Abstract: A position sensor including a guide bar carrying a magnetic tape generating a magnetic field whose intensity varies sinusoidally along a longitudinal axis of the guide bar. A pick-up head is mounted adjacent the guide bar for translational movement therealong to detect the magnetic field. More particularly, the pick-up head comprises two magnetic field detectors spaced apart by a predetermined distance in the direction of translational motion of the pick-up head, each magnetic field detector generating an output signal representative of the magnetic field intensity at the position of detection thereof. By processing the output signals of the magnetic field detectors, it is possible to accurately determine the position of the pick-up head with respect to the guide bar. Advantageously, the position sensor may be used for the construction of a torque meter.

Abstract: A method and apparatus for testing steel components for temper embrittlement uses magneto-acoustic emission to nondestructively evaluate the component. Acoustic emission signals occur more frequently at higher levels in embrittled components. A pair of electromagnets are used to create magnetic induction in the test component. Magneto-acoustic emission signals may be generated by applying an AC current to the electromagnets. The acoustic emission signals are analyzed to provide a comparison between a component known to be unembrittled and a test component. Magnetic remanence is determined by applying a DC current to the electromagnets, then turning the magnets off and observing the residual magnetic induction.

Abstract: A method and apparatus for ascertaining internal stresses in a hardened region to be tested for a component made of a predetermined material includes measuring coercive field strength and amplitude of magnetic Barkhausen noise as a function of mechanical stress and hardness in calibration samples of a predetermined material of known hardness and known internal stress. Calibration functions are ascertained from the measured values indicating the dependency of the hardness and the amplitude of the magnetic Barkhausen noise as functions of the hardness and mechanical stress. The coercive field strength and the amplitude of the magnetic Barkhausen noise is measured in a location-dependent manner over the region of the component to be tested. The measured values of the coercive field strength and the amplitude of the magnetic Barkhausen noise are converted in the region to be tested into location-dependent hardness and into location-dependent mechanical stress using the ascertained calibration functions.

Abstract: An applied magnetic field direction indicating device comprising a magnetic sensor (1) having an omnidirectional characteristic and an output which is non-linearly related to the magnitude of the applied field. The sensor (1) is subjected to two mutually perpendicular sinusoidal magnetic biassing fields of the same frequency and in time quadrature relationship. A characteristic of the output of the sensor (1) is indicative of the direction of the applied field.

Abstract: The apparatus includes excitation windings (5, 6, 7) for imparting to an elongate specimen (1) of ferromagnetic material longitudinal oscillations. A device (30) is provided for cutting off a power amplifier (21) of one (5) of the excitation windings, along with a device (28, 29, 30, 32, 33) for detecting and counting the damped oscillations, after the cutting off of the excitation, whose amplitude is greater than or equal to the initial amplitude of the oscillations multiplied by a coefficient so as to permit the determination of the coefficient of internal friction. The excitation winding are constituted by three coaxial cylindrical windings (5, 6, 7) disposed around the specimen (1).

Abstract: A torque sensor for a cylindrical shaft subject to torque employs an electrically conductive loop on the shaft, which loop exhibits changing electrical impedance with changing stress and strain as the shaft is torqued. In another embodiment, a pair of loops exhibit oppositely changing electrical impedance as the shaft is torqued. In another embodiment, a magneto-elastic electrically conductive loop on the shaft exhibits changing magnetic permeability and changing electrical impedance with changing stress and strain as the shaft is torqued.

Abstract: A torque detecting device has a measuring shaft and a magnetic circuit incorporating the measuring shaft into a magnetic path which includes a device for detecting a magnet-ostrictive force passing through said measuring shaft. The device is able to increase the output sensitivity, decrease the rotative fluctuation of output and decrease the hysteresis by making the measuring shaft forming the magnetic path from an iron base alloy having a specific composition.

Abstract: A liquid level detector of the type in which a magnetostrictive wire extends through the liquid level measurement range and is captured in a tensioned vertical orientation within a stainless steel tube. Liquid level is measured as a function of the time required for a torsional disturbance imparted the wire near the top to travel along the wire to a magnet which is contained within a liquid level float which slides up and down along the tube. The torsional disturbances imparted to the wire by means of a piezoelectric crystal to which the wire is easily clamped. Accuracy is enhanced by measuring liquid level as a function of the elapsed time between an actuation signal and the first zero crossing of the voltage which is induced as the torsional strain passes through the area of influence of the sliding magnet.

