Abstract: A pinch detection system and method controls the speed of a motor moving an object by first calculating the actual motor force and then comparing the actual motor force with a reference force value in a reference field. A pinch condition is indicated if the difference between the actual force and the reference force exceeds a selected pinch threshold. The difference is also used to update the reference field, the pinch threshold and the desired speed of the motor so that the reference field will eventually reflect the actual force profile of the object. The updated pinch threshold is also used to control the motor speed so that the pinching force remains constant regardless of the pinch threshold value.

Abstract: The invention proposes a connecting element (5) with an elongated shaft (19), in particular a screw or bolt, for connecting two bodies, wherein at least part of the shaft (19) has a slot (14) and a recess (13). The invention also proposes that a component (10) that generates a magnetic field, and spaced apart from it, a magnetically sensitive element (11) be disposed in the vicinity of the recess (13). The proposed connecting element is particularly suitable for detecting a force or mechanical strain acting on the seat of a motor vehicle.

Abstract: An apparatus and method for measuring the tension in bolts, screws, rivets, and other fasteners, is disclosed wherein the deformation of the fastener head is measured, (or the end of fastener in such cases as there is not a distinct formed head, for example stud bolts). The deformation generally is an analytic function of the tension in the fastener. The deformation is a continuous two-dimensional distribution over the surface of the fastener head, which allows redundant measurement and therefore more reliable measurement of fastener total axial tension, and also allows in some instances an evaluation of the bending stresses in the fastener from the distortion of the deformation pattern on the head. An advantage of the invention is that the length of the fastener or its temperature need not be known. The measurements can be determined by optical, capacitance, optical imaging, air gauging and piezoresistive techniques.

Abstract: A testing for screw connections, comprising a sensor carrier plate with sensors on both sides and being mounted on a base plate, whereby the sensors are sandwiched between a torque introduction plate and a torque sustaining plate, the sensors detecting separately both head and thread friction forces and a preload force.

Abstract: A measuring device (1; 21; 33) for controlling an installation torque of a fastening element (4; 32) and securable to engagement means (3; 35) of the fastening element (4; 32), includes an indicator (5; 24) for a visual display of the installation torque, a plurality of microcapsules filled with a dispersible color die and supported on the indicator (5; 24), and a transparent, at least regionwise, covering (7.1; 7.2; 22) provided on an outer surface of the indicator (5; 24); and an opening (27) through which a fastening element (4; 32) can extend.

Abstract: A screw-and-nut assembly comprising a support secured to the nut, which support is provided with a surface in contact with the thread of the screw, and an electrical sensing member responsive to mechanical interaction with the thread of the screw, the sensing member being placed in the support close to said surface to come into interaction with the thread of the screw in the event of said surface wearing, wherein the support and the nut are constituted by the same block of material, the sensing member thus being placed inside the nut.

Abstract: A tamper-indicating fastener has a cylindrical body with threads extending from one end along a portion of the body, and a tamper indicating having a transducer for converting physical properties of the body into electronic data; electronics for recording the electronic data; and means for communicating the recorded information to a remote location from said fastener. The electronics includes a capacitor that varies as a function of force applied by the fastener, and non-volatile memory for recording instances when the capacitance varies, providing an indication of unauthorized access.

Abstract: A mechanical-force sensor includes two piezoelectric vibrators which are arranged such that stresses in mutually opposite directions are applied thereto by a mechanical force such as an acceleration. A current-voltage converter and signal-summing circuit converts current signals that flow through the two piezoelectric vibrators into voltage signals. A voltage-amplifier and amplitude limiter circuit amplifies a sum signal of the two voltage signals, and provides a positive feedback of a voltage signal that is in phase with the current signals, thereby causing an oscillating operation. A phase difference-voltage converter circuit generates a voltage signal that is proportional to the phase difference between the voltage signals yielded by the conversion. An amplifier and filter circuit DC-amplifies the voltage signal and removes unwanted frequency components therefrom.

