113 results about "Fiber strain" patented technology

An actuator device (2) includes a piezoelectric or electro-strictive solid state actuator element (6) that is elongated upon application of an electric voltage thereto, and a transmission mechanism (8) that amplifies the stroke displacement of the actuator element. The transmission mechanism (8) includes a plurality of rigid frame members (12), including unitary frame members (12.1, 12.2) and divided frame members (12.3), and elastically flexible joints (10) that respectively interconnect the frame members. Each one of the divided frame members (12.3) is made up of a plurality of separate parallel link rods (16). Each flexible joint (10) is made up of a plurality of individual parallel hinge members (18) that respectively connect an end of each one of the link rods (16) to the adjacent unitary frame member (12.1, 12.2). By this division of the flexible joints and of the divided frame members into parallel sub-components, the cross-sectional thickness of each individual hinge member is reduced, and thereby the bending stiffness and the outer fiber strain of the material of the hinge members is significantly reduced while providing the same total tensile strength and tensile stiffness. The link rods of each divided frame member effectively form a parallelogram linkage for moving and guiding the output members (12.1) in a parallel manner.

This invention relates to a strain monitor system for slope distributed fibers, which lays out several parallel special optical cables along the slope or at least lays out one close to the slope top and the corner separately, adheres symmetrically two fibers on the outer surface of a tilt testing tube to get the distortion of deep soil helped by the strain of the tube, the special optical cables are melted orderly to constitute a sensor circuit to be connected to BOTDR, which links with remote computers via local computer and internet to constitute distributed fiber strain monitor system and gets the distortion or displacement of the slope by integrating and summing the measured strain distribution further to evaluate and preset to the side slope.

A method and system for rendering the shape of a multi-core optical fiber or multi-fiber bundle in three-dimensional space in real time based on measured fiber strain data. Three optical fiber cores arc arranged in parallel at 120° intervals about a central axis. A series of longitudinally co-located strain sensor triplets, typically fiber Bragg gratings, are positioned along the length of each fiber at known intervals. A tunable laser interrogates the sensors to detect strain on the fiber cores. Software determines the strain magnitude (ΔL/L) for each fiber at a given triplet, but then applies beam theory to calculate curvature, beading angle and torsion of the fiber bundle, and from there it determines the shape of the fiber in s Cartesian coordinate system by solving a series of ordinary differential equations expanded from the Frenet-Serrat equations. This approach eliminates the need for computationally time-intensive curve-tilting and allows the three-dimensional shape of the optical fiber assembly to be displayed in real-time.

The invention discloses a submarine photoelectric composite cable omni-directional monitoring and fault point accurate positioning method in the technical field of measurement. According to the method, the Brillouin distributed strain/temperature measurement technology is employed, the online monitoring of the real-time operation of a submarine photoelectric composite cable is realized, the real-time operation state information of the submarine photoelectric composite cable is obtained through analyzing Brillouin distributed fiber strain/temperature measurement data and is combined with actual submarine cable state information, submarine photoelectric composite cable routing feature information is extracted, and the detection and accurate positioning of a submarine cable fault point are realized. When the submarine photoelectric composite cable is failed, a megohmmeter is employed to detect the characteristic of the cable fault, the cable fault type is judged, and a time domain reflection method is employed to carry out fault monitoring and position the cable fault point in the photoelectric composite cable. Combined with a fiber fault point obtained through a Brillouin light time domain reflection test and the cable fault point position obtained through the time domain reflection method, the fault point geographical position information of the submarine photoelectric composite cable is accurately obtained.

The invention provides a fiber mine water inrush precursor information monitor comprising a sensor array, a fiber splitter, a fiber grating demodulation device and a computer. The sensor array comprises a fiber temperature sensor, a fiber strain sensor, a fiber displacement sensor and a fiber osmotic pressure sensor which are all fiber grating sensors, and temperature, strain, displacement, osmotic pressure, and other physical quantities collected by the fiber grating sensors are sent to the fiber grating demodulation device by the fiber splitter through optical fibers; and the fiber grating demodulation device converts collected light wavelength signals into electric signals and finally sends the electric signals to the computer, and the computer analyzes and monitors on-site information by a software system in real time.

