49 results about "Strain difference" patented technology

The invention relates to a method for determining the crack initiation strength of a rock under compressive conditions. The method includes the following steps: 1, processing a rock sample; 2, arranging the rock sample on the sample bench of a press; 3, axially loading the sample in a load control mode until the sample is destroyed; 4, calculating the volumetric strain of the sample; 5, determining the crack damage strength in a volumetric strain-axial stress curve; 6, connecting a zero point with the crack damage strength point in the volumetric strain-axial stress curve to form a reference line; 7, calculating a difference between the strain value in the volumetric strain-axial stress curve and a strain valve corresponding to the reference line under a same stress level from the zero point to the end of the crack damage strength; and 8, making a volumetric strain and axial stress relation point diagram, and determining the stress corresponding to the peak of the volumetric strain difference as the crack initiation strength of the rock. The method is suitable for mechanical test of the rock, serving for underground engineering.

The invention discloses a variable tension adjustment and control device capable of being used for precision winding of an optical fiber. The device comprises a releasing mechanism, a dance wheel adjusting mechanism, a tension detection mechanism and a panel, wherein a printed winding motor is used as a releasing motor of the variable tension adjustment and control device; a micro ball screw transmission pair is driven through a step motor to accurately change a rider position in the length direction of a swing rod; the position of the swing rod is detected by using an angle sensor, so that the swing rod is kept at a horizontal position in a moment balance state; the optical fiber tension after layer replacement winding achieves a new stable value requirement by changing the rider position, and precision detection and control of the horizontal balance position of the swing rod; thus variable tension adjustment and control during layer replacement winding of the optical fiber winding are realized, the inner and outer layer stress and strain differences caused by increase in number of layers of the optical fiber winding can be eliminated, and finally stress winding of inner and outer layers of the optical fiber winding and the like is realized so as to obviously improve the signal transmission performance and stability of the optical fiber winding.

The invention discloses a packaging structure applied to a long-pulse-width and high-power semiconductor laser. The packaging structure comprises a high-temperature hard solder, a semiconductor laser bar, a p-surface secondary heat sink, an n-surface secondary heat sink, an electric insulation cooling fin, a soft solder and a heat sink, wherein the p-surface secondary heat sink, the n-surface secondary heat sink, the semiconductor laser bar, the high-temperature hard solder piece and the electric insulation cooling fin are stacked according to a certain structure and a certain sequence to form a laser bar stack through one-time or multi-time high-temperature backflow molding; the stack and the heat sink are subjected to backflow welding molding through the soft solder with relatively low temperature. According to the technical scheme, the temperature difference between a p surface and an n surface is small under the working condition of laser, the cooling efficiency is high, the stress-strain difference caused by the temperature difference is effectively reduced, and on the premise that the service life, conversion efficiency and other photoelectric performances of a device are not affected, the device of the structure can be used under the condition that the current duty ratio reaches 40 percent, namely the pulse width is 1-400mS.

The invention provides a method for measuring the internal force and the deformation of a precast pile. After a piling procedure is accomplished, a sensor and vertical pile foundation static load experiment equipment which is connected with the sensor are installed; before the next stage of load is exerted, the numerical reading of the sensor under one stage of load is recorded, namely, the relative deformation at an observation point (at which a force transmission rope is connected) and a reference part; the relative deformation is divided by the pile length of the section so as to obtain the relative strain of the observation section relative to a reference plane; the strain difference between two sections is obtained through the strains of two adjacent observation sections relative to the reference plane; and the axial force of the pile body at each anchoring head section is calculated according to the elastic modulus calibration result of the pile body concrete. According to the method for measuring the internal force and the deformation of the precast pile provided by the invention, the sensor is installed after the piling procedure is accomplished, so that the sensor is prevented from being damaged in the piling process, and moreover the measurement precision is high, and the cost can be controlled effectively.