Abstract: A precision clamp accurately measures force over a wide range of conditions. Using a full bridge or other strain gage configuration, the elastic deformation of the clamp is measured or detected by the strain gages. The strain gages transmit a signal that corresponds to the degree of stress upon the clamp. The strain gage signal is converted to a numeric display. Calibration is achieved by zero and span potentiometers which enable accurate measurements by the force-measuring clamp.

Abstract: A screwer test bench includes a coupling designed for coupling with the head of a screwer. The coupling is connected to a braking unit through a sensor unit for detection of mechanical magnitudes transmitted between the coupling and the braking unit. The braking unit includes a cap connected to the coupling and a movable member thrust on command in the brake operation direction. The movable member is constrained against rotation around the brake axis by an inextensible wall with a configuration deformable in the braking direction. Advantageously the wall is in the form of a bellows into which is fed pressurized fluid to bring about its elongation and operate the brake.

Abstract: A load indicating member is provided with a permanent identifying mark which can be read and used to determine ultrasonic measurement parameters specific to the load indicating member to provide more precise and more reliable load measurements by compensating for differences resulting from manufacturing variations in individual load indicating members. The parameters specific to the load indicating member can be stored in coding applied to the load indicating member or in a database that can be accessed remotely, for example, using the Internet.

Abstract: A screwer test bench including a coupling designed for coupling with the head of a screwer and a controlled braking unit. A sensor unit detects mechanical magnitudes transmitted between the coupling and the braking unit. The braking unit includes a brake with carbon friction surfaces in an oil bath.

Abstract: A threaded bolt having a proximal head end and a distal insertion end, the proximal head end and the distal insertion end are each provided with a single, exposed radial measurement plane, the radial measurement plane at the distal insertion end is formed by a flat bottom of a recess at the distal insertion end, the recess is bounded by a circumferential wall which at a point of change transitions into the flank of the distal end via a buckle, and wherein the radial measurement planes are for use in ultrasonic length measurement for determining the tension in the threaded bolt after it has been used in a connection.

Abstract: A device used for measuring the angle of torque beyond a specific reference point. The device is comprised of a tool that applies torque to a fastener, an adapter that is attached to the fastener to transfer the torque from the tool, and an apparatus that connects a first end to the tool and a second end to the adapter. The apparatus comprises an angle selector that is adjustable to the desired torque angle, an angle rate sensor that measures the speed and direction of the torque applied, a processor which calculates the current angle from the rate sensor measurements, a zero point indicator that serves as the basis point for the processor to calculate the selected angle, and an angle indicator that alerts as to the torque angle calculated by the processor.

Abstract: A high-speed rotation testing apparatus includes a spindle 11 holding a test object S at its lower end, a driving motor 20 for applying torque to the spindle 11, and a frame 30 for supporting a rotor shaft 21 of the driving motor 20 so that the shaft is arranged toward the vertical direction of the apparatus, wherein the spindle 11 is driven directly by a driving motor 20 by inserting the spindle 11 into a through-hole 21a that penetrates the center of the rotor shaft 21 and coupling the upper ends of the rotor shaft 21 and the spindle 11 together, and the through-hole 21a has an inner diameter set so as to form a clearance in which the lower end of the spindle can swing, and further, a damping mechanism 40 that restrains swing is arranged in the vicinity of the lower end of the spindle 11, which projects from the lower end of the rotor shaft 21.

Abstract: The test device for determining the friction and prestress values of screwed connections consists of a transportable device having a central support plate (1), whereby shearing force sensors and axial force sensors (7, 8, 11) are arranged on both sides of said plate. The sensors are screwed between an application plate (2) and a torque receptor plate (3) and can be replaced or provided with adapters (4, 5). The sensors (7, 8, 11) can be extension sensors or piezoelectric sensors. The amplifiers of the piezoelectric sensors can be miniaturized in such a way that they can also be placed in the central support plate (1). During tightening, the following values are determined: total torque Mtot, head friction torque MK, thread friction torque MG, prestress force Fz, to obtain the following values: thread friction value &mgr;G and head friction value &mgr;K.