Abstract: The object of the invention is a method and a device for materials testing using the eddy-current principle. If a coil (30) is moved in relation to test specimens, magnetic alternating fields with differing frequencies are generated, these fields induce eddy-currents that cause a secondary field in the coil (30). A number of test specimens having the same structure and the same dimensions are measured. The measured values are stored. The coordinates of the center of gravity of the measured values in the complex plane are then determined. The the phase angle is determined of that axis which runs longitudinally through the field (20) formed by the measured values in the complex plane. The center of gravity is then rotated into the origin of the coordinate system and the axis into a coordinate axis. Then a threshold value envelope determining a fault boundary is placed around the field of the measured values.

Abstract: The long-term measurement stability of a magnetostrictive effect strain or stress sensor that uses an amorphous magnetic alloy excited by a magnetic field is improved by generating a magnetic field from an electric current formed from a superposed alternating current waveform and a recurring rectangular current waveform that has a larger amplitude at its start-up and which converges to a smaller amplitude after a predetermined time period or an electric current formed from a superposed direct current component and an alternating current component having constant amplitude and a frequency that varies in a recurring manner between a high frequency and a lower frequency.

Abstract: A mechanical quantity sensor element making use of a stress-magneto effect of noncrystalline magnetic alloy. This mechanical quantity sensor element is manufactured by coupling a piece of noncrystalline magnetic alloy having positive magnetostriction with another material such as, for example, thermo-setting resin at a temperature exceeding an operating temperature range of the mechanical quantity sensor element, and then cooling them to the operating temperature range. Due to a difference in a coefficient of thermal expansion between the piece and the material, compression strain is preliminarily given to the noncrystalline magnetic alloy piece, and the mechanical quantity sensor element has an excellent linearity and a wide detectable range for mechanical quantities.

Abstract: A torque sensor includes a cylindrical body disposed concentrically around a shaft and having its opposite ends secured to the surface of the shaft through elastic bodies, a layer of soft magnetic alloy having a magnetostriction property and secured to the surface of the cylindrical body, and a coil disposed concentrically around the layer with an air gap between it and the layer. The torque sensor is constructed such that a strain produced on the surface of the cylindrical body by a torque is converted into a change of a relative permeability of the soft magnetic alloy due to a reverse magnetostriction effect which is detected as a change of inductance of the coil. When the shaft thermally expands or deflects, the elastic bodies act to permit only a torque to be transmitted to the cylindrical body, so that a uniform output is provided without the influence of a thermal strain and deflection of the shaft.

Abstract: Rapid nondestructive testing of a ferromagnetic workpiece for creep damage is carried out by placing an eddy current coil adjacent to the workpiece, passing an alternating current through the coil, measuring the eddy current response as influenced by the workpiece, and comparing the current measurement to a current calibrated to known creep damage for the given ferromagnetic material. Correlations of the eddy current response to creep rate and time to failure are generated from creep rupture tests performed on specimens of the given material subjected to varying conditions of time, temperature and stress. Qualitative tests can also be performed to identify the point of greatest creep damage by passing the eddy current coil over the workpiece to find the location of the lowest eddy current response. Conventional creep damage tests can then be performed at that location if desired.

Abstract: A stress detector including an AC power source for generating an AC symmetrical wave form voltage, an exciting coil driven by the AC power source for alternatingly magnetizing at least a portion of a ferromagnetic material to be measured in a predetermined direction, a detecting coil for detecting a magnetic flux generated due to the alternating magnetization, and an adder circuit for taking out a part of a voltage applied to the exciting coil, setting an amplitude and a phase of a wave form of the taken-out part of the voltage to preset values, adding the voltage thus obtained to a voltage induced in the detecting coil. The detector gives an output signal representative of a value of stress applied to the material to be measured as a variation either in amplitude or phase depending on the preset phase.

