388 results about "Axial strain" patented technology

A well logging cable including an optical fiber and a pressure sealed enclosure surrounding the fiber. The enclosure is adapted to be able to be elongated to the maximum expected axial strain on the logging cable without permanent deformation. In one embodiment, the enclosure is a corrugated-wall tube surrounding the optical fiber. The tube contains toroidally shaped rings within the maximum diameter portions of the corrugations in the tube wall. The cable includes armor wires wound around the corrugated-wall tube. In the preferred embodiment, the tube is surrounded by an elastomeric jacket, and is filled with hydraulic oil or the like to prevent entry of wellbore fluids into the tube under hydrostatic pressure.

The invention relates to a method and a system for monitoring and warning a pipeline landslide based on a fiber Bragg grating and a method for constructing the system. The monitoring is performed on four parts including landslide depth displacement, landslide surface displacement, thrust of landslide on a pipeline and pipeline strain, and comprises the steps of: firstly, inserting an inclinometerpipe (1) pasted with a fiber Bragg grating sensor from the landslide (13) to all potential sliding surfaces (15); secondly, embedding a slender concrete ground beam (2) of which two ends are fixedly restrained and the axial direction of a central reinforced bar (17) is stuck to a ground beam fiber Bragg grating sensor (20) in a direction vertical to the deformation direction of the landslide (13)below the surface of the landslide (13); thirdly, measuring the thrust of the landslide (13) on the pipeline by using an earth pressure cell fiber Bragg grating sensor (4) fixed on the pipeline (14);and fourthly, arranging monitoring sections on edges on two sides and the pipeline (14) in the center of the landslide (13), and uniformly arranging three pipe strain fiber Bragg grating sensors (3) on each monitoring section to monitor the axial strain of the pipeline (14).

An interferometric measurement system includes a spun optical fiber including multiple optical waveguides configured in the fiber. Interferometric detection circuitry detects measurement interferometric pattern data associated with each of the multiple optical waveguides when the optical fiber is placed into a bend. Data processing circuitry determines compensation parameters that compensate for variations between an optimal configuration of the multiple optical waveguides in the fiber and an actual configuration of multiple optical waveguides in the fiber. The compensation parameters are stored in memory for compensating subsequently-obtained measurement interferometric pattern data for the fiber. The compensation parameters are applied to the subsequently-obtained measurement interferometric pattern data in order to distinguish between axial strain, bend strain, and twist strain on the fiber and to accurately determine one or more strain values for the fiber corresponding to one or more of the axial strain, bend strain, or twist strain on the fiber.

A system for measuring parameters of a structure, the system in certain aspects having a plurality of strain gauges emplaceable on the structure, signal transmission apparatus associated with the plurality of strain gauges for transmitting signals therefrom indicative of gauge measurements to computer apparatus for processing the signals, the gauges, in one aspect, including at least three strain gauge apparatuses for providing axial strain measurements, and computer apparatus for receiving signals from the transmitting apparatus indicative of the measurements and for determining bending moment and bending direction of the structure at a location of the gauge apparatuses, and in one aspect wherein the computer apparatus is programmed to calculate internal pressure and/or bending direction of the structure based on the measurements, and in one aspect to do so in real time.

The invention relates to a method for monitoring the stress of a casing in a well by applying optical-fiber sensors, which mainly solves the problem that the existing research field of the casing erosion of an oil field and oil-water well does not have a direct method for monitoring the stress loading process of the casing in the well and the morphological characters of the casing erosion. The method is characterized in that: optical-fiber grating sensors are circumferentially arranged along the outer surface of the casing; a ground optical-fiber grating demodulation instrument connected with the optical-fiber grating sensors is utilized to monitor the circumferential strain Epsilon Theta of the casing and obtain the circumferential strain data of the casing; meanwhile, Brilliouin optical-fiber sensors are axially arranged along the outer surface of the casing; a ground Brilliouin optical-fiber demodulation instrument connected with the Brilliouin optical-fiber sensors is utilized to monitor the axial strain Epsilon Z of the casing and obtain the axial stain data of the casing; and the obtained circumferential strain Epsilon Theta and the axial strain Epsilon Z of the casing are utilized to obtain the stress of the outer layer of the casing in the well according to a ground stress explanation model. The method is characterized by being capable of permanently monitoring the deformation of the casing and obtaining corresponding stratum pressure under the condition without knowing the casing erosion and the stratum pressure.

