Various embodiments of the present disclosure are directed to a measurement system. In one example embodiment, a measurement system is disclosed including a flat measurement element receptacle and at least one piezoelectric measurement element. The flat measurement element receptacle having substantially parallel cover surfaces, and is installed between torque- and/or force-transmitting machine parts. The at least one piezoelectric measurement element arranged in a through-opening of the measurement element receptacle and mechanically fixed, with play, in the through-opening.

In a screw device where a shim is disposed between two nuts, a screw device that can detect preload is provided. The preload detectable screw device includes: two nuts; a shim sandwiched and compressed between the two nuts; a coupling portion configured to couple the two nuts in such a manner as to be incapable of relative rotation to each other; and a force sensor for detecting preload. A contact surface of at least one of the two nuts with the shim is provided with a recess, spaced apart from the coupling portion, in such a manner as to reduce the contact area. The force sensor is attached near the recess on an outer surface of the shim.

A connecting component includes a connecting component body, a sensor which is configured to convert a value of a sensor measured variable acting on the sensor into an electrical output variable, and a radio interface which is configured to communicate with a communication device by a radio signal on a basis of the electrical output variable. The sensor is configured to convert the value of the sensor measured variable into the electrical output variable in accordance with a continuous switching stage characteristic having a sensor measured variable threshold value.

A method of loading bolts of a bolted flange connection includes obtaining an initial bolt load value for each of the bolts; loading each of the bolts, in sequence, to a respective initial bolt load value; wherein each of the bolts achieves a resultant bolt load value that meets a predetermined bolt load value.

A bolt clamping force sensing washer includes a sensing washer, connection line assembly, and signal processor. The sensing washer includes a body, sensing component, and bushing. The body has an axial hole that matches outer diameter of a bolt's thread. The circumferential surface of the body has a circumferential groove for receiving the sensing component which measures a deformation signal generated by the body under an axial load. Two end surfaces of the body are perpendicular to the axial hole and each have a loosening-proof structure. The bushing is made of metal or plastic or formed by plastic insulating material casting to enclose the sensing component. The signal processor has a signal amplifier, microprocessor, pairing switch, power circuit unit, signal transmission unit, memory unit, RF antenna and alert unit. The connection line assembly is disposed at the bushing to electrically connect the sensing component and signal processor.

A pressure sensing device may include a body configured to distribute a load applied between first and second parts positioned one against the other, and a pressure sensor carried by the body. The pressure sensor may include a support body, and an IC die mounted with the support body and defining a cavity. The IC die may include pressure sensing circuitry responsive to bending associated with the cavity, and an IC interface coupled to the pressure sensing circuitry.

A loosening detection device according to the present embodiment includes multiple washers having holes that allow bolts to pass therethrough, and including metals insulated from each other, a transmission line that electrically connects between the metals and between the metals of the washers, and a transmission line that includes a terminal pair at one end thereof, and that has the other end electrically connected to the metals of the washer. A resonance frequency is measured from the terminal pair to detect loosening of the bolts on the basis of a change in the resonance frequency.

In a screw device where a shim is disposed between two nuts, a screw device that can detect preload is provided. The preload detectable screw device includes: two nuts; a shim sandwiched and compressed between the two nuts; a coupling portion configured to couple the two nuts in such a manner as to be incapable of relative rotation to each other; and a force sensor for detecting preload. A contact surface of at least one of the two nuts with the shim is provided with a recess, spaced apart from the coupling portion, in such a manner as to reduce the contact area. The force sensor is attached near the recess on an outer surface of the shim.

Provided is a nut and a bolt tightening method for fastening an object, wherein a tightening force is applied on the object by rotating a nut or a bolt in a state in which a predetermined tension force is applied on the bolt in the axial direction of the bolt. When the tensile force exerted on the bolt decreases as the tightening force increases and after a timing when an inflection point occurs in a time course change in a ratio of an amount of change in the tensile force exerted on the bolt to an amount of change in an angle of rotation of the nut or the bolt, the tightening resulting from the rotation of the nut or bolt is terminated and the tensile force applied on the bolt is removed.

The invention resides in a sensor unit (100) for measuring and monitoring a plurality of parameters associated with an asset or equipment (126, 128) having a fixing connected thereto. The asset can typically be an object, such as a rail or motor casing, that is fixed, using a fixing (122) such as a bolt. The sensor unit has a housing (112) having a portion (120) for receiving a fixing therethrough; sensors (114) arranged to measure and/or monitor (i) parameters associated with a fixing that is secured to the asset via housing and/or (ii) parameters influencing the performance of the asset; a processor (142) configured to process data from the sensors; and a communicator (116) adapted to transmit said data to a remote device. At least one of the sensors can be an inductive sensor, which can measures the displacement or force applied to a fixing against the asset to which it is fixed, said fixing is biased against a resilient member located in the housing. The sensor unit can operate in at least one of a plurality of modes including: a first mode, in which the sensor unit samples one or more parameters periodically at a first sample rate, a second mode, in which the sensor unit detects the occurrence of an event, and a third mode, in which the sensor unit monitors one or more parameters periodically at a second sample rate, which second sample rate is greater than the first sample rate, and wherein the data obtained in said modes is communicable with the system and/or the reader.