A pure rolling rigid-link beam mechanical standard static strain generator

Abstract

The application discloses a kind of pure rolling rigid hinge beam mechanical standard static strain generating device, comprising: horizontal base, horizontal base is provided with ball linear guide, there is a short micro-motion roller guide in two ball linear guides, speed reducer is provided on the short roller guide, left knife edge and right knife edge, speed reducer and two knife edges are connected by screw rod to make speed reducer can drive two knife edges axial translation movement, speed reducer is drivingly connected with servo motor.Ball screw outer side end is equipped with corresponding cylindrical rolling bearing and is in contact to compression spring.The end of tool holder fixed force rod, two force rods are supported by six sets of equal-height steel ball supports, loading port for clamping calibration beam is formed in force rod, wedge self-locking clamping mechanism is defined in loading port to ensure the locking of calibration beam.The structure of the application can realize the ideal rigid closed plane static mechanical equilibrium system without constraint, and the loading of calibration beam ±5000με, Kt beam ±3000με at room temperature, thereby improving the strain measurement accuracy and range.

Description

Technical Field

[0001] This invention relates to the field of strain gauge testing, and in particular to a mechanical standard static strain generator for a pure rolling rigid hinged beam. Figure 7 Schematic diagram of a rigid hinged beam. Background Technology

[0002] The K-value (sensitivity coefficient) of a strain gauge (resistance strain gauge) is its most important parameter, defining its ability to convert sensed mechanical strain into a relative change in resistance. Simply put, the K-value directly determines the accuracy of the strain gauge in detecting minute deformations. Therefore, the K-value is the crucial bridge and conversion basis between the geometric deformation (strain) of the measured object and the measurable resistance change signal of the electrical measurement system. Without this known K-value, it is impossible to accurately calculate the actual strain value by measuring the resistance change. Therefore, only by obtaining the true K-value can a reliable conversion relationship be established between the measured physical quantity (such as load) and the electrical signal (such as voltage), thereby ensuring the accuracy of the measurement results from the corresponding measuring device of the strain gauge.

[0003] K-value measurements are typically performed using a K-value meter. Currently, domestic and international K-value meters operate on the principle of four-point simply supported pure bending moment beams and cantilever beams. However, their structure lacks self-locking. Loading and environmental temperature changes cause thermal expansion and contraction of the calibration beam or Kt beam, resulting in an open and constantly changing surface strain with energy loss, making calculation impossible. This prevents the formation of a rigid, closed planar static mechanical equilibrium system (i.e., a static equilibrium state where every component of the planar system is highly rigid and undergoes complete elastic deformation without any strain energy loss). For example, in a rigid hinged beam planar system, all components except the calibration beam or Kt beam undergo complete elastic deformation are highly rigid, and the deformation of other components is negligible relative to the calibration beam or Kt beam. Therefore, the temperature sensitivity coefficient, temperature coefficient, and creep of the strain gauge cannot be accurately measured. In summary, the accuracy of existing K-value meters is not high. Summary of the Invention

[0004] The applicant's research revealed that existing K-value meters not only cannot form a rigid, closed-plane static mechanical equilibrium system, but also, due to the presence of three-point deflectometers, strain measurement at high temperatures becomes extremely difficult.

[0005] In view of the aforementioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a standard static strain generator for a pure rolling rigid hinge beam mechanical system, which aims to improve the accuracy of strain measurement under various conditions, and thus improve the accuracy of the measured K value.

[0006] To achieve the above objectives, the present invention discloses a mechanical standard static strain generator for a pure rolling rigid hinge beam, the device comprising: a horizontal base, a drive assembly, a rolling support assembly, a left force bar, a right force bar, a calibration beam, and a three-point deflectometer;

[0007] The drive assembly includes a left ball linear guide, a right ball linear guide, and a middle ball linear guide located between the left ball linear guide and the right ball linear guide on the horizontal base. The middle ball linear guide is equipped with a reducer and a servo motor that are in transmission cooperation.

[0008] The worm gear output center shaft of the reducer is connected to a left ball screw and a right ball screw at both ends. A left screw nut and a right screw nut are respectively fitted on the left ball screw and the right ball screw. The left screw nut and the right screw nut are controlled by the control rod mechanism on the ball linear guide to not rotate and to translate only along the ball linear guide on the ball screw.

[0009] A left cutting edge is fixedly connected to the left lead screw nut, and a right cutting edge is fixedly connected to the right lead screw nut; a left cutting edge corresponding to the left cutting edge is provided at the end of the left force rod, and a right cutting edge corresponding to the right cutting edge is provided at the end of the right force rod.

[0010] The reducer is connected to the servo motor for transmission. The servo motor is used to drive the left ball screw and the right ball screw to rotate through the reducer, thereby driving the left cutter and the right cutter to push the left cutter holder and the right cutter holder to move axially on the ball linear guide.

[0011] The outer ends of the left and right ball screws are respectively fitted with corresponding cylindrical rolling bearings and abut against the compression spring. The compression spring is used to give the entire system of left and right ball screws axial floating characteristics.

[0012] The rolling support assembly includes six steel ball supports of equal height set on the horizontal base. The top of the six steel ball supports is provided with two micro tension springs that control the rolling recovery of the steel balls. The three steel ball supports of equal height form a group through the steel balls to support the left force rod and the right force rod, so as to realize a rigid closed unrestrained pure rolling with one degree of freedom that can be symmetrically stretched and expanded when loaded, and the two forces are equal and opposite in direction.

[0013] The left and right force rods are respectively provided with loading ports at the ends away from the loading tool holder, and the calibration beam is loaded through the loading ports. The left and right force rods and the calibration beam form two rigid hinges, forming a theoretically rigid closed plane static mechanical rigid hinge beam.

[0014] The three-point deflectometer is used to measure the deformation deflection of the calibration beam and record the servo motor pulse value corresponding to the required deformation deflection so that the servo motor can directly drive the beam to the required deformation deflection. The left ball screw and the right ball screw travel in opposite directions so that the left and right levers move simultaneously toward the reducer or move away from the reducer, so that the calibration beam bends and deforms in an arc or reverse arc parabolic shape.

[0015] It should be noted that the axial floating characteristic proves that the overall sleeve mechanism is unconstrained under load.

[0016] Optionally, the left and right cutting edges each include an inner cutting edge and an outer cutting edge; the left and right force rods are provided with grooves corresponding to the inner and outer cutting edges, and there is a gap between the cutting edge and the groove when not loaded. When loaded, the cutting edge and the groove are in line contact to ensure the unidirectionality of the loading force direction. After unloading, they are out of contact, ensuring that the calibration beam is in a natural state without external force interference before and after loading.

