Abstract: A system for measuring stress including a coilless sensor including at least one band of electrically conductive and magnetostrictive material, the band having a first end and a second end defining a gap therebetween, a measuring circuit electrically connected to the first and second ends of the coilless sensor, the measuring circuit being configured to pass a current through the coilless sensor and measure at least one of an inductance, a resistance and an impedance of the coilless sensor in response to the current, and a processor in electrical communication with the measuring circuit, the processor being configured to calculate an amount of stress being applied to the coilless sensor based upon the measured inductance, resistance and impedance.

Abstract: A force measuring apparatus comprises has a force-transmitting component, that holds a strain measuring element with a carrier element and a displacement transducer. The carrier element has two fixing sections at a predefined distance from each other in a direction of the strain with which it is fixed to the component. Furthermore, the carrier element has a strain section, which is provided between the fixing sections and which has a shorter length in the direction of the strain than the distance between the fixing sections, and which has a smaller cross section than the remaining carrier element. The displacement transducer is connected to the strain section in order to register the strain of the strain section.

Abstract: A system that uses capsules or micro-capsules containing a dye or indicator embedded in a polymer matrix to indicate or measure the degradation of structural materials. The capsules can contain an agent that will be transparent or not detected when the capsule is intact. When the capsule is ruptured, the agent will be either visible to the human eye or measurable by other detection methods. The indicator can either activate upon release or be already activated but not readily visible or detectable in the capsule. An activator compound also can be distributed in the bulk material matrix that activates the indicator upon release. For totally opaque materials like concrete or metal, a surface coating or applied tape containing the capsules can be used.

Abstract: The invention relates to an apparatus for the determination of loadings on fiber composite components (1), especially of vehicle and aircraft parts, whereby the components (1) are provided with a prescribed number of sensor elements (3), for the determination of strains. The sensor elements (3) are connected with an evaluating apparatus (4), which is especially embodied for the monitoring and also for the determination of loadings that tend to cause damage. The apparatus is characterized in that the sensor elements are embodied as strain gages (3). In that regard, the strain gages (3) are preferably integrated into the fiber composite component (1) in such a manner so that the measuring grids (5) thereof are laid between the individual fiber layers (2) and are guided out of the fiber composite component (1) ready for connection via special connecting pins (8).

Abstract: A device for monitoring the integrity of a flexible pipe used for transporting a pressurized fluid in a terminal end-fitting. The pipe includes an internal pressure sheath, plies of tensile armor wires and an outer sheath fastened to the end-fitting. A device monitors the change in a phenomenon associated with a failure of the armor plies as a result of a fracture of several tensile armor wires inside the end-fitting. The device detects an increase in the twist in the pipe near the end-fitting, which twist is a phenomenon of a fracture of tensile armor wires inside the end-fitting.

Abstract: A force sensor assembly includes a force sensor, a first support member, a threaded portion, an opening made in the first support member, a nut, a restricting member and a spacer. The nut is screwed onto the threaded portion which is inserted through the opening. The restricting member is provided between the force sensor and the nut. The spacer, which is provided between the force sensor and the nut, is deformable in a direction of its thickness. The shape of the spacer is adapted to avoid interference with the restricting member. Before the nut is tightened onto the threaded portion, a summation of thickness for the first support member and the spacer is adapted to be not less than a height of the restricting member. The nut is tightened up with a predetermined fastening torque until the spacer deforms so that the nut strikes the restricting member.

Abstract: A pressure converter insusceptible to the error of hydraulic pressure introducing position or the interference of installation depth of water and producing a signal corresponding to the effective soil pressure accurately while realizing cost reduction. Since filters are provided in an air gap defined by two rigid plates receiving the soil pressure, a hydraulic pressure is applied but sand pressure is not applied. A load gauge insensitive to the hydraulic pressure detects only the effective soil pressure. Since a signal cable can be passed through the air gap, a plurality of pressure converters can be coupled efficiently and since the signal cable can be inserted internally, a pressure distributed in the depth direction can also be measured accurately.

