Abstract: A system for use when measuring a magnetostriction value of a magnetoresistive element according to one embodiment includes a mechanism for applying a first magnetic field about parallel to a substrate having one or more magnetoresistive elements, and for applying a second magnetic field about perpendicular to the substrate and about parallel to magnetoresistive layers of the elements; and a mechanism for applying a mechanical stress to the substrate during application of the magnetic fields.

Abstract: A magnetostrictive stress sensor (11, 12, 13, 14, 15, 16) includes: a magnetic member {20, (107, 108, 109, 110, 111, 112)} having a magnetostriction; a permanent magnet (30, 35, 113) adjacent to the magnetic member; a magnetic sensor (40, 104A, 104B) for detecting a leak magnetic flux on a side opposite to the permanent magnet with respect to the magnetic member, wherein the leak magnetic flux changes according to a stress acting on the magnetic member and the magnetic sensor detects the change of the leak magnetic flux, to thereby detect the stress acting on the magnetic member, and a direction (21, 108A, 109A) of the stress acting on the magnetic member is substantially orthogonal to a magnetizing direction (31, 31, 113A) of the permanent magnet.

Abstract: An eddy current system and method enables detection of sub-surface damage in a cylindrical object. The invention incorporates a dual frequency, orthogonally wound eddy current probe mounted on a stepper motor-controlled scanning system. The system is designed to inspect for outer surface damage from the interior of the cylindrical object.

Abstract: An innovative method is provided for assessing structural integrity of a sample. The method comprises: capturing a signal indicative of magnetic flux density caused by an Eddy current flowing in the sample; extracting an envelope of the captured signal using a demodulation scheme; sampling the envelope at a frequency that is lower than the frequency of the excitation current signal which generated the Eddy current; and examining the sampled envelope to assess structural integrity of the sample.

Abstract: Described are methods for monitoring of stresses and other material properties. These methods use measurements of effective electrical properties, such as magnetic permeability and electrical conductivity, to infer the state of the test material, such as the stress, temperature, or overload condition. The sensors, which can be single element sensors or sensor arrays, can be used to periodically inspect selected locations, mounted to the test material, or scanned over the test material to generate two-dimensional images of the material properties. Magnetic field or eddy current based inductive and giant magnetoresistive sensors may be used on magnetizable and/or conducting materials, while capacitive sensors can be used for dielectric materials. Methods are also described for the use of state-sensitive layers to determine the state of materials of interest. These methods allow the weight of articles, such as aircraft, to be determined.

Abstract: The present invention discloses that the magnetic elastic body of magnetic conduction is stretched or shrunk by changes of passing magnetic fluxes or by the internal stress or external pushing or pulling force, the peripheral magnetic field surrounding the force bearing point is varied according to the stretching push or shrinking push, wherein its force bearing value or position is calculated by comparing the magnetic field distribution before and after the force bearing.

Abstract: A sensor includes a substrate having a mechanically deformable region that is deformable in a direction non-parallel to a surface of the substrate, and a magnetostrictive multi-layer sensor element configured to detect a mechanical deformation of the mechanically deformable region in a direction that is non-parallel to the substrate surface. The multi-layer sensor element includes a sensor layer having a material having a positive or a negative magnetostriction constant. The sensor further includes a device, arranged on the substrate, that is configured to generate a controllable magnetic field by which a performance of the magnetostrictive multi-layer sensor element is influenced, wherein the magnetostrictive multi-layer sensor element exhibits an electrical resistance that is a function of the controllable magnetic field and a deformation of the mechanically deformable region.

Abstract: The present invention is directed toward a multivalent product including a nanoparticle with a metal, metal alloy, or metal oxide core, a plurality of non-polymerizing ligands bound to the nanoparticle, and a plurality of paramagnetic ions coupled to the nanoparticle by the ligands. Methods of making and using the multivalent product are also disclosed.

