79 results about "Axial strain" patented technology

The invention discloses a roadway roof damage time prediction method and system, and belongs to the technical field of mine rock mechanics and safety engineering. Comprising the following steps: recognizing a roof rock stratum structure and lithology of each layer through drilling peeping, and drilling a representative rock sample; determining the crack initiation strength and peak strength of the rock sample through a uniaxial compression test; selecting a plurality of stress levels between the axial strain and the acoustic emission signal to carry out a creep test, synchronously monitoring the axial strain and the acoustic emission signal, and determining an accelerated creep starting moment as the damage time under the stress according to the abrupt change characteristics of the axial strain and the acoustic emission signal; establishing a stress-failure time relation model of each lithology; finally, selecting a corresponding model to predict the damage time of rocks at different layers of the roof according to the actual rock stratum structure and ground stress state of the roadway; according to the method, accurate and reliable time prediction of the progressive damage process of the roadway roof is realized.

The invention relates to the technical field of nickel alloy pipe water pressure detection, and discloses a thin-wall nickel alloy pipe inner wall water pressure test detection system and method. The method comprises the steps that a closed water pressure environment is established in a pipe, a preset pressure gradient is applied, and pipe wall deformation response data are collected through a distributed sensing array; and generating a composite feature matrix containing axial strain, circumferential stress and radial displacement features through multi-dimensional feature extraction, inputting the composite feature matrix into a material performance degradation evaluation model, and simulating microstructure change to output a potential defect distribution map. Dynamically adjusting the water pressure gradient and the pressure maintaining time according to the map, executing a secondary water pressure test, and capturing a microscopic deformation sequence image through high-frequency imaging; comparing the image with a model prediction result identification deviation value, and iteratively updating a model parameter to optimize a detection threshold value; the test is completed by optimizing the threshold value, qualified pipe section marks and defective pipe section positioning coordinates are output, and the comprehensiveness and accuracy of thin-wall nickel alloy pipe inner wall defect detection are improved.

This application relates to the field of automotive fuel injector forging technology, and particularly to a forging method and equipment for automotive fuel injector forgings. The method includes: acquiring metal flow resistance, metal flow velocity, forging vibration data, and lateral force; determining a target flow velocity based on the metal flow resistance, metal flow velocity, and forging vibration data; determining axial strain coefficient and radial strain coefficient based on the metal flow resistance, metal flow velocity, forging vibration data, and lateral force; generating a slider control command based on the axial strain coefficient and the target flow velocity, and generating a push rod control command based on the radial strain coefficient; and controlling a forging device and a hydraulic device to forge the automotive fuel injector forging according to the slider control command and the push rod control command, respectively. This method can significantly improve the forging accuracy, production efficiency, and the level of intelligence and automation in the forging process.

The application relates to a kind of high strain rate under fiber concrete material dynamic axial tensile performance test method, comprising: setting Hopkinson tensile rod device, using the verified Hopkinson tensile rod device to pulse wave is applied to test piece, and the deformation of resistance strain gauge is collected;The deformation is converted into voltage signal, for calculating the strain of resistance strain gauge and the average compressive stress of test piece;Based on strain and average compressive stress, determine the dynamic tensile stress-strain relationship of test piece, according to the dynamic tensile stress-strain relationship of test piece, the dynamic tensile stress time history and dynamic axial strain time history are point by point corresponding pairing on time axis, and the dynamic tensile stress-strain curve of test piece under high strain rate is obtained.The application can make the performance test of fiber concrete and other materials under high strain rate more easily realized, provide the basis for the dynamic performance characterization of material, help the application and popularization of high-performance materials under extreme working conditions such as explosion impact.