Abstract: A system for measuring the weight of a seat occupant is used to control airbag deployment. The system is incorporated into a vehicle seat supported on inboard and outboard track assemblies. The inboard and outboard track assemblies are mounted to a vehicle structure such that a center track portion remains unsupported. A first sensor assembly is mounted to the inboard track assembly and a second sensor assembly is mounted to the outboard track assembly. The first sensor assembly generates a first signal in response to measuring deflection of the inboard track assembly due to seat occupant weight. The second sensor assembly generates a second signal in response to measuring deflection of the outboard track assembly due to seat occupant weight. A central processor determines seat occupant weight based on the first and second signals. The central processor communicates with the airbag system to control the deployment of the airbag based on seat occupant weight.

Abstract: A frame-based occupant weight estimation apparatus for a vehicle seat includes a compliant linkage assembly that translates vertically applied seat loads to a horizontal plane, where the horizontal forces are measured by a set of force sensors. A compliant member, which may be a spring or a linkage arm, preloads the force sensors to enable off-loading detection, and an overload device securely anchors the seat to the vehicle floor without interfering with normal load measurement.

Abstract: A system comprising a reticle, a pellicle and a plurality of sensors attached to at least one of the reticle or pellicle. The sensors are configured to sense in-situ strains on the pellicle as the pellicle is mounted to the reticle or frame.

Abstract: A force transducer for sensing the weight introduced into the mounting of a motor vehicle seat is disclosed. The force transducer includes a force introduction element that is connected to the motor vehicle seat, a force transfer element that is connected to the mounting, and an extension member that is arranged between the force introduction element and the force transfer element. The force transducer makes it possible to accurately determine the weight introduced into the mounting of the motor vehicle seat independently of other influencing forces by the fact that the force introduction element or the force transfer element surrounds the extension member in a plane that extends parallel to the effective direction of the weight, and that at least one wire strain gauge for sensing a shearing force parallel to the weight is arranged on the extension member.

Abstract: A sensor device (11) for a vehicle seat, in particular a motor vehicle seat, has at least one sensor (15) for the detection of forces inside the vehicle seat. The vehicle seat has at least one bearing area between two components that are mobile relative to one another, and the sensor device (11) is installed in the bearing area.

Abstract: A vehicle seat assembly 12 is mounted to a vehicle base member 24 such as a riser or a vehicle floor. Weight sensor assemblies 32 for measuring weight on the vehicle seat are mounted to a seat structural component. The weight sensor assemblies 32 each include plate 44 having a bendable center body portion 46 for supporting a strain gage 48. The strain gage 48 measures bending in the center body portion 46 caused by normal weight force applications on the vehicle seat 12. A secondary resilient beam member 34 is mounted between each weight sensor 32 and the vehicle base member 24. The beam member 34 and the weight sensors 32 deflect to prevent failure of the weight sensors 32 in response to an overload force applied in an opposite direction to the direction of a normal weight force application. The beam member 34 prevents permanent deformation of the plate 44 and strain gage failure by allowing the weight sensor 32 to deflect upwardly away from the vehicle floor.

Abstract: Sensor assembly for measuring a load on a bearing having at least one bearing ring (11), the at least one bearing being provided with a cavity (12) for holding the sensor assembly. The sensor assembly comprises a series mounting between opposing sides (17, 18) of the cavity (12), the series mounting comprising a piezoelectric plate (16) and a spring (13) with spring stiffness. Alternatively, the sensor assembly further comprises a body (14) with mass in mounted between the piezoelectric plate (16 ) and the spring (13), to allow simultaneous load measurement and health monitoring.

Abstract: An apparatus for measuring a contact pressure exerted by a winding compression element on a winding in a power device such as a power transformer includes a sensor having a sensor element which reacts to pressure or strain. The sensor is disposed in the winding compression element. The sensor is configured to communicate, via a radio link, with an electronic checking device.