Abstract: A non-contacting, inductively coupled leakage flux torque sensor particularly adapted for automobile power steering systems. The input and output shafts of the system are coupled by a lost motion mechanism. Discontinuities are formed in a ferromagnetic member. The discontinuities may comprise sets of slots or ferromagnetic projections on facing end surfaces of the ferromagnetic member. As a result of torsional stress on the member, the discontinuities change shape and dimension or are displaced, resulting in a change in leakage flux. The change in leakage flux is detected by two differentially connected coils. A modulator-demodulator circuit provides a determination of torque as a function of the changed flux.

Abstract: A non-contacting, inductively coupled leakage flux torque sensor and method of measuring torque by determining the change in leakage flux at a surface discontinuity as a result of a torsion stress. Two identical, mirror image discontinuities are formed in a ferromagnetic member. The discontinuities may comprise sets of slots or ferromagnetic projections on facing end surfaces of the ferromagnetic member. As a result of torsional stress on the member, the discontinuities change shape and dimension or are displaced, resulting in a change in leakage flux. The change in leakage flux is detected by two differentially connected coils. A modulator-demodulator circuit provides a determination of torque as a function of the changed flux.

Abstract: A torque sensor for electrically detecting torque, such as the torque of an automobile engine, wherein a strain disk is provided in the path of torque transmission and the torque is magnetically detected in terms of the magnetostriction generated in the strain disk. The torque sensor comprises a magnetic rotating disk and a magnetic sensor disposed in the vicinity of and opposed to the strain disk. The magnetic sensor comprises a detection coil and an excitation coil oriented perpendicularly to each other with the excitation coil ordinarily being disposed outside of the detection coil. Supplying alternating current to the excitation coil causes an alternating field to be produced within the strain disk and the configuration of this alternating magnetic field is varied by the anisotropy of the strain caused within the strain disk by the transmitted torque.

Abstract: In a method for testing steam turbine rotors for embrittlement to determine which rotors to retire and which rotors to continue in operation, a varying magnetic field is applied to the rotor in a waveform to produce a detectable Barkhausen effect in the flux density developed in the rotor. The resulting Barkhausen burst of pulses is detected and is displayed on an oscilloscope. In addition, the pulse amplitude distribution of the pulses in the burst is plotted. The oscilloscope display and the pulse height distribution curve are compared with corresponding representations of the Barkhausen effect produced from a test sample known not to be embrittled, or from the rotor itself at a previous time, to make a determination of whether the rotor has become embrittled and whether to continue operation of the rotor.

Abstract: A non-destructive method for using the mechanical Barkhausen noise phenomenon, caused in fereromagnetic materials by the dislocation motion and the changing external mechanical loading, especially in determining the fatigue strength of the material. The test piece is cyclically loaded with continuously or incrementally increasing amplitude in the presence or absence of a stable magnetic field by which the test piece is magnetized and, simultaneously, measurement is made of the maximum value obtained as a function of one of: the effective value, the size distribution and the mean value of the mechanical Barkhausen noise pulses induced during fatigue of the test piece. The loading amplitude at which such maximum value is reached corresponds to a fatigue strength equal to the fatigue limit of the test piece, the latter having been subjected to a prior loading process to create a lattice defect pattern in the test piece when no stable magnetizing field is present.

Abstract: The contactless angular displacement and/or torque pickup is characterized in that it comprises two electrically insulating coaxial disks (7a, 7b) that can turn in relation to one another by an angle to be detected and that carry on their opposing faces conductive plane coils (8) in the shape of spirally wound sectors coiled alternately in both directions and whose mutual induction varies as a function of the relative angular position of the detection disks (7a, 7b). Also included is a rotary transformer (6a, 6b) to supply one of the detection disks (7a, 7b), a circuit (18) for supplying the primary (11a) of the rotary transformer and a circuit (17, 18) for processing the signal (S) collected on one of the detection disks (7a, 7b).

Abstract: A nonintrusive torquemeter for measuring torque in a shaft having variable reluctance as a result of torque stresses developed in the shaft. The torquemeter includes an annular first coil, a second coil wound about the first coil coaxially of the annular axis of the first coil to be in space quadrature therewith, structure for mounting the coil assembly coaxially about the shaft to include the shaft in the magnetic flux coupling path between the coils, and structure for providing a signal corresponding to the voltage developed in the pickup winding as a result of changes in the magnetic reluctance of the shaft resulting from torque developed therein. One of the coils is electrically excited to define an excitation winding, and the other of the coils serves as a pickup winding, with the coils being effectively uncoupled in the absence of torque in the shaft and being variably coupled as an incident of torque being developed in the shaft causing a corresponding change in the reluctance thereof.