[0017] Optionally, the corresponding area of ​​the loading port for loading the calibration beam is further provided with a wedge-shaped self-locking clamping mechanism. The wedge-shaped self-locking clamping mechanism includes a pressed wedge and a driving wedge. One side of the pressed wedge is in contact with the calibration beam, and the inclined surface of the pressed wedge matches the inclined surface of the driving wedge. The driving wedge is connected to a triangular threaded pair, which is used to convert rotation into linear motion, thereby causing the driving wedge to move axially and push the pressed wedge to move laterally along the guide key to clamp the calibration beam. The left force rod, the right force rod, and the calibration beam form a rigid hinge beam. During the bending process of the calibration beam, the tangent at the intersection of the longitudinal center line of the calibration beam and the center line of the left force rod is perpendicular to the left force rod, forming a left rigid hinge. The tangent at the intersection of the longitudinal center line of the calibration beam and the center line of the right force rod is perpendicular to the right force rod, forming a right rigid hinge.

[0018] Optionally, the calibration beam is installed in two sets of clamping mechanisms connected in series, consisting of two force bars with an angle smaller than the friction angle and a triangular threaded pair, both of which have self-locking properties, forming a rigid connection and a stable and reliable rigid hinge.

[0019] Optionally, the device is configured to: obtain the total mechanical strain based on the total number of loading pulses of the servo motor; obtain the thermal expansion strain of the calibration beam based on the thermal expansion coefficient and the temperature change difference of the calibration beam; and obtain the thermal expansion strain based on the energy conservation ε. s =(αΔt)+ε c The mechanical strain of the calibration beam is obtained; wherein, ε s Let ε be the total mechanical strain energy, α be the coefficient of thermal expansion, and Δt be the temperature change difference. The mechanical strain ε of the calibrated beam under load is... c

[0020] This measurement method also solves the loading speed requirement of resistance strain gauge creep testing. It also overcomes the problem that the slow stepper motor speed in resistance strain gauge creep testing cannot meet the national standard requirement of loading 1000±50με within 15s.

[0021] Optionally, the left and right force rods of the device are respectively equipped with adjustable positioning pins for positioning. The adjustable positioning pins are used to verify the reliability of the rigid hinge beam floating reset system after the calibration beam is subjected to strain unloading. Specifically, if the left and right force rods reset to the positions corresponding to the positions of the adjustable positioning pins after the calibration beam is subjected to strain unloading, the system is considered reliable; otherwise, the standard static strain loading is considered unreliable and needs to be reapplied.

[0022] This invention ensures the formation of a rigid hinged beam mechanical model, which is placed on six steel balls of equal height that are automatically reset by two micro-force tension springs. Two pairs of inner and outer knife edges are installed on the ball screw as driving force rods, so as to achieve a rigid, closed, unconstrained, one-degree-of-freedom, symmetrically expandable pure rolling motion with equal and opposite forces during loading.

[0023] Optionally, the left and right force bars are positioned by four adjustable positioning pins to ensure the formation of a rigid hinged beam mechanical model. The whole is placed on six steel ball supports of equal height that are automatically reset by two micro-force tension springs. Two pairs of inner and outer knife edges are installed on the ball screw pair as push force bars to achieve a rigid, closed, unconstrained, one-degree-of-freedom symmetrically expandable pure rolling state when loaded. The rigid rod principle is that the two forces are automatically and absolutely equal and loaded in opposite directions. The experiment test is conducted to calibrate the pure rolling state of the beam in both concave and convex directions.

[0024] The four cylindrical locating pins under the left and right force bars of the device not only ensure the correct installation of the calibration beam, forming a theoretically rigid hinge beam in a ready-to-work state, but also check whether there is a slight change of 5-10 με during the loading process of the entire system. When the rigid hinge beam returns to zero, the tightness of the four locating pins inserted into the locating holes at room temperature will show a significant change from the last locating hole. Because it is a rigid closed system, only when there is basically no change can it be said that the entire test process is stable and normal, and the test data is reliable. This is ensured by using two parallel measuring standards to position the four cylindrical locating pins during assembly and adjustment.

[0025] Based on data from K-value meters from various countries, none of them possess process self-check and zero-return self-check capabilities. This is because they lack pulse count and high-precision four fixed pins.

[0026] Optionally, based on the pure couple strain measured by the equivalent comparison three-point deflectometer, a displacement sensor is also installed on the horizontal base. This displacement sensor is used to detect the relative displacement of the left and right tool holders. The device is configured to: calculate, based on the thickness of the calibration beam and the distance from the point of application of the force bar to the longitudinal centerline of the calibration beam, the unique real-time distance between the intersection points of the centerlines of the left and right force bars and the longitudinal centerline of the calibration beam after loading, and then calculate the mechanical strain using relevant formulas.

[0027] The measuring head of the three-point deflectometer's grating displacement sensor and the two small blades of the gauge are kept in gentle contact with the calibration beam by screws and nuts. The blades slide as the calibration beam bends, ensuring accurate measurements and preventing damage to the high-precision beam surface from the small blades, thus reducing grinding and extending service life. The three-point deflectometer includes two gauge distance blade positions: a large gauge distance with a blade spacing of 500mm and a small gauge distance with a blade spacing of 300mm.

[0028] Optionally, a micro-motion short roller guide rail is placed between the two ball linear guide rails, on which a reducer and a servo motor are installed. Corresponding cylindrical rolling bearings are fitted onto the outer ends of the left and right ball screws, respectively, and contact a compression spring, ensuring that the entire system has axial floating characteristics. This ensures that the entire system is in an unconstrained, rigidly closed state before loading, and during loading, it is subjected to rigid rod loading, meaning the two forces automatically become equal and opposite in direction, resulting in a pure rolling plane static state.

[0029] Currently, most calibration beams in similar devices, both domestically and internationally, cannot achieve loading in both concave and convex directions during the same clamping process. Especially under high-temperature conditions, similar devices, both domestically and internationally, can only load in one direction. This results in a significant and non-negligible directional error during testing.

[0030] According to the pure bending moment beam theory in mechanics of materials, a plane perpendicular to the neutral axis remains a plane after bending. In the design of the calibration beam, derivation shows that its cross-sectional shape should preferably be square or approximately square. This invention determines the thickness of the calibration beam and optimizes the error distribution to make it as small as possible to be negligible. Specifically, the thickness of the approximately square beam should not exceed 35mm, preferably 25-26mm; if ground to below 18mm, the accuracy grade should be reduced. This design also reduces quenching deformation, improves service life, and provides a theoretical basis for the use and maintenance of the calibration beam. Furthermore, using a rectangular beam instead of a square beam will introduce quantitative errors. Calibration beam (or K...) t The smaller the thickness of the beam, the more significant the decrease in accuracy, and the decrease is exponential.

