In a management system for an attachment state of an attachment object, a sensor capable of detecting a value equivalent to stress of stress loaded, or a predetermined value from which the value equivalent to stress can be calculated, a washer storage unit storing identification information of a sensing washer, and a washer control unit transmitting the value equivalent to stress and the identification information of the sensing washer via a communication unit, are provided in the sensing washer between a bolt and a nut that attach an attachment object to a structural object. A management processing device acquires the value equivalent to stress and identification information of the sensing washer transmitted from the sensing washer, and presents the value equivalent to stress of the sensing washer of the identification information, or a corresponding stress value, as relational information with respect to a reference value stored in a storage unit.

A measurement system comprising a sensor and a controller configured to communicate with the sensor, the controller comprising a display. The sensor comprises at least two measurement assemblies and at least one processing circuit connected to one or more sensing elements each measuring a current value of the same parameter. Each processing circuit emits to the controller a measurement signal as a function of the current value measured by the one or more sensing elements and of a stored reference value. The controller is configured: i) to transmit the reference value to each processing circuit that stores it if the reference value is equal to within a margin of the measured current value, and ii) to receive the measurement signals and display respective symbols on the display, the symbols being at least dissimilar or displayed alternately.

A detector is a detector that detects fastening axial force applied by a fastening unit in an axial direction. The detector includes a strain element that has a through hole through which a bolt portion that the fastening unit has is inserted, and a strain sensing sensor that senses strain of the strain element. The strain element has a block-like form and has a planar portion following the axial direction on a side face thereof. The strain sensing sensor is provided on the planar portion.

The invention relates to a monitoring attachment for monitoring a nut (9) of a screw connection for cracking, deformation and/or breakage, wherein the monitoring attachment has a conductor loop which is guided around an outer periphery of the nut (9) and which is interrupted in the event of deformation, cracking and/or breakage of the nut (9). The monitoring attachment is characterised by at least two segments (1, 1, 1, 1) which together enclose the periphery of the nut (9) and are held together frictionally at at least one radial connection point, wherein the conductor loop is guided over contacts at the connection point.

A method for determining the state of at least one sensor whose mechanical behaviour is nonlinear as a function of the amplitude of the pressure exerted against the sensor, the sensor and an electromechanical transducer being able to be coupled to a support, the method comprising the steps of: applying an electrical signal at a first amplitude to the terminals of the first electromechanical transducer, and determining a first set of values of a parameter characteristic of the electrical impedance of the first electromechanical transducer in response to the application of the electrical signal; applying the electrical signal at a second amplitude to the terminals of the first electromechanical transducer, and determining a second set of values of the parameter characteristic of the impedance; measuring a deviation between the first set of values and the second set of values; determining a state of the sensor as a function of the deviation between the first set of values and the second set of values.