Abstract: Magnetic or electric field sensors are mounted against a material surface and used for stress, strain, and load monitoring of rotating components such as vehicle drive trains. The stationary sensors are mounted at multiple locations around the component and used assess the stress on the component at multiple rotational positions. The sensor response is typically converted into a material property, such as magnetic permeability or electrical conductivity, which accounts for any coating thickness that may be present between the sensor and mounting surface. The sensors are not in direct contact with the rotating component and are typically mounted on an annular material or ring that encircles the rotating component. Measurements of the annular material properties, such as the stress, are related to the stress on the rotating component and discrete features on the component.

Abstract: Methods and systems for monitoring rotating shaft shafts and couplings in an aircraft propulsion system is described. The measurement system/method provides for accurate and precise monitoring of a rotating shaft flexible coupling in a fixed wing aircraft vehicle propulsion system. The measuring system/method provides for a high reliability short take off vertical landing fixed wing aircraft in which the vertical propulsion dynamically rotating drive shaft system and couplings are monitored in real time. The vehicular shaft coupling misalignment measuring system utilizes multiple positional sensors to provide highly reliable and precise determination of the dynamic characteristics of the rotating sensor target components of the propulsion system drive shaft. The relative position of the sensors is rigidly fixed externally from the rotating targets with a structural frame.

Abstract: An apparatus for the nondestructive measurement of materials that includes at least two layers of electrical conductors. Within each layer, a meandering primary winding is used to create a magnetic field for interrogating a test material while sense elements or conducting loops within each meander provide a directional measurement of the test material condition. In successive layers extended portions of the meanders are rotated so that the sense elements provide material condition in different orientations without requiring movement of the test circuit or apparatus. In a bidirectional implementation the angle is 90° while in a quadridirectional implementation the relative angles are ?45, 0, 45, and 90°. Multidirectional permeability measurements are used to assess the stress or torque on a component. These measurements are combined in a manner that removes temperature effects and hysteresis on the property measurements.

Abstract: A magnetization arrangement includes an inner element having an outer surface, an outer element having an inner surface, a connecting device, and a magnetic field measuring device. At least one element of the inner and outer element has a magnetizable area. The magnetic field measuring device is designed to measure a magnetic field generated by the magnetized magnetizable area. The connecting device joins the inner surface of the outer element and the outer surface of the inner element non-positively in such a way that a force acting on the magnetic sensor device can be transmitted in a defined manner between the outer element and the inner element.

Abstract: A system for use when measuring a magnetostriction value of a magnetoresistive element according to one embodiment includes a mechanism for applying a first magnetic field about parallel to a substrate having one or more magnetoresistive elements, and for applying a second magnetic field about perpendicular to the substrate and about parallel to magnetoresistive layers of the elements; a mechanism for applying a mechanical stress to the substrate during application of the magnetic fields; and a measuring subsystem for measuring a signal from at least one of the magnetoresistive elements, wherein the second magnetic field is a magnetic alternating field, wherein the measuring subsystem is locked to a frequency of the alternating field.

Abstract: A magnetic field sensor comprises one or more magnetic layers of magnetostrictive material that is mechanically bonded to one or more layers of electroactive material. When a magnetic field is applied to the device, it rotates the magnetization that is present in the in the magnetostrictive material thereby generating a magnetostrictive stress in the material. The magnetostrictive stress generated by this layer, in turn, stresses the piezoelectric layer to which the magnetostrictive layer is bonded. In order to increase sensitivity, the voltage across the piezoelectric material is measured in a direction that is parallel to the plane in which the magnetization in the magnetic material rotates.

Abstract: A wireless, non-powered fatigue monitoring sensor uses a piezoelectric element that is attached to the surface of or embedded within a structure to be monitored. When subjected to stress over time, the material properties of the element change reliably and permanently. These properties are used to determine the fatigue history of the structure. The monitoring device requires no power for monitoring and is nondestructively queried to determine the stress history using wireless means such as radio frequency technology.