A method and system for determining strain impressed on an optical fiber at a possibly indeterminate temperature. The fiber (14) is formed with at least two sensors having different strain and temperature characteristics, preferably a Bragg Fabry-Perot sensor having a Fabry-Perot cavity (16) formed between two like Bragg gratings (10, 12) and another Bragg grating 18 of a different pitch written into the Fabry-Perot cavity. Many such pairs can be written if the Bragg gratings reflect in different bands. The fiber is irradiated with broadband light, and the reflection is spectrally separated to produce separate spectra for all sensors. Wavelength shifts from two types of sensors can be correlated with strain and temperature according to predetermined variations of the shifts with known strain and temperature changes.

A tunnel convergence deformation distribution fiber monitoring method is disclosed. A setting method of a distributed fiber convergence deformation monitoring sensor is adopted. The method is characterized in that: a sensing fiber is arranged on a matrix sheet material surface which has a same shape with an inner-side curved surface of a shield tunnel concrete segment so as to form a distributed fiber convergence deformation sensor and two ends of the sensor are respectively fixed on the inner side of the concrete segment; a cross section is in shapes of a rectangle, a U shape, a semi-circle or an arc or a circular ring; the sensing fiber has two parallel paths; one path is tight buffer fiber, which is used to measure strain alonga radial direction of the sensor; the sensing fiber is arranged on the surface of the sheet material sensor; using Brillouin optical time domain analysis (BOTDA) method, through calibrating correlation between a sensor gauge length convergence value and sensing fiber strain variation, convergence state change information of the tunnel section can be converted and measurement of the tunnel section convergence value can be performed. By using the invention,monitoring and measuring precision of the convergence state of the any representative section of the tunnel is high.

The invention relates to a scheme for quickly positioning breakage of an inner geomembrane in anti-seepage engineering, belonging to the technical field of anti-seepage in hydraulic engineering (civil engineering). The method of the invention comprises the following steps of: integrating continuous fibers and the geomembrane, wherein the fibers are arranged uniformly like a snake in the geomembrane, and the distance among the optical fibers is less than or equal to a strain sensitive distance of double fibers; taking the geomembrane as an anti-seepage material and conducting light paths of the fibers in the whole anti-seepage area; leading out the terminals of the fibers to a fiber strain detecting device for covering a protective layer of the geomembrane; and according to the arrangementdesign of the anti-seepage engineering, establishing a conversion expression between the fiber length L and the XY coordinate values of an anti-seepage surface. Fiber open circuit or abnormal strain caused by the breakage of the geomembrane can be found by a distributed detection system, and the breakage position of the geomembrane can be quickly and accurately determined by the conversion between the fiber length and a laying distance, thereby gaining precious emergency repair time for a dam of which the geomembrane is damaged, and effectively reducing the occurrence of dam collapse disasters.

The utility model discloses a distributed high-precision long-gauge-length carbon fiber strain test device and a method, and relates to the technical field of health detecting and monitoring in a civil engineering traffic structure. One of long-gauge-length carbon fiber strain sensors is taken as a working piece, the other long-gauge-length carbon fiber strain sensor is taken as a temperature compensating piece; a signal output end of a Wheastone temperature compensating bridge is connected with a signal input end of a primary signal, a signal output end of the primary signal is connected with a signal input end of a singlechip, and a signal output end of the singlechip is connected with a signal input end of a high-credibility approximate truth value. The invention aims at providing the distributed high-precision long-gauge-length carbon fiber strain test device for sensing performance of the comprehensive carbon fiber materials in the small strain range, which realizes the sensing of small strain of structures in large range under the condition of long-term unstable temperature so as to achieve the continuous detecting and monitoring on the stress (strain) of the structure.

The invention discloses a fiber strain sensitive structure and a manufacturing method thereof. The fiber strain sensitive structure comprises a left fiber fixing seat, a spring and a right fiber fixed seat which are in fixed connection in sequence, wherein the left fiber fixed seat is provided with a first through hole of which the left and right ends are communicated; the right fiber fixed seat is provided with a second through hole of which the left and right ends are communicated; and after penetrating through the first through hole of the left fiber fixed seat, the spring and the second through hole of the right fiber fixed seat, the fiber is stretched and fixed to the left and right fiber fixed seats; and a fiber strain sensitive unit on the fiber is positioned in the spring. The fiber strain sensitive structure has the characteristics of bidirectional stress strain, wide elastic range, favorable linearity, fatigue resistance, simple manufacturing method and low cost.

