General Electric Company

John R Viertl

Mederic E Auger

Marshall Gordon Jones

Elizabeth Lockenberg Dixon

Peter T Wu

Fred R Burkhardt, Jr

A configuration flexible computer-controlled ultrasonic diagnostic test equipment arrangement for examining large turbine rotors incorporates improved ultrasonic signal 'pulser-receiver' circuitry that is used to drive one or more an ultrasonic transducers and to receive and amplify ultrasonic returns from a specimen under test. The improved pulser-receiver circuitry comprises both an ultrasonic pulse generating circuit and an associated ultrasonic return signal linear amplification circuit. The pulse generating circuitry and the ultrasonic return signal amplification circuitry are modular and functionally independent of each other and, consequently, may be used together in the testing system or as stand-alone instrumentation. Overall ultrasonic diagnostic system flexibility is significantly enhanced by providing improved pulser-receiver circuitry with digitally driveable computer control inputs in addition to manual controls to enable selecting initial parameters and transducer position settings. A menu-driven display machine-operator interface is also provided as a user-friendly and efficient means for setting and accessing system configuration information and test data.

Ultrasonic pulser/receiver for ultrasonic test equipment

A thermoelectric potential probe inspects the surface coating thickness of a turbine bucket blade using a rolling ball probe head to traverse the surface of the bucket. The probe may be hand-held or affixed to a computer controlled robotics coordinate measuring machine. The rolling ball head has embedded heating elements and is a thermal-electric sensor that gathers data regarding the thickness of coating on a turbine surface.

Rolling-ball thermoelectric potential probe and housing for

A microcomputer or PC based non-destructive coated-object testing system and method combines thermoelectrically measured surface coating thickness data with flaw/crack depth data determined from eddy current measurements of the surface of the object to locate and selectively identify faults or cracks which penetrate the surface coating. The microcomputer controls scanning of eddy-current and thermoelectric probes over the object surface and stores measured data along with surface coordinate information to provide a color-keyed graphics display of surface conditions for visual analysis.

Combined thermoelectric and eddy-current method and apparatus for

A method and apparatus for metal flaw detection using multiple eddy current probes contained in a single carriage. An interlaced scanning method allows the scanning line spacing to be narrower than the spacing between probes on the probe carriage. The probes are held at a constant lift-off distance from the surface by a probe carriage that slides across the surface in a straight scan line. The probe carriage moves relative to a motorized bracket that slides the carriage across the surface.

Eddy current probe apparatus and interlaced scanning method for interior

An eddy current probe for detecting material flaws by inducing and measuring eddy currents in the surface of a material. The probe is held at a constant lift-off distance from the surface by a probe carriage that slides across the surface in a straight scan line. The carriage moves relative to a motorized bracket that slides the carriage across the surface. This relative movement allows the carriage to move across an uneven surface without deflecting the probe from a straight scan line. The probe has a split core so that an adjacent pair of coils project and detect electromagnetic fields on the surface being measured. Both coils have opposing flat sides that allow the coils to be closely packed together within the probe body.

Carriage for eddy current probe having contact ball engagement between

A system for non-destructively determining the thickness of a coating on a metal substrate includes using a first probe to locally heat the coating so as to establish a temperature gradient therein. The probe is configured so as to also provide electrical contact to the coating surface. This first probe is formed from a material having high thermal conductivity, and is at least partially plated with a material having high resistance to oxidation. Preferably, the probe plating material is chosen to also have high resistance to mechanical wear. The testing system also includes an electrical power supply for controllably heating the first probe in order to maintain the temperature thereof at a constant predetermined value. A second probe provides an electrical return contact in order to form a circuit for measuring the thermoelectric voltage between the two probes. This thermoelectric voltage may be conveniently measured by an AC amplification circuit. The thermoelectric voltage reading obtained may be processed by several different methods in order to provide the desired indication of the presence of a coating and/or its thickness. In one embodiment, the first probe is configured so as to be rollable along the coating surface, and the testing system further includes an electrical signal generator for determining the speed of movement of the rollable probe. In such an embodiment, the true coating thickness is determined from the measured thermoelectric voltage and the speed of movement of the probe.

Method and apparatus for determining the thickness of a coating on a

An eddy current probe, excitable at frequencies equal to or greater 7 mhz., includes a substantially planar, spiral-like, unilaminar coil mounted on an insulative substrate. A protective layer covers the coil and is adopted to present only a minimal mechanical barrier between the coil and a region of material under test. The coil is a continuous run of copper having an effective diameter no greater than 2 mils. The coil, substrate and protective layer are a printed circuit board. A method of detecting flaws is also disclosed.

High frequency eddy current probe with planar, spiral-like coil on

An eddy current probe, excitable at frequencies equal to or greater 7 mhz., includes a substantially planar, spiral-like, unilaminar coil mounted on an insulative substrate. A protective layer covers the coil and is adapted to present only a minimal mechanical barrier between the coil and a region of material under test. The coil is a continuous run of copper having an effective diameter no greater than 2 mils. The coil, substrate and protective layer are a printed circuit board. A method of detecting flaws is also disclosed.

Eddy current method for detecting a flaw in semi-conductive material

Residual stress measurements are made using a strain gage and stress relief achieved by local melting of a region of the object being tested by a laser beam or other finely directed heat source. Surface strain is measured dynamically before the heat of the molten region diffuses under the gage and results in thermal stress. The method is semi-nondestructive because the molten region recasts with little loss of material, is rapid, and can be utilized on difficult geometries such as the interior surface of reactor pipe.

Semi-nondestructive residual stress measurement

A loaded spring in a pressure relief valve or other spring-loaded device is excited with acoustic vibrations and the resonant frequencies of selected vibration modes are measured. Changes in spring constant due to aging and high temperature are detected by monitoring the longitudinal vibration mode resonant frequency, and changes in loading by monitoring the transverse and/or torsional vibration mode resonant frequency. The pressure set point is ascertained from manufacturing data of resonant frequency versus set point.

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Niskayuna, NY, United States of America

John R Viertl