[0031] Optionally, the calibration beam is a Kt beam composed of a whole-body normal temperature test beam and a split high and low temperature thermal insulation connecting sleeve containing auxiliary beams.

[0032] Optionally, a standard beam calibrated at 20°C can produce a large strain of 0-±5000με, or a Kt beam can produce a strain of 0-±3000με.

[0033] Optionally, during room temperature experiments, once the pulse is positioned when the device is loaded, the entire rigid hinge beam is in a state of static equilibrium in a rigid closed plane. If a stressed part or structure creeps or is disturbed by a certain factor, the displacement display will not repeat during several loading cycles, and the displacement display will not return to zero when returning to its original position, thus achieving process self-checking.

[0034] Optionally, the device further includes a low-temperature room-temperature furnace, a high-temperature furnace, and a heat-insulating pad. The low-temperature room-temperature furnace and the high-temperature furnace are used to heat the assembled Kt beam to a preset temperature; the heat-insulating sleeve and the heat-insulating pad are used to insulate and heat-insulate the high-temperature furnace.

[0035] Sensitivity coefficient K of resistance strain gauge t and temperature coefficient d k Especially the temperature sensitivity coefficient K of the strain gauge at high temperatures t and temperature coefficient d k In the past, measurements were inaccurate. This led to inaccurate experimental stress analysis data under high-temperature conditions, causing serious consequences. The device described uses displacement loading, avoiding the influence of temperature variations in the elastic modulus E. Combined with the relative measurement method, accurate measurements are possible. This is the same both domestically and internationally. The strain gauge's temperature sensitivity coefficient K... t and temperature coefficient d k They don't provide any data at all; they only rely on their experimental experience to provide reference data.

[0036] The beneficial effects of this invention are as follows: 1. In this embodiment, a rigid hinge beam is formed by a left force bar, a right force bar, and a calibration beam or Kt beam. Simultaneously, by setting a compression spring, the rigid hinge beam is kept in a floating, unconstrained state (i.e., it can move slightly 1 to 2 mm along the screw axis), avoiding errors caused by jamming. This structure ensures that the rigid hinge beam, after loading, is theoretically an unconstrained, rigid, closed-plane static mechanical equilibrium system, guaranteeing a truly perfect realization of the rigid hinge beam's mechanical model, thereby improving the accuracy of strain measurement.

[0037] 2. The wedge-shaped self-locking clamping mechanism of the present invention includes a pressed wedge and a driving wedge, one side of which is attached to the calibration beam or Kt beam (see...). Figure 6The inclined surface of the pressed wedge and the inclined surface of the driving wedge are in contact. The driving wedge is connected to a triangular threaded pair, which converts rotation into linear motion, thereby causing the driving wedge to move axially and push the pressed wedge to clamp the calibration beam or Kt beam. This embodiment of the invention uses a wedge-shaped self-locking clamping mechanism to hold the calibration beam or Kt beam, ensuring adaptive locking for calibration beams or Kt beams of different specifications. This ensures that the calibration beam or Kt beam produces equal bending without any slippage during measurement, further improving the performance of the rigid closed-plane static mechanical equilibrium system and increasing the accuracy of strain measurement.

[0038] 3. In the bending process of the calibration beam or Kt beam, the tangent at the intersection of the longitudinal centerline of the calibration beam or Kt beam and the centerline of the left force member is perpendicular to the left force member, and the tangent at the intersection of the longitudinal centerline of the calibration beam or Kt beam and the centerline of the right force member is perpendicular to the right force member. This ensures that the measurement is always in an ideal state, thereby guaranteeing the accuracy of strain measurement.

[0039] 4. The horizontal base of this invention is provided with six steel ball supports of equal height. A steel ball is placed inside the top of each support, and the supports support the left and right force rods through the steel balls, achieving a purely horizontal rolling state. The small nylon sleeves that move with the steel balls are controlled back to the center position by two small tension springs. This mechanism can greatly reduce the influence of friction on the measurement, thereby improving measurement accuracy.

[0040] 5. This invention can solve for the mechanical strain of a calibration beam or Kt beam by measuring the total number of loading pulses of the servo motor. The measurement is highly efficient, accurate, and has excellent repeatability. This method completely and ideally avoids the problem of not being able to use a three-point deflectometer in the heating furnace, and the servo motor and programmable logic controller (PLC) electrical control system enable full automation of the loading test.

[0041] 6. This invention can measure the displacement of the two blade seats using displacement sensors such as grating rulers, and then solve the mechanical strain of the calibration beam or Kt beam. This structure can avoid the problem that the heating furnace cannot use a three-point deflectometer, and thus measure the Kt value and temperature coefficient dk under high temperature environment.

[0042] 7. The loading blade and the bearing blade holder do not contact each other when not under load, and there is a certain distance between them. During loading, the protrusion and the groove of the blade holder are in line contact to ensure the unidirectionality of the loading force. After unloading, they disengage, ensuring that the calibration beam is in a natural state free from external interference before and after loading and unloading.

[0043] 8. This invention employs a servo motor, solving the problem of slow creep measurement speed of resistance strain gauges. Testing a fiber optic grating sensor with zero creep demonstrates that the device itself exhibits no creep after loading. Since there is no displacement change, there is no change in external force; therefore, the calibration beam or Kt beam exhibits no creep, enabling accurate measurement of strain gauge creep. Furthermore, it overcomes the limitation of slow stepper motor speeds in resistance strain gauge creep testing, which fails to meet the national standard requirement of loading 1000±50με within 15 seconds. This is also why a servo motor is necessary.

[0044] 9. This invention is applied to the calibration beam or K. t During beam bending, using a positional loading method instead of weight loading naturally eliminates many large errors caused by temperature variations in the elastic modulus E of the calibrated beam or Kt beam material. This is especially true for testing at high and low temperatures.

[0045] 10. The entire loading test is automated by a servo motor and a programmable logic controller (PLC) electrical control system. Only when loading or unloading the calibration beam or Kt beam does the operator need to be close to the device; all other operations can be performed remotely. For example, the device can be placed in a vacuum chamber or other special environment for aircraft wind turbine experiments. This strain measurement method not only greatly improves strain resolution but also ensures accuracy, stability, repeatability, and reproducibility by maintaining the ideal state of standard room temperature (around 20°C). Furthermore, by applying forces to two load cells on two levers and installing a linear guide ruler, the mechanical strain on the calibration beam, Kt beam, or high-temperature Kt beam can be calculated by measuring the relative displacement distance between the two load cells. Multiple measurement methods are cross-calibrated to prevent errors.

