch-catch (different transmitter and receiver).

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 high-voltage pulser circuit for Electromagnetic Acoustic Transducer (EMAT) coils using a Capacitive Discharge push-pull converter. The present invention relates in particular to the operation of the converter into an Electromagnetic Acoustic Transducer (EMAT) differential coil. The present invention reduces ringing of the coil current resulting in a smaller blind zone and a well-defined broadband ultrasonic wave from the coil. The pulser can be used to generate one or more cycles and work in either pulse-echo (same transmitter and receiver) or pitch-catch (different transmitter and receiver).

Abstract: A method and apparatus for simultaneously inspecting and grinding roll mills which utilizes a transducer assembly which produces a creeping wave propagation in conjunction with a couplant fluid provider and data acquisition circuit which allows the operator to see the crack and imperfections in on the surface of the mill rolls as they are rotated and to grind them off.