Abstract: A sensor for a system that detects stresses and defects in a metal piece by employing the Barkhausen phenomenon enables static or dynamic testing of such metal pieces as hard steel in which only low levels of Barkhausen noise can be generated or which are configured in one of a large variety of shapes. The sensor includes apparatus that ensures that a uniform time-varying magnetic field can be produced in all the metal pieces of a variety of shapes. The sensor can include an energizing coil assembly which generates the magnetic field in the metal piece having a core constructed from such a material in which a low level of magnetic noise is generated as ferrite. The level of the magnetic noise generated in the ferrite core is so low that, even if the magnetic noise is sensed by the sensing coil assembly, which receives the Barkhausen noise gererated within the metal piece, that noise cannot interfere with the higher levels of Barkhausen noise generated in all ferromagnetic metals, including hard steel.

Abstract: In a torque sensor of a noncontact type for sensing a rotary torque applied to a shaft, a magnetic ribbon of a film shape formed of a magnetic material and applied in advance with an induced magnetic anisotropy in the direction of an angle .theta. along the circumference of a shaft is bonded to the shaft along its circumference. A U-shaped first core member having end faces opposite to the ribbons is provided in the vicinity of the shaft. An exciting coil for producing a magnetic flux and a detecting coil are wound around the core member, and the magnetic flux produced by the exciting coil and introduced through the ribbon to the core member is detected by the detecting coil. When an exciting current of a predetermined frequency is supplied from an oscillator to the exciting coil to produce a magnetic flux, an output signal is generated from the detecting coil and is measured by a voltmeter.

Abstract: A torque gauge using magnetoelastic ribbons is presented wherein changes in the magnetic characteristics of these ribbons are detectable in a push-pull mode for determining torque forces applied to the ribbons. Respective tensile and compressive forces applied to the ribbons cause a change in the magnetic qualities of the ribbons and of the inductance of coils wound about the ribbons with the change of inductance being a measure of the torque forces applied to the input of the device.

Abstract: A method for analyzing the anisotropic properties of ferromagnetic steels by use of Barkhausen noise simultaneously sensed in a plurality of directions without contact with the steel specimen.

Abstract: A method and apparatus for contact-free measurements of stress, temperature, torque, or other physical conditions which affect the magnetic properties of a non-ferromagnetic test object 10. The non-contacting magnetic sensor detects the large Barkhausen effect. Magnetic layers 12,14 of thin magnetic material are formed on surface 16 of test object 10. An easy axis of magnetization is formed on the magnetic layers 12,14 making them susceptible to the large Barkhausen effect. A physical condition, such as stress 17,17', is applied to test object 10 and magnetic field 18 is generated by source 19. Magnetic field 18 causes large Barkhausen effects to be generated in magnetic layers 12,14 which are detected by detector 20. The level of the physical condition is a function of the time required for the large Barkhausen effect to occur in the different magnetic layers 12,14.

Abstract: In a torque sensor of a noncontact type for sensing a torque applied to a shaft, a magnetic ribbon is bonded to a circumferential portion of the peripheral surface of the shaft, and a core member made of a magnetic material is arranged above the shaft surface so that its end faces are faced to the magnetic ribbon. A exciting coil and a detecting coil wound around the core so that a magnetic flux produced by the exciting coil and delivered to the detecting coil is detected by the detecting coil. The magnetic ribbon has a length L0 equal to or smaller than one half of the circumferential length Ls of the shaft 4 and satisfying an inequality given byL1.ltoreq.L0.ltoreq.2L1where L1 is the center-to-center distance between the end faces of the core.

Abstract: The present invention relates to an ergometer having an eddy current brake serving as a loading device, comprising a rotatably mounted brake wheel placed into rotation by means of a drive device and having a cylindrical ring made from an electrically conductive material. A stationary magnet system acts as a loading device and has an air gap disposed between the poles of the magnet system directed toward the ring and the ring itself. Depressions in the surface of the brake wheel run laterally to the direction of movement and are provided at one side of the air gap opposite the poles of the magnet system. The magnet system supports a measurement coil permeated by the magnetic flux which closes over the brake wheel. The fluctuations in the magnetic flux resulting from the grooves cause a voltage to be induced in the measurement coil, from which the rotational speed of the brake wheel and the effective braking torque can be calculated.