[0046] In summary, this invention improves the accuracy of strain measurement under various conditions, thereby improving the accuracy of the temperature-dependent Kt value and temperature coefficient dk value of the high-temperature strain gauge, as well as the creep and mechanical hysteresis of the strain gauge at high temperatures. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the structure of a pure rolling rigid hinge beam mechanical standard static strain generator according to a specific embodiment of the present invention;

[0048] Figure 2 This is a front structural schematic diagram of a pure rolling rigid hinge beam mechanical standard static strain generating device provided in a specific embodiment of the present invention;

[0049] Figure 3 This is a side view of a standard static strain generator for a pure rolling rigid hinge beam according to a specific embodiment of the present invention.

[0050] Figure 4This is a schematic diagram of the top surface structure of a pure rolling rigid hinge beam mechanical standard static strain generator according to a specific embodiment of the present invention;

[0051] Figure 5 This is a schematic diagram of the structure of a wedge-shaped self-locking clamping mechanism provided in a specific embodiment of the present invention.

[0052] Figure 6 This is an assembly drawing of a Kt beam provided in a specific embodiment of the present invention;

[0053] Figure 7 This is a schematic diagram of a rigid hinged beam provided in a specific embodiment of the present invention. Detailed Implementation

[0054] This invention discloses a standard static strain generator for a purely rolling rigid hinged beam. Those skilled in the art can refer to this document and appropriately modify the technical details to achieve the desired result. It is particularly important to note that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The device and application of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the device and application described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0055] The applicant's research revealed that: K-value measurements typically employ K-value meters. However, current domestic and international K-value meters, based on the principles of four-point simply supported pure bending moment beams and cantilever beams, lack self-locking in structure. Due to factors such as loading and environmental temperature changes causing thermal expansion and contraction of the calibration beam, the surface strain of the calibration beam is in an open and constantly changing state, resulting in energy loss and making calculation impossible. This prevents the formation of a rigid, closed planar static mechanical equilibrium system (i.e., each component of this planar system is highly rigid, undergoing complete elastic deformation, and in a static equilibrium state without any strain energy loss. For example, in a rigid hinged beam planar system, all components except the fully elastically deformed calibration beam are highly rigid, and the deformation of other components is negligible relative to the calibration beam). Therefore, the temperature sensitivity coefficient, temperature coefficient, and creep of the strain gauge cannot be accurately measured. In summary, the accuracy of K-value measurements obtained by existing K-value meters is low. Furthermore, existing K-value meters not only fail to form a rigid, closed planar static mechanical equilibrium system, but the presence of three-point deflectometers makes strain measurement at high temperatures extremely difficult.

[0056] Therefore, embodiments of the present invention provide a mechanical standard static strain generator for a pure rolling rigid hinge beam, such as... Figure 1 , Figure 2 , Figure 3 , Figure 4 as well as Figure 5As shown, the device includes: a horizontal base 101, a drive assembly, a rolling support assembly, a left force bar 102, a right force bar 103, a calibration beam 104, and a three-point deflection meter 105;

[0057] The drive assembly includes a left ball linear guide 106, a right ball linear guide 107 and a middle ball linear guide 108 located between the left ball linear guide 106 and the right ball linear guide 107, which are mounted on a horizontal base 101. A reducer 109 and a servo motor 110 are mounted on the middle ball linear guide 108 for transmission.

[0058] The worm gear output center shaft of the reducer 109 is connected to the left ball screw 111 and the right ball screw 112 at both ends respectively. The left ball screw 111 and the right ball screw 112 are respectively fitted with the left screw nut and the right screw nut. The left screw nut and the right screw nut are controlled to not rotate and to translate only along the ball linear guide by the control rod mechanism on the ball linear guide.

[0059] A left cutting edge 113 is fixedly connected to the left lead screw nut, and a right cutting edge 114 is fixedly connected to the right lead screw nut; a left tool holder 115 corresponding to the left cutting edge 113 is provided at the end of the left force rod 102, and a right tool holder 116 corresponding to the right cutting edge 114 is provided at the end of the right force rod 103.

[0060] The reducer 109 is connected to the servo motor 110 for transmission. The servo motor 110 is used to drive the left ball screw 111 and the right ball screw 112 to rotate through the reducer 109, thereby driving the left cutter 113 and the right cutter 114 to push the left cutter holder 115 and the right cutter holder 116 to move axially on the ball linear guide.

[0061] The outer ends of the left ball screw 111 and the right ball screw 112 are respectively fitted with corresponding cylindrical rolling bearings and abut against the compression spring 117. The compression spring 117 is used to make the entire system of left and right ball screws 112 have axial floating characteristics.

[0062] The rolling support assembly includes six equal-height steel ball supports 118 set on a horizontal base 101. The top of the six equal-height steel ball supports 118 is provided with two micro tension springs that control the rolling recovery of the steel balls. Three equal-height steel ball supports 118 support the left force bar 102 and the right force bar 103 through the steel balls as a group, so as to achieve a horizontal pure rolling state.

[0063] The left force bar 102 and the right force bar 103 are respectively provided with loading ports 119 at the ends away from the loading tool holder, and the calibration beam 104 is loaded through the loading ports 119. The left force bar 102, the right force bar 103 and the calibration beam 104 form two rigid hinge beams on the left and right, which constitute a theoretically rigid closed plane static mechanical rigid hinge beam.

[0064] The three-point deflectometer 105 is used to measure the deformation deflection of the calibration beam 104 and record the pulse value of the servo motor 110 corresponding to the required deformation deflection so that the servo motor 110 can directly drive the required deformation deflection. The left ball screw 111 and the right ball screw 112 travel in opposite directions so that the left force rod 102 and the right force rod 103 move towards the reducer 109 at the same time or move away from the reducer 109 at the same time, so that the calibration beam 104 bends in an arc shape or a reverse arc shape.

[0065] In this specific embodiment, the ball linear guide and ball screw can also be common linear guides and common screws. The servo motor 110 can also be replaced by a stepper motor, or other general motors.

[0066] In this specific embodiment, the horizontal base 101 adopts a grade 0 or grade 00 marble platform to create a large flatness in order to form a rigid closed planar static mechanical balance system, thus laying a good planar foundation for the main equipment.