Abstract: For indicating relative rotational displacement between a fixed first member, such as a stud (20) on a wheel hub, and a second member, such as a wheel nut (22), which is rotatably engaged with the first member, a safety device (24) comprises a body (26) having a bore formed with equispaced grooves enabling the device to be releasably secured to the second member (22) in one position of a plurality of positions and having indicating means, such as a pointer (28), to indicate the position of the device (24) relative to a reference, such as a mark (32) on the rim (16) covering the wheel hub (14). The bore within the body (26) is closed at one end, e.g. by bevelled top wall (36), so that the body additionally serves as a dust cap for the conjoined first and second members (20, 22).

Abstract: In the present method for monitoring and controlling a screwing process in creating a screw connection, ultrasonic pulses are coupled into the screw using a pulse-echo method before and during the tightening of the screw. The time for the pulses to traverse the length of the screw, i.e., the propagation time, is measured. A dependency of the propagation time on the predetermined tension of the screw is calculated from the material specific characteristic values of the screw and the measured propagation time. By comparing the values of a change in propagation time dependent on a parameter of the screw with the values of a change in propagation time dependent on the predetermined tension of the screw, the screwing process can be monitored.

Abstract: A taut wire sensor includes an actuator that is movably coupled to a housing. The actuator includes a taut wire terminal. The actuator has two contacts that are maintained in a spaced apart orientation by the mating of parts, which are held in place by a spring element. The actuator deforms when force is applied to the taut wire terminal of the sensor. When the actuator deform, an electrical connection is made between the two contacts to produce an alarm indication by the sensor. The orientation of the actuator is maintained by the mating of parts which are also held by a spring element. One of the contacts in the actuator is a flexible contact pin that is adapted to bend when high force is applied to the taut wire terminal. The sensor housing also includes a movement limiter that overcomes a weakness in prior sensors which employ compensating flowable materials to adjust sensor position.

Abstract: An instrument is connected to a driving-in tool or drilling tool for elements on or in the form of an implant or drill for dentine. The tool includes an electric motor, the torque of which can be sensed, and which can be controlled by a control unit. A display unit is arranged so as to partly or fully display a curve representing the driving-in function performed. A tightening function is determined by a scale based on the slope of the curve, wherein a flatter slope represents a lower quality function and a steeper slope represents a higher quality function. A frictional resistance which exists for an element during the driving-in of the element can be determined in order to allow secure locking (preload) of the element by tension in the material of the element. A torque-time curve can be used assess the bone quality of bone being implanted or drilled.

Abstract: An inventive method of manufacturing precisely-compressed multi-layer stacks is presented. Two stacks are assembled. One stack, having a compression sensor between two layers, is then compressed with an initial compression force, and the signal from the sensor is measured. The other stack is then compressed with a force derived from the measurement.

Abstract: A variably amplified load indicating fastener includes fastener (100) detachably secured to a load indicator via a base member. The fastener (100) has an abutment which is moved by a change in length under an applied load. The load indicator includes a dial plate (16), a needle (24) pivotally supported by the plate (16), a compensating slot (36), a driving slot an elongated U-shaped element (50) disposed in the direction in which the load is applied when the fastener (100) is in use, and a first reference mark (40a). One side of the U is rigidly attached to the fastener. The closed end of the U is proximate to and movable by the abutment. The other side of the U extends through the compensating slot (36) and the driving slot (26). The needle (24) is operatively coupled to the outer end of said second side. A sleeve with a second reference mark fits over the outer circumference of both the load indicator and the base member.

Abstract: A tension indicator for use with a fastener that is formed from a stack of conical washers confined in the stack by a cage having a longitudinally extending slot formed therein provides readily discernible visual indication of tension or loss of tension in the fastener joint. The indicator includes a body configured for receipt over the stack of conical washers. The body can include at least one stanchion extending inwardly of the body from the interior surface to define a stanchion end longitudinally spaced from the body end. At least one detent extends inwardly of the body and is longitudinally spaced from the body end. When the stack of conical washers is placed under tension with the uppermost washer in a planar condition, the stanchion lies adjacent the uppermost washer at the interior region.