Abstract: The magnetic head of a magnetostriction torque sensor is covered by a magnetic head holder made of a synthetic resin and supported by an outer tubular member via an elastic supporting member. The magnetic head holder is formed with bearing portions by which an axle to be measured is rotatably supported in such a way that a predetermined clearance is always kept at a constant value between the magnetic head and the axle. Therefore, even if the axle to be measured or the outer tubular member to support the magnetic head deforms or if the concentricity of the outer tubular member with respect to the axle is inferior, it is possible to stably and precisely detect the torque applied to the axle to be measured. The above-mentioned structure of the magnetostriction torque sensor can reduce the manufacturing cost and improve the productivity.

Abstract: A noncontact torque sensor for measuring torsional loading of a shaft the magnetic permeability of which changes in response to changes in torsion loading of the shaft. The sensor includes an excitation coil for generating a magnetic field passing through the shaft, and sensing coils for detecting changes in the magnetic field caused by changes in the permeability of the shaft. At least one pole is disposed adjacent the shaft, separated by an air gap, for coupling magnetic flux into or out of the shaft. The shaft has a radially extending surface adjacent to which the pole is disposed, and the air gap is represented by the axial spacing between the pole and the radially extending surface. The air gap is thus axial, and does not vary with radial movements of the shaft. In some of the embodiments described, plural poles are arranged symmetrically around the shaft such that other translational movements of the shaft produce offsetting changes in the sizes of various pole air gaps.

Abstract: A nonintrusive torquemeter for measuring torque in a shaft having variable reluctance as a result of torque stresses developed in the shaft. The torquemeter includes an annular first coil disposed axially about the shaft, a second coil wound about the first coil coaxially of the annular axis of the first coil to be in space quadrature therewith, structure for mounting the coil assembly coaxially about the shaft to include the shaft in the magnetic flux coupling path between the coils, and structure for providing a signal corresponding to the voltage developed in the pickup winding as a result of changes in the magnetic reluctance of the shaft resulting from torque developed therein.

Abstract: A torque detector, particularly a torque detector for detecting a torque applied to a torque transmission shaft which is connected to a load such as a wheel of an automobile, has a driving member connected to an engine, a driven member connected to a load and driven by the driving member to be rotated, an elastic member for connecting the driving member to the driven member, a transmission for varying the rotating speed ration of the engine to the load, which is provided in the driving member or the driven member, electromagnetic pickups for detecting the angular phase difference between the driving member and the driven member which is produced due to the deformation of the elastic member, a rotating speed ratio counting circuit for detecting the rotating speed ratio of the engine to the load, which is controlled by the transmission, and a microcomputer for calculating engine torque and load driving torque from the rotating speed ratio detected by the rotating speed ratio counting circuit and the angular pha

Abstract: An operating circuit for use with a magnetoelastic force/pressure sensor provides for changing the current flow through at least one sensor coil at a frequency responsive to the magnitude of a force impingent upon the sensor. The sensor operating circuit operates in a manner to prevent the sensor magnetoelastic core from being driven deeply into saturation, thus providing an operating circuit with a reduced current drain. A number of embodiments, including clock-driven and self-clocking (toggling) circuit providing digital and/or analog outputs are described.

Abstract: The stress or strain in a magnetic workpiece is measured by a method in which the workpiece is locally magnetized by a constant magnetic field, an eddy current probe is placed adjacent to the workpiece, and an electrical characteristic of the probe, which is proportional to stress or strain in the workpiece is measured. The measured value is compared to calibration data to obtain the actual stress or strain. By continually subjecting the workpiece to a constant magnetic field, a maximum value of applied stress can be determined by making a first measurement before an external force is applied to the workpiece and making a second measurement after the force is removed. The difference between the two measurements is proportional to the maximum stress applied to the workpiece by the force between the two measurements. If stress or strain in a nonmagnetic workpiece is to be measured, a layer of magnetic material is bonded to the workpiece at the measurement point.