Abstract: A microstrain sensor is provided for measuring deformation, and indirectly, other parameters such as acceleration, temperature, pressure, and force. Rather than providing several discreet resistance paths, the microstrain sensor utilizes input and output conductors connected to a single piece of film through which current travels to indicate resistance. The film provides superior resistance to external effects, such as temperature gradients, that decrease the accuracy of the sensor's readings. Such sensors may be easily adapted for use in situations in which opposing stresses are present, such as dually constrained members, by disposing separate or unitary film sections on opposite sides of a zero stress point, such as a central plane of a fixed-guided beam. Such sensors may be utilized in many different applications, including automotive safety systems.

Abstract: A composite material has a laminated structure of fiber-reinforced resin layers and films of a shape-memory alloy. A predetermined strain has been applied to each film. A damage sensor has a film of an alloy of nickel and titanium. An electric circuit is bonded to the film, and strain gages are connected to the electric circuit. The damage sensor can be laminated to the resin layers in place of the film of the shape-memory alloy. Damage to the composite material is suppressed as follows: A current is applied to the films of the shape-memory alloy, to monitor change in electric resistance of the films. The damage is located in response to the change in electric resistance. Another current is applied to a film of the shape-memory alloy for which the change is larger than the other films to generate heat for deforming the film to generate shrinking stress or shear stress to the damage.

Abstract: An electronic foot pedal vehicle control system includes a foot pedal of rigid one-piece molded plastic construction having a base and a pedal arm cantilevered from the base. An electronic subassembly is insert molded into the base of the foot pedal, and includes a force sensor disposed in the base adjacent to the pedal arm for providing an electrical sensor signal as a function of force applied to the pedal arm by a vehicle operator. Electronic circuitry is responsive to the sensor signal for providing a pedal output signal to control at least one variable of vehicle operation. The electronic circuitry preferably has programmed hysteresis characteristics so as to allow limited force variation on the pedal without changing the output signal from the electronic circuitry.

Abstract: A method and sensor for detecting strain using shape memory alloys is disclosed. The sensor comprises a substrate material, a flexible diaphragm provided on the substrate material and a thin film SMA material deposited on the flexible diaphragm. The thin film SMA material is capable of undergoing a phase transformation in response to a physical stimulus being applied thereto. During such a phase transformation, a change occurs in the electrical resistance of the thin film SMA material. By measuring the value of the electrical resistance of the thin film SMA material immediately before and after the thin film SMA material undergoes a phase transformation, the difference in the value of the electrical resistance can be determined and utilized to determine the magnitude of the physical stimulus that was applied to the thin film SMA material causing it to undergo a phase transformation.

Abstract: A method of sensing strain in a material includes the steps of embedding in a material at least one wire formed of a conductive core and a magnetoelastic film coated around the conductive core and having a known level of saturation, interconnecting an input lead to one end portion of the wire and an output lead to another end portion of the wire, inputting an electrical current in the wire through the input lead so as to drive the magnetoelastic film of the wire to saturation such that the electrical impedance is sensitive to changes in strain in the material, and outputting an electrical signal from the output lead being proportional to a strain imposed on the material surrounding the wire.

Abstract: A device for detecting a side impact of a vehicle an acceleration sensor provided in components of the vehicle and controlling a release of a side bag for protecting vehicle occupants, and a sensor for sensing a beginning of a plastic deformation of components provided on the components of the vehicle and reducing a release threshold for activation of the side bag.

Abstract: A sensor device (15) for a prosthesis, in particular for a leg prosthesis, is provided for measuring forces acting on the prosthesis, having a ring-shaped outer member (16) of closed construction and an inner member (21, 22) connecting two opposite inner sides (17a, 17b) of the outer member having a sensor element (31) for measuring the force acting in the direction of the connecting axis. The outer member deforms under the action of a bending moment while the inner member (21) feels only the axial force acting in the direction of its connecting axis. By this means measurement of the axial force unaffected by bending moments is possible. Furthermore, the sensor device is able to transmit loads.