The invention relates to a tunnel runtime deformation monitoring forecast system and method. The system comprises distributed fiber sensors (1) arranged in a monitoring section (A) of a tunnel, a fiber strain analyzer (2), a fiber (3), a data transmission unit (4), a GPRS module (5) and a monitoring center computer (6), wherein tunnel deformation quantity and tunnel deformation rate data which are collected by the distributed fiber sensors (1) are stored in the fiber strain analyzer (2) and is transmitted to the data transmission unit (4) disposed outside the tunnel through the fiber (3), and the data transmission unit (4) transmits the tunnel deformation quantity and tunnel deformation rate data to the monitoring center computer (6) through the GPRS module (5). The system and method combine a neural network method with a gray model method to carry out tunnel surrounding rock deformation quantity and deformation rate prediction, enable a monitoring result to be more scientific and reasonable, is more accurate in prediction result and is more scientific and systemic in monitoring prediction management.

The invention discloses a long-scale-distance carbon fiber strain sensor which comprises a long-scale-distance carbon fiber strain sensor core wire, an anchorage section and a packaging layer. The two ends of the long-scale-distance carbon fiber strain sensor core wire are fixed to the anchorage section and packaged into the packaging layer in an insulating mode. The long-scale-distance carbon fiber strain sensor core wire is provided with a notch enabling the section of the long-scale-distance carbon fiber strain sensor core wire to be reduced in the fiber direction of the long-scale-distance carbon fiber strain sensor core wire, and the notch is the inner notch penetrating through the interior of the long-scale-distance carbon fiber strain sensor core wire or the outer notch formed in the outer surface of the long-scale-distance carbon fiber strain sensor core wire. The area of the notch is 0.5-5 percent that of the long-scale-distance carbon fiber strain sensor core wire. Long-term monitoring on small strain variation by the long-scale-distance carbon fiber strain sensor core wire is achieved, the long-scale-distance carbon fiber strain sensor has a sensing substrate and a packaging material which have the stable chemical quality, the measuring requirement for the small strain variation in long-term monitoring is met, and the precision of the sensor is improved.

The invention discloses a long-gauge length carbon fiber strain sensing device. The long-gauge length carbon fiber strain sensing device comprises two groups of long-gauge length carbon fiber strain sensing elements with the same geometric size, three isolation film layers with the same size, a measurement connector, two anchoring sections and two parallel connectors, wherein one ends of the long-gauge length carbon fiber strain sensing elements are connected with the parallel connectors through electrodes respectively, the other ends of the long-gauge length carbon fiber strain sensing elements are connected with the measurement connector in series, and the two groups of long-gauge length carbon fiber strain sensing elements are located between adjacent isolation films respectively and have the same strain sensitivity coefficient and the same thermosensitivity coefficient. The long-gauge length carbon fiber strain sensing device achieves sensing of micro structural strain within a large range under long-term instable temperature and humidity conditions to meet civil engineering structural stress (strain) continuous detection and monitoring requirements.

A cable including an outer metal tube and a first layer wire inside the outer metal tube, wherein the first layer wire has five inner elements surrounding a metallic center member and at least one of the inner elements is a metal tube containing an optical fiber.

The invention discloses a total-stress fiber monitoring device for a thread-steel anchor rod, so as to achieve the long-time monitoring of the total stress state of the thread-steel anchor rod on thebasis of guaranteeing the overall integrity of the thread-steel anchor rod, and accurately monitor the stress and temperature change conditions of the thread-steel anchor rod as the reliable data support for the analysis of the stress state and slope stability of a support and protection structure. The thread-steel anchor rod is fixedly provided with buckle parts at intervals in the length direction, and a distributed fiber sensor is connected with the buckle sensors, thereby forming a thread-steel anchor rod - distributed fiber sensor assembly. The distributed fiber sensor comprises a distributed fiber strain sensor and a distributed fiber temperature sensor, which are arranged at intervals in the peripheral direction of the section of the thread-steel anchor rod. The buckle parts achievethe multi-point clamping of the distributed fiber strain sensor. The thread-steel anchor rod - distributed fiber sensor assembly is buried in a slurry solidified body in a monitoring hole.