Abstract: A torquemeter 10 comprising a magnetostrictive element 12 which is formed in the shape of a ribbon upon the surface of the subject rotating member 14 and is capable of producing internal, avalanche Barkhausen reversals, permanent magnets 16 and 18 positioned adjacent to the subject rotating member 14 for successively triggering the avalanche Barkhausen reversals in the magnetostrictive element and for resetting the magnetostrictive element after each reversal, a pickup coil 20 for generating signals responsive to the avalanche Barkhausen reversals and a readout circuit 22 in communication with pickup coil 20 for correlating the responsive signals to an indication of the level of torque and/or power in the subject rotating member 14.

Abstract: A torque sensor is used for non-contacting measurement of torques in accordance with the eddy current principle. This sensor is arranged closely in front of the surface of the test object (shaft). The torque is determined on the basis of permeability changes in the surface of the test object material. There is a state of dependence between the measuring voltage and the distance of the torque sensor from the test object. As the distance increases, the measuring voltage decreases. The measuring voltage acquires a substantial distance independence by virtue of the exciting winding of the torque sensor forming with a capacitor a resonant oscillatory circuit tuned to the exciting frequency.

Abstract: This disclosure relates to a nondestructive method of measuring stress in a ferromagnetic structural material. One method involves the measurement of the change in ultrasonic velocity induced by an externally applied magnetic field; the method enables nondestructively determining the magnitude, the direction, and the sign (i.e., tensile or compressive) of a stress in a ferromagnetic material. The magnetically induced velocity change of an ultrasonic wave is caused by the magnetoelastic coupling in the ferromagnetic material. This magnetically induced velocity change is characteristically dependent on the magnitude and the sign of the stress and also on the relative orientation of the stress, the magnetic field, and the polarization and propagation direction of the ultrasonic wave. The dependence of magnetically induced velocity changes can be utilized for nondestructive stress measurements. In one version, for measuring bulk stresses, either a longitudinal ultrasonic wave or a shear ultrasonic wave is used.

Abstract: The present invention is directed to a rapid nondestructive method for determining the extent of strain hardening in an article of tungsten-nickel-iron alloy. The method comprises saturating the article with a magnetic field from a permanent magnet, measuring the magnetic flux emanating from the article, comparing the measurements of the magnetic flux emanating from the article with measured magnetic fluxes from similarly shaped standards of the alloy with known amounts of strain hardening to determine the hardness.

Abstract: A magnetic field is generated in the vicinity of a rotatably driven, loaded shaft. A Wiegand device in the shaft is differentially displaced by twisting of the shaft. Changes in magnetization in the regions during rotation of the shaft are detected by a coil. The characteristics of the pulses generated by the coil are representative of the twisting of the shaft and accordingly the torque transmitted thereby. A first signal is derived, which is representative of a characteristic of the generated pulses and a second signal is derived, which is representative of the period of the changes in magnetization. Power is represented by the quotient of the first signal divided by the second signal.

Abstract: A torque sensor device for sensing the torque applied to a drive shaft and for producing an electrical signal representative of the applied torque. The sensor includes a non-magnetic drive shaft having a magnetic layer affixed to its outer surface. The magnetic permeability of the magnetic layer changes due to torque applied to the shaft. The permeability of the magnetic layer is detected and converted to an electrical signal representative of the torque applied to the drive shaft. The magnetic layer takes the form of one or more elongated ribbons of magnetic material helically wound about the surface of the drive shaft. Alternatively, the magnetic layer is formed from a plurality of segments of magnetic material affixed to the periphery of the shaft. Magnetically soft amorphous metal material is preferably used to form the magnetic layer.

Abstract: A method and apparatus for measuring static or dynamic torques on a test piece, in a contact free manner is possible where the test piece is made of magnetically permeable material which permeability changes due to the occurrence of torques on the test piece. These changes are sensed by the apparatus of the invention, according to the method of the invention, utilizing a four pole test probe forming a magnetic bridge.

Abstract: This disclosure is directed to an acoustic Barkhausen stress detector apparatus and a method of obtaining measurements of stress in or determination of the microstructure of ferromagnetic materials. In the preferred and illustrated embodiment, stress or microstructure information in a ferromagnetic specimen is tested and measured through application of a variable magnetic field. A sensitive acoustic detecting device including an input transducer(s) and amplifier(s) forms a signal based on Barkhausen acoustic phenomena which arise from a change in the magnetic field strength. Barkhausen acoustic information is in the form of vibrations produced within the material which occur as magnetic domain walls shift. The domain wall shifts occur at various locations within the material of interest, and the acoustic vibrations are propagated through the material and are observable at the surface by one or more transducers.