The invention relates to the technical field of marine flexible riser monitoring, in particular to a marine flexible riser axial strain monitoring and verification method. The strain monitoring device comprises a corrosion-resistant pipe clamp and a stepped shaft type strain rod, a fiber bragg grating sensor is packaged on the strain rod and is fixed on a vertical pipe through a metal pipe clamp, and the strain value of the vertical pipe is calculated through the change of the central wavelength of the fiber bragg grating sensor. The strain relation between the strain of the vertical pipe and the strain rod is obtained; finite element models of the riser and the strain monitoring device are established by adopting Ansys finite element analysis software, theoretical values of riser strain are calculated, the theoretical values are compared with simulation values, the strain monitoring device shows high accuracy, the actual monitoring accuracy is as high as 90%, the actual monitoring accuracy is remarkably improved compared with a traditional mode, and the reliability of monitoring data is ensured.

A medical probe is presented including an expandable basket assembly coupled to a distal end of a tubular shaft. The basket assembly includes a cloverleaf cutout structure at its distal end and spines extending proximally from the cloverleaf structure and coupling to the tubular shaft. The cloverleaf structure includes a sinusoidal-like member extending from one spine to an adjacent spine in a direction around the longitudinal axis. Dimensions of the sinusoidal-like member can be configured to provide a lateral stiffness of the expandable basket assembly within a predetermined range and a maximum peak stress during retraction of the expandable basket assembly into an intermediate catheter such that the maximum peak stress is less than a predetermined threshold.

The application particularly relates to a cast stainless steel multiaxial low-cycle fatigue prediction method, which comprises the following steps: measuring or calculating the axial strain amplitude and the corresponding axial stress, the shear strain amplitude and the corresponding shear stress, and the phase difference between the axial strain amplitude and the shear strain amplitude of a cast stainless steel concerned part; calculating the equivalent axial strain amplitude and the equivalent shear strain amplitude of the cast stainless steel concerned part after correction and containing the influence of thermal aging; and substituting the equivalent axial strain amplitude and the equivalent shear strain amplitude of the cast stainless steel concerned part after correction and containing the influence of thermal aging and the phase difference therebetween into a cast stainless steel multiaxial low-cycle fatigue prediction model containing the influence of thermal aging to calculate the multiaxial low-cycle fatigue life and the fatigue crack direction of the cast stainless steel after thermal aging. The cast stainless steel multiaxial low-cycle fatigue prediction method can accurately predict the fatigue life of the cast stainless steel under multiaxial low-cycle fatigue loading and the direction of fatigue crack initiation and initial propagation.

The invention provides an optical fiber shape sensing system, method, medium and equipment, in the system, a sensing unit comprises a multi-core optical fiber, the multi-core optical fiber is provided with at least three eccentrically distributed sensing cores and a central core, each sensing core is inscribed with a fiber bragg grating used for sensing axial strain caused by bending and torsion, and the central core is provided with a fiber bragg grating used for sensing the axial strain caused by bending and torsion. The central core is used for providing temperature compensation reference; the signal processing unit is used for receiving the original wavelength and strain data acquired by the sensing unit and executing filtering, temperature compensation and curvature and torsion calculation processing; and the shape reconstruction and display unit reconstructs a three-dimensional space curve through numerical integration based on the geometric parameters output by the signal processing unit, and realizes real-time visual display of a three-dimensional shape. According to the invention, high-precision and high-stability optical fiber shape sensing can be realized in a complex dynamic scene, and application requirements of complex scenes such as medical catheter navigation and flexible robot control can be met.

The invention relates to the technical field of rail shape monitoring, in particular to a rail deformation sensing method and device based on a flat-ribbon optical cable. The device is characterized by comprising a bandlet optical cable, a conduction optical fiber, a demodulator and a computer, a fiber bragg grating array which is weak in reflectivity, determined in grating distance and capable of being calibrated in position is accurately inscribed in two optical fibers in the flat-ribbon optical cable, interference of temperature fluctuation and axial strain is effectively eliminated through double-optical-fiber cooperative measurement and differential calculation, and when a rail is subjected to sedimentation or bending deformation under the action of train loads and environmental factors, the fiber bragg grating array is accurately inscribed in the flat-ribbon optical cable. Deformation is synchronously transmitted to the bandlet optical cable and causes the wavelength change of the reflection center of each fiber bragg grating, a wavelength change signal is transmitted to the demodulator through the conduction optical fiber to be demodulated in real time and output to the computer, and the computer is based on a wavelength-strain-curvature mapping relation and combines a Freen-Serret shape reconstruction and vertex error correction algorithm. The spatial shape reconstruction of the rail is realized, and the settlement height change is output, so that the real-time, continuous and visual monitoring of the settlement process of the rail is realized. The method is suitable for the technical field of rail deformation and settlement monitoring.