Abstract: A sensor device for registering strain of a component, which comprises a sensor chip and a supporting substrate, which are connected to each other by a connecting layer such that they form a prefabricated sensor module. The sensor module is attached to the component by a durable creep-free connection such that the strain of the component is transferred to the sensor chip.

Abstract: A sensor package includes a force sensing element and a housing. The force sensing element has an element surface, a well, and first and second shelves within the well. The housing has a housing surface. The first and second shelves of the housing are arranged to support the force sensing element so that the element surface and the housing surface are substantially coplanar and so that the element surface of the force sensing element directly senses a force without need of an actuator.

Abstract: The present invention relates to a piezo-electric stretching detector which is used for measuring the positive and negative stretching on the surfaces of rigid structures using electric signals, wherein said detector can be attached by a force connection onto said surfaces in a compressible or non-removable relation. This stretching detector has a high sensitivity in all stretching directions and is made of a piezo-ceramic material which is applied in a thin layer on at least one surface of a flexible metal sheet or which is fixedly attached to said metal sheet in the shape of a moulded body. At least one of said stretching detectors can be arranged on the free abutting end of at least one resilient pressure body which is imbedded in the reception housing of a stretching sensor. The stretching sensor further comprises members for pressing the reception housing onto the surface to be measured.

Abstract: A sensor array for nondestructively monitoring a structure to detect a critical event. The sensor array includes a plurality of discrete sensor nodes, each of the discrete sensor nodes producing an electrical signal in response to a structural event. In the preferred embodiment, the sensor nodes include a plurality of piezoceramic fibers arranged in a planar array in which the fibers are aligned substantially parallel to each other, each of the fibers having a plurality of polarized regions that are substantially oriented according to their polarity in either a series, parallel, or combined arrangement of series and parallel orientations, and an electrical interface connecting the plurality of polarized regions of each fiber in series with one another. A signal adder receives and combines the electrical signals from each of the discrete sensor nodes to form a single sensor array output signal.

Abstract: A sheet-shaped carbon fiber base material is made up from reinforcing carbon fiber and metal wire integrally formed into a carbon fiber base material which may be a a woven fabric, a tow sheet and a prepreg. The volume fraction of metal in the sheet-shaped reinforcing carbon fiber base material is no more than 4% of the carbon fiber. A laminate may also be formed from the sheet-shaped carbon fiber material, where the reinforcing carbon fiber and the metal wire are laid-up in such a way that the metal wire insertion positions are mutually different. Also disclosed is a method of detecting the number of plies in a laminate that includes non-destructively sensing with a detector the presence of metal wire in a laminate of plies of a sheet-shaped carbon fiber base material made up of reinforcing carbon fiber and metal wire integrally formed to make the sheet-shaped carbon fiber laminate material and determining the number of the plies in the laminate based on the metal wires detected.

Abstract: An existing vehicle seat design is equipped with strain gauges welded to structural seat members to sense occupant seated weight. A microprocessor compensates for preload on the sensors and multiplies each signal by an empirically determined gain, and then combines the gauge outputs. The combined output is low pass filtered to avoid motion induced errors. The measured occupant seated weight is used by decision logic to decide whether to allow passenger airbag deployment.

Abstract: A system for, and method of, empirically determining stress in a molded package and a power module embodying the system or the method. In one embodiment, the system includes: (1) a sensor, having a magnetic core exhibiting a known complex permeability in a control environment, that is embedded within the molded package and therefore subject to the stress and (2) a measurement circuit, coupled to the sensor, that applies a drive signal to the sensor, measures a response signal received from the sensor and uses the drive signal and the response signal to determine a complex permeability under stress of the core. The magnitude of the stress can then be determined from the core's complex permeability under stress.

