34 results about "Hoop strain" patented technology

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 method of repairing a section of pipe is described. The method includes applying a first split sleeve and a second split sleeve to the pipe section, functionally associating the first end of the first split sleeve with the first end of the second split sleeve, and applying a compressive force until the internal diameter of the pipe experiences compressive shear hoop strain. The method described produces substantially uniform compressive hoop strain along the length of the pipe section, and may exceed a predetermined value, such as 100 microstrain in compression, for example. The amount of force required may be calculated utilizing maximum operating conditions. The method described may produce an acceptable permanent repair by ensuring that the inner diameter of the section of pipe experiences compressive strain. Also described is a method of reinforcing a section of pipe utilizing these apparatus and methods.

A bolt shear force sensor for in-service monitoring is provided in which the sensor includes a deformable ring with channel-like cross-sections and a wire egress hole. The ring surrounds a bolt or fastener to be tested. The channel-like cross sections face exterior to a center of the ring. Strain sensing elements are mounted within the channel cross-sections as an outer circumference of the ring. The sensing elements capture hoop strain from surrounding plates of the operating system which holds the fastener. A signal conditioner operationally connected via wire conductors is used to convert strain sensing signals from the sensing elements to strain output. The strain outputs are then used in conjunction with a calibration curve of shear force versus strain to determine the magnitudes and directions of the resultant shear forces.

The invention discloses a strain hoop sensor used for measuring the hoop strain of a pipeline and belongs to the technical field of sensing. The strain hoop sensor is characterized by being packaged by a double-layer capillary steel pipe, wherein the strain hoop sensor packaged by a double-layer capillary steel pipe is tightly looped to the pipeline by virtue of a metal support and a clamping piece, and the capillary steel pipe is pasted to the outer wall of the pipeline by virtue of epoxy resin. The arc diameter of the contact surface of the metal support and the pipeline is equal to the external diameter of the pipeline, and the metal support is tightly contacted with the pipeline. The measuring sensitivity of the sensor can be adjusted by changing the sizes of elements of the sensor according to the actual requirements. The strain hoop sensor provided by the invention has the effects and advantages that the strain hoop sensor used for measuring the hoop strain of the pipeline can measure the hoop strain of the section of the pipeline, and has high sensitivity; and moreover, the strain hoop sensor can be used for overcoming the defects of small measuring scope, low precision, high possibility of influence caused by electromagnets, poor long-term stability and the like of a resistance strain gauge.

The invention discloses a mine filling material compression characteristic experiment device and an experiment method thereof. The experiment device is arranged on a pressure machine, and comprises a cavity for holding a filling material, wherein a bleeding structure is arranged at the bottom end of the cavity; the other end of the cavity is sealed through a slidable piston in the cavity; the bottom end of the cavity is arranged on a lower pressure-bearing plate of the pressure machine; a pressure-bearing column connected with the piston contacts an upper pressure-bearing plate of the pressure machine; an outer wall of the cavity is provided with a plurality of hoop strain foils at different axial positions in a pasting way; the hoop strain foils are connected with a statical strain indicator; a displacement sensor is also arranged between the upper pressure-bearing plate and the lower pressure-bearing plate of the pressure machine; the statical strain indicator and the displacement sensor are in signal connection with a computer connected with a pressure machine measuring system. The mine filling material compression characteristic experiment device provided by the invention can be used for monitoring compression amounts of the filling materials under different stresses and a strain level of an outer wall of a steel cylinder through the pressure machine measuring system, and is simple in structure, convenient to operate, and applicable to compression characteristic tests of dry filling bodies, water sand filling bodies, cemented filling bodies and other filling bodies.

The invention provides a calculation method of a pipe joint hoop strain of a tide load sinking pipe tunnel. The method includes steps of, assuming a back silt layer on the pipe joint as an impervious bed, and regarding the change of the tide level as a large area load pO added on the impervious bed, wherein the location of an underground level is the top face of the impervious bed; not considering about influence of tide on the pipe joint structure, calculating water, soil pressure and subgrade reaction acted on the outer wall of the pipe joint; applying a winkler foundation module, regarding the loop strain calculation as the plane strain problem; analyzing the loop stress and deformation of the pipe joint structure by a load-structure method; through the calculation of cross model stress of the pipe joint, acquiring the relationship of the loop stress strain relationship of the pipe joint; finally, through calculation, acquiring the loop strain distribution of inner and outer walls of the pipe joint under one tide level and influence of the loop strain of every point of inner and outer walls of the pipe joint along with the change of the tide level. The calculation result can be used for predicting the loop strain of the pipe joint of the sinking pipe tunnel in operation stage, judging the part where may generate crack, and carrying out key monitoring and prevention.

The invention discloses an improved pleated trocar seal membrane. Said seal membrane comprises a proximal opening, a distal aperture, and a sealing wall which extends from the distal aperture to the proximal opening, said distal aperture formed by a sealing lip for accommodating the inserted instrument and forming a gas-tight seal. Said sealing lip comprises a longitudinal axis and a transverse plane substantially perpendicular to said axis. Said sealing wall comprises a plurality of pleats extending laterally from the sealing lip. Each said pleat comprises a pleat peak, a pleat valley and a pleat wall extending there between. And the lip-adjacent area, the depth of the pleat wall gradually increases along the longitudinal axis; while outside the lip-adjacent area, the depth of which gradually decreases along the longitudinal axis. Said pleats enlarge hoop circumference, and reduce the cylinder hoop strain (stress) when a large diameter instrument is inserted, thereby reducing the hoop force and the frictional resistance.

