18 results about "Small strain" patented technology

The invention discloses a numerical simulation analysis method for a near-river ultra-deep foundation pit under the action of seepage flow, and the method comprises the following steps: S1, constructing a three-dimensional numerical model based on finite element software PLAXIS 3D, and constructing a non-uniform stratum model in combination with a Borehole module; s2, fine modeling is conducted through the underground diaphragm wall, the reinforced concrete supports and the latticed columns; s3, simulating a small strain hardening characteristic and a rigidity attenuation effect of the soil body by adopting an HSS model; s4, simulating underground water flow by combining plastic steady-state seepage analysis, and simplifying the three-axis cement mixing pile into an underground diaphragm wall structure through an equivalent stiffness principle; and S5, step-by-step excavation and support sequential control construction procedures are adopted, and finally, the reliability of the model is verified by comparing a horizontal displacement simulation result of the diaphragm wall with field monitoring data. According to the method, the foundation pit deformation rule is predicted through HSS constitutive model and seepage coupling analysis, and the foundation pit deformation prediction precision is remarkably improved.

The invention relates to a method for establishing a clay small strain elastic model by considering inherent anisotropy and stress history, which comprises the following steps of: establishing a mathematical model for describing the degradation of clay rigidity along with strain on the basis of a modified Hardin-Drnevich curve; introducing a stress path rotation angle, and constructing an interpolation function to quantify the influence of the recent stress history on the small strain stiffness of the clay; introducing a fabric tensor to describe the inherent anisotropy of the clay, and establishing an elastic modulus expression to reflect the anisotropy of the clay in an initial state; the effectiveness of the model is verified by comparing various natural clay test data. The method has the beneficial effects that the model provided by the invention can more accurately describe the anisotropic rigidity response of the soil in a small strain range, and particularly, the prediction precision of the model is greatly improved after the influence of the rotation angle of the stress path and the orientation of the laying surface is considered.

The application discloses a preparation method of titanium / titanium alloy wire with a double-gradient structure, which comprises the following steps: (1) performing large-strain drawing on the titanium / titanium alloy wire with a strain of not less than 0.5; (2) performing heat treatment on the drawn wire at a medium-low temperature; (3) performing large-strain torsion on the heat-treated wire with a torsion angle of 3600-20000 degrees to obtain a wire with a gradient increase of strain from a core to an edge along a radial direction; (4) performing heat treatment on the torsioned wire at a medium temperature to obtain a wire with a gradient decrease of ultra-fine grain size from the core to the edge along the radial direction; and (5) performing small-strain torsion on the heat-treated wire with a torsion angle of 720-3600 degrees to obtain the titanium / titanium alloy wire with the double-gradient structure. By obtaining the titanium / titanium alloy wire with a double-gradient heterogeneous structure of grain size and strain, the application greatly improves the strength-plasticity matching of the wire and overcomes the problem that the existing strengthening methods of titanium / titanium alloy result in the deterioration of plasticity of the wire.

The invention discloses a detection device with small strain monitoring and a piezoelectric crystal and a testing method of the detection device, and aims to solve the problem that multi-scale real-time observation and accurate monitoring are difficult to carry out in a multi-gas hydrate replacement process in the prior art. The device is used for detecting the replacement efficiency and the micromechanical rigidity of the hydrate in different sediment mineral environments in a reaction kettle, during use, a hydrate replacement experiment is carried out between soil particles or ore sheets, and the change of the resistivity and the rigidity of the hydrate in the replacement process under the micro-micro scale is recorded in detail; the bending element performs real-time monitoring and effective analysis recording on soil body small strain in the replacement process so as to reflect soil body void ratio change, pore pressure change and structural damage of fine-grained soil and characterize important parameters of soil body deformation and dynamic characteristics. Powerful technical support and experimental means are provided for the research on the macro-fine-micro phenomenon of hydrate replacement in different simulated sediment geological environments under laboratory conditions.