The invention discloses a detecting method and device for a flexural fatigue crack initiation process of a submarine pipeline. The detecting method comprises: arranging a strain gage in the middle of a pipeline test piece; placing the pipeline test piece on a fatigue pressure application mechanism platform; taking two ends of the pipeline test piece as supporting points and enabling the middle of the pipeline test piece to be suspended; applying a downward cyclic load to two positions symmetric along the middle of the pipeline test piece by a fatigue pressure application mechanism; and detecting whether fatigue cracks are initiated on the pipeline through a strain difference measured by the strain gage arranged on the pipeline test piece, and determining extension length of cracks according to strain values measured by different strain gages in the circumferential direction to further obtain a relationship between the cyclic load times of the pipeline test piece and the length of the fatigue cracks. The detecting method has the advantages that the crack initiation condition of the submarine pipeline can be predicted by detection on the pipeline test piece, the detecting method is simple and accurate, a submarine pipeline which is not mounted can be detected, and whether the submarine pipeline meets requirements of submarine services can be judged.

The invention discloses a dancer detecting mechanism capable of achieving variable-tension adjustment and control. The dancer detecting mechanism can be particularly used for variable-tension precise adjustment and control during layer changing winding of optical fiber windings. According to the dancer detecting mechanism capable of achieving variable-tension adjustment and control, a minitype ball screw transmission pair is driven by a stepping motor to enable the position of a sliding poise in the length direction of a swing rod to be changed accurately, position detection is conducted on the swing rod through an angle transducer, and thus the swing rod is kept at the horizontal position in the moment balance state. Through changing of the position of the sliding poise and precise detection and control over the horizontal balanced position of the swing rod, the tension of an optical fiber which is wound after layer changing can meet the requirement for a new stable value, automatic variable-tension adjustment and control during layer changing winding of the optical fiber windings are achieved, the stress difference and the strain difference, which are caused by increase of the number of layers of the optical fiber windings, between an inner layer and an outer layer can be eliminated, the optical fiber windings can be finally wound on the premise that that the stress of the inner layer and the stress of the outer layer are equal, and thus the signal transmission performance and the stability of the optical fiber windings are improved remarkably.

The invention discloses a bridge strain data abnormal value identification method based on data relevance. The bridge strain data abnormal value identification method comprises the steps of obtaining the sensor original data installed at the same position; extracting the long-period trend data from the original strain data through the wavelet decomposition to obtain a difference value between the original strain data and the long-period trend data; according to the mean value and the standard deviation of the strain difference value data, obtaining a change range of the potential abnormal values in the original strain data; extracting the long-period trend data from the original acceleration data through wavelet decomposition to obtain a difference value between the original acceleration data and the long-period trend data; obtaining a change range of a potential abnormal value in the original acceleration data according to a mean value and a standard deviation of the acceleration difference data; comparing the occurrence position of the potential abnormal value in the original strain data with the occurrence position of the potential abnormal value in the original acceleration data, and judging and identifying the true abnormal value of the original strain data. According to the method, the problem of the strain data abnormal values in the bridge health monitoring can be accurately and efficiently solved.

The invention provides a water flow velocity and direction sensor and belongs to the technical field of sensors. The water flow velocity and direction sensor comprises a universal plate, wherein one side edge of the universal plate is fixedly connected with a steering shaft, and the upper part of the steering shaft is rotatably connected with a rack base; a supporting frame is arranged above the rack base, a first cam and a second cam sequentially sheathe on the upper end of the steering shaft, and the left end of the first cam and the right end of the second cam are respectively connected with the supporting frame by virtue of a horizontal stretchable element; a water wheel is arranged in a hollow universal plate, a gear coaxially fixed with the water wheel is in single tooth meshing withthe tail end of a lever, the middle part of the lever is hinged on the universal plate, the other end of the lever is hinged with a conduction shaft, and the top of the conduction shaft runs throughthe rack base and is connected with the supporting frame by virtue of a vertical stretchable element; a strain grating connected with a receiver is arranged on the horizontal stretchable element and the vertical stretchable element respectively. Water flow impacts the universal plate and the water wheel to rotate, water flow direction is measured by virtue of strain difference of the strain grating on the horizontal stretchable element, and flow velocity is measured by virtue of strain change frequency sensed by the strain grating on the vertical stretchable element.

