An optical interrogation system, e.g., an OFDR-based system, measures local changes, of index of refraction of a sensing light guide subjected to a time-varying disturbance. Interferometric measurement signals detected for a length of the sensing light guide are transformed into the spectral domain. A time varying signal is determined from the transformed interferometric measurement data set. A compensating signal is determined from the time varying signal which is used to compensate the interferometric measurement data set for the time-varying disturbance. Further robustness is achieved using averaging and strain compensation. The compensation technique may be applied along the length of the light guide.

The method for warning of risk of rupture or deformation of a part made of a composite material when it is subjected to a force relates to a part including a fibre-reinforced thermoplastic or thermohardenable matrix. The method includes arranging the fibers in a lattice structure produced by winding fibers to form bars that join together or intersect at nodes. The method includes designing at least one bar of the lattice and/or integrating, into the part, at least one additional bar with a determined location and tensile strength and associating, with the at least one bar, inside the part, a sensor to detect the rupture thereof. The method further includes associating, with the sensor, an emitter, outside the part, for a signal relating to the rupture.

Disclosed is a temperature and strain sensing optical fiber including a first doped radial zone (Z1) with an associated first Brillouin shift (BS1) caused by the doping of said zone (Z1) and a second doped radial zone (Z2) with associated second Brillouin shift (BS2) caused by the doping of said second zone (Z2). The concentration and/or composition of the doping materials in said first and second radial zones are chosen such that the first Brillouin Shift (BS1) is different from the second Brillouin Shift (BS2) for all variations of said Brillouin Shifts (BS1, BS2) caused by temperature and/or strain.

Provided is a method for providing a strain measurement value in a sensing optical fiber. The method may include outputting light to an optical fiber, in which the optical fiber includes a standard sensing optical fiber and a sensing optical fiber extending from the standard sensing optical fiber, in which the standard sensing optical fiber is accommodated inside an external environmental protection case, providing a strain measurement value in the sensing optical fiber based on Rayleigh scattered light reflected back from points of the optical fiber, and providing a final strain measurement value by compensating for an error caused by a change in light source in the strain measurement value in the sensing optical fiber.

The purpose of the present invention is to provide a bonded structure, a method for manufacturing the same, and a bonding state detection method which are capable of determining whether or not members are bonded together appropriately. A bonded structure 10 includes a laminated sheet 12A, a laminated sheet 12B, an adhesive 14 that bonds the laminated sheet 12A and the laminated sheet 12B together, and a distributed optical fiber 16 sandwiched between the laminated sheet 12A and the laminated sheet 12B. The cross-sectional shape of the distributed optical fiber 16 is deformed in accordance with the bonding state.

Aspects of the present disclosure generally relate to systems and methods for monitoring the structural health of components. In an aspect is provided a system for monitoring structural health of a component that includes a mechanotropic elastomeric (ME) layer at least partially disposed on a surface of the component, the ME layer having a first portion corresponding to a first end of the component and a second portion corresponding to a second end of the component; a fiber optic light guide coupled to the first end; and a detector coupled to the second end. In another aspect is provided a method that includes pulsing an electromagnetic energy source coupled to a system comprising a ME layer; and detecting a wavelength or wavelength range by a detector, the detected wavelength or wavelength range being responsive to an amount of stimulus and being indicative of a deformation in a component.

Distributions of a Brillouin frequency shift and a Rayleigh frequency shift in optical fibers set up in a material are measured from scattered waves of pulse laser light entered into the optical fibers, and distributions of pressure, temperature, and strain of the material along the optical fibers at a measurement time point are analyzed using coefficients that are inherent to the set up optical fibers and correlate pressure, temperature, and strain of material with the Brillouin frequency shift and the Rayleigh frequency shift.

A strain detector 1 includes: a metal plate 4 that is fixed to a first end 210 of a first tube 21 and a second end 220 of a second tube 22 while the metal plate 4 straddles a weld 3 between the first end 210 and the second end 220, the first tube 21 and the second tube 22 forming part of a boiler tube 2; and an optical fiber 5 that is fixed to a top of the metal plate 4 and that extends in an axial direction (a first direction D1) of the first tube 21 and the second tube 22. In this manner, the metal plate 4 is fixed to the first tube 21 and the second tube 22 while straddling the weld 3, and the optical fiber 5 is fixed to the top of the metal plate 4, which enables the strain detector 1 to accurately detect a strain in the weld 3 of the boiler tube 2.

A system can calculate estimated strain data for a fracture in a geological formation at each of a plurality of selected locations detectable by a strain measurement device. The system can receive real strain data from the strain measurement device for the geological formation. The system can perform an inversion to determine a probable distribution of fluid volume and hydraulic fracture orientation in the geological formation based on the estimated strain data and real strain data. The system can determine adjustments for a fracturing operation based on the inversion.

In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.