The invention provides a nondestructive testing system and method for the bearing capacity of an uplift pile, and the system comprises a strain sensing unit which comprises a distributed annular fiber grating array disposed on a target uplift pile and is used for detecting the strain information of the target uplift pile on the whole pile length; the displacement monitoring unit comprises an MEMS inclinometer and a laser range finder which are arranged at the top of the pile, and an LVDT displacement meter pre-embedded in a pile-soil interface, and is used for synchronously monitoring absolute displacement and relative slippage of the target uplift pile; and the processor unit is used for carrying out inversion calculation on the bearing capacity of the target uplift pile by adopting an FPGA accelerated LSTM-GRU hybrid neural network based on the strain information, the absolute displacement and the relative slippage. According to the method, the differential coupling model of the axial strain of the pile body, the relative displacement of the pile soil and the side friction resistance is established, accurate mapping from the distributed optical fiber strain to the bearing capacity subitem index is achieved, therefore, the nondestructive testing target is achieved, the detection cost is low, and the detection accuracy and reliability are high.

The present application relates to the technical field of nickel alloy pipe water pressure detection, and discloses a thin-walled nickel alloy pipe inner wall hydraulic test detection system and method. The method comprises establishing a closed water pressure environment in the pipe and applying a preset pressure gradient, collecting pipe wall deformation response data through a distributed sensing array; generating a composite feature matrix containing axial strain, circumferential stress and radial displacement features through multi-dimensional feature extraction, inputting a material performance degradation evaluation model, simulating microstructure changes to output a potential defect distribution map. The water pressure gradient and pressure holding time are dynamically adjusted according to the map, a second hydraulic test is performed, and micro-deformation sequence images are captured through high-frequency imaging; the deviation amount is identified by comparing the images with the model prediction results, the model parameters are iteratively updated to optimize the detection threshold; the test is completed using the optimized threshold, and the qualified pipe section marker and defect pipe section positioning coordinates are output, thereby improving the comprehensiveness and accuracy of thin-walled nickel alloy pipe inner wall defect detection.

The invention discloses an axial strain rate field simulation method of a distributed optical fiber DAS-VSP based on strain tensor projection under a non-vertical well layout condition, and belongs to the field of exploration. Aiming at the problem that a traditional vertical well simulation method is difficult to accurately simulate wave field propagation characteristics in a curved well trajectory, high-precision wave field simulation under a non-vertical well type condition is realized by establishing a parameterized well trajectory model based on a curvilinear function and combining a first-order speed-stress elastic wave equation and a finite difference algorithm. A tangential direction projection algorithm is introduced to convert a velocity field into optical fiber axial strain rate response, and a dynamic scale distance segmentation method is adopted to truly simulate the spatial sampling characteristics of an actual DAS system. By constructing PML absorption boundary conditions and a stability control mechanism, the numerical stability of highly-deviated well section wave field simulation is ensured. According to the method, a reliable numerical experiment method is provided for DAS-VSP data interpretation and forward modeling under the non-straight well type condition, and important technical support is provided for non-straight well optical fiber earthquake monitoring in oil-gas exploration.

The invention relates to the technical field of tunnel monitoring, and discloses a device and method for monitoring deformation of an existing subway interval tunnel caused by pipe-jacking construction, and the device comprises an optical fiber which is laid on the arc surface of the inner wall of the tunnel in a snake-shaped wave shape, and the optical fiber is spread towards the two sides with the top of the tunnel as the center. And bending back and forth between the left and right side walls while extending longitudinally along the tunnel, so that the crest part is positioned on one side wall of the tunnel, the trough part is positioned on the other side wall of the tunnel, and the crest part and the trough part are flush in height in the cross section of the tunnel. The optical fiber is laid on the arc surface of the inner wall of the tunnel in a snakelike wave shape, radial deformation of the section of the tunnel is converted into axial strain of the optical fiber through wave geometry, and meanwhile the optical fiber extends in the longitudinal direction and can also sense longitudinal differential settlement.