The invention discloses a synchronous calibration device and method for strain and a temperature of a distributed sensor fiber (cable). The synchronous calibration method comprises the following stepsof uniformly winding fibers (cables) to be calibrated around an outer wall of a calibration barrel during calibrating a strain coefficient, gradually adding weights, calculating hoop strain of the calibration barrel under different loads according to elastic modulus of the calibration barrel and poisson ratio, reading spectrum information under each level of load by a fiber data demodulator, building a relation between the hoop strain and the spectrum information, and calibrating the strain coefficient; achieving control on a temperature of the calibration barrel by a temperature control boxduring calibrating a temperature coefficient, acquiring the spectrum information under different temperatures by the demodulator, and calibrating the temperature coefficient. By the synchronous calibration method, the strain coefficient and the temperature coefficient can be independently or synchronous calibrated, the strain generated by an external force effect and the influence of environmentaltemperature change on the spectrum information can be simultaneously determined, the cross effect between the strain and the influence is analyzed, and a calibration effect has high accuracy and is more confirm to an actual application condition.

The invention discloses a controllable-pretension FBG (Fiber Bragg Grating) strain hoop gripper system, and belongs to the technical field of a sensor. The controllable-pretension FBG strain hoop gripper system is characterized by being applied to an FBG strain hoop sensor and being used for measuring hoop strain of a pipeline; the controllable-pretension FBG strain hoop gripper system has the key that a long-rod screw is screwed in the end part by penetrating through a screw hole so as to push a wedge to slide forwards, the increment of an FBG wave length is controlled according to the reading of an interrogator, the controllable pretension is realized, the sensor is tightly attached to the outer wall of the pipeline, and optical fibers at the inner part of the sensor can be always in an effective tension measuring state. The pretension-controllable FBG strain hoop gripper system disclosed by the invention has the beneficial effects that problems that the FBG strain hoop sensor cannot be in tight contact with the pipeline, and the hoop strain of the pipeline cannot be accurately measured are solved, the accuracy of the FBG strain hoop sensor is increased, and the pretension-controllable FBG strain hoop gripper system has the advantages that the pretension can be controlled, the manufacturing and the installing are simple and convenient, the mass production is suitable for being carried out, and the like.

The invention provides a method for testing a rock expansion force, comprising the following steps: S1, processing the rock into a rock sample; S2, wrapping an adhesive layer on the outer peripheral surface of the rock sample, and determining an elastic modulus E; S3, soaking an artificial core with water, and recording a hoop strain epsilon of the adhesive layer; and S4, taking the data obtainedin the S2 and S3 into the formula: sigma is equal to Eepsilon, and calculating the formula to obtain an expansion force sigma at the junction of the adhesive layer and the rock sample, wherein sigma is the expansion force of the rock sample. By processing a rock sample into an artificial core having an adhesive layer, pre-calculating the elastic modulus E of the adhesive layer, then soaking the artificial core with water, and obtaining the expansion force due to formula calculation by recording the hoop strain epsilon of the adhesive, the method for testing a rock expansion force provided by the invention greatly reduces personal errors and improves the accuracy of the test, compared with the traditional method of reading for many times by a vertical dial gauge.

The invention provides a method and system for calculating extrusion stress of an isotropic double-pipe concrete column, and the method comprises the steps: 1, obtaining calculation parameters of a double-pipe concrete column, including the Poisson's ratio and elastic modulus of internal core concrete and external interlayer concrete, and the Poisson's ratio, elastic modulus, inner diameter and wall thickness of an internal pipe and an external pipe; 2, establishing an extrusion stress relationship among all parts of the double-pipe concrete column; 3, substituting calculation parameters into the step 2 to obtain the extrusion stress between the parts; 4, based on the calculation parameters and the result obtained through solving in the step 3, obtaining the annular and radial strain of the inner core concrete, the annular stress and the annular strain of the inner pipe, the radial and annular stress of the outer interlayer concrete changing along the thickness and the radial and annular strain of the outer interlayer concrete changing along the thickness, the circumferential strain of the inner side and the outer side of the outer interlayer concrete and the circumferential stress and the circumferential strain of the outer pipe.

The invention discloses a radial deformation measuring device based on an LVDT sensor. The device comprises an auxiliary tooling and a sensor device. The sensor device comprises a flexible iron wire,an LVDT coil, an LVDT core, a spring and a bolt. A sample is fixed between the flexible iron wire and the auxiliary tooling, one end of the flexible iron wire is connected to a bolt and is fixed on one side of the auxiliary tooling, the other end of the flexible iron wire is sequentially connected to the spring and the LVDT core in series and passes through the LVDT coil, and the LVDT coil is fixed to the other side of the auxiliary tooling. The device is simple to assemble, the radial deformation value can be effectively amplified, the measurement accuracy is improved, and the hoop strain ismeasured without affecting an explosive test.

The invention discloses a coke tower inner wall stress calculation method. The method comprises steps: hoop strain epsilon(theta)o and axial strain epsilon(z)o data of an outer wall measurement point on the coke tower are acquired; according to the hoop strain epsilon(theta)o and axial strain epsilon(z)o data, the outer wall hoop stress sigma(theta)o of the outer wall measurement point on the coke tower is calculated and acquired; the outer wall hoop stress sigma(theta)o is equal to outer wall thermal stress sigmaTo, the change rate capped tau of a temperature difference between the inner wall and the outer wall along with time is calculated and acquired through a thermal stress formula; according to the change rate capped tau of the temperature difference between the inner wall and the outer wall along with the time and the inner wall hoop stress sigma(theta)i equal to the inner wall thermal stress sigmaTi, the inner wall hoop stress sigma(theta)i is calculated and acquired through the thermal stress formula. The coke tower inner wall stress calculation method is high in precision and low in cost.