Abstract: A method for measuring a magnetostriction value of a magnetoresistive element according to one embodiment includes placing a substrate carrying one or more magnetoresistive elements on a fixture; applying a first magnetic field about parallel to the substrate; applying a second magnetic field about perpendicular to the substrate and about parallel to magnetoresistive layers of the one or more elements; measuring a signal from at least one of the one or more elements; applying a mechanical stress to the substrate; and monitoring the signal from the at least one of the one or more elements while changing the first magnetic field.

Abstract: An apparatus (10) is set forth for measuring a return signal of a magnetostrictive sensor (20) that detects a force, torque, or pressure. The return signal includes noise, a DC resistance (44), an AC resistance and an inductance and the inductance is shifted ninety degrees from the AC resistance. The apparatus (10) includes a sensor filter (22) to remove the noise from the return signal. A sensor filter (22) shifts the return signal and more specifically, the inductance by an additional angle and the sum of the additional angle and the ninety degrees phase shift is defined as the final detection angle. To detect the inductance at the final detection angle, a wave filter (16) and a reference filter (28) shifts a reference signal by the final detection angle to trigger a first demodulator (26) to detect the inductance at the final detection angle. The inductance detected by the first demodulator (26) varies due to temperature.

Abstract: Sensor condition verification may be performed on electromagnetic sensors and sensor arrays mounted to a material surface. The sensors typically have a periodic winding or electrode structure that creates a periodic sensing field when driven by an electrical signal. The sensors can be thin and flexible so that they conform to the surface of the test material. Monitoring the conductivity changes of a test material, with changes in temperature, may provide a mechanism for testing the integrity of the sensor. Changes in the conductivity, due to changes in temperature, without significant lift-off changes may verify the calibration of the sensor and that the sensor elements themselves are intact.

Abstract: An electronic load regulation system for a locomotive may comprise a solid state replacement for existing electro-mechanical load regulators that are used to adjust the excitation current in the field windings of the locomotive's generator. A pressure sensor may include a first chamber and a second chamber, each chamber having a pressure switch. The pressure sensor may be installed in place of a prior art vane motor and may connect to the existing governor hydraulic output. The pressure switches send status data to an electronic load regulator circuit that may replace a prior art rheostat. The electronic load regulator may increase or decrease the excitation current depending upon the status data received from the pressure sensor.

Abstract: A sensor has a substrate having a mechanically deformable region, a magnetostrictive spin-valve sensor element being arranged to detect a mechanical deformation of the mechanically deformable region. On the substrate, there is a device for generating a controllable magnetic field by which a performance of the sensor element is influenced.

Abstract: In a method of measuring stress/strain by detecting Barkhausen noise, an exciting/sensing device is arranged at least adjacent to a magnetic or magnetizable element, and passing an increasing magnetizing current through the exciting device. The start of the Barkhausen noise in the element, as a function of the magnetizing current is detected by the sensing device, and the magnetizing current at that time represents a measurement of the stress/strain condition of the element.

Abstract: A system for directly measuring a magnetostriction value of a magnetoresistive element includes a fixture for receiving a substrate carrying one or more magnetoresistive elements. A magnet assembly applies a first magnetic field parallel to the substrate, and a magnetic alternating field perpendicular to the substrate and parallel to magnetoresistive layers of the elements. A stress-inducing mechanism applies a mechanical stress to the substrate, the stress being oriented parallel to the substrate. A measuring subsystem measures a signal from at least one of the magnetoresistive elements.

Abstract: A magnetostrictive transducer generating a torsional wave in a subject having a predetermined section and measuring a torsional wave propagating in the subject. In the magnetostrictive transducer having a ferromagnetic patch attached to a predetermined position of a subject, a cylindrical insulator installed around the periphery of the ferromagnetic patch, and a coil wound around the cylindrical surface of the insulator, a torsional wave is generated based on a magnetostrictive effect to then be induced to the subject when current is applied to the coil. The ferromagnetic patch includes a strip unit attached to the subject in an inclined manner with respect to an axial direction of the subject and transferring the torsional wave to the subject; and tail units formed at opposite ends of the strip unit and concentrating a magnetic flux on the strip unit when current is applied to the coil.