The invention discloses a submarine cable temperature stress state simulation experiment device and method. The device integrates an optical fiber coil assembly, a temperature displacement simulation box, a stretching mechanism, a wave making circulation cavity and a distributed optical fiber sensing system. The same submarine cable sample is subjected to adjustable temperature in a temperature control bath, axial strain is applied and measured by a stretching mechanism, a wave making circulation cavity reproduces periodic / aperiodic ocean current impact through a wave making plate, a driving paddle and a wave suppression grid, temperature, strain and flow field multivariable synchronous or independent loading is achieved, a distributed optical fiber sensing system obtains Brillouin frequency shift of the same section, and the Brillouin frequency shift is subjected to temperature control. And calibrating temperature and strain coefficients. The problem of signal aliasing errors caused by the fact that an existing experimental device can only test in a single-variable and segmented mode is solved, and the reliability and precision of submarine cable temperature stress monitoring by the BOTDR are improved.

This invention discloses a uniaxial acceleration sensing chip based on a pure axial strain beam and its operating method. Each sensitive beam has a force-sensitive resistor. The inner frame of the fixed frame is rectangular, and all vibration units are identical and sequentially arranged at the four corners of the inner frame. A groove is provided on the mass block for the movement of the support beam. One end of the support beam is fixedly connected to a corner of the inner frame, and the other end is connected to the bottom of the groove on the mass block. Sensitive beams are arranged between the two adjacent sides of the mass blocks of the first and second vibration units; sensitive beams are also arranged between the two adjacent sides of the mass blocks of the third and fourth vibration units; all sensitive beams are parallel to each other. This invention can produce the effect of pure axial tension or compression of the sensitive beam. Furthermore, this significantly reduces the overall stiffness of the movable structure of the chip in a small size, allowing the sensitive core to still have good sensitivity and high bandwidth characteristics even in a small size.

This invention relates to a time-varying evolution inversion method for fracture morphology, net pressure, and minimum geostress, belonging to the field of petroleum technology. The method includes: acquiring on-site bottomhole pressure data, monitoring well information, and LF-DAS data during fracturing operations; discretizing the fracture along its length into several units based on the three-dimensional displacement discontinuity method and constructing a net pressure distribution matrix; using a pre-constructed mechanical response relationship between net pressure and fracture width distribution to solve for the fracture width distribution corresponding to the current net pressure distribution; calculating the axial strain response of the fracture at the monitoring well based on the fracture width distribution to form a forward model for pressure-fracture width-strain solution; iteratively updating the fracture half-length and net pressure using the least squares method, constructing a residual between the inverted strain and the on-site strain to minimize the residual, and obtaining the time-varying inversion results for the fracture half-length and net pressure. The time-varying evolution process of minimum geostress can be characterized by the difference between the on-site bottomhole pressure and the inverted net pressure.

The invention provides a concrete column damage evaluation method based on a piezoelectric sensing technology, and the method comprises the steps: pre-burying a plurality of piezoelectric sensors in the most sensitive damage section of a column body before the pouring of a to-be-monitored concrete column; collecting charge signals output by each piezoelectric sensor in the process that the concrete column to be monitored is subjected to an external load, respectively converting the charge signals into concrete axial strain at the corresponding sensor arrangement position, and calculating concrete axial stress at the corresponding position based on the concrete axial strain; according to the concrete axial stress and axial strain data of each monitoring point, concrete compression damage factors of the corresponding monitoring points are calculated; calculating an average value of concrete compression damage factors of all monitoring points on the most sensitive damage section, and taking the average value as an average damage index of the section; and judging the overall damage grade of the to-be-monitored concrete column by taking the section average damage index as an evaluation index of the to-be-monitored concrete column from material damage to component overall damage.