The invention discloses a method and a system for constructing a constitutive model of prestressed tendon relaxation loss, relates to the technical field of material constitutive model construction, and solves the technical problems that factors considered in prestressed relaxation calculation are not comprehensive and long-term deformation of a large-span PC box bridge cannot be accurately evaluated in the prior art. The method comprises the following steps: 1, constructing a rate expression of the total strain of the prestressed tendon based on a small strain and strain additive splitting principle; 2, considering variable strain and variable temperature conditions in the rate expression of the total strain of the prestressed tendons, and exporting a stress rate expression of the prestressed tendons; and 3, by using the prestressed tendon rate expression, considering the influence of fatigue damage on the stress relaxation of the prestressed tendon, introducing a damage variable, and completing the construction of the prestressed tendon relaxation loss constitutive model considering fatigue damage, the method considers the influence of multiple factors, and has the advantages of high evaluation accuracy and the like.

The small strain testing system is for measuring the velocities of pressure and shear waves in different ground materials, especially soil, and for measurement of the modulus of elasticity in various civil engineering materials by various vibrating elements. It performs non-destructive tests on a wide range of laboratory samples of ground materials. The components are the transmitter actuator, receiver sensor, function generator, oscillator, amplifier, and reducer. The types of transmitter operators and receiver sensors of this device include unidirectional bending, bidirectional bending, pressure, or combination. The electrical wave is converted into a mechanical wave by the transmitter operator, then into a stress wave in the tested materials. The wave passing through the material is received by the receiver sensor, the time difference between the transmitted, and received wave, and the distance between the operator and the sensor can obtain the moduli of elasticity of the tested ground material.

This invention provides a method for testing the roller tilt angle distribution of a double-row tapered roller bearing. First, a calibration experiment is performed. At least three strain gauges are arranged equidistantly on the outer surface of the bearing outer ring corresponding to each roller in the load-bearing area. By loading a single roller, the strain response of all strain measurement points on the outer ring corresponding to each roller in the load-bearing area of ​​the test bearing is obtained. This allows for the determination of the load measurement point positions unaffected by roller tilt under different tilt directions, as well as the corresponding load transfer coefficient and roller tilt angle calibration coefficient. Then, the strain measurement points of the test bearing are rearranged. The newly arranged test bearing and test bearing housing are installed at the work site. Combined with the calibration results, the roller tilt angle distribution of the bearing in its in-situ state can be calculated. This invention uses smaller strain gauges, making installation in practical environments more convenient and allowing for easier tilt angle distribution testing. This invention can be directly installed at the work site after calibration on a simple test bench, thus having wider applicability. This invention can monitor the roller tilt state of the load-bearing area of ​​the rolling bearing online in real time.

When the hammer for small strain detection is used, the left end and the right end of the cross rod are held by two hands respectively, the hammer is lifted, the lower end of the vertical rod of the hammer abuts against the pile top of a pile foundation to be detected, one end of the pull rope is wound through the pull rope winding device, and therefore the balance weight and the knocking head are pulled to rise. The counterweight is blocked by the lower end of the first vertical hole until reaching the upper limit position and cannot continue to rise; then, one end of the pull rope is not wound through the pull rope winding device any more, the balance weight and the knocking head freely fall, and knocking is completed through the knocking head. The hammer for small strain detection can conveniently and quickly knock a pile top in a small strain experiment, so that the working efficiency is improved, the same knocking force is ensured each time, and errors are reduced.

The invention relates to a method for calculating foundation settlement, which comprises the following steps of: partitioning a base plane of a building or a structure and the like into blocks, giving an additional pressure coefficient of each block area, and obtaining a geological section of a settlement part to be calculated and physical and mechanical parameters of soil; the method comprises the following steps: dividing foundation soil into a plurality of thin layers, calculating self-weight stress and additional vertical stress of each thin layer, determining an initial small strain modulus under a corresponding stress level, and determining initial rigidity of a spring for simulating a transverse constraint effect of a soil body; the initial deformation modulus and the spring stiffness are reduced according to the shear strain in the small strain stage, the tangent modulus and the vertical strain of each thin layer are calculated according to the shear stress level in the large strain stage, and then the compression amount of each thin layer is calculated and accumulated to obtain a foundation settlement value. According to the method, by considering the horizontal elastic-plastic constraint of the surrounding soil body on the soil body of the to-be-calculated settlement part, the problems that the lateral confinement compression modulus adopted by an existing method does not conform to the actual stress condition of the foundation, and settlement of saturated soil under the undrained condition cannot be calculated are solved.