Abstract: This publication discloses a method and arrangement for determining the hardening depth of steel or other ferromagnetic substances without breaking the object being measured. According to the invention, a varying magnetic field, which causes magnetic Barkhausen noise (MBN), is created in the measurement object with the aid of a magnetization coil 13. The varying magnetic field is regulated in such a way that the maximum force of the magnetic field does not exceed the coercitive force of the unhardened part of the measurement object. The MBN caused is measured with the aid of an MBN sensor. The measured signal is filtered and Fourier transformed. The signal in the frequency range is integrated over a suitable frequency band, in order to determine the value depicting the energy of the MBN. This value correlates with the hardening depth and on the basis of this value it is thus possible to determine the hardening depth.

Abstract: A sensor-equipped hub unit comprises a hub unit 1 having a wheel-side raceway member 4, a body-side raceway member 5, and two rows of rolling bodies 6, and a sensor device 2 provided on the hub unit 1. The sensor device 2 has a magnetostrictive sensor 31 for detecting a reverse magnetostrictive effect of the raceway member 4 produced by a force exerted thereon by the rolling bodies 6. The sensor device 2 detects rotation from the number of repetitions of a variation in strain and also detects the force acting on the wheel-side raceway member 4 from the amplitude of strain.

Abstract: A lifecycle analyzer includes a temperature control element for controlling the temperature of a plurality of magnetoresistive (MR) elements, which may be, e.g., in bar, slider, head gimbal assembly, or head stack assembly form. The MR elements are in electrical contact with a stress probe element for applying a bias voltage or current stress. The MR elements and/or a magnetic field generator are moved to place one or more MR elements within the magnetic field of the magnetic field generator for testing. During testing, the MR elements are in electrical contact with a test probe element. The temperature of the MR elements may be controlled during both the stressing and testing.

Abstract: Material properties such as stress in a ferromagnetic material may be measured using an electromagnetic probe. While generating an alternating magnetic field in the object, and sensing the resulting magnetic field with a sensor, the signals from the magnetic sensor may be resolved into in-phase and quadrature components. The signals are affected by both geometrical parameters such as lift-off and by material properties, but these influences may be separated by mapping the in-phase and quadrature components directly into material property and lift-off components, and hence a material property and/or the lift-off may be determined. The mapping may be represented in the impedance plane as two sets of contours representing signal variation with lift-off (A) (for different values of stress) and signal variation with stress (B) (for different values of lift-off), the contours of both sets (A, B) being curved. The stress contours (B) intersect any one liftoff contour (A) at a constant angle.

Abstract: Systems and methods for analyzing structural test data are disclosed. In one embodiment, a method includes applying a sequence of loads to a test article, receiving raw test data indicative of the applied loads from at least one sensor operatively associated with the test article, receiving predicted test data indicative of the predicted loads on the test article, filtering out invalid test data, cycle counting to pair loads in the test data, performing a first fatigue damage computation based on the raw test data, performing a second fatigue damage computation based on the predicted test data, and comparing the first and second fatigue damage computations. The filtering, cycle counting, and performing of the first and second fatigue damage computations, and the comparison of the first and second fatigue damage computations, may be performed simultaneously using a spreadsheet program.

Abstract: Material condition monitoring may be performed by electromagnetic sensors and sensor arrays mounted to the material surface. The sensors typically have a periodic winding or electrode structure that creates a periodic sensing field when driven by an electrical signal. The sensors can be thin and flexible so that they conform to the surface of the test material. They can also be mounted such that they do not significantly modify the environmental exposure conditions for the test material, such as by creating stand-off gaps between the sensor and material surface or by perforating the sensor substrate.

Abstract: Fabrication of samples having material conditions or damage representative of actual components inspected by nondestructive testing involves sensors placed near or mounted on the material surface, such as flexible eddy current sensors or sensor arrays, to monitor the material condition while the sample is being processed. These sample typically have real cracks in or around holes, on curved surfaces, in and under coatings, and on shot peened or otherwise preconditioned surfaces. Processing, such as mechanical or thermal loading to introduce fatigue damage, is stopped once the material condition reaches a predetermined level.

