Abstract: A device and method for indicating if a fastening element upon fastening to a piece has reached a tensile yield limit load. The fastening element includes a threaded shaft having a magnetostrictive material. The device includes a mechanism for generating an alternating magnetic field that penetrates the shaft, a mechanism for measuring a physical quantity that depends on the momentary magnetic susceptibility of the shaft and a control unit adapted to detect a significant change of the physical quantity and determine and indicate if the shaft of the fastening element has reached the tensile yield limit load.

Abstract: The present invention discloses an MEMS sensor and a method for making the MEMS sensor. The MEMS sensor according to the present invention includes: a substrate including an opening; a suspended structure located above the opening; and an upper structure, a portion of which is at least partially separated from a portion of the suspended structure; wherein the suspended structure and the upper structure are separated from each other by a step including metal etch.

Abstract: A system and method for determining remaining fatigue life of a component experiencing stress/strain cycles. In one embodiment the fractional life expended per clock cycle of the component is determined and multiplied by a data type value indicating whether a full cycle, half cycle or no stress/strain amplitude information was present during a given clock cycle. The product is then summed with the result of the previously clock cycle, to produce a running total of the fractional life expended. The running total is then subtracted, at each clock cycle, from an initial fatigue life value, and the output represents the residual fatigue life remaining for the component.

Abstract: A Foreign Object Damage (FOD) detection system is disclosed for detecting and analyzing ultrasound or stress waves emitted when an object enters the intake of a turbine engine and impacts one or more of the blades in the engine. Upon detection the FOD detection system can immediately inform the operator, inform another electronic device (computer, etc.) and/or latch the event for review by maintenance personnel. The detection system generally consists of one or more stress wave sensors and an electronic assembly to process the stress wave signal received from the sensor(s). The electronic assembly is in communication with the sensor(s) via conventional cabling.

Abstract: Magnetic shields for plastic molded electricity meter frames are positioned to substantially block external magnetic fields from adversely affecting operation of meter components. The shield can be utilized with either electromechanical or electronic energy meters. In an electromechanical watthour meter which employs an aluminum disk driven to rotate through a magnetic field produced by a retarding magnet, the meter frame includes an integrally formed retarding magnet shield and an integrally formed bearing shield. The shields are coextensive with the frame, and extend from an inner periphery of the frame toward the retarding magnet and the bearing, respectively. The shields are formed of a magnetically permeable powder, such as a ferrite powder mixed with the plastic material from which the meter frame is molded. The shields divert externally applied fields away from the magnetically sensitive components of the meter without adversely affecting meter accuracy.

Abstract: The present invention is a device to measure the parallel shear force on a mattress. The device has a motor, a weighted object, a high friction material pad, and a load cell. The motor moves by pushing and pulling the weighted object on the high friction material pad which is on the mattress. The load cell measures the peak shear force when the weighted object is pulled and when the weighted object is pushed.

Abstract: A strain isolated optical fibre Bragg grating sensor (1) has an optical fibre (2) provided at or adjacent one end (2a) with the Bragg grating (3). An open mouth cap (4) surrounds the fibre end (2a) and region provided with the Bragg grating (3) at a spacing from the fibre, fibre end and Bragg grating. The cap (4) is sealed to the fibre (2) at the open mouth at a side of the grating (3) remote from the fibre end (2a). The cap (4) is made from a low Young's modulus material and is operable to isolate the grating (3) from strain.

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: The object of the present invention is to provide a maximum value storage sensor when detecting the maximum strain by generating an invariable electrical resistance change correlative to the strain of the detection object in a conductive body having a plurality of conductive elements. The maximum value storage sensor of the present invention has; a conductive body having a circuit which gives correlative resistance changes corresponding to the sequential cutoff of a plurality of conductive elements each having a given electrical resistance arrayed in parallel; a cutting means for cutting the conductive elements of the conductive body; and a structure for allowing one of the conductive bodies and the cutting means to move relatively to each other.

Abstract: An optical fiber strain sensor is provided which remembers the maximum stn a structure has experienced in a given timeframe. A pair of multi-mode optical fibers with flat ends meet end-to-end within a microbore capillary tube with which the fibers have frictional contact. The fibers are fastened to the structure at two points a known distance apart on either side of the capillary tube. Increasing strain in the structure pulls the fiber ends apart in proportion to the amount of strain; however, when strain is decreasing, the fibers buckle rather than move closer together. Therefore, the maximum strain is reflected as a maximum distance between the fiber ends. When the maximum strain experienced is to be measured, the free end of one fiber is connected to a light source and the free end of the other fiber is connected to a detector.

Abstract: An optical fiber strain sensor is provided which remembers the maximum stn a structure has experienced in a given timeframe. A reflective surface is fixed at one location on the structure, and a multi-mode optical fiber with a flat end is fixed at another location on the structure and is positioned so that its flat end is in contact with the reflective surface. A microbore capillary tube attached to the reflective surface encloses the fiber at its flat end and frictionally retains it in contact with the reflective surface. Increasing strain in the structure pulls the fiber end away from the reflective surface in proportion to the amount of strain; however, when strain is decreasing, the fiber buckles rather than moving closer to the reflective surface. Therefore, the maximum strain is reflected as a maximum distance between the fiber end and the reflective surface.