A three-dimensional on-line tool pose detection device and method, belonging to the technical field of machining. It can realize on-line detection of the tool in three axial directions, improving the machining stability and reliability. The cylindrical workpiece is clamped by a four-jaw chuck. A displacement amplification device is arranged between the jaws of the four-jaw chuck and the connecting plate. The connecting plate is installed on the square cavity, and the square cavity is installed on the micro-force sensing device. Strain gauges are installed on both the micro-force sensing device and the displacement amplification device for detecting displacements in three axial directions. Without contacting the workpiece, the present invention can accurately detect the tool pose, avoiding interference with the object to be measured, being able to adapt to moving objects, and improving the flexibility of detection. The present invention can accurately detect the micro-strain of an object, is very sensitive to the change of micro-strain, and can quickly respond to the detected information, thus obtaining high-precision information. The present invention can obtain the displacement information of the object to be measured from different angles, providing a more comprehensive and accurate detection result.

The utility model relates to the technical field of power measurement, in particular to a riding power measuring device which comprises a main shaft, a chip and a spiral strain gauge. The main shaft is of a cylindrical structure, and one end of the main shaft is provided with a connecting structure used for being connected with external equipment. The spiral strain gauge is fixedly arranged at the end, close to the connecting structure, of the main shaft and used for detecting the strain condition of the main shaft in the riding process and sending measured strain data to the chip, and output power and power data are obtained through calculation of the chip and wirelessly transmitted to a user side. The spiral strain gauge is tightly attached to the main shaft, tiny strain changes in the riding process can be accurately captured, and accurate motion feedback is provided for a rider in combination with the computing power of a high-performance chip and real-time output power and power data.

The invention discloses a non-contact strain measurement method and system for a rotating structure, and the method comprises the steps: obtaining a displacement estimation value and a rotation angle estimation value of a single first measurement point in a deformation image based on ring projection transformation; converting the displacement estimation value and the rotation angle estimation value, and obtaining a target deformation parameter through a local digital image correlation method; according to the target deformation parameter, acquiring local strain of the single first measuring point; acquiring initial displacements of a plurality of second measuring points; according to the initial displacement, obtaining displacement fields of the plurality of second measuring points through a global digital image correlation method; according to the displacement field, obtaining the distance change between the second measuring points; and obtaining the global strain of the plurality of second measuring points according to the distance change, and meeting the strain measurement requirement in small strain through local and global strain calculation. The method can improve the precision of strain measurement, and can be widely applied to the technical field of strain measurement.

This invention relates to a method for establishing a small-strain elastic model of clay considering inherent anisotropy and stress history. The method includes: establishing a mathematical model describing the stiffness degradation of clay with strain based on a modified Hardin-Drnevich curve; introducing a stress path rotation angle and constructing an interpolation function to quantify the influence of recent stress history on the small-strain stiffness of clay; introducing a fabric tensor to describe the inherent anisotropy of clay and establishing an expression for the elastic modulus to reflect the degree of anisotropy of clay in its initial state; and verifying the effectiveness of the model by comparing data from various natural clay experiments. The beneficial effects of this invention are: the proposed model can more accurately describe the anisotropic stiffness response of soil within a small strain range, especially after considering the influence of the stress path rotation angle and pavement orientation, which greatly improves the model's prediction accuracy.

This invention discloses a method for identifying fatigue cracks in wind turbine blades based on distributed optical fiber strain response, belonging to the field of wind power equipment condition monitoring technology. The method includes the following steps: collecting continuous optical strain response records formed during the wind turbine blade's operation; organizing these records according to a unified time scale to form a strain change trajectory; calculating the difference in amplitude between adjacent strains within the strain change trajectory and extracting continuous, slowly fluctuating segments to form a list of low-frequency oscillation segments. This invention identifies low-frequency oscillation segments in the strain change trajectory and constructs an oscillation unfolding trajectory, enabling the time unfolding of local strain changes in the low-frequency oscillation background, thereby revealing the minute strain change characteristics of the crack initiation stage; further, by extracting suspected crack fragments and reconstructing crack release trajectories, a crack strengthening trajectory is formed, allowing crack release changes to be continuously presented in a continuous time series, improving the early identification capability and the ability to identify the change process of fatigue cracks in wind turbine blades.