[0067] The structure of this invention also realizes two self-testing functions: the testing process and the return to zero position. This function is very important for this kind of high-precision and high-rigidity measuring equipment and is the key to ensuring the reliability of the test data.

[0068] In this specific embodiment, the left blade 113 and the right blade 114 respectively include an inner blade and an outer blade; the left force bar 102 and the right force bar 103 are provided with grooves corresponding to the inner blade and the outer blade, and there is a gap between the blade and the groove when not loaded. When loaded, the blade and the groove are in line contact to ensure the unidirectionality of the loading force direction. After unloading, they are out of contact, ensuring that the calibration beam 104 is in a natural state without external force interference before loading and after unloading.

[0069] In this specific embodiment, a wedge-shaped self-locking clamping mechanism 120 is also provided in the corresponding area of ​​the loading port 119 for loading the calibration beam 104. The wedge-shaped self-locking clamping mechanism 120 includes a pressed wedge 121 and a driving wedge 122. One side of the pressed wedge 121 is in contact with the calibration beam 104, and the inclined surface of the pressed wedge 121 matches the inclined surface of the driving wedge 122. The driving wedge 122 is connected to a triangular threaded pair 123, which is used to convert rotation into linear motion, thereby driving the wedge 122. Axial movement pushes the pressed wedge 121 to move laterally along the guide key, clamping the calibration beam 104; the left force bar 102, the right force bar 103, and the calibration beam 104 form a rigid hinge beam, and during the bending process of the calibration beam 104, the tangent at the intersection of the longitudinal center line of the calibration beam 104 and the center line of the left force bar 102 is perpendicular to the left force bar 102, forming the left rigid hinge, and the tangent at the intersection of the longitudinal center line of the calibration beam 104 and the center line of the right force bar 103 is perpendicular to the right force bar 103, forming the right rigid hinge.

[0070] Furthermore, the calibration beam 104 is installed in two sets of clamping mechanisms connected in series, consisting of two force bars with an angle smaller than the friction angle and a triangular threaded pair, both of which have self-locking properties, forming a rigid connection and a stable and reliable rigid hinge.

[0071] In this specific embodiment, the device is configured to: obtain the total mechanical strain energy based on the total number of loading pulses of the servo motor 110; obtain the thermal expansion strain of the calibration beam 104 based on the coefficient of thermal expansion and the temperature change difference of the calibration beam 104; and obtain the thermal expansion strain of the calibration beam 104 based on the energy conservation ε. s =(αΔt)+ε c The mechanical strain of the calibration beam 104 was obtained; where ε s Let ε be the total mechanical strain energy, α be the coefficient of thermal expansion, and Δt be the temperature change difference. The mechanical strain ε of the calibrated beam under load is... c .

[0072] This measurement method also solves the requirement for loading speed in the creep test of resistance strain gauges.

[0073] It should be noted that the total number of pulses applied by the high-speed servo motor 110 directly calculates the pure bending mechanical strain of the calibration beam 104, which is fast, accurate, and has the best repeatability, determined by the number of pulses. This method completely and ideally avoids the influence of furnace temperature changes, and the entire loading test is automated by the servo motor 110 and the programmable logic controller (PLC) electrical control system. Except for the operation of loading and unloading the calibration beam 104, which requires proximity to the device of this embodiment, all other operations can be performed remotely. For example, when conducting wind experiments on aircraft, the device of this embodiment can be used in special environments such as a vacuum chamber. This strain measurement method not only greatly improves the strain resolution but also ensures the accuracy, stability, repeatability, and reproducibility of the strain under ideal conditions of standard room temperature.

[0074] In this specific embodiment, the left force bar 102 and right force bar 103 of the device are respectively equipped with adjustable positioning pins. These adjustable positioning pins are used for assembly positioning and for verifying the system reliability of the floating reset of the rigid hinge beam after the calibration beam 104 has been subjected to strain relief. Specifically, if the left force bar 102 and right force bar 103 reset to their positions corresponding to the adjustable positioning pins after the calibration beam 104 has been subjected to strain relief, the system is considered reliable; otherwise, the standard static strain loading is considered unreliable and needs to be reapplied. The calibration beam needs to be reinstalled, clamped, and the experiment repeated.

[0075] This embodiment ensures the formation of a rigid hinged beam mechanical model, which is placed on six steel ball supports 118 of equal height that are automatically reset by two micro-force tension springs. Two pairs of inner and outer knife edges are installed on the ball screw as push rods, so as to achieve a rigid, closed, unconstrained, one-degree-of-freedom symmetrically expandable pure rolling motion with equal and opposite forces when loaded.

[0076] In this specific embodiment, the left and right force bars are positioned by four adjustable positioning pins to ensure the formation of a rigid hinge beam mechanical model. The whole is placed on six steel ball supports 118 of equal height that are automatically reset by two micro-force tension springs. Two pairs of inner and outer knife edges are installed on the ball screw as push force bars to achieve a rigid, closed, unconstrained, one-degree-of-freedom symmetrically expandable pure rolling state when loaded. The rigid rod principle is that the two forces are automatically and absolutely equal and loaded in opposite directions. The pure rolling state of the calibrated beam 104 is tested in both concave and convex directions.

[0077] Currently, most of the calibration beams 104 in similar devices, both domestically and internationally, cannot achieve loading in both concave and convex directions during the same clamping process. Especially under high-temperature conditions, similar devices, both domestically and internationally, can only load in one direction. This results in a significant and non-negligible directional error during testing.

[0078] The four cylindrical locating pins below the left and right force bars 103 of the device not only ensure the correct installation of the calibration beam 104, forming a theoretically rigid hinge beam in a ready-to-work state, but also check that if there is a slight change of 5-10 με during the loading process of the entire system, the tightness of the four locating pins when inserted into the locating holes at room temperature will show a significant change when the rigid hinge beam returns to zero. Because it is a rigid closed system, only when there is basically no change can it be said that the entire test process is stable and normal, and the test data is reliable. This is ensured by positioning the four cylindrical locating pins with two parallel measuring standards during assembly and adjustment.

[0079] Based on data from K-value meters from various countries, none of them possess process self-check and zero-return self-check capabilities. This is because they lack pulse count and high-precision four fixed pins.

[0080] In this specific embodiment, based on the pure couple strain measured by the equivalent comparison three-point deflectometer 105, a displacement sensor is also provided on the horizontal base 101. The displacement sensor is used to detect the relative displacement of the left tool holder 115 and the right tool holder 116. The device is configured to: calculate the unique real-time distance between the intersection points of the centerlines of the left and right force bars 102 and 103 with the longitudinal centerline of the calibration beam 104, based on the thickness of the calibration beam 104, the distance from the point of application of the loading blade to the longitudinal centerline of the calibration beam 104, and the above parameters. Then, calculate the mechanical strain according to the relevant formula.