Abstract: A highly accurate method of tensioning threaded fasteners into assembled units is presented. A mechanical process for locating the initial point that a threaded male fastening unit enters into the female fastening unit provides a definite reference point from which angular movement of the fastener can be digitally measured with the greatest accuracy. Accurate measurement of angular rotation of a threaded unit into a receiving unit provides a direct relationship to allow an accurate measurement of the tension applied to the fastener inside the recess. Multiple fasteners can be randomly indexed to start at the zero point and be driven into the receiving unit with equal tension in each fastener in timed increments of rotation during the entire process of driving the fasteners into the fastened unit. A digital printout of the process certifies the reference numbers of all components assembled and timed movement activity of each of the assembled components.

Abstract: A highly accurate method of tensioning threaded fasteners into assembled units is presented. A mechanical process for locating the initial point that a threaded male fastening unit enters into the female fastening unit provides a definite reference point from which angular movement of the fastener can be digitally measured with the greatest accuracy. Accurate measurement of angular rotation of a threaded unit into a receiving unit provides a direct relationship to allow an accurate measurement of the tension applied to the fastener inside the recess. Multiple fasteners can be randomly indexed to start at the zero point and be driven into the receiving unit with equal tension in each fastener in timed increments of rotation during the entire process of driving the fasteners into the fastened unit. A digital printout of the process certifies the reference numbers of all components assembled and timed movement activity of each of the assembled components.

Abstract: A tightening tool that includes a microprocessor for management and measurement of tightening parameters and a transponder for communication with a monitoring station. The monitoring station is equipped with at least one decoder for communication with the transponder. The tool microprocessor unit receives control parameters from the station through the transponder and sends tool data to the station through the transponder.

Abstract: A tamper-indicating fastener has a cylindrical body with threads extending from one end along a portion of the body, and a tamper indicating having a transducer for converting physical properties of the body into electronic data; electronics for recording the electronic data; and means for communicating the recorded information to a remote location from said fastener. The electronics includes a capacitor that varies as a function of force applied by the fastener, and non-volatile memory for recording instances when the capacitance varies, providing an indication of unauthorized access.

Abstract: A method and apparatus are provided for determining the preload in a dental implant system. The preload is determined by transmitting a sonic impulse, which is preferably an ultrasonic impulse, at a predetermined frequency to the head of the implant screw through a transducer, which may be incorporated into the head of the screw, the head of a wand which generates the sonic impulse, or the transducer and pulse-generating instrumentation may be incorporated into a torque generating instrument used to tighten the screw. The preload is determined by measuring the delay between the first and second reflections through the preloaded screw to determine a preload value and comparing that value with a pre-established baseline value for the screw, and comparing the difference with a predetermined table of values to determine the preload on the screw.

Abstract: A method and a device for checking a screwed connection and to special screws to implement the method. The method is based on the utilization of a special screw with a one-piece cored hole pressing together two components with a prestress force. The method includes determining the original length of the special screw by measuring the length of the cored hole; determining the length of the special screw when stressed by measuring the distance from the head of the screw to the bottom of the bore and comparing the measuring values of the lengths with predetermined data. According to predetermined criteria, it is determined whether sufficient prestress force has been applied or whether it is necessary to further tighten the screw. The device for checking the prestress force includes the special screw and a length measuring device determining the distance from the base surface of the cored hole to the screw head and the distance between the front face of the core of the cored hole to the screw head.

Abstract: The present invention relates to a method for monitoring and, if need be, controlling a screwing process in the creation of a screw connection using a screw, in which ultrasonic pulses are repeatedly coupled into the screw starting from the head of the screw using a pulse-echo method before and during the tightening process and the time it takes the ultrasonic pulses to traverse the length of the screw (propagation time) is measured. Before starting the tightening process, a dependency of the propagation time of the ultrasonic pulse on the predetermined tension of the screw is calculated from the material-specific characteristic values of the screw utilizing the measured propagation time through the load-free screw. Comparison of a change in propagation time dependent on a screw parameter with a calculated change in propagation time dependent on the predetermined tension of the screw permits drawing conclusions about the control of the screwing process.

