Systems and methods are provided for responding to theft of a sensor enclosure of an autonomous vehicle. Theft of the sensor enclosure can be detected using at least one piezoelectric sensor. An electrical signal to the at least one piezoelectric sensor can be generated. The at least one piezoelectric sensor can be caused to emit a sound based on the electric signal.

An axial force measurement apparatus measuring an axial force of a bolt member by measuring a clamping force, of a nut member threaded onto the bolt member, which is applied to fasten a structure, includes: a sensor that applies vibration to the structure through one side of the tightened nut member and obtains, on an opposite side of the nut member, a signal by the vibration that propagates through the structure and passes through the nut member; and an analyzer that analyzes the signal received from the sensor and determines the axial force of the bolt member using a difference in propagation velocity of the signal by the vibration according to the clamping force of the nut member.

The invention relates to a solution for how to measure the strain in a washer mounted in a bolt assembly comprising a bolt, nut and washer. The invention concerns a strain measuring washer assembly comprising a plate shaped washer body, sound emitting means and sound detecting means, and a method for using such.

The present invention discloses a method and system for detecting the fastening state of a fastening structure which fixes structural elements. At least a first vibration sensor is mounted on a first structural element for collecting vibration data of the first structural element. At least a second vibration sensor is mounted on a second structural element or on the fastening structure for collecting vibration data of the second structural element or the fastening structure. The fastening state of the fastening structure is determined using the vibration data collected. The method and system enable detection of the fastening state of a fastening structure with low-power consumption and low cost.

The present invention discloses a piezoelectric patch-based real-time and high-precision bolt preload detection method and system. A piezoelectric patch is used as an ultrasonic excitation source and pasted on the head of a bolt, and the high-precision fitting relationship between the ultrasonic change of time-of-flight and the bolt preload is established according to the law of the ultrasonic change of time-of-flight of single echo with the stress so that the real-time detection of the bolt preload is realized by using the mathematical relationship. Compared with the previous method using ultrasonic probes, the present invention eliminates the error caused by the uncertainty of couplant thickness and further improves the measurement precision by using the change of time-of-flight of single echo. Meanwhile, the low-error rate measurement of the bolt preload is realized at a low cost and without affecting the structural performance.

A bolt axial force measurement apparatus of the present invention includes an echo detection section and an axial force calculation section. The echo detection section sets a head echo gate for the head echo and sets a bottom echo gate for the bottom echo, and executes tracking for a plurality of ultrasonic pulses emitted during tightening of the bolt so that the head echo gate and bottom echo gate are shifted independently to include the predetermined positions at the same position in the head echo gate and bottom echo gate.

The invention relates to a system for the in-line measurement of mill liner wear and mill bolt tension, which includes: an acoustic-wave emitter, an acoustic-wave receiver, an electronic circuit, an energy source and a communication device, all at the threaded end of a certain number of bolts; a device in the vicinity of the mill for administering communication and gathering data; and a system in a remote position for processing and displaying data.

A device for inspecting clamping means, including an electromagnetic ultrasonic transducer including a winding for generating pulsed eddy currents on the surface of a clamping element, built into a system for generating a magnetic field including a cylindrical magnet arranged above the winding with the axis of rotation thereof coinciding with the axis of the winding and a magnetic circuit surrounding the magnet and the winding to guide the generated magnetic field so that the field lines pass obliquely towards the axis of the coil through an interface plane with the clamping element, opposite the winding, the interaction of the field lines and pulsed eddy currents being suitable for simultaneously generating longitudinal and transverse ultrasonic waves in the clamping element.

Exemplary embodiments are directed to instrumented fasteners and associated damage detection systems for detecting damage in an assembled structure secured together by at least one instrumented fastener. The instrumented fastener forms a transducer assembly for detecting damage in the assembled structure. The fastener can include a cavity disposed at one end of the fastener. The transducer assembly includes an electromechanical unit at least partially inserted into and mechanically coupled within the cavity of the fastener. The electromechanical unit can include a piezoelectric element.

A system, probe and method accurately measure the strain or extension of a fastener that occurs as a nut on the fastener is tightened and the fastener is put under load. The measurement technique is based on measurement of the time for an ultrasonic wave generated on one end of the fastener to travel a round trip through the fastener. As the fastener is tightened, the applied stress causes an associated increase in length. This length can be determined from a measurement of the increase in transit time. In various embodiments, the disclosed device and method uses laser ultrasonic testing (LUT), in which a pulsed laser generates the ultrasonic wave and a type of laser vibrometer detects the wave when it returns to the position of generation following a combination of longitudinal and shear wave reflections, which result in a higher magnitude and more easily and precisely measurable reflected signal peak than a signal peak associated with a signal directly reflected against the opposite end of the fastener.