Abstract: A passive deflection gauge to detect peak deflection in a structural material or system since a given time is disclosed. The gauge includes any type of mechanical deflection sensor using a moveable or extensible core for measuring deflection. A stop moves the core only if a strain greater than the previously occurring maximum strain is present in the structural material or system. Any other movement of the stop will not move the core. Furthermore, a friction member may be incorporated to prevent spurious movement of the core.

Abstract: A method is provided for quantitative determination of the pressure comfort of a seat cushion. For this purpose, the sitting surface of the seat cushion to be tested is loaded mechanically in a manner that corresponds to a normal individual sitting in it, and the seat distribution is then determined with an interposed measuring mat. The signals from the individual pressure sensors of the measuring mat are summarized in accordance with anthropomorphically determined loading ranges with different pressure sensitivity thresholds groupwise and evaluated separately for the individual areas. For this purpose, the pressure measurement signals are multiplied by a factor or a pressure-dependent progressively increasing evaluation function and the product function is integrated. The pressure sensitivity threshold is assigned a value of 1. Depending on the difference between the respective pressure measurement value and the pressure sensitivity threshold (p.sub.

Abstract: The measurement of ejection tonnage in a die in forming process uses an embedded, in-die sensor and signal filtering methods for a more refined interpretation of the weaker signals associated with die vibrations. In particular, a self-tuning (adaptive) filter, matched to the embedded sensor, is used to reconstruct the stimulus of the die vibrations to reveal otherwise non-measurable knock-out tonnage parameters from the strain signal output by the sensor. Necessary information is obtained by means of a suitable dynamics identification procedure. Information necessary for self-tuning is obtained by means of a suitable die-set dynamics identification procedure.

Abstract: A new strain/stress sensor based on the concept of reversible crack opening in a composite material. Crack opening increases the electrical resistance, which is the signal provided by the sensor. The new technology is manifested in concrete and mortar containing electrically conducting short fibers (e.g., carbon fibers and steel fibers). Carbon fibers serve to greatly decrease the crack height so that apparently reversible crack opening occurs. The crack opening is accompanied by fiber pull-out, resulting in fiber-matrix contact resistivity increase, thus allowing sensing under cyclic as well as static loading. A part of the resistance change is irreversible, so it provides memory of the first deformation.

Abstract: A thin film stress sensor measures the maximum compressive stress between two elements that are compressed together. The sensor is formed from a thin RTV film impregnated with microballoons and reinforced with carbon fibers to restrain the lateral deformation of the RTV so that more uniform pressure can be exerted on the microballoons when the sensors are uniaxially compressed.

Abstract: In a system for in-situ delamination detection in composites, the invention employs a system which evaluates the mechanical vibration response of composite material structures. The damping characteristics of the composite structure are extracted from the detected wave properties generated by imbedded piezoelectric ceramic actuators and received by imbedded high strain sensitive fiber optic sensors. Such a sensor system is simple to operate for real-time non-destructive strain and displacement monitoring and delamination detection, without the need to remove the tested surface from operation.During the routine structural integrity monitoring operation, mechanical vibration pulses are launched into the composite from one actuator. The strain signal's propagation patterns are measured in real time by the fiber-optic sensors at different grating locations. Different travel times are computed dependent on the location of the receiving gratings.

Abstract: A thin film stress sensor measures the maximum compressive stress between two elements that are compressed together. The sensor is formed from a thin RTV film impregnated with microballoons and reinforced with carbon fibers to restrain the lateral deformation of the RTV so that more uniform pressure can be exerted on the microballoons when the sensors are uniaxially compressed. The testing method includes applying a compressive stress up to an maximum compressive stress to rupture a first portion of the microballoons, and then applying an interrogating pressure causing acoustic emissions emitted by a second portion of the microballoons when the interrogating pressure equals the equivalent maximum compressive stress, so as to determine the maximum compressive stress.