Abstract: An assembly for monitoring torsional loading of a drive shaft comprises a magnetic-field generator juxtaposed to a cylindrical body of magnetostrictive material rigidly surrounding the shaft, the body being in the form of a thin foil attached to the shaft via a layer of magnetically insulating material, or a sleeve attached to the shaft by at least two spaced brackets or an outer layer of the shaft specially treated to have a homogeneous magnetic permeability in an unstressed state. A pick-up or magnetic-field sensor is juxtaposed to the body or sheath for detecting differential changes in the magnetic permeability thereof, the pick-up advantageously being connected to a demodulator which extracts a signal whose polarity is determined by the direction of loading of the shaft.

Abstract: An acceleration or deceleration sensor is provided which includes a casing, a core disposed within the casing having an elastic member and a magnetically soft member of an amorphous metal that is integrally bonded to the elastic member, and an electrical coil wound around the core.

Abstract: An apparatus for measuring dynamic magnetostriction subjects a test sample to a spatially uniform, sinusoidal magnetic field of constant peak amplitude. Accelerometers mounted on the test sample produce a first electrical signal representative of the acceleration of the test sample due to the induced magnetic field. The first electrical signal is integrated twice producing a signal representative of the displacement of the test sample due to the induced magnetic field. This signal is representative of the magnetostrictive movement of the test sample.

Abstract: A method and device are described for measuring a change in the mechanical state aiming at detecting the disturbance the change in state has on a magnetic flux (.phi.). This flux is brought to flow through at least a part of the body (1) under the influence of a driving magnetizing force (H.sub.0).In order to achieve an unambiguous measuring result the average length (l) of the magnetic circuit is kept constant and independent of the change in the mechanical state. The flux (.phi.) consists partly of a main flux (.phi..sub.0) having a definite direction and being of such a magnitude that the magnetic properties of the body depart from the region of irreversibility and partly of an alternating, gradually vanishing flux (.phi..sub.v) superimposed upon the main flux. The alternating flux must have such an initial magnitude that saturation is obtained in both directions of the alternating flux (.phi..sub.v). After the vanishing of the alternating flux (.phi..sub.

Abstract: Direct method for measuring the magnetostriction constant .lambda..sub.s of soft magnetic and isotropic magnetic materials. A thin film sample is cantilevered and clamped at one edge. Under the influence of a magnetic AC field and the magnetostriction effect of the sample material, the free end of the cantilevered sample is deflected and oscillates with twice the frequency of the AC field. The resonance amplitude a.sub.res is measured by using a laser beam impinging upon the oscillating sample and measuring the reflected beam amplitude by means of a position-sensitive photodiode. The AC output signal of the photodiode is proportional to the sample amplitude. The magnetostriction constant .lambda..sub.s is directly proportional to the resonance amplitude a.sub.res multiplied by a constant factor which depends on known geometry and properties of the sample material.

Abstract: A residual stress measuring apparatus for sensing a magnetic state of an object to measure a residual stress of the object comprises a magnetic sensor for sensing a magnetic state of the object to provide its state in the form of current and voltage, an AC power source for feeding an AC power to the magnetic sensor, a wattmeter for multiplying the current and the voltage supplied from the magnetic sensor to provide a variation of a core loss, and a calculator for converting the variation of the core loss into a residual stress of the object.

Abstract: A torque transducer for measuring the torque in the outgoing crankshaft of automobile engines comprises two two-pole magnetic cores, arranged perpendicular to each other, with coils around the poles. The coils of one core are adapted to be supplied with alternating current for generation of an alternating field in the surface of the shaft. The second core with its coils is adapted to sense the changes in the alternating field which are caused by the torque of the engine. The poles of the primary core are located opposite to diametrically opposed points on the crankshaft.

Abstract: A system for indicating torque and/or speed of a rotatable shaft includes a transducer positioned adjacent the shaft. The transducer has two primary windings wound in a bifilar arrangement on the same magnetic core structure. The primary windings are connected in a manner to facilitate driving of the transducer primary windings with a simple switching circuit.