The application relates to a method and system for monitoring axial and bending deformation of a full-length anchor rod, comprising the following steps: obtaining strain data of each optical fiber sensing unit; obtaining axial strain values of each monitoring point in the length direction of the anchor rod based on the strain data of each optical fiber sensing unit; and obtaining the cross-section bending degree of each optical fiber sensing unit at each monitoring point based on the strain data of each optical fiber sensing unit and the central angle between adjacent optical fiber sensing units. The method can effectively separate the composite strain measured by the optical fiber, which is the superposition of axial and bending, into independent axial strain component and bending strain component, capture the stress concentration phenomenon and deformation gradient change of the anchor rod at the joint intersection position, and truly and comprehensively restore the actual stress and deformation characteristics of the anchor rod.

This invention relates to a method, system, storage medium, and equipment for monitoring soil pressure on closed-end pipe piles based on fiber optic grating (Fiber Bragg grating) sensing technology, belonging to the field of geotechnical engineering monitoring technology. This invention, for the first time, combines the theory of thick-walled cylinders based on elastoplastic mechanics with distributed fiber optic grating sensing technology to construct a precise analytical model relating the axial strain, circumferential strain, and soil pressure on the pile body of the closed-end pipe pile, achieving a technological leap from "point measurement" to "distributed sensing." Compared to traditional point-based soil pressure cell monitoring methods, this invention enables high-precision, quasi-distributed, and long-term stable monitoring along the entire length of the pile. Simultaneously, the fiber optic grating possesses unique advantages such as small size, resistance to electromagnetic interference, corrosion resistance, and wear resistance, causing no damage to the pile itself and being easy to operate. This significantly improves the continuity and reliability of soil pressure measurement, effectively overcoming the technical shortcomings of traditional sensors, such as susceptibility to damage during pile driving and the inability to monitor in real time.

The invention relates to the technical field of geotechnical engineering and mining safety monitoring, and discloses an earth surface deformation prediction method based on a three-dimensional optical fiber sensing network and a displacement inversion model, and the method comprises the steps: constructing a three-dimensional monitoring network in overlying strata through employing a directional drilling technology according to geological conditions and earth surface building distribution; a sensing optical fiber is arranged to a drill hole along with a drill rod and fixed through grouting, and a three-dimensional monitoring structure is formed; axial strain data of the drill hole infinitesimal segments are collected in real time through a distributed optical fiber measurement system, and after discretization processing, the direction cosine and the axial displacement increment of each infinitesimal segment are calculated; inverting a three-dimensional displacement vector of a spatial point from the multi-direction strain data by using a weighted least square method, and reconstructing a three-dimensional displacement field of the overlying strata; displacement time sequence data of the key horizon are identified based on the displacement field, a displacement transfer function and an ARIMA time sequence model are established, and advanced prediction of the key horizon and the future settlement amount of the earth surface is achieved; and finally, setting a multi-level early warning threshold according to a prediction result to realize risk level-to-level management.

The utility model provides a kind of smart bolt based on grating strain gauge, including bolt and grating strain gauge, the inside of the bolt is opened with hole, grating strain gauge is provided with quick-drying adhesive, grating strain gauge is pasted in the hole by the quick-drying adhesive.By quick-drying adhesive, grating strain gauge is directly pasted in bolt hole, and this directly pasting mode in bolt hole makes grating quickly and sensitively "feel" the axial strain inside bolt, so that its sensitivity is at least increased by 5 times relative to traditional scheme using capillary steel tube, greatly improves the sensitivity of grating strain gauge in monitoring the bolt tightness state online, and its manufacturing cost is low, so a kind of high-sensitivity, low-cost optical fiber type smart bolt is realized.