Abstract: Devices and methodology are provided for measuring mechanical strain in a structural member. The devices and methodology utilize a material which undergoes a change in phase when strained so that measurement of the phase change indicates strain. Preferably the phase change material is a transformation induced plasticity steel alloy. The elements may be configured as gauges secured to a structural member, but also the elements may perform as part of the structure. A plurality of elements may be organized into a monitoring system, either passive or active, for a complex structure.

Abstract: An apparatus for providing an indication of the amplitude of a length signal having a top peak, a bottom peak and an intrinsic offset and being indicative of viscoelasticity of a sample. A peak measurement circuit is provided for measuring values of top and bottom peaks of the length signal to determine the amplitude thereof and an offset circuit is connected for providing a compensative offset. An adder circuit is provided for adding the compensative offset to the length signal. An offset calculation circuit receptive of the values of the top and bottom peaks from the peak measurement circuit is provided for outputting to the offset circuit, according to the received values, a control signal effective to control the offset circuit to provide an update compensative offset effective to cancel the intrinsic offset of the length signal.

Abstract: A signal conversion circuit converts variations in resistance into an electrical signal. The conversion circuit comprises both a bridge circuit and a single operational amplifier with a capacitor between them to store voltage samples produced by an unbalancing of the bridge. The bridge circuit has a detector element such as a strain gauge for providing a resistance variation. A capacitor is connected through switches to both the bridge circuit and signal operational amplifier. The switches operate in a sequence whereby the operational amplifier is disconnected from the capacitor during the storage of the sample and the bridge is disconnected from the capacitor during intervals while the charged capacitor is connected to the amplifer.

Abstract: A plurality of individual frames or stampings provided in a sheet strip material by a stamping device are passed in proximity to a sensing device. As each individual frame or stamping is passed in proximity to the sensing device, the sensing device provides a voltage signal to a controller. The voltage signal is proportional to the amount of, or mass of, metallic material in each frame or stamping and the distance between the frame or stamping and the sensing device. The controller generates an individual waveform from the voltage signal for each frame passed in proximity to the sensing device. Each individual waveform is a function of the position of the movable portion of the stamping device for one cycle. As the plurality of individual frames are passed in proximity to the sensing device, a plurality of individual waveforms are generated within the controller. The waveforms are compared within the controller to detect a deviation between waveforms.

Abstract: A load monitor for a cyclic machine has a peak load signal detector the output of which is displayed indefinitely on an analog meter. On each cycle of the machine, the analog load signal is converted to a digital signal and the digital signal is converted to an analog signal connected with the analog meter. Overload and underload reference signals are established during a selected single cycle of machine operation.

Abstract: A torque wrench having a torque plug integral with the back side of the torque wrench handle and with strain sensing elements mounted on the torque plug and connected to signal processing circuits supported by the handle which control a digital display unit mounted on the handle. The processing circuits include a peak hold detector enabling display of the peak torque value during a torquing operation, and a peak hold response delay insuring capture of the peak torque value.

Abstract: A press control system monitors and is responsive to the loads associated with individual die stations in a progressive die. The system detects chipped, dull, or excessively loaded portions of the progressive die and provides automatic quality monitoring of the parts produced by the press. The system provides a display of press load as a function of time scaled by the speed of the press. The press load as a function of time is automatically analyzed to determine and display the number of die stations and the peak loads associated with each die station in the progressive die. The peak loads are compared to limit values that depend in part on the past history of the press in order to monitor the condition of the progressive die and if necessary to shut down the press. The number and quality of parts produced by the press are also determined from the peak loads. Gradual wear of the die is monitored to determined when sharpening is required.

Abstract: Apparatus which measures loads imposed on load carrying members, and particularly such members in presses, to indicate the peak load reached during a press cycle, has circuits for amplifying the electrical signal from a sensing device such as a strain gage bridge, a peak detector which provides an output representing the peak load, and a digital indicator. Zero setting is achieved by integrating and holding an offset voltage derived by an integrating circuit in negative feedback relationship with the circuit which amplifies the signals from the sensing device. Calibration of the apparatus for press factor is obtained by adjusting the gain of a variable gain stage in the amplifier. The peak detector is reset each press cycle when the load sensed bears a predetermined ratio to rated or full capacity load.

Abstract: An indicator for recording the load at which a fatigue specimen breaks during the last cycle of a fatigue test. A load cell is attached to the specimen which is alternately subjected to tension and compression loads. The output of the load cell which is proportional to the load on the specimen is applied to the input of a peak detector. Each time that the specimen is subjected to a compression load, means are provided for appyling a positive voltage to the reset of the peak detector to reset it. Hence, during the last cycle of the tension load the peak detector measures the maximum load on the specimen. Means are also provided for disconnecting the load cell from the peak detector when there is a failure in the specimen.