The invention discloses a mechanical connection prestressed concrete precast pile with an end plate and a construction method.The mechanical connection prestressed concrete precast pile with the end plate comprises a prestressed steel bar, a concrete pile body, the end plate and a mechanical connecting piece, and the mechanical connecting piece comprises a sleeve assembly, a lining, an inserting rod and a plurality of occlusion petals; the sleeve assembly comprises a first sleeve and a second sleeve, and the first sleeve and the second sleeve between the adjacent mechanically-connected prestressed concrete precast piles with the end plates are connected through an inserting rod to achieve mechanical connection between the adjacent precast piles. According to the mechanically-connected prestressed concrete precast pile with the end plates and the construction method, the strength of the pile head of the precast pile can be guaranteed, meanwhile, connection and positioning between piles are more accurate, the stress concentration phenomenon does not exist in the connection position, and the small strain detection qualification rate is higher.

The invention discloses a shield cutter abrasion dynamic monitoring system and a monitoring method thereof. The monitoring system comprises a hob, hob shafts are arranged at the two ends of the hob, and the hob is provided with side pressed faces; the strain gauge is fixed on the side pressed surface of the hobbing cutter in a welding manner and is used for converting the mechanical strain of the hobbing cutter into a resistance change signal; the resistance strain gauge is connected with the strain gauge through a flexible wire, is arranged at a position far away from a welding point of the strain gauge, and is used for receiving and processing a resistance change signal of the strain gauge; and the conductive slip ring coaxially sleeves the peripheral side of the hob shaft through a fixing structure and is used for leading out an output signal of the resistance strain gauge in a rotating state. According to the invention, the strain gauges are mounted in a high-stress area near the cutting edge, so that the tiny strain change of the tool can be sensitively captured, and accurate early warning of early wear such as microcracks and tipping can be realized.

The present invention discloses an online testing method and device for the strain field during the hot pressing process of a reconstructed bamboo slab. The testing method uses the end face of a painted bamboo bundle as a strain observation surface to obtain the displacement deformation between the same strain observation surface and the reference strain observation surface at different hot pressing moments, thereby detecting the strain behavior of the reconstructed bamboo slab during the hot pressing process. Compared with the displacement strain sensors currently used, the present invention can accurately obtain the strain of the reconstructed bamboo slab during the hot pressing process, greatly reducing the measurement error caused by small differences in the slab strain field. Compared with other popular stress field detection methods based on image recognition on the market, the present invention uses the end face of the painted bamboo bundle as the strain observation surface to solve the problem of difficulty in taking points due to uneven levels of the slab end face. It has low cost and small strain field measurement error, effectively overcoming the limitations of the current mainstream digital speckle method on the complex production site of reconstructed bamboo, while ensuring that the measurement accuracy meets actual production needs while reducing the measurement cost.

The invention discloses a three-dimensional crustal stress prediction method based on structure size deformation and numerical simulation. The method specifically comprises the following steps: S100, a first stage: constructing large deformation simulation; comprising the following steps: S110, establishing a three-dimensional frame model by using depth domain horizon data according to a seismic interpretation result; s120, setting a constitutive model and a strain softening mode; s130, stratum mechanical parameters are set; s140, setting a boundary condition; s150, setting speed boundary loading; s160, carrying out numerical calculation, comparing strain distribution in a simulation result with fault distribution obtained through geological exploration, and checking the correctness of a large-deformation simulation result of the structure; s200, in the second stage, small strain simulation is constructed, the simulation result in the first stage serves as an initial model, and speed boundary loading is modified into stress boundary loading; carrying out numerical calculation, and comparing stress distribution of a simulation result with an actual measurement result; according to the method, the model constraint degree is increased, and the reliability of a three-dimensional crustal stress prediction result can be improved.