Abstract: A method and apparatus for pre-straining a bolt-on strain sensor. The pre-strain is preferably adjusted by inserting a strain adjusting tool through strain adjusting holes in the sensor and the structural member. The portion of the tool engaging the sensor is preferably offset from the portion of the tool engaging the hole in the support structure to provide a camming function. After the strain has been adjusted to a desired value, a bolt adjacent the strain adjusting hold of the sensor is tightened to fixedly secure the sensor to the support structure and maintain the preadjust strain at the desired value.

Abstract: A vehicle load measuring device includes a sensing element for detecting a strain to measure the load of a vehicle, in which the sensing element is formed in a pin shape, and a device for supporting a suspension of the vehicle, in which a hole is formed in the supporting device and the sensing element is fitted into the hole, wherein the load of the vehicle is measured based on the strain detected by the sensing element produced in response to the load supported by the supporting device, and a positioning groove being formed on a surface of the device for supporting a suspension, wherein when the device for supporting a suspension connects a suspension with a bracket on the vehicle the device for supporting a suspension is positioned by use of the positioning groove, thereby determining the direction of the load to be applied to the sensing element and preventing the device for supporting a suspension from moving in a predetermined direction with respect to the bracket.

Abstract: In measuring the stress of a ferromagnetic linear metal member, an alternating current is supplied to flow between a pair of terminals mounted to the ferromagnetic linear metal member to measure an impedance .vertline.Z.vertline. of the ferromagnetic linear metal member between the terminals by an analyzer. Then, a stress .sigma. is determined based on the measured value of the impedance .vertline.Z.vertline. from an impedance .vertline.Z.vertline.-stress .sigma. relationship possessed by the ferromagnetic linear metal member. The stress distribution in a sheet-like sensor can be likewise measured by inserting into the sensor a plurality of intersecting ferromagnetic linear metal members. The stress .sigma. is determined for each individual member as described above, and then the stress distribution in the sheet-like sensor is determined by summing up the stresses of mutually intersecting members.

Abstract: The device that is used to measure the switching force in railway points incorporates a measuring bolt (5) that can be inserted into a joint in the point drive. At the unattached end of the measuring bolt there is a head (7) in which an electro-mechanical sensor (8) is arranged. The precise adjustment of the measuring bolt (5) within the joint is effected by using a spacer (10), which simplifies the removal of the measuring bolt once the measurements have been made.

Abstract: A strain indicator of the type wherein a change in length of the strain indicator gives a visual indication of the change in length. The strain indicator has an elongate strip supported at either end such that the curvature of the strip changes with changes in strain. An optical indicator such as a reflector is mounted on the strip so that the change in curvature can be measured.

Abstract: A bolt-loaded compact tension test specimen load apparatus includes: a) a body having first and second opposing longitudinal ends, the first end comprising an externally threaded portion sized to be threadedly received within the test specimen threaded opening; b) a longitudinal loading rod having first and second opposing longitudinal ends, the loading rod being slidably received in a longitudinal direction within the body internally through the externally threaded portion and slidably extending longitudinally outward of the body first longitudinal end; c) a force sensitive transducer slidably received within the body and positioned to engage relative to the loading rod second longitudinal end; and d) a loading bolt threadedly received relative to the body, the loading bolt having a bearing end surface and being positioned to bear against the transducer to forcibly sandwich the transducer between the loading bolt and loading rod.

Abstract: A recoverable, multiple position borehole strainmeter is provided. The strainmeter includes at least two anchors having pistons for releasably engaging the borehole whereby to mount the strainmeter in the borehole. A pneumatic actuator for controllably, independently actuating the pistons to engage the borehole is provided. A biasing mechanism prevents the pistons from engaging the borehole when the pistons are not being actuated by the actuator, and a relative displacement sensor senses changes in relative displacement between adjacent anchors whereby to monitor relative mass displacement axially along the borehole between the anchors.