The invention relates to a method and a system for monitoring and warning pipeline landslide depth displacement and a method for constructing the system. The monitoring is divided into three parts including landslide depth displacement monitoring, monitoring of thrust of landslide on a pipeline and pipeline strain monitoring, and comprises the steps of: inserting an inclinometer pipe (1) pasted with a fiber Bragg grating sensor into the landslide (13), penetrating all potential sliding surfaces (15), extending the inclinometer pipe to a drilling hole 3 to 5m deep under a bedrock surface, and measuring the maximum tension strain born by the inclinometer pipe (1); measuring the front thrust of the landslide (13) on the pipeline by using a packaged earth pressure cell fiber Bragg grating sensor (4) fixed on the pipeline (14); and uniformly arranging pipeline (14) monitoring sections on edges on two sides of the landslide and the pipeline (14) in the center of the landslide (13), and uniformly arranging three pipe strain fiber Bragg grating sensors (3) on each monitoring section to monitor the axial strain of the pipeline (14).

An intravascular catheter having a shaft, at least a portion of which includes a braid reinforcement with an axial wire or fiber disposed between the helical members that form the braid. The axial member prevents the elongation of the shaft of the catheter thereby maintaining one-to-one correspondence in axial manipulation of the catheter, even when the shaft is placed in tension. By positioning the axial member between the helical members, the axial member does not create a protrusion and does not become fixed to any adjacent polymer layer. Thus, the axial member limits axial strain of the catheter, without creating the undesirable effects of friction caused by an axial protrusion and without creating the undesirable effects of limited flexure caused by an adjacent polymer layer becoming fixed to the axial member.

The invention provides a cable force monitoring device for an attached-type stay cable. In the technical scheme of the invention, a reliable composite semi-rigid contact cohesion-type mechanical deformation transmitter is installed at the position of a fixed scale distance on a stay cable with a traditional structure; a temperature self-compensating fiber grating precision strain transducer is adhered to the surface of the stay cable through the composite semi-rigid contact cohesion-type mechanical deformation transmitter; and the axial strain caused by the change of the pulling force applied to the stay cable in a scale distance is measured; the axial strain of the stay cable is converted into optical signals through the fiber grating precision strain transducer, and the optical signals are transmitted to a collecting demodulation terminal through an optical cable for demodulation; and testing software automatically calculates the corresponding cable force variation value according to strain measurement data, stay cable cross section geometric parameters and mechanical property parameters of stay cable materials, and further the automatic real-time dynamic monitoring of the stay cable is realized.

The invention belongs to the technical field of building construction stress testing and relates to a method for testing the pile shaft stress of a static pressure high-strength pre-stressed concrete pipe pile. When tensile force or pressure is received by a fiber Bragg grating sensor, the optical fiber grating period is changed due to the extension or the compression of the sensor, and therefore the effective refraction rate of the FBG sensor is changed. According to the axial strain of one section of the high-strength pre-stressed concrete pipe pile, the pile shaft stress of the static pressure high-strength pre-stressed concrete pipe pile is obtained, and therefore the axial force of a pile shaft, the side friction and the pile tip resistance are obtained. The method for testing the pile shaft stress of the static pressure high-strength pre-stressed concrete pipe pile is simple, convenient to operate, high in measuring accuracy, high in sensitivity, strong in electromagnetic field interference resistance, high in rate of survival, and capable of achieving quasi-distributed and automatic monitoring easier compared with a method of a traditional force testing element.

The invention discloses a large-scale true tri-axial test method and a large-scale true tri-axial test device, which can be used for carrying out the true tri-axial test on an original grading rockfill body. The device is arranged in a concrete cave chamber; six faces of a sample are loaded by rigid slabs; three directional main stress is applied by a hydraulic jack controlled by adopting a hydraulic system; two layers of rubber membranes are sleeved at the inner side of a steel plate so as to reduce friction; silicone grease is coated between the rubber membranes; and rigidity compression plates are respectively provided with a displacement sensor or a dialgage used for determining the deformation of the sample in all directions. The device can be used for testing a large-sized original grading sample of the rockfill body, therefore, the size effect can be completely avoided, larger axial strain can be achieved, and a complicated stress-strain path can be simulated.

A system and method are provided for determining wall thickness of a structure such as a metallic pressurized pipe. The system includes an optical fiber having a plurality of Fiber Bragg Gratings (FBGs), and a mounting for securing the FBGs over discrete portions of the exterior surface of the pipe such that strain in the pressurized pipe wall is transmitted to the FBGs. The system further includes a light source and a light sensor coupled to an end of the optical fiber. The light sensor converts light reflected back from the FBGs into electrical signals that a digital processor converts into strain measurements. The FBGs are mounted around portions of the pipe expected to have significant metal loss as well as portions of the pipe expected to have negligible metal loss. The method includes at least one of comparing relative strains at locations with negligible metal loss to those with significant metal loss to accurately determine the thickness of the wall with metal loss; compensating for temperature effects by considering relative strains at areas of the pipe with and without metal loss; and measuring axial strain on the pipe with one or more of the FBGs to correct for at least one of bending and torsion effects on hoop strain.