Abstract: In order to measure in situ the residual tension F1 of a pre-stressed bar braced between two anchorages, the two-way propagation time T1 of an ultra-sonic wave between the two ends of the bar is measured, and F1 is evaluated by the formula F1=F0+kb.(T1−T0). During a preliminary calibration carried out without demounting, the bar is subjected to a variable traction effort F.

Abstract: A method for determining the axial load in a threaded fastener when tightened above its yield point by using the variation in travel time (&Dgr;t) for ultrasonic waves induced in the fastener to determine the axial load (N) in the fastener, both in the yield point and at the final pretension state of the fastener. The yield point of the fastener is detected by indicating a significant change in the growth of the momentary transferred torque per angle unit of rotation, and comparing the actual travel time (&Dgr;t) for ultrasonic waves in the fastener to a pre-tightening determined relationship between the axial load (N), the rotation angle (&PHgr;) and the ultrasonic wave travel time (&Dgr;t) for the actual type of fastener.

Abstract: A washer having a plurality of strain gauges, at least one of which is positioned on a portion of the washer subjected to axial force and at least one of which is positioned on a portion of the washer not subjected to axial force. In a preferred embodiment, each such washer portion has two strain gauges and the total of four strain gauges are connected into a common bridge circuit. In the preferred embodiment the portion of the washer not subjected to axial force is a wedge partially cut into the washer structure and shortened axially to form a gap between the wedge and a surface abutting the washer. In this manner, axial force applied to the washer is not applied to the wedge. The resulting strain gauge configuration provides an electrical signal indication of axial stress that is high resolution and temperature insensitive.

Abstract: The present invention provides several embodiments of tension-indicating fasteners that include tension indicators having indicating arms equipped with a laterally-extending contact member or a foot portion. A contact member extends in a tangential direction from the fastener head. The indicating arm is secured to the fastener and, by having laterally-distant contact points, the deflection of a substrate caused by the fastener head causes a distal end of the indicating arm to move with amplified magnitude. In still other embodiments of the invention, a fastener includes tension indicia for indicating a target degree of substrate deflection. The tension indicator may be disposed within a recess in the fastener head to allow the use of conventional tightening tools.

Abstract: The apparatus for tightening or installing a screw connection includes a screwdriver device (20) having a drive motor (20a) and a screwdriver spindle (20b); a control device (30) for controlling a torque, rotation speed, rotation angle, rotation direction, advance and/or tightening time of the screwdriver spindle (20b) and an operating device (40) including an input and/or output device (40a) for selecting a predetermined tightening or screwing process program which is assembled in a modular manner from individual tightening or screwing process program steps and which is used by the control device (30) to control the screwdriver device. The input and/or output device (40a) includes a device for providing an input display (40b) having a multi-dimensional, advantageously two-dimensional, field (40c) with a plurality of predetermined distinct field locations (40d) and a device for associating the respective field locations with predetermined tightening or screwing process program steps.

Abstract: A fastener system employs a portable, sensing device, such as one or more reactance capacitors or an image processor such as a camera or a laser, which removably attaches adjacent to the fastener to detect and measure the change in a gap or specialized form of the bolt head or associated washer caused by the relative movement of portions of the fastener system when the fastener is under strain without contacting the sensed portions undergoing the significant relative movement. Associated electronic components process and indicate the clamp load of the fastener system.

Abstract: A system by which the torque applied to a fastener such as a bolt or nut may be measured simply and accurately. More particularly, the invention relates to apparatus and methods by which the torque applied to a fastener by a socket wrench can be measured through a simplified extension element accurately and displayed quickly so that the placement of possibly damaging excessive amounts of pressure on the fastener can be avoided.