The invention discloses a coal and rock mass tension-shear deformation decoupling monitoring method, system and equipment based on a generalized equivalent geometric model and a medium, and relates to the field of coal mine rock mechanics monitoring, the method comprises the following steps: collecting a Brillouin frequency shift signal of each analysis unit to obtain the total optical fiber axial strain of each analysis unit; for any analysis unit, obtaining a real dislocation displacement vector to be determined according to the initial length and the deformation length; decomposing a real dislocation displacement vector to be determined into a projection component and equivalent shear displacement along the axial direction of the optical fiber; forming an equivalent right triangle model based on the initial length, the deformation length, the projection component along the axial direction of the optical fiber and the equivalent shear displacement; obtaining a tension-shear coupling equation based on the equivalent right triangle model; and based on the total axial strain of the optical fiber of the analysis unit, determining equivalent axial strain and equivalent shear displacement by adopting a tension-shear coupling equation. According to the method, accurate decoupling of the complex tension-shear deformation field of the coal and rock mass is realized.

The invention discloses a reinforcing steel bar and concrete interface displacement field testing method and device.The displacement field testing device is mainly composed of a top plate, a bottom plate, a balance plate, a lead screw assembly, a sleeve, an upper loading head, a lower loading head, a testing machine and a DIC testing device.According to the displacement field testing method, a shear test piece is fixed through the displacement field testing device; carrying out a shear experiment; collecting a speckle pattern of the interface through the DIC test device, and processing the speckle pattern to obtain a displacement field; the method comprises the following steps: firstly, dividing a single-side J-integral path in a displacement field, determining a change curve of single-side J-integral along with loading time through a J-integral calculation formula, finally, extracting axial strain of a stage line on the displacement field, and determining a bonding-slip curve by utilizing a relationship between interface shear stress and the axial strain. The method has the advantages of low experiment cost, high experiment success rate, simplicity and convenience in operation and the like.

This invention discloses a three-string multifunctional measuring anchor and its measurement method, belonging to the field of geotechnical engineering monitoring technology. The anchor consists of an anchor section and three-string steel wire strain gauges connected coaxially in alternating configurations. The three steel wires are distributed at 120° intervals along the circumferential cross-section. The strain gauge center column is stiffly matched to the anchor body and can be arranged according to the magnitude of the bending moment. During measurement, the three-string steel wire strain gauges are first calibrated, followed by installation, frequency acquisition, and data calculation. This allows for the simultaneous acquisition of the anchor's axial strain, maximum curvature and direction, axial force, and maximum bending moment. Based on the curvature, further integration can be performed to obtain the deflection and internal settlement curves of the soil and rock mass, determining the maximum settlement value and location. This invention features a segmented combined structure with flexible length adaptation, enabling remote automated monitoring. It combines axial force, bending moment, and internal deformation monitoring functions of the soil and rock mass, and can be used for safety monitoring of tunnels, slopes, foundation pits, and underground mining engineering.

The invention discloses a Hopkinson pressure-shear experimental device and method based on an oblique-section incident bar. The Hopkinson pressure-shear experimental device comprises a bullet, the incident bar, a transmission bar, an absorption bar and a damper which are arranged in sequence, the sample is arranged between the incident bar and the transmission bar, the end face of one end, close to the sample, of the incident bar is a flat oblique section, an included angle theta is formed between the oblique section and the axis of the incident bar, and the oblique section is attached to and matched with the end face of the sample; the data acquisition system comprises an axial strain gauge and a shear strain gauge; two groups of axial strain gauges are symmetrically adhered to the middle parts of the incident bar and the transmission bar; two shear strain gauges are adhered to the end surface, in contact with the sample, of the transmission rod. The device is simple in structure, low in modification cost, clear in loading principle and adjustable in compression-shear ratio, and an accurate and reliable testing means is provided for research on dynamic compression-shear composite mechanical behaviors of materials such as rocks.

