Commissariat a L'energie Atomique

Commissariat &#xc0; L'&#xc9;nergie Atomique Et Aux &#xc9;nergies Alternatives

Institut Francais Du Pe'trole

Snecma

Electricite De France - Service National

Safran Aircraft Engines

Pierre Ferdinand

Sylvain Magne

Stéphane Rougeault

Gilles Grand

Christian Wittrisch

Valerio Gerez

Christophe Martinez

Daniel Averbuch

Guillaume Laffont

Jean-Claude Gaucher

Andre Leroux

David Tourin

Laurent Maurin

Chieh Liu

Pierre-Jean Daniel

Véronique Dewynter-Marty

Shamyr Ali Alvarez

St&eacute;phane Rougeault

André Leroux

Shamir Ali Alvarez

A system for detecting deformation of a fan for an aeroengine, the fan including a rotor including plural blades made of composite material including woven fibers. At least one of the fibers in each of the blades is an optical fiber including at least one portion defining a Bragg grating. The system further includes a transceiver connected to the optical fiber and configured to send an optical signal into the optical fiber and to receive an optical signal in response from the optical fiber, and a detector module connected to the transceiver to detect deformation of the fan when the received optical signal presents correlation with a predetermined signature of a damped impact on a blade at a determined speed of rotation. This deformation may be the result of a foreign object impacting against a blade of the fan or may follow from variation in an internal defect.

Detecting and tracking damage to an aeroengine fan or an impact of a foreign object thereagainst

Device for measuring corrosion in a structure. It comprises: at least one assembly comprising a metallic part () intended to be fixed to the structure and able to deform under the effect of corrosion and/or a thermomechanical variation, and transduction means () comprising an optical fibre () fixed to the metallic part in a prestressed state, the transduction means being able to modify light propagating in the fibre under the effect of a stress applied to the fibre; means for measuring and processing the spectral responses supplied by the transduction means of said at least one assembly. The metallic part is segmented longitudinally in order to form an alternation of segments covered by a corrosion-protection material () and uncovered segments, in order to distinguish the thermomechanical influence of the structure from the mechanical effects caused by corrosion.

Device for measuring the corrosion in a metallic structure or a structure comprising at least one metallic reinforcement, associated uses and method

The invention relates to an instrumented tubular device for transporting a pressurized fluid notably in the field of oil exploration and in that of the transport of gas or hydrocarbons. This device comprises a tube in which this fluid flows, with which are associated means for measuring the main deformations of this tube, and means for measuring the temperature of the fluid in the tube. This tube is equipped with measurement means integral with its surface and offset by at least one remote optical cable towards an electronic measurement system. These measurement means are means for assembling at least two non-parallel optical fibers which comprise at least three assemblies of at least two optical gages with Bragg gratings attached to at least three measurement locations and connected to the remote optical cable via optical fibers. At least one assembly further comprises a temperature gage.

Instrumented tabular device for transporting a pressurized fluid

The present invention relates to a temperature-compensated optical fiber pressure detector for detecting pressure variations in at least one medium in relation to a reference medium such as the atmosphere or a medium where a back pressure prevails. The detector essentially comprises a deformable element () such as a bellows () exposed on one side to the reference medium and on the opposite side to the pressure to be measured, an optical fiber portion (F) including at least one optical grating such as a Bragg grating (B), which is connected on one side to deformable element () and on the opposite side to a fixed point. The optical fiber portion is subjected to a prestress by a device () and its elongation varies with the displacements of the deformable element. The device applies the prestress to optical fiber portion (F) between deformable element () and another fixed element () isolated from the medium by a rigid housing (). An optical system () detects the deformations undergone by said optical grating in response to the pressure variations undergone by the deformable element. Another part (F) of the optical fiber that is not subjected to stresses (or another non-stressed fiber portion connected to the first one) preferably comprises another similar optical grating (B) also allowing measurement of the temperature variations. By duplicating the deformable elements and possibly the stress applying device (), differential pressure variations can also be measured. Such a detector can notably be applied to pressure and temperature measurements in wells where difficult conditions prevail.

Pressure sensor with temperature compensated optical fiber

A refractometer with blazed Bragg gratings. In order to measure the refractive index of a medium, for example a liquid or a gas, the refractometer includes a waveguide having a blazed Bragg grating, the spectral response of which depends on the refractive index of the medium and a light source in order to make this light interact with the grating. Further, spectral analysis of the light which has interacted with the grating is performed, the spectrum provided by the spectral analysis is recovered, and, from the recovered spectrum, the spectral response of the grating is correlated with one value of the refractive index of the medium.