Abstract: Both end surfaces of a head portion and an axial portion of a bolt are formed into a curved surface having a predetermined curvature in order to provide a bolt which allows accurate axial tension measurement without changing various settings of an axial tension detection device. Upon ultrasonic radiation applied from a piezoelectric element into a top surface of a head portion of the bolt, the top surface thereof serves as an ultrasonic lens to allow ultrasonic propagation in convergence within the bolt. If the bottom end surface of the axial portion of the bolt is formed into a curved surface, the bottom end surface thereof will also serve as the ultrasonic lens to allow propagation of the reflection to return to the piezoelectric element in convergence. The ultrasonic propagation path within the bolt is not diffused, which allows the ultrasonic radiation to be reflected from the bottom surface of the axial portion of the bolt so as to be detected by the piezoelectric element.

Abstract: A power screwdriver has a drive unit and an input circuit for inputting screw size, material quality, pitch, and clamping length of a screw. An evaluation circuit is provided for determining a nominal prestress force based on input screw size, material quality, and clamping length, for determining a nominal torque based on the nominal prestress force and the pitch, and for determining the screw clamping angle resulting from the nominal prestress force and the pitch. A sensing device for sensing the actual torque is provided, and a further sensing device for sensing the actual screw clamping angle is present. A control and switch-off device controls further rotation of the drive unit when the actual torque coincides with the nominal torque and switches off the drive unit when the actual screw clamping angle coincides with the nominal screw clamping angle.

Abstract: A method for determining the axial load on an elongate member by measuring the differences in time of flight for transversely and longitudinally ultrasonic waves introduced in the elongate member under a zero load condition and at a current temperature and the time of flight for both of these types of waves introduced into the elongate member under the actual load condition, and calculating from these differences in the time of flight the actual load on the elongate member taking into account the influence of any occurring difference in temperature of the elongate member between the zero load condition time of flight measurement and the actual load condition time of flight measurement.

Abstract: A safety device used in preloading of bolts for providing the bolts with an internal stress in a mounted condition, wherein a first end of the bolt is secured to a first element and extends through a second element, which clamps to the first element, and where a hydraulic preloading device is temporarily applied to a second end of the bolt for axially stretching the bolt to create the external stress. The safety device incorporates a safety tensile bar detachably fitted to the first end of the bolt, and extending through a central bore in the bolt, and further through the hydraulic preloading device while being held adjacent its opposite end in an expanding plug. The expanding plug is provided in a frictional contact with a sleeve, which guides the plug to create a counter hold for absorbing relieved energy in case of the breaking of the bolt during the preloading operation.

Abstract: A load-indicating device including a load-bearing member adapted to deform when stressed. Ultrasonic waves are directed into one end of the load-bearing member and ultrasonic echoes are received at the same end by ultrasonic wave transmitting and receiving equipment. In one embodiment, ultrasonic waves are transmitted and received using an ultrasonic transducer disposed on either the head or the opposite end of the load-bearing member. The head, the end, the shank or a combination thereof are contoured to reduce the influence of geometric variations and asymmetrical stress in the load-bearing member on the ultrasonic measurement. A method is also provided, which encompasses a model, by which preferred geometries of the contoured surfaces of the load-bearing member can be designed.

Abstract: The invention pertains to the arrangement of a sensor housing (5) on a wall (2) on which the sensor housing (5) is held by means of a threaded nipple (4) in a tapped hole (3). In order to protect the sensor housing against disturbing environmental factors, especially dirt, moisture and wind without impairing the accessibility of torque transmitting features adjacent to the threaded nipple (4), an attachment (12) arranged on the wall (2) centrally around the sensor housing (5) is provided on whose cylindrical surface (13) facing toward the inner side the edge (15) of a soft elastic washer (14) engages. The washer also is sealably connected to the sensor housing (5). The washer (14) and the attachment (12) form a chamber (16) encapsulating the sensor housing (5). When a tool is positioned on the torque transmitting features the washer (14) yields elastically. Additional encapsulation is unnecessary to protect the sensor housing (5). The mounting activity is not impaired by the protection provided.