The invention discloses a bridge damage identification method based on multiple cross validation. The method comprises the following steps that: continuously arranging n pieces of distributed long-gauge-length fiber grating sensors along a bridge extension direction below a bridge; connecting all sensors to demodulation equipment to collect the long-gauge-length strain response of the bridge whena vehicle passes; carrying out permutation and combination on all sensors, taking any three sensors as a group, and carrying out intra-class second order difference on the correspondingly obtained long-gauge-length strain; solving an area surrounded by each group of strain difference curves and a time horizontal axis; carrying out statistics on the number of the sensor related to an exceptional damage index S* out of a threshold value range; and substituting the number into a damage calculation formula to obtain a structure damage degree [Beta]. By use of the method, through the multiple crossvalidation, the exception and the randomness of an individual sensor are avoided, an obtained result has a high confidence coefficient, and meanwhile, the sensor is higher in durability and accuracy.The method is suitable for the bridges of a simply supported beam and continuous beam structure, low cost and large range application can be realized, the potential damage of the bridge is found in time, and accidents are avoided.

The invention relates to a cold-rolled thin strip steel shape control method. The cold-rolled thin strip steel shape control method comprises the steps that (1) strip steel is divided into n sectionsin the width direction, and each section is provided with a back strain adjusting controlling device; (2) if it is detected that a shape defect exists, the back strain adjusting controlling device inthe corresponding position is started; and if no shape defects exists, all the back strain adjusting controlling devices are stopped. According to the cold-rolled thin strip steel shape control method, based on the relation between back strain and extension strain, by adjusting distribution of the back strain of the strip steel in real time, the uneven plastic extension strain difference, generated in the width direction, of the strip steel is eliminated, and the shape defect is overcome. The problem that through an existing shape control mode, the thin strip steel control effect is poor is solved.

The invention relates to an axle counting method and an axle counting system based on wheel-rail coupling shear force detection. The axle counting method comprises the following steps of measuring and acquiring deformation data at a steel rail measuring point in real time; obtaining a wheel-rail coupling shear force curve at the measuring point according to the deformation data; obtaining a strain difference curve according to the wheel-rail coupling shear force curve; and performing axle counting according to the strain difference curve; the axle counting system comprises a plurality of fiber bragg grating sensing elements, an elastic substrate and a calculation unit, wherein the elastic substrate is used for fixing the fiber bragg grating sensing elements; the fiber grating sensitive element is used for measuring and acquiring deformation data at a steel rail measuring point; and the calculation unit is used for receiving the deformation data from the fiber grating sensing element, obtaining a wheel-rail coupling shear force curve according to the deformation data, obtaining a strain difference curve according to the wheel-rail coupling shear force curve, and finally performing axle counting according to the strain difference curve.

The invention provides a water flow direction sensor and belongs to the sensor technical field. The water flow direction sensor comprises a universal board for inducing a water flow direction; one side edge of the universal board is fixedly connected with a steering shaft; the upper part of the steering shaft is arranged on a rack base; the steering shaft is rotatably connected with the rack base;a supporting frame is arranged on the rack base; the upper end of the steering shaft is sequentially sleeved with a first cam and a second cam; the left end of the first cam and the right end of thesecond cam are connected with the supporting frame through horizontal telescopic components; and the horizontal telescopic components are provided with strain gratings connected with a receiver. The impact force of water flow is utilized to make the universal board rotate to a direction consistent with the direction of the water flow from an initial position; the rotation of the universal board drives the steering shaft, the first cam and the second cam to rotate, which results in the strain difference of the horizontal telescopic components and the strain gratings thereof at two sides; the strain gratings are utilized to measure the strain difference of the horizontal telescopic components, so that the direction of the water flow can be measured indirectly; and 360-degree monitoring of the direction of the water flow can be realized.