A bending beam load cell can be compensated for side-to-side off center load sensitivity by simple electrical adjustments if a pair of shear sensing strain gages are bonded to each bending beam midway between axial strain gages used to measure bending strains. The shear sensing strain gages measure torque on the load cell, and are incorporated in bridge circuits that make it possible to vary the amount of torque sensitivity correction by changing the value of a trimming resistor. The bridge circuits also include circuit components for compensation of front-to-back off center load error and for zero adjustment. Four strain gages on each bending beam can be part of a single composite strain gage element, so the shear sensing strain gages do not add any cost to the load cell. Such a load cell can also be hermetically sealed before any compensation of offset load errors is done.

An instrumented pin member is provided that is capable of measuring bending moments, and optionally of measuring bending and axial strain in real or near real time. The instrumented pin member includes a pin member body disposed about a pin member axis, wherein the pin member body includes a bending portion. A sensing device is positioned at the pin member body within the bending portion for sensing a bending strain in the bending portion exclusive of a net axial strain, and for outputting a sensor measurement signal representative of the bending strain. A sensor measurement signal output device is provided for outputting the sensor measurement signal from the sensor device. A related system includes a plurality of pin members, among other things. Related methods also are disclosed.

The invention discloses a temperature-controllable rock uniaxial compression sound emission test device and a temperature-controllable rock uniaxial compression sound emission test method. The test device comprises a loading system, a heating system, a temperature control system, a strain system and a sound emission system, wherein the heating system, the temperature control system, the strain system and the sound emission system are all arranged on the loading system. According to the test method, a rock sample is arranged inside a soft shell, heating resistance wires are distributed around the outside of the shell, and a temperature sensor, radial and axial strain gauges and a sound emission sensor are arranged, so that the uniaxial compression multi-channel sound emission detection test can be implemented. According to the test device and the test method, the sound emission detection of the rock sample under different temperature environment influences can be simulated. The test device has a simple structure, is convenient to operate and can be used for simulating the sound emission detection demands of rock materials under different temperature environments indoors.

The invention relates to an operational method for measuring creep parameters and infiltration parameters of smashed rocks simultaneously, which realizes loading of axial pressure and infiltration pressure difference by the aid of a smashed rock creep-infiltration full-process coupling testing device. The operational method includes: firstly, determining initial height of rock in a cylinder before loading, starting an axial loading device then, starting an electric test pump to saturate rocks, applying axial load, injecting water to the rocks to infiltrate according to set water pressure, finally changing the axial load to perform the creep-infiltration test of the next-grade stress stage. The infiltration characteristic parameters are obtained by matching of a scatter diagram of hole pressure gradient and average infiltration speed and the Forchheimer formula, and the creep parameters are obtained by matching of Kelvin-Volgt creep model and an axial strain time curve. The operational method has the advantages that creep model during creep and infiltration full-process couple of the smashed rocks can be acquired, mutual affection of creep and infiltration can be indicated through the parameters, operation results can provide theoretical basis for theoretical analysis and numerical value simulation of creep-infiltration of the smashed rocks.

The utility model provides a measuring device of a tubular part inner wall processing stress and a measuring method thereof, relating to the technical field of a measuring method of a tubular part inner wall processing stress. The device comprises a measured tubular part, and the outer peripheral surface of the measured tubular part is respectively provided with an axial strain piece and a tangential strain piece. The axial strain piece and the tangential strain piece are respectively connected with a strain gauge through conductive wires. The strain gauge is connected with a PC through a conductive wire. According to the device and the method, the measuring device has a simple structure, the measurement result is accurate, and the device is suitable for different tube diameters.

The invention discloses a method for constructing an elastoplasticity-damage coupling mechanical constitutive model of a rock material. The method comprises the following steps of obtaining the rock material on an engineering site, and manufacturing a standard cylinder sample; carrying out conventional triaxial compression mechanical tests under different confining pressures; obtaining a rock yield criterion, a plastic hardening criterion and a non-associated fluidity rule in combination with a test result; calculating a rock damage variable according to the stress-strain curve, and obtaininga rock damage evolution equation according to a damage variable-axial strain evolution rule; deriving a constitutive equation based on an elastic-plastic mechanics theory and an irreversible thermodynamic damage constitutive theory; combining the test data to obtain model parameters; writing the mechanical model into a UMAT subprogram, embedding the UMAT subprogram into ABAQUS finite element software, and carrying out triaxial test numerical simulation, so as to verify and improve the model. The method is clear in mechanical significance, simple in parameter acquisition, wide in application range and relatively high in accuracy.