[0081] The three-point deflectometer 105 uses a grating displacement sensor. The measuring head and two small blades of the gauge are kept in gentle contact with the calibration beam 104 by screws and nuts. As the calibration beam 104 bends, the two blades slide against the beam surface, improving measurement accuracy and preventing damage to the high-precision beam surface from the blades. This reduces grinding and extends the service life. The three-point deflectometer 105 includes two gauge distance settings: a large gauge distance with a blade spacing of 500mm and a small gauge distance with a blade spacing of 300mm.

[0082] Furthermore, in this specific embodiment, the strain value can be obtained using a three-point deflectometer 105. The two sides of the calibration beam 104 are divided into surface A and surface B, resulting in two possibilities: surface A is concave and surface B is convex, or surface A is convex and surface B is concave.

[0083] Concave surface A:

[0084]

[0085] B-side convex:

[0086]

[0087] A-side convex:

[0088]

[0089] B-side concave:

[0090]

[0091] Where, a is the distance from the point of application of the loading blade to the longitudinal centerline of the calibration beam 10413 (the centerline is not the perpendicular bisector), c is the distance between the blade on the three-point deflectometer 10516 and the measuring head, μ is the Poisson's ratio of the calibration beam 10413, h is the thickness of the calibration beam 10413, and f is the distance between the loading blade and the measuring head. + Let f be the deflection of the concave deformation of surface A. - Let ε be the convex deformation deflection of surface A. AY For concave strain at surface A, ε BT For the convex strain of plane B, ε AT For the convex strain on surface A, ε BY The strain is concave on surface B.

[0092] It should be noted that in this embodiment of the invention, the measurement of the three-point deflection gauge 105 is divided into two gauge lengths. The large gauge length, currently the largest domestically and internationally, is 500mm and is distributed on the outside, while the small gauge length, 300mm, is distributed internally and is retractable. Both have been accurately calibrated using a Class 1 standard large gauge. The large gauge length of 500mm is fixed and has high accuracy, better than 1μm, and is used for standard ambient temperature (20 degrees Celsius) calibration beam 104 with a length of 780-800mm. Although the small gauge length of 300mm is calibrated in the same way, it uses a movable positioning and screw-locking mechanism, and is used for high-temperature combined calibration beam 104, which is very suitable for high-temperature measurements. Because the elastic alloy materials for high-temperature beams are particularly expensive, it is difficult to make a large Kt calibration beam 10413 with a length of 460mm, a thickness of 10mm, and a width of 25mm. Some can only be made to a length of about 100mm, and other elastic materials need to be welded to both ends to extend it, and the mechanical properties of the materials need to be studied.

[0093] In another specific embodiment, strain values ​​are obtained using displacement sensors, and the two sides of the calibration beam 10413 are divided into surface A and surface B. There are two possibilities: surface A is concave and surface B is convex, or surface A is convex and surface B is concave.

[0094] Concave surface A:

[0095]

[0096] A-side convex:

[0097]

[0098] Where, 'a' is the distance from the point of application of the loading cutterhead to the longitudinal centerline of the calibration beam 10413 (the centerline is not the perpendicular bisector), 'h' is the thickness of the calibration beam 10413, and 'L' is the initial distance between the two tool holders (i.e., the distance between the two tool holders when no load is applied). YA Let L be the real-time value when surface A is concave, ΔL MY L represents the relative displacement between the force application points on the two tool holders when surface A is concave. TA Let L be the real-time value when surface A is convex, ΔL MT ε is the relative displacement between the force application points on the two tool holders when surface A is convex. AY For concave strain at surface A, ε AT The strain is the convex strain on surface A.

[0099] It should be noted that this structure can circumvent the problem that the heating furnace cannot use a three-point deflectometer 105, thus enabling the measurement of the K value under high-temperature conditions.

[0100] In this specific embodiment, a micro-motion short roller guide is placed between the two ball linear guides, on which a reducer 109 and a servo motor 110 are installed. Corresponding cylindrical rolling bearings are fitted onto the outer ends of the left ball screw 111 and the right ball screw 112, respectively, and abut against a compression spring 117, ensuring that the entire system has axial floating characteristics. This means that the entire system is in an unconstrained rigid closed state before loading; during loading, the two forces of the rigid rod loading are automatically equal and opposite in direction, resulting in a pure rolling plane static state.

[0101] In this specific embodiment, the calibration beam 104 is a whole-body normal temperature test beam and a split high and low temperature thermal insulation connecting sleeve containing auxiliary beams, which are combined to form a Kt beam.

[0102] Further assembly diagram of the Kt beam is shown below. Figure 6 As shown, Figure 6 In the middle section, 1 and 6 are auxiliary beams, 2 and 5 are thermal insulation connecting sleeves, 3 is a set screw, and 4 is a Kt beam.

[0103] Currently, most of the calibration beams 104 in similar devices, both domestically and internationally, cannot achieve loading in both concave and convex directions during the same clamping process. Especially under high-temperature conditions, similar devices, both domestically and internationally, can only load in one direction. This results in a significant and non-negligible directional error during testing.

[0104] According to the pure bending moment beam theory in mechanics of materials, a plane perpendicular to the neutral axis remains a plane after bending. In the design of calibration beam 104, derivation shows that its cross-sectional shape should preferably be square or approximately square. This invention determines the thickness of calibration beam 104 and optimizes the error distribution to minimize the error to negligible levels. Specifically, the thickness of the approximately square beam should not exceed 35 mm, preferably 25-26 mm; if ground to below 18 mm, the accuracy grade must be reduced. This design also reduces quenching deformation, improves service life, and provides a theoretical basis for the use and maintenance of calibration beam 104. Furthermore, using a rectangular beam instead of a square beam introduces quantitative errors. The smaller the thickness of calibration beam 104 (or Kt beam), the more significant the decrease in accuracy, exhibiting a quadratic geometric progression.

[0105] In this specific embodiment, the calibrated beam 104 at room temperature (20°C) can generate a large strain of 0-±5000με, or the Kt beam can generate a strain of 0-±3000με.

[0106] In this specific embodiment, the reducer is slidably connected to the ball linear guide via a short roller guide, so that the reducer has axial floating characteristics.