The invention discloses a model pile body internal force rating device and method. The model pile body internal force rating device comprises a vertical frame, wherein the bottom of the vertical frame is provided with an axial loading device; the axial loading device is provided with a model pile; the middle of the frame is provided with a horizontal loading device; loading sensors are arranged in the axial loading device and the horizontal loading device respectively; the model pile is provided with a strain sensor; the loading sensors and the strain sensor are connected with a control center through a strain collection instrument; the control center is in control connection with the axial loading device. According to the model pile body internal force rating device and method, the accurate axial loading is performed on the model pile through a small hydraulic jack and strain values of different positions of strain pieces of the model pile are measured to obtain the axial force rating coefficient between the strain of every strain piece and the axial force of a corresponding position of pile body; a concentrated load is applied to the middle section of the pile through a pulley and the strain difference of the strain pieces of the section of the model pile is measured to obtain the bending moment rating coefficient of the strain difference of the strain pieces and the bending moment of the section of the pile body; the internal force of the pile body can be accurately determined.

The invention provides a high-voltage electric field measuring method and device based on non-vertical fiber bragg gratings. According to the method and the device, two composite piezoelectric materials manufactured in a mutual attaching mode are placed into an electric field, the thickness direction of the piezoelectric materials is identical with the direction of the electric field to be measured, the two fiber bragg gratings are fixed parallel to the piezoelectric materials, the change of strain difference of the two pieces of the fiber bragg grating is detected and calculated to obtain shape change difference, caused by the electric field, of the piezoelectric materials, and therefore the accurate electric field intensity and direction can be obtained. The method and the device solve the problems that a traditional optics electric field sensor is complex in structure, a light path is difficult to adjust, and optical elements are dispersed and can not be assembled and carried easily, the processing process is simplified, the cost is lowered, and the measuring precision is improved.

The invention provides a pneumatic tire with dual bead fillers. The pneumatic tire comprises a tire body, a tire bead, a first bead filler and a tire side wear-resisting adhesive, the tire body surrounds the tire bead and the first bead filler and achieves anti-package from the inner side in the axial direction of the tire to the axial direction of the tire, the first bead filler and the tire sidewear-resisting adhesive extend upwards in the radial direction of the tire from the tire bead, a second bead filler is arranged between one side of the anti-package part of the tire body and the tireside wear-resisting adhesive, the height L1 of the upper end of the second bead filler is equal to (0.3-0.8)SDH, and the perpendicular distance between the bead toe and the lower end of the second bead filler is 0-20 mm, wherein the SDH is the perpendicular distance between the widest position of the tire side wall and the bead toe. The second bead filler and a reinforcing film are additionally arranged as a buffer region, the stress-strain difference between different components is decreased, and therefore the separation risk among various materials is lowered.

The invention relates to the technical field of gradient material mechanical analysis, in particular to a calculation method of a gradient material macro equivalent elastic modulus, and the problem that the acquisition efficiency of an existing gradient material macro equivalent elastic modulus is low is solved. The calculation method comprises the steps that relation expressions of the average stress sigma bar of a homogeneous medium layer and the internal stress of materials of all phases are obtained; a relation expression of a disturbance strain difference epsilon' of an inclusion phase and equivalent eigen strain epsilon* is obtained; a disturbance stain difference sigma', disturbance stress sigma bar of a primary phase and disturbance stain epsilon bar of the primary phase are obtained; relation expressions of the homogeneous medium layer average stress sigma bar and the average strain epsilon bar are determined; equivalent moduli L of all homogeneous medium layers are obtained; equivalent bulk moduli K and equivalent shear moduli G of all the homogeneous medium layers are obtained. According to the calculation method of the gradient material macro equivalent elastic modulus, macro equivalent elastic models and the Poisson ratio can be obtained, the material property distribution situation in the gradient region can be obtained to conduct detail stress analysis conveniently, and the modeling workload for conducting detail analysis on the gradient region can be greatly reduced.