The invention discloses a resonant type infrared detector structure capable of isolating packaging stress and a manufacturing method thereof, and belongs to the field of micro-electronic mechanical systems. The resonant type infrared detector structure is characterized by being composed of a micro-bridge resonator chip and a lower bottom plate. The micro-bridge resonator chip is composed of a micro-bridge resonator (1), a rectangular framework (2), two supporting beams (3) and a substrate (4). One end of each supporting beam (3) is fixedly supported by the substrate (4), and the other ends of the supporting beams (3) are connected with a pair of opposite sides of the rectangular framework (2). The two ends of the micro-bridge resonator (1) are fixedly supported between the other pair of opposite sides of the rectangular framework (2). The micro-bridge resonator (1), the rectangular framework (2) and the supporting beams (3) are suspended above a lower bottom plate (5). The thermal expansion of the lower bottom plate (5) cannot change the distance between one pair of opposite sides, supporting the micro-bridge resonator (1), of the rectangular framework (2), and the length, the axial strain and the resonant frequency of the micro-bridge resonator (1) cannot be changed.

In one aspect of the invention, each bolt is modeled using a beam element in a FEA model. To apply desired pretension to one or more bolts, at least one pretension-versus-time curve is specified. Each pretension-versus-time curve includes ramp portion, desired pretension portion and optional unloading portion. Duration_of the pretension-versus-time curve generally covers first 0.5-1% of total simulation time of a car crashworthiness analysis. Ramp portion starts from zero to desired pretension in a substantially linear manner, and hence being configured for applying desired pretension to a bolt gradually with smaller increments. Desired pretension portion is configured for ensuring the desired pretension can actually be applied to the beam element during an initialization process—a series of quasi-static analyses. Since the method is independent of the deformation of the beam, the method completely avoids the need to iteratively determine an axial strain or displacement that gives the desired pretension.

The invention discloses an asphalt mixture dynamic modulus testing method comprising the steps that: 1, with an asphalt mixture rotation compaction instrument, an asphalt mixture sample is formed; and through cutting, an asphalt mixture cylindrical sample with a fixed size is obtained; 2, two pressure heads are prepared; the sample and the two pressure heads are plated into an environment box with a target temperature; and the temperature is maintained for 5h; 3, the two pressure heads and the sample are fetched; the two pressure heads are respectively placed at central positions on two ends of the cylindrical sample; and sinusoidal axial compressive stress is applied to the sample with different frequencies under a specified test temperature; and 4, during the loading process, applied stresses and generated axial strains at corresponding times are determined, and the dynamic modulus is a ratio of the amplitude of sinusoidal load to the amplitude of generated sinusoidal strain. According to the method provided by the invention, with the local loading test, lateral restraint of the asphalt mixture in an actual pavement can be effectively simulated. The test device is simple, the operation is easy, and the method can be popularized.

The invention relates to an axial pre-tightening force sensor. The axial pre-tightening force sensor comprises a regulating gasket 2, a left end cover 3, an elastic sensitive element 4, a strain gage 5, a right end cover 6, a thrust ball bearing 7, an axial hole groove 9, a right bolt 10, a fairlead 11, a package shell 12 and a left bolt 13. The regulating gasket is used for regulating the axial position of the sensor on a shaft, the left end cover and the right end cover support the elastic sensitive element through bosses, the elastic sensitive element generates axial strain because of bearing axial force, and the axial force can be measured through the resistance strain effect and a measuring circuit. The axial hole groove 9 in the right end cover 6 of the sensor is matched with the right bolt 10 to be used for preventing the elastic sensitive element from generating circumferential strain in a pre-tightening process, axial displacement of the right end cover 6 and axial strain of the elastic sensitive element 4 are allowed, and the thrust ball bearing is used for insulating circumferential twisting force generated when the pre-tightening force is exerted so that the axial twisting force can be prevented from being transmitted to the elastic sensitive element 4.

The invention provides a distributive stress measurement-based pipeline interior corrosion monitoring method, belonging to the technical field of optical fiber sensing. The monitoring method comprises the following steps: measuring circular and axial strain distribution on the surface of a metal pipeline by adopting an optical fiber monitoring network, and drawing a circular and axial strain cloud picture, and positioning the corrosion position and corrosion range according to the stress distribution on the surface of the metal pipeline; calculating the strain of a corrosion area through the measured circular and axial stress of the corrosion area, and judging whether the pipeline in the corrosion area is invalid according to the stress and strain. The monitoring method has the effects and benefits that the safety situations of the metal pipeline can be monitored in real time, the corrosion defects can be positioned to obtain corrosion range, and whether the pipeline is invalid can be directly judged according to the stress and strain of the pipeline; and the monitoring method has the advantages of being safe and reliable, high in measurement precision, and non-destructive to a structure.