Abstract: To provide diagnosis of service life and maintenance requirements, a sintered ceramic body which in use is subjected to stress and undergoes change with time as a result of the stress is provided with an electrically conductive element in contact with the sintered ceramic material The element has a measurable electrical resistance which increases in dependence on the change of the ceramic body. This permits information to be obtained about said change of said body. Measuring means for the electrical resistance is connected to the conductive element. The electrically conductive element as seen in cross-section, may comprise a bundle of elongate members such as fibers or whiskers.

Abstract: A process and device for detecting fouling of an axial compressor by measuring of pressure fluctuations within at least one of the stages of said compressor in the region of the compressor housing by means of at least one pressure sensing device, deriving a frequency signal from the signals delivered from said pressure sensing device, checking whether each of said frequency signals comprises at least one characteristic peak in the region of a characteristic frequency assigned to one of said compressor stages, and deriving a fouling parameter from said frequency signal, which parameter depends on a peak parameter indicative of the form of said characteristic peak and indicating the status of fouling of the compressor.

Abstract: The invention concerns a sensor arrangement which is installed in the surface of carriageways or runways and serves to detect the wheel loads of vehicles or aircraft and/or their shear components on the surface during travel. The construction of the flanged tube sensor with piezoelectric crystal plates makes possible modular assembly, in that either piezo-plates sensitive to pressure P only, or to shear S, or to combinations of both are installed, since all piezo-plates have the same dimensions. The force introduction flange makes possible a concentration of the force lines onto the measuring arrangement with a substantial mechanical amplifying effect. The packing of the flanged tube sensor ready to install ensures proper fitting and positioning in the installation groove. Here the two rolling force insulation compounds and the foam insulator of the tubular part are important. The application of the invention lies in traffic management for weight detection.

Abstract: A sensing element in a load measuring device includes two cylindrical holders, each having a hole along the central axis; and a plate-shaped member provided between the two cylindrical holders, the plate-shaped member having protrusions at both ends, a coil being provided on a center portion of the plate-shaped member, wherein the cylindrical holders is welded to the plate-shaped member with the protrusions engaged with the holes in the two cylindrical holders.

Abstract: An apparatus for sensing forces applied to a structure includes a generally cylindrical body having a pair of end portions and a smaller diameter intermediate portion with a central aperture extending longitudinally through the body. The end portions are slotted to form radially outwardly translatable legs for engaging a wall of a cavity formed in the structure. Strain gauges are attached to the intermediate portion for sensing forces applied to the structure when the body is positioned in the cavity and the legs are engaging the wall of the cavity. The wall of the central aperture has a pair of threaded sections for threadably receiving bushing and bearing assemblies inserted from opposite ends of the central aperture. Each of the assemblies has a tapered surface for radially outwardly translating the legs.

Abstract: A strain or stress gauge 1A is presented for measuring the stress of a structure or a member. The gauge 1A comprises a bundle of electric conductive fibers 3, and a pair of terminals 4, for measuring an electric resistance of the bundle of electric conductive fibers provided on both ends thereof. It presents a strain or stress gauge having a simple structure, which can be produced inexpensively, and its size can be chosen freely. It is possible to know not only the state of a strain or stress but also the history of stress in a structure or a structural member which, by the characteristics of a specific curve relating the stress/strain relationship of the gauge.

Abstract: The present invention relates to a method of instrumenting an already erected concrete or rock structure in order to determine the state of deformation of that structure. A cylindrical inclusion made of concrete having substantially the same mechanical properties as the concrete or the rock of the structure is inserted into a hole drilled into the concrete or rock. Sensors capable of detecting deformations are embedded in the concrete of the inclusion. The empty space between the inclusion and the hole is tightly filled with a grout whereby any deformation of the concrete or rock structure also deforms the inclusion and is therefore detected by the sensors embedded therein. The invention also extends to the inclusion and the so instrumented concrete or rock structure.