The present invention discloses a strain test method using multiple balance reference points. Multiple measurements are carried out in group i in a certain test period and group j in another test period through a strain sensor, temperature influence functions yiw(s) and yjw(s) of a strain under constant environment humidity, and humidity influence functions yis(w) and yjs(w) of a strain under constant temperature are obtained, and strain values yi(w,s) and yj(w,s) under a specific temperature and humidity can be obtained by conversion. Thus, strain values xigm and xj-n in different working conditions in a same group i and in another different group j under different temperature conditions and humidity conditions are respectively measured, and converted into strain values yigm(w,s) and yj(w,s), strain differences delta y(igm-i)(w,s), delta y(j-i)(w,s), and temperature influence functions delta y(igm-i)w(s) and delta y(j-1)w(s) of the strain differences or humidity influence functions delta y(igm-i)s(w) and delta y(j-i)s(w) under a specific temperature and humidity condition. The strain test method using multiple balance reference points aims to eliminate the influence of environment temperature and humidity on the measurement of the strain of a member, and improve the accuracy of the measurement of the strain.

The invention provides a crack width variation test method based on strain gauge. A crack width variation test device used in the method comprises the first strain gauge and the second strain gauge, the cross-joint section of the first strain gauge is provided with a protruding part which does not generate strain along with the change of the crack width, and the cross-joint section of the second strain gauge generates strain along with the change of the crack width. When the method is used for testing, the strain difference value delta epsilon 21 of the first strain gauge and the second straingauge is measure and substituted into the formula that delta f equals to l2delta epsilon 2f and equals to l1delta epsilon 21, and the variation delta f of the crack width can be obtained, wherein l2fis the length of a sensitive grid of the cross-joint section of the second strain gauge, epsilon 2f is the strain capacity of the cross-joint section of the second strain gauge, and l1 is the lengthof a sensitive grid of the first strain gauge. It is known from the formula that the crack width variation obtained through the method can exclude size change values, generated due to stress, of components on the two sides of a crack, and therefore the measurement accuracy is improved.

The invention relates to a method for testing elasticity modulus of a nano thin film on a flexible substrate, and belongs to the technical field of mechanical property testing of the nano thin films.According to the method, on the basis that a traditional stepping motor is combined with a ball screw in a loading mode, an upper baffle piece, a lower baffle piece and a sliding block are designed, wherein the position relation among the upper baffle piece, the lower baffle piece, the sliding block and the flexible substrate is adjustable, so that it is ensured that the pre-stretched flexible isnot affected by the contact of other components, a coating area on the surface of the substrate is controlled, and the surfaces of an upper part and a lower part of the substrate can be coated symmetrically under a pre-stretching condition; in addition, the requirement for synchronous testing of the deformation of a coating-free part and a coating part of the flexible substrate in the compressionprocess is met. In addition, the combination of the pre-stretching technology and a strain difference method is achieved for the first time, the problem of easy buckling of the thin film in compression is solved, and the elasticity modulus of the nano thin film on the flexible substrate is obtained.

The invention discloses an abrasion-resisting and corrosion preventing sucker rod connector and an oil pipe connector, relates to an oil field oil pumping tools, and aims at providing the abrasion-resisting and corrosion preventing sucker rod connector and the oil pipe connector which are small in strain difference of a coating and a base body under the alternating load, and therefore the coating is effectively prevented from cracking or disengaging from the base body. According to the abrasion-resisting and corrosion preventing sucker rod connector, the surface of the base body of the sucker rod connector is coated with the coating, and the coating comprises, by mass percent, 0.03%-0.05% of C, 3.6%-8% of Cr, 1.0%-3.5% of Mn, 0.5%-4.3% of Ni, 2.5%-6.7% of Mo, 0.5%-2.0% of Cu, 1.5%-8.6% of W, 3.5%-7.3% of V, 0.05%-0.07% of Nb, 0.1%-0.2% of Ti and the balance Fe.