[0107] In this specific embodiment, when the device is loaded, once the pulse is positioned, the entire rigid hinge beam is in a state of static equilibrium in a rigid closed plane. If a certain stressed part or structure creeps or is interfered with by a certain factor, then the displacement display will not repeat during several loading cycles, and the displacement display will not return to zero when returning to its original position, thus realizing process self-checking.

[0108] In this specific embodiment, the device further includes a low-temperature room-temperature furnace, a high-temperature furnace, and a heat-insulating pad. The low-temperature room-temperature furnace and the high-temperature furnace are used to heat the calibration at a preset temperature; the heat-insulating connecting sleeve ( Figure 6 () and heat insulation pads are used to keep high-temperature furnaces warm and insulated.

[0109] The sensitivity coefficient Kt and temperature coefficient dk of the resistance strain gauge, especially the temperature sensitivity coefficient K of the strain gauge at high temperatures. t and temperature coefficient d k Inaccurate measurements have been a persistent problem in the past. This inaccurate data in experimental stress analysis under high-temperature conditions has led to serious consequences. The new device uses displacement loading, avoiding the influence of temperature variations in the elastic modulus E. Combined with relative measurement methods, accurate measurements are possible. This is the case both domestically and internationally. The strain gauge's temperature sensitivity coefficient K... tand temperature coefficient d k They don't provide it at all, not even in the high-temperature strain gauge product catalog; they only provide reference data based on their experimental experience.

[0110] The embodiments of the present invention utilize a left force bar 102, a right force bar 103, and a calibration beam 104 or K. t The beams form a rigid hinge beam, and by incorporating a compression spring 117, the rigid hinge beam is kept in a floating, unconstrained state (i.e., it can move slightly 1 to 2 mm along the screw axis), preventing it from jamming and causing errors. This embodiment of the invention, through such a structure, ensures that the rigid hinge beam, after loading, is theoretically an unconstrained, rigid, closed-plane static mechanical equilibrium system, guaranteeing a truly perfect realization of the rigid hinge beam's mechanical model, thereby improving the accuracy of strain measurement.

[0111] The wedge-shaped self-locking clamping mechanism 120 of this embodiment includes a pressed wedge 121 and a driving wedge 122. One side of the pressed wedge 121 is connected to the calibration beam 104 or K. t The beams are in contact, and the inclined surface of the pressed wedge 121 matches the inclined surface of the driving wedge 122. The driving wedge 122 is connected to the triangular threaded pair 123, which converts rotation into linear motion, thereby causing the driving wedge 122 to move axially and push the pressed wedge 121 to clamp the calibration beam 104 or Kt beam. In this embodiment of the invention, the wedge-shaped self-locking clamping mechanism 120 clamps the calibration beam 104 or Kt beam, ensuring clamping of calibration beams 104 or Kt beams of different specifications. t The beam undergoes adaptive locking, causing the calibration beam 104 or K to be locked. t The beam can produce equal bending without any slippage during the measurement process, which further improves the performance of the rigid closed plane static mechanical equilibrium system and improves the accuracy of strain measurement.

[0112] In this embodiment of the invention, during the bending process of the calibration beam 104 or Kt beam, the tangent at the intersection of the longitudinal centerline of the calibration beam 104 or Kt beam and the centerline of the left force member 102 is perpendicular to the left force member 102. t The tangent at the intersection of the longitudinal centerline of the beam and the centerline of the right force member 103 is perpendicular to the right force member 103, ensuring that the measurement is always in an ideal state, thereby guaranteeing the accuracy of strain measurement.

[0113] In this embodiment of the invention, a horizontal base 101 is provided with six steel ball supports of equal height. A steel ball is disposed inside the top of each support, and the supports support the left and right force rods 102 and 103 via the steel balls, simultaneously achieving a horizontal pure rolling state. The small nylon sleeves that move with the steel balls are controlled back to the center position by two small tension springs. This mechanism can greatly reduce the influence of friction on the measurement, thereby improving measurement accuracy.

[0114] In this embodiment of the invention, the calibration beam 104 or K can be calibrated by the total number of loading pulses of the servo motor 110. t The mechanical strain of the beam is calculated, resulting in high measurement efficiency, accuracy, and excellent repeatability. This method completely and ideally avoids the problem of not being able to use a three-point deflectometer 105 due to the heating furnace, and the servo motor 110 and programmable logic controller (PLC) electrical control system enable full automation of the loading test.

[0115] In this embodiment of the invention, the displacement of the two-blade seat can be measured using a displacement sensor, such as a grating ruler, and then the calibration beam 104 or K can be used to calibrate the beam. t The mechanical strain of the beam is solved, and this structure can avoid the problem that a three-point deflectometer 105 cannot be used due to the heating furnace, thus allowing for the measurement of K under high-temperature conditions. t Value, and temperature coefficient d k ...

[0116] In this embodiment of the invention, the loading blade and the groove on the bearing rod are not in contact with each other and are kept at a certain distance when not under load. During loading, the blade and the groove are in line contact to ensure the unidirectionality of the loading force. After unloading, they are no longer in contact, ensuring that the calibration beam 104 is in a natural state free from external force interference before and after loading and unloading.

[0117] This invention employs a servo motor 110, which solves the problem of slow creep measurement speed of resistance strain gauges. Testing of a creep-free fiber optic grating sensor showed zero creep, sufficiently proving that the device itself exhibits no creep after loading. Since there is no displacement change, there is no change in external force; therefore, the calibration beam 104 or K... t Since the beam exhibits no creep, the creep of the strain gauge can be accurately measured. This also overcomes the limitation of slow stepper motor speeds in resistance strain gauge creep testing, which cannot meet the national standard requirement of loading 1000±50με within 15 seconds. This is why a servo motor 110 must be used.

[0118] In this embodiment of the invention, the calibration beam 104 or K is used. t During the beam bending process, the positional loading method, instead of using weights, naturally opens up the calibration beam 104 or K. t The elastic modulus E of beam materials is subject to significant errors due to temperature variations, especially during testing at high and low temperatures.

[0119] This invention automates the entire loading test using a servo motor 110 and a programmable logic controller (PLC) electrical control system, allowing for the loading and unloading of only the calibration beam 104 or K. tWhen operating the beam, the operator needs to be close to the device, but the rest can be done from a separate room. For example, the device can be placed in a vacuum chamber or other special environment for wind experiments on aircraft. This method of strain measurement not only greatly improves the strain resolution, but also ensures the accuracy, stability, repeatability, and reproducibility of the strain by always maintaining the ideal state of standard room temperature (around 20°C). Additionally, a linear guide grating ruler can be installed on both load cells of the two-force member to measure the relative displacement distance between the two load cells to calculate the calibration beam 104 or K. t Beam or high temperature K t Mechanical strain on the beam. Multiple measurement methods are cross-checked to prevent errors.