Abstract: A fluxgate magnetometer including a fluxgate and a digital processor. The digital processor includes an analog to digital converter for digitizing the back EMF from the fluxgate and a signal generator to generate the fluxgate driving signal. Further, a current sourcing circuit is provided to receive the fluxgate driving signal from the signal generator and transmit a current amplified driver signal to the fluxgate capable of driving the fluxgate in and out of saturation. The signal generator is a pulse width modulator used in conjunction with a voltage shaper and driver to create a triangle-shaped driving signal to excite the fluxgate. The digital processor is further configured to reverse the sign of the digital back EMF signal at a frequency corresponding to two times the frequency of the fluxgate driving signal thereby capturing only the second harmonic of the back EMF signal.

Abstract: A force sensor, or a method, determines a force using at least a measured inductance in a coil wherein a quantum tunneling composite is located in a magnetic path created by the coil, is positioned in a load path of the force, and is under strain from the force. A strain sensor, or a method, determines a strain using at least a measured inductance in a coil wherein a quantum tunneling composite is located in a magnetic path created by the coil, is positioned in a load path of a force, and is under strain from the force.

Abstract: In a railway line, thermally-induced stresses are a factor for both rail breaks and rail buckling. These stresses are in the longitudinal direction. A nondestructive measuring technique enables the residual stress in a rail to be determined, and hence the thermally-induced stress. An electromagnetic probe is used to measure the stresses in the rail web in the vertical direction, and in the direction parallel to the longitudinal axis. The residual stress in the longitudinal direction can be deduced from the measured stress in the vertical direction; hence the thermally-induced stress can be determined.

Abstract: A method and system for performing in-line measurement of stresses in pipeline walls by continuous Barkhausen method comprises an inspection pig including permanent or DC electromagnets for generating a magnetic field that moves with the inspection pig through a pipeline, inductive or other types of magnetic field sensors for reading Barkhausen noise signals generated by the moving magnetic field, and associated instrumentation for amplifying, filtering, detecting and storing the Barkhausen noise signals. The size of the sensors may be selected to match the size of defects being investigated. By comparing trending data over time to determine changes in Barkhausen noise levels, greater detection sensitivity may be achieved. The method may be particularly advantageous for use in inspection pigs that also use magnetic flux leakage to determine pipeline defects, since the magnetic flux leakage method also use permanent or DC electromagnets.

Abstract: A non-contact rotation speed and torque sensing device which uses the natural inhomogeneities in the magnetic properties of a rotating element (4) to measure movement, displacement and deformation of the rotating element. An alternating magnetic field is applied in the region of a rotating element (4) and a signal representing the change in magnetic flux caused by the inhomogeneities of the magnetic structure of the object is received at a sensor (1). By processing the sensed signal using the auto-correlation function, the speed of rotation of the element (4) may be determined through inspection of the periodicity of the signal.

Abstract: An apparatus for inspecting a metallic post contoured in a single dimension for defects. The apparatus has a clamp having at least one jaw with a surface conforming to the contour to the metallic post. The conforming jaw or jaws also have a plurality of eddy current coils and the probe has at least one sensor configured to sense at least one of position or motion.

Abstract: A method for detecting a change in permeability of a magnetostrictive object due to a change in strain. At least one first coil and at least one second coil are obtained and positioned such that magnetic flux lines induced by an electric current in the first coil(s) pass through at least one portion of the object in a direction substantially parallel to the strain direction, such that magnetic flux lines induced by an electric current in the second coil(s) pass through at least one portion of the object in a direction substantially parallel to the strain direction, and such that any electromagnetic interference sensed by the first coil(s) is sensed oppositely by the second coil(s). The total inductance of the positioned first and second coil(s) is measured over time. A change in permeability of the object is detected from a change in the measured total inductance over time.