The invention belongs to the technical field of underground tension measurement, and particularly relates to a tension sensor measuring circuit and a tensiometer. The device comprises four groups of strain units which are sequentially connected to form a full-bridge circuit, and the strain units on oppositely arranged bridge arms of the full-bridge circuit are respectively a first strain unit and a second strain unit; the two first strain units are arranged in parallel to the axial direction and are used for sensing axial strain; a certain included angle is formed between the two second strain units and the axial direction and is used for sensing circumferential strain; the strain sensitivity coefficient of the second strain unit is different from that of the first strain unit, so that the signal variation of the adjacent first strain unit and second strain unit is the same. The method is used for solving the problems that tension measurement is complex and high in cost, the complex mechanical compensation problem is converted into circuit configuration through source compensation design, and therefore comprehensive optimization is achieved in multiple dimensions such as structural reliability, cost, performance and maintainability, and the method is suitable for petroleum logging scenes with strict requirements.

The invention discloses a steel bridge bolt group stress real-time monitoring and loosening intelligent diagnosis system, which belongs to the technical field of steel bridge detection and comprises a fiber grating sensing network, an optical fiber demodulator, a data acquisition and processing module and an intelligent diagnosis cloud platform. A fiber bragg grating strain sensor and a temperature compensation sensor are arranged on a monitored bolt group to sense the axial strain of the bolts in real time; a sensing network is formed by adopting series bus topology, and pure strain signals are corrected and separated through temperature drift; real-time axial force is calculated according to the strain-axial force relation; looseness identification is realized based on a multi-dimensional intelligent diagnosis model, and comprises collaborative performance analysis, mechanical topology network modeling, pseudo-looseness identification and three-stage progressive early warning. According to the invention, real-time accurate monitoring of the stress state of the bolt, early-stage recognition of loosening and accurate positioning are realized, and the safety monitoring capability of steel bridge bolt connection is obviously improved.

A medical probe is presented including an expandable basket assembly coupled to a distal end of a tubular shaft. The basket assembly includes a cloverleaf cutout structure at its distal end and spines extending proximally from the cloverleaf structure and coupling to the tubular shaft. The cloverleaf structure includes a sinusoidal-like member extending from one spine to an adjacent spine in a direction around the longitudinal axis. Dimensions of the sinusoidal-like member can be configured to provide a lateral stiffness of the expandable basket assembly within a predetermined range and a maximum peak stress during retraction of the expandable basket assembly into an intermediate catheter such that the maximum peak stress is less than a predetermined threshold.

The application discloses a kind of method and system for monitoring the state of fan blade and variable pitch bearing bolt connection, it is related to bolt monitoring technical field for wind power generation, including monitoring and obtaining the real-time axial strain data of bolt, real-time temperature data;Real-time pressure and real-time yield strength of bolt are calculated;When real-time pressure is greater than real-time yield strength, if the sum of real-time pressure and make-up strength is less than real-time yield strength, then the real-time yield strength of bolt is made to standard yield strength by heat exchange, if the sum of real-time pressure and make-up strength is greater than or equal to real-time yield strength, then fan equipment is stopped and maintained, the application is when the sum of real-time pressure and make-up strength is less than real-time yield strength, by the way of heating bolt, make bolt from failure risk dissociation, and when the sum of real-time pressure and make-up strength is greater than or equal to real-time yield strength, fan equipment is stopped and maintained, avoid the problem of bolt and lead to safety accident.

The utility model discloses a stress measuring device in the field of stress measurement, which comprises a mounting seat plate I, a mounting seat plate II and a fixed supporting bent plate fixed on one side of the mounting seat plate I. One side of the mounting seat plate I is fixedly connected with two clamping fixtures, one side of each clamping fixture is provided with a strain gauge, the number of the clamping fixtures is two, and the strain gauge is arranged on the other side of each clamping fixture. And the other clamping fixture is arranged at the other end of the strain gauge. When the stress measuring device is used for measuring stress and the first mounting seat plate and the second mounting seat plate move relatively, one end of the strain gauge can be pulled to move upwards through the stay wire under the guidance of the supporting rollers, tensile strain of the strain gauge is converted into radial inclined strain, and due to the fact that the radial strain capacity is far larger than the axial strain capacity, the strain gauge can be changed into radial inclined strain. Therefore, amplification of a corresponding variable measurement result can be realized, the measurement accuracy can be greatly improved, and after the arrangement, the overall width increase of the strain gauge can be neglected, and packaging and transportation are facilitated.