Refractometer with blazed bragg gratings

Extensometer with flexible test specimen and Bragg gratings applied in particular to the monitoring of concrete structures, is configured to measure deformations of a host material and comprises at least one test specimen which undergoes linear bending stresses, and at least one Bragg grating formed in an optic fibre and fixed to the test specimen. The extensometer configured such that any deformation of the host material is transmitted to the grating via the test specimen. The extensometer also comprises mechanical means which transform deformation of the material into bending of the test specimen, which deforms the grating.

Extensometer comprising a flexible sensing element and Bragg gratings

An extensometer including a base, a tensioned optical fiber, and a Bragg grating. The extensometer relates particularly to monitoring of structures. Part of the optical fiber containing the Bragg grating is arranged in a tube. This part is tensioned between the two ends of the tube. The ends of this part are fixed to the ends of the tube, and the tube is rigidly fixed to a host material.

Long base, stretched fiber-optic Bragg network extensometer and production method for same

A differential measurement system using pairs of Bragg gratings including at least one optical sensor having two Bragg gratings in two optical waveguides and having sensitivities adjusted so that respective spectra of the two gratings have a relative spectral shift dependent on a parameter or parameters to be measured. The system also includes an optical source to supply light to the two optical waveguides to interrogate them, a mechanism enabling light to pass successively through the two Bragg gratings of the same sensor, photodetectors to measure the power level of light having passed only through one of the two optical waveguides and the power level of light having passed successively through the two optical waveguides, and a processor to process the power levels and supply values of the parameter or parameters measured. The system is applicable in particular to measurements of temperatures, stresses, and pressures.

Differential measurement system based on the use of pairs of Bragg gratings

A Bragg grating inclinometer that includes an upper part, a lower part forming a pendulum suspended from the upper part by an articulation, at least two portions of optic fiber placed on either side of the articulation, the ends of each portion being fastened to the two parts, each portion being previously put under tension between the two parts, and at least one Bragg grating in one of the portions. Any variation in the inclination of a structure to which the upper part is fastened induces a stress on the grating, which then modifies a light propagating in the portion where it is placed. The variation in inclination is determined from the modified light. The inclinometer can be applied in particular to the surveillance of civil engineering structures.

Inclinometer with bragg grating

This device comprises a device (DD) for demultiplexing these lines in terms of wavelength, a device (DM) for measuring, by filtering, the wavelengths of the demultiplexed lines, comprising, for each of these lines, a measuring channel (VM) provided with a filter and a reference channel (VR), and means (MP) for the photodetection, for each line, of the light intensity transmitted by the corresponding measuring and reference channels. The wavelength of each of these lines is determined by calculating the ratio of the intensities thus detected. Application to the monitoring of structures.

Device for reading spectral lines contained in an optical spectrum

The present invention relates to a device for demultiplexing spectrum lines contained in an optical spectrum. This device comprises a energy separator (,) and selective wavelength light reflectors (,), each selective wavelength light reflector having a wavelength bandpass that contains the spectral region associated with one of the lines and that, therefore, reflects only this particular line. Applications to surveying constructions, such as buildings and aircraft.

Device for demultiplexing light paths contained in an optical spectrum

The present invention relates to a planar, rosette-type, optical microsystem with strain gauges having dielectric guides used for measuring a system of strains or stresses applied to a part, in which the part is under purely longitudinal strain, at least one rosette being formed by at least two strain gauges with dielectric guides (J1, J2, J3) and in which a calculating circuit makes it possible to determine said strain by resolving a system of equations.

Rosette-type optical microsystem of strain gauges having dielectric

The present invention relates to a high capacity, high signal-to-noise ratio sensor incorporating an array of Bragg grating transducers photoinscribed on a dielectric guide and a feedback loop incorporating a wavelength selective element which is time modulated making it possible to obtain a laser sensor selectively switched by each Bragg grating. Application to monitoring strains or temperatures in a structure.

Photoinscribed bragg grating sensor with a good signal-to-noise ratio

The interferometer comprises an emitter arm (10) excited by a source (11) and a receiver arm (20) associated with a photodetector (21) united by an optical coupler (50) so as to form a reference arm (30) and a measurement arm (40) terminating in a sensor (41). The arms (30) and (40) are constituted by one and the same optical fiber whose diopter of its free end (31) acts as a partially transparent mirror for the reference optical wave. This end (31) is coupled to the sensor (41) which returns the measurement optical wave through said diopter. Application in particular in the measurement of temperatures, for example in turbo-machines or of fluctuations of flow density.

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Houilles, France

Pierre Ferdinand