Abstract: A strain sensor includes a sensor section having a magnetic material provided on one surface of a conductor, the magnetic material being formed integrally with the conductor and having a magnetic strain constant with an absolute value larger than 1×10?7, a fixing mechanism which fixes at least a part of the sensor section, an inductor disposed in a surface side of the sensor section which is opposite the surface on which the magnetic material is provided, the inductor being disposed opposite and away from the sensor section, and a detection unit which detects the amount of deformation of the sensor section caused by stress applied thereto on the basis of a change in inductance of the inductor.

Abstract: A lifecycle analyzer includes a heating element for heating a plurality of magnetoresistive (MR) elements, which maybe, e.g., in bar form. At one location the MR elements are in contact with a stress probe card for applying a bias voltage or current stress. The MR elements are moved to a separate location, where there is a test probe card and magnetic field generator for testing the MR elements after being stressed. In one embodiment, a subset of the plurality of MR elements is tested at a time. The lifecycle analyzer includes an in-situ abrasive element that is used to abrade the probe pins of the stress probe card to remove oxidation that results from extended contact with the heated MR elements.

Abstract: A method and apparatus for implementing magnetostrictive sensor techniques for the nondestructive evaluation of pipes or tubes. A magnetostrictive sensor generates guided waves in a pipe or tube, which waves travel therethrough in a direction parallel to the longitudinal axis of the pipe or tube. This is achieved by using a magnetized ferromagnetic strip being pressed circumferentially against the pipe or tube. For improved efficiency, the strip may be made from an iron-cobalt alloy. The guided waves are generated in the strip and coupled to the pipe or tube and propagate along the length of said pipe or tube. For detection, the guided waves in the pipe or tube are coupled to the thin ferromagnetic strip and are detected by receiving MsS coils. Reflected guided waves may represent defects in the pipe or tube.

Abstract: A torque detecting device includes an elastic member disposed between an input shaft and an output shaft of a torque transmitting apparatus, first and second resolvers detecting rotational angles of the elastic member at sides of the input shaft and the output shaft. The first resolver includes a first excitation winding coil and a first output winding coil, and the second resolver includes a second excitation winding coil and a second output winding coil. The first and second excitation winding coils are connected to a ground, and the first and second output winding coils are connected to the other ground.

Abstract: The variation in properties of a ferromagnetic material with depth below the surface is assessed in a nondestructive fashion using a probe that incorporates an electromagnet. An alternating magnetic field is generated in the electromagnet and so in the object, and a magnetic sensor is arranged to sense a magnetic field due to the electromagnet. Signals from the magnetic sensor are analysed into an in-phase component and a quadrature component, and these are mapped directly into material property and lift-off components; this analysis enables accurate measurements of material property (such as stress) to be distinguished from changes in lift-off. The measurements are repeated for at least five different frequencies of the alternating magnetic field; and the measurements at different frequencies are deconvolved assuming a functional form for the variation of material property with depth, the function having no more than five unknown constants. The stress at depths for example in the range 0.5 mm to 5.

Abstract: A method for detecting a change in permeability of a magnetostrictive object due to a change in strain. At least one first coil and at least one second coil are obtained and positioned such that magnetic flux lines induced by an electric current in the first coil(s) pass through at least one portion of the object in a direction substantially parallel to the strain direction, such that magnetic flux lines induced by an electric current in the second coil(s) pass through at least one portion of the object in a direction substantially parallel to the strain direction, and such that any electromagnetic interference sensed by the first coil(s) is sensed oppositely by the second coil(s). The total inductance of the positioned first and second coil(s) is measured over time. A change in permeability of the object is detected from a change in the measured total inductance over time.

Abstract: A lifecycle analyzer includes a heating element for heating a plurality of magnetoresistive (MR) elements, which maybe, e.g., in bar form. At one location the MR elements are in contact with a stress probe card for applying a bias voltage or current stress. The MR elements are moved to a separate location, where there is a test probe card and magnetic field generator for testing the MR elements after being stressed. In one embodiment, a subset of the plurality of MR elements is tested at a time. The lifecycle analyzer includes an in-situ abrasive element that is used to abrade the probe pins of the stress probe card to remove oxidation that results from extended contact with the heated MR elements.