The invention discloses a distributed measurement device and method of pile body deformation of a cast-in-place X-type pile. The distributed measurement device comprises the cast-in-place X-type pile, a fiber strain tester, reinforcing steel bars and single-mode fibers. The single-mode fibers are laid inside the reinforcing steel bars, the reinforcing steel bars are arranged at the outer edge of the cast-in-place X-type pile in a cast mode, and the fiber strain tester is connected with the single-mode fibers. The new measurement method includes the steps of arranging the single-mode fibers at the outer edge of the cast-in-place X-type pile, receiving Brillouin back scattered light at the pulsed light incidence ends of the single-mode fibers through the Brillouin optical time domain reflecting technology, completing the measurement and positioning functions of Brillouin frequency shifting of points on the single-mode fibers by analyzing the power of Brillouin back scattered light, and then obtaining deformation of the cast-in-place X-type pile to be measured. Strain measurement is carried out on the cast-in-place X-type pile through the single-mode fibers, and the survival rate of fiber sensors is remarkably improved; meanwhile, the method has the advantages of being high in measurement accuracy, small in shifting, good in stability and the like; in addition, the method further has the advantages that the sensors are easy to arrange, wires connected with the sensors are fewer, and the construction technology is simple.

The invention provides a split type optic fiber strain sensor assembly. Under the premise that fiber bragg grating prestressed encapsulation is not influenced, an encapsulation mode and an assembling mode are decoupled, and the problem that a sensor cannot be used again after being mounted once is solved through separation of a metal encapsulation protection piece and an assembling base. The split type optic fiber strain sensor assembly comprises a sensing element, the encapsulation protection piece and the assembling base. The sensing element is a fiber bragg grating, and the encapsulation protection piece is a metal tube. After the fiber bragg grating penetrates through the mental tube, the clearance between the fiber bragg grating and the metal tube is welded and fastened in an ultrasonic welding mode. Optical fibers are led out from the two ends of the metal tube. The two ends of the metal tube are banded tightly through flange plates. The metal tube with the encapsulated sensing element is supported by the assembling base, and the flange plates at the two ends of the metal tube are connected with the assembling base.

An exhaust duct for a gas turbine engine has an inner wall and an outer wall connected by a plurality of spaced ribs. The duct extends axially. The ribs extend circumferentially across an entire cross-section of the inner and outer walls. The plurality of ribs is spaced axially along the exhaust duct. The inner wall has an inner surface facing an inner chamber. The inner surface receives a coating. The coating is deposited on a metal wire fiber strain isolation pad which is connected to the inner surface.

The invention discloses a distributed fiber strain demodulation method based on a subset window length optimization algorithm. According to the invention, through two parameters of noise variance andRayleigh scattering spectrum quality, a user is guided to carry out optimal selection on the size of the subset window. By mainly use of the mutual correlation analysis, the offset quantity between areference Rayleigh scattering spectrum and a measurement Rayleigh scattering spectrum is calculated, so strain information in a measured fiber is obtained. The lengths of the two groups of Rayleigh scattering spectrum subsets used for mutual correlation calculation is the subset window defined by the user based on experience. The subset window significantly affects the reliability of the mutual correlation calculation and the precision of strain measurement. By rationally optimizing the subset window, important effects are achieved for improving of the mutual correlation reliability and the strain calculation precision.

A socket-type pipe joint deformation measurement device based on a distributed optical fiber strain sensor and a measurement method thereof belong to the field of structural health monitoring. The measuring device includes three distributed optical fibers and three bow-shaped measuring devices, and the three bow-shaped measuring devices are evenly distributed around the socket-type pipeline interface; one end of the bow-shaped measuring device is fixed on the outer wall of the insertion head, and the other end is fixed on the bearing On the outer wall of the plug, the distributed optical fibers are sequentially fixed on the outer wall of the insertion head, in the arcuate optical fiber groove and on the outer wall of the socket plug. The outer side of the bow-shaped measuring device is provided with a protective shell fixed on the socket-type tube. The measuring device can operate normally after being buried in the ground, can make the distributed optical fiber measure the deformation of the socket-type pipeline interface, broaden the application range of the distributed optical fiber in pipeline health monitoring, and is easy to operate and simple and practical in structure. By analyzing the deformation state of the actual pipe joint through the monitoring data, it can be found in time when the socket joint is dangerously deformed.