The invention relates to a brazing method for a tungsten carbide die punching head and a steel base. According to the brazing method, the big square block brazing face of the steel base is machined and divided into 3*3mm<2> small blocks at intervals, the width of a groove between every two small blocks is preferably 3mm, and the depth of the groove is preferably 2mm; when the tungsten carbide die punching head is brazed on the steel base, the heating temperature of a whole workpiece is smaller than 650 DEG C; high-frequency heated areas are controlled, and after brazing is finished, the workpiece is cooled slowly so that internal stress of the brazing face can be reduced. The brazing method has the advantages that in the process of brazing, the size of the small blocks is very small, and therefore the strain difference of steel and tungsten carbide in the areas is very small; the process of brazing cooling is very balanced, cooling is performed from the edge of each small block to the inside, and due to the small area of each small block, synchronous cooling is basically achieved. Therefore, the stress of the whole brazing face can not be superposed, and the internal stress of brazing is reduced below 10% of the internal stress of the big square block brazing face. In the follow-up machining process, the workpiece can not be cracked and scrapped.

The invention relates to a method for measuring internal stress of a concrete structure, which comprises the following steps of: detecting elastic modulus: manufacturing a first concrete test piece by adopting concrete with the same proportion as a concrete member, and measuring tensile elastic modulus E (t) of the first concrete test piece at different ages; detecting a strain difference: detecting a differential strain epsilon difference (t) between the first vibrating wire strain gauge and the concrete members at different ages; detecting the comprehensive strain of the concrete member; measuring the comprehensive strain epsilon < comprehensive > (t) of each point of the concrete member; and detecting the internal stress of the concrete member: rejecting the differential strain epsilon difference (t) caused by the difference between the first vibrating wire strain gauge and the thermal expansion coefficient of the concrete from the measured comprehensive strain epsilon set (t), and then combining the tensile elastic modulus E (t) of the concrete member at different ages to obtain the internal stress of the concrete member at different ages. According to the invention, errors of internal stress detection of the concrete member can be effectively reduced.

The invention discloses a method for identifying the heat resistance of cabbage germplasm. The cabbage germplasm to be identified is sown in a facility in August, and the temperature of the cabbage germplasm is identified under the temperature condition of ≥ 35°C in the facility in October. Heat resistance, after eliminating the cabbage germplasm that does not meet the requirements for heat resistance, keep the germplasm of cabbage that meets the requirements for heat resistance, and directly pair the parents after flowering in the second spring. The identification method of the cabbage heat-resistant germplasm of the present invention, its core is to use the high-temperature microclimate formed by the facility in autumn to replace the summer high temperature in the traditional method for heat-resistant screening, which has the advantage of shortening the screening period by 5-6 months, At the same time, the errors caused by strain differences, mechanical mixing, and annual climate differences in the cabbage germplasm are reduced, the accuracy of identification is improved, and the amount of seeds used can be reduced.

The invention relates to the technical field of gradient material mechanical analysis, in particular to a calculation method of a gradient material macro equivalent elastic modulus, and the problem that the acquisition efficiency of an existing gradient material macro equivalent elastic modulus is low is solved. The calculation method comprises the steps that relation expressions of the average stress sigma bar of a homogeneous medium layer and the internal stress of materials of all phases are obtained; a relation expression of a disturbance strain difference epsilon' of an inclusion phase and equivalent eigen strain epsilon* is obtained; a disturbance stain difference sigma', disturbance stress sigma bar of a primary phase and disturbance stain epsilon bar of the primary phase are obtained; relation expressions of the homogeneous medium layer average stress sigma bar and the average strain epsilon bar are determined; equivalent moduli L of all homogeneous medium layers are obtained; equivalent bulk moduli K and equivalent shear moduli G of all the homogeneous medium layers are obtained. According to the calculation method of the gradient material macro equivalent elastic modulus, macro equivalent elastic models and the Poisson ratio can be obtained, the material property distribution situation in the gradient region can be obtained to conduct detail stress analysis conveniently, and the modeling workload for conducting detail analysis on the gradient region can be greatly reduced.