Abstract: A method for determining a “safe-operation” point for a metal structural element subjected to repeated loading, the same or different, generating variable levels of strain and residual stress in the worked element; and, predicting the imminent failure of the structural element. The surface of the metal element is worked to provide a residual strain, for example, by shot-peening. Measurements of electrical conductivity are compared at various chosen frequencies corresponding to different depths in the “near-surface” of the element. Similar measurements are made in the near-surface of a “standard” and a first difference is computed between the conductivity of the shot-peened surface and the “standard” surface. This first difference provides a basis for comparison of the effects of residual stress after successive loadings of the shot-peened metal element.

Abstract: A method for determining a “safe-operation” point for a metal structural element subjected to repeated loading, the same or different, generating variable levels of strain and residual stress in the worked element; and, predicting the imminent failure of the structural element. The surface of the metal element is worked to provide a residual strain, for example, by shot-peening. Measurements of electrical conductivity are compared at various chosen frequencies corresponding to different depths in the “near-surface” of the element. Similar measurements are made in the near-surface of a “standard” and a first difference is computed between the conductivity of the shot-peened surface and the “standard” surface. This first difference provides a basis for comparison of the effects of residual stress after successive loadings of the shot-peened metal element.

Abstract: A system for measuring the magnetostriction coefficient &lgr; of a sample material applied to a substrate element fixed at one end leaving the other end free to be deflected. An external rotating magnetic field of rotation frequency f and intensity Hext is applied to the cantilever substrate element the amplitude Am of the deflection of the free end is measured at each of a plurality of rotation frequency harmonics {fm} by, for example, using a plurality of lock-in amplifiers. The harmonic deflection amplitudes {Am} are combined to determine the magnetostriction coefficient &lgr; of the sample material. At an Hext equal to the sample saturation moment Msat and assuming a 15 Oe sample anisotropy Hk and coupling bias Hp, the error in the saturation magnetostriction coefficient &lgr;S measured according to this invention may be reduced by 80% to 90% over the error seen when using only the second harmonic deflection amplitudes A2.

Abstract: Inductive sensors measure the near surface properties of conducting magnetic materials. The sensors generally include parallel winding segments to induce a spatially periodic magnetic field in a material under test. The sensors may provide a directionally dependent measure with measurements made in varying orientations of the sensor with respect to the material property variation directions. The sensors may be thin, conformable sensors that can be mounted on a test material and, for example, monitor crack initiation under the sensor. A second sensor may be left in air to provide a reference measurement, or the temperature of the material under test can be varied to verify the response of the individual sensing elements. Sensors can be mounted to materials under test in order to not modify the environment that is causing the stress being monitored.

Abstract: A temperature sensing apparatus including a sensor element made of a magnetically soft material operatively arranged within a first and second time-varying interrogation magnetic field, the first time-varying magnetic field being generated at a frequency higher than that for the second magnetic field. A receiver, remote from the sensor element, is engaged to measure intensity of electromagnetic emissions from the sensor element to identify a relative maximum amplitude value for each of a plurality of higher-order harmonic frequency amplitudes so measured. A unit then determines a value for temperature (or other parameter of interst) using the relative maximum harmonic amplitude values identified. In other aspects of the invention, the focus is on an apparatus and technique for determining a value for of stress condition of a solid analyte and for determining a value for corrosion, using the relative maximum harmonic amplitude values identified.

Abstract: Methods are described for the use of conformable eddy-current sensors and sensor arrays for characterizing residual stresses and applied loads in materials. In addition, for magnetizable materials such as steels, these methods can be used to determine carbide content and to inspect for grinding burn damage. The sensor arrays can be mounted inside or scanned across the inner surface of test articles and hollow fasteners to monitor stress distributions. A technique for placing eddy-current coils around magnetizable fasteners for load distribution monitoring is also disclosed.