Abstract: A method of measuring in a material a time-of flight of a signal having a first signal burst and a second signal burst, the first signal burst having a first set of cycles and the second signal burst having a second set of cycles. The method includes identifying a cycle in the second signal burst corresponding to a cycle in the first signal burst, to measure the time-of-flight of the signal.

Abstract: An ultrasonic bolt gage is described which uses a cross-correlation algorithm to determine a tension applied to a fastener, such as a bolt. The cross-correlation analysis is preferably performed using a processor operating on a series of captured ultrasonic echo waveforms. The ultrasonic bolt gage is further described as using the captured ultrasonic echo waveforms to perform additional modes of analysis, such as feature recognition. Multiple tension data outputs, therefore, can be obtained from a single data acquisition for increased measurement reliability. In addition, one embodiment of the gage has been described as multi-channel, having a multiplexer for performing a tension analysis on one of a plurality of bolts.

Abstract: A NASTRAN-programmed computer calculates force and moment data for a structure including joints of interest. The NASTRAN data is read by a computer programmed with the invented program. For each joint, the user selects the members which contribute forces to the joint, and also selects the nearest grid point. A computer programmed with the invented program calculates the resultant force and moment at the proximate grid point. The force and moment are originally defined in a global coordinate system, subsequently transformed into a local coordinate system, and then translated to the centroid of the joint's fastener pattern. Axial and shear forces for each fastener are calculated for the nominal case wherein all of the fasteners are operative. Furthermore, each fastener, in turn, is assumed not to transmit axial force and the resulting fail-safe axial forces respectively acting on the remaining operative fasteners are calculated.

Abstract: An annularly configured device for use on each earthquake restrainer cable of a bridge, which device, will deform due to its internal configuration upon the occurrence of an earthquake, if the earthquake stresses the bridge cable with which the device is associated excessively. The result of the stress is a visual indication of the cable's elongation as manifested by a "crowning" of the annular indicator and a shortening of its length. The specific configuration required of the annular member is one of a reduced thickness section of the interior wall, with tapered edges leading to the main cross section of the annular member.

Abstract: A force sensor including a cylindrical body having a central section and two distal sections wherein selected acoustic resonant modes are trapped in the central section and decays exponentially in the distal sections. An electromechanical acoustic transducer (EMAT) can be used to excite and detect the selected resonant modes in the central section. Force applied to the distal sections, including axial stress and torque, alter the resonant frequencies of the selected modes.

Abstract: A sealing fastener includes a unique identifier device for the individual fastener that enables ultrasonic identification of the device using an ultrasonic fault measuring system, and a frangible element within the fastener integrated with the identifier device that provides an ultrasonic signature indicating an attempt to loosen or remove the fastener when subjected to an ultrasonic signal generated by an ultrasonic fault measuring system. The unique identifier device includes a stack of individual metallic washer elements brazed together, with each washer element including discontinuities or cavities that are randomly arranged with respect to the cavities of the other washers in the stack. The fastener includes relatively movable portions that cause fracture of the frangible element upon any attempt to loosen or remove a fastener after it has been tightened or secured at its sealing location.

Abstract: A U-bolt testing apparatus includes a pair of motors coupled to and selectively driving a pair of spindles. The spindles include sockets which are selectively movable vertically and horizontally as may be desired and which are placed over the U-bolt nuts. A U-bolt to be tested is placed on the chassis table with the component parts that are to be retained or clamped within the U-bolt and the U-bolt characteristics are tested by advancing the nuts onto the U-bolt threaded ends. In the alternative, a holding fixture is provided for securely retaining the U-bolt during testing. U-bolts having various different shapes and length of legs can be accommodated and tested by the apparatus. A computer controls the torque of the motors and nuts being advanced on the U-bolt threaded ends and monitors strain gauges which are attached to the U-bolt legs. The test data and characteristics of the tested U-bolts are viewable on an output module connected to the computer.