The invention discloses a model pile body internal force rating device and method. The model pile body internal force rating device comprises a vertical frame, wherein the bottom of the vertical frame is provided with an axial loading device; the axial loading device is provided with a model pile; the middle of the frame is provided with a horizontal loading device; loading sensors are arranged in the axial loading device and the horizontal loading device respectively; the model pile is provided with a strain sensor; the loading sensors and the strain sensor are connected with a control center through a strain collection instrument; the control center is in control connection with the axial loading device. According to the model pile body internal force rating device and method, the accurate axial loading is performed on the model pile through a small hydraulic jack and strain values of different positions of strain pieces of the model pile are measured to obtain the axial force rating coefficient between the strain of every strain piece and the axial force of a corresponding position of pile body; a concentrated load is applied to the middle section of the pile through a pulley and the strain difference of the strain pieces of the section of the model pile is measured to obtain the bending moment rating coefficient of the strain difference of the strain pieces and the bending moment of the section of the pile body; the internal force of the pile body can be accurately determined.

The invention discloses a strain benchmarking method of hub bearing dynamic test beds. The strain benchmarking method mainly comprises the following steps of: manufacturing a strain type standard sample; matching a test tool and formulating a load spectrum; implementing a test; and analyzing and evaluating data. The method is used for comparing and evaluating the strain difference of two or more test beds under the same loading load; a terminal sample piece strain measurement and evaluation mode is directly adopted; and the problem of transmission from a load sensor to a loading arm and a connecting fastener is fully considered, so that the influence degree of different test beds on the dynamic life test of a product is evaluated, and the reasons of the influence can be deeply analyzed, and an effective analysis means is provided for the dynamic life difference of two or more test beds.

A method for measuring the actual stress of steel bars in existing reinforced concrete shear walls and columns, to obtain the elastic modulus E and yield strength f of steel bars in non-important parts y and ultimate tensile strength f u ; Chisel off the concrete to expose a section of the steel bar to be tested; grind off the oxide layer on the surface until it is smooth and clean it, and attach four strain gauges in the circumferential direction of the same section; before being cut off, obtain the initial strain ε 30 , ε 40 , ε 50 and ε 60 , and the initial strain value obtained from the mean value after being cut off, respectively to obtain the release strain ε 31 , ε 41 , ε 51 , ε 61 , and the released strain value is obtained from the average value, the strain difference Δε of the steel bar under test before and after being cut; the actual stress value σ is obtained by using the difference between the sum and the value; comparative analysis σ, f y and f u The size relationship of the measured steel bar and determine the stress state at the steel bar under test; reconnect the steel bar under test. The method can effectively detect the actual stress state of the steel bars in the existing reinforced concrete shear walls and columns.

The invention discloses an abrasion-resisting and corrosion preventing sucker rod connector and an oil pipe connector, relates to an oil field oil pumping tools, and aims at providing the abrasion-resisting and corrosion preventing sucker rod connector and the oil pipe connector which are small in strain difference of a coating and a base body under the alternating load, and therefore the coating is effectively prevented from cracking or disengaging from the base body. According to the abrasion-resisting and corrosion preventing sucker rod connector, the surface of the base body of the sucker rod connector is coated with the coating, and the coating comprises, by mass percent, 0.03%-0.05% of C, 3.6%-8% of Cr, 1.0%-3.5% of Mn, 0.5%-4.3% of Ni, 2.5%-6.7% of Mo, 0.5%-2.0% of Cu, 1.5%-8.6% of W, 3.5%-7.3% of V, 0.05%-0.07% of Nb, 0.1%-0.2% of Ti and the balance Fe.

The invention provides a method for measuring the internal force and the deformation of a precast pile. After a piling procedure is accomplished, a sensor and vertical pile foundation static load experiment equipment which is connected with the sensor are installed; before the next stage of load is exerted, the numerical reading of the sensor under one stage of load is recorded, namely, the relative deformation at an observation point (at which a force transmission rope is connected) and a reference part; the relative deformation is divided by the pile length of the section so as to obtain the relative strain of the observation section relative to a reference plane; the strain difference between two sections is obtained through the strains of two adjacent observation sections relative to the reference plane; and the axial force of the pile body at each anchoring head section is calculated according to the elastic modulus calibration result of the pile body concrete. According to the method for measuring the internal force and the deformation of the precast pile provided by the invention, the sensor is installed after the piling procedure is accomplished, so that the sensor is prevented from being damaged in the piling process, and moreover the measurement precision is high, and the cost can be controlled effectively.