[0120] In summary, the embodiments of the present invention improve the accuracy of strain measurement under various conditions, thereby improving the Ka of the high-temperature strain gauge as a function of temperature. t Accuracy of value and temperature coefficient d k Values ​​and creep and mechanical hysteresis of strain gauges at high temperatures.

[0121] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0122] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0123] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A mechanical standard static strain generator for a pure rolling rigid hinged beam, characterized in that, The device includes: a horizontal base, a drive assembly, a rolling support assembly, a left force bar, a right force bar, a calibration beam, and a three-point deflection meter; The drive assembly includes a left ball linear guide, a right ball linear guide, and a middle ball linear guide located between the left ball linear guide and the right ball linear guide on the horizontal base. The middle ball linear guide is equipped with a reducer and a servo motor that are in transmission cooperation. The worm gear output center shaft of the reducer is connected to a left ball screw and a right ball screw at both ends. A left screw nut and a right screw nut are respectively fitted on the left ball screw and the right ball screw. The left screw nut and the right screw nut are controlled by the control rod mechanism on the ball linear guide to not rotate and to translate only along the ball linear guide on the ball screw. A left cutting edge is fixedly connected to the left lead screw nut, and a right cutting edge is fixedly connected to the right lead screw nut; a left cutting edge corresponding to the left cutting edge is provided at the end of the left force rod, and a right cutting edge corresponding to the right cutting edge is provided at the end of the right force rod. The reducer is connected to the servo motor for transmission. The servo motor is used to drive the left ball screw and the right ball screw to rotate through the reducer, thereby driving the left cutter and the right cutter to push the left cutter holder and the right cutter holder to move axially on the ball linear guide. The outer ends of the left and right ball screws are respectively fitted with corresponding cylindrical rolling bearings and abut against the compression spring. The compression spring is used to give the entire system of left and right ball screws axial floating characteristics. The rolling support assembly includes six steel ball supports of equal height set on the horizontal base. The top of the six steel ball supports is equipped with two micro tension springs to control the rolling recovery of the steel balls. Three steel ball supports of equal height form a group through the steel balls to support the left force bar and the right force bar, so as to realize a rigid closed unrestrained pure rolling with one degree of freedom that can be symmetrically stretched and expanded when loaded, and the two forces are equal and opposite in direction. The left and right force rods are respectively provided with loading ports at the ends away from the corresponding tool holders, and the calibration beam is loaded through the loading ports. The left and right force rods and the calibration beam form two rigid hinges, forming a theoretically rigid closed plane static mechanical rigid hinge beam. The three-point deflectometer is used to measure the deformation deflection of the calibration beam and record the required deformation deflection of the calibration beam, and the corresponding servo motor pulse value so that the servo motor can directly drive the beam to the required deformation deflection. The left ball screw and the right ball screw travel in opposite directions so that the left and right levers move simultaneously toward the reducer or move away from the reducer, so that the calibration beam bends and deforms in an arc or anti-arc parabolic shape. The left and right cutting edges each include an inner cutting edge and an outer cutting edge; the left and right force bars are provided with grooves corresponding to the inner and outer cutting edges, and there is a gap between the cutting edge and the groove when not loaded. When loaded, the cutting edge and the groove are in line contact to ensure the unidirectionality of the loading force. After unloading, they are out of contact, ensuring that the calibration beam is in a natural state without external force interference before and after loading. The loading port, corresponding to the area where the calibration beam is loaded, is also equipped with a wedge-shaped self-locking clamping mechanism. The wedge-shaped self-locking clamping mechanism includes a pressed wedge and a driving wedge. One side of the pressed wedge is in contact with the calibration beam, and the inclined surface of the pressed wedge matches the inclined surface of the driving wedge. The driving wedge is connected to a triangular thread pair, which is used to convert rotation into linear motion, thereby causing the driving wedge to move axially and push the pressed wedge to move laterally along the guide key to clamp the calibration beam. The left force rod, the right force rod, and the calibration beam form a rigid hinge beam. During the bending process of the calibration beam, the tangent at the intersection of the longitudinal center line of the calibration beam and the center line of the left force rod is perpendicular to the left force rod, forming a left rigid hinge. The tangent at the intersection of the longitudinal center line of the calibration beam and the center line of the right force rod is perpendicular to the right force rod, forming a right rigid hinge. The left and right force rods of the device are respectively positioned by adjustable positioning pins. The adjustable positioning pins are used for assembly positioning and system reliability verification of the rigid hinge beam floating reset after the calibration beam is loaded with strain and unloaded. When the calibration beam is loaded with strain and unloaded, the left and right force rods reset to the positions corresponding to the positions of the adjustable positioning pins. A micro-motion short roller guide is set between the left and right ball linear guides. A reducer and a servo motor are installed on the micro-motion short roller guide. Corresponding cylindrical rolling bearings are sleeved on the outer ends of the left and right ball screws and abut against the compression springs to ensure that the entire system has axial floating characteristics.

2. The pure rolling rigid hinge beam mechanical standard static strain generator according to claim 1, characterized in that, The device is configured to: obtain the total mechanical strain energy based on the total number of loading pulses of the servo motor; obtain the thermal expansion strain of the calibration beam based on the thermal expansion coefficient and temperature change difference of the calibration beam; and obtain the thermal expansion strain based on energy conservation. The mechanical strain of the calibration beam is obtained; wherein, The total mechanical strain energy, The coefficient of thermal expansion is... The mechanical strain of the beam under load is calibrated based on the temperature change difference. .

3. The pure rolling rigid hinge beam mechanical standard static strain generator according to claim 1, characterized in that, Based on the pure couple strain measured by the equivalent comparison three-point deflectometer, a displacement sensor is also provided on the horizontal base. The displacement sensor is used to detect the relative displacement of the left and right tool holders. The device is configured to: calculate the unique real-time distance between the intersection points of the center lines of the left and right tool holders and the longitudinal center line of the calibration beam after loading, based on the thickness of the calibration beam, the distance of the force bar from the point of action of the tool edge to the longitudinal center line of the calibration beam, and the above parameters; and then calculate the mechanical strain according to the relevant formula.

4. The pure rolling rigid hinge beam mechanical standard static strain generator according to claim 1, characterized in that, The calibration beam comprises a solid ambient temperature test beam and a separate Kt beam consisting of an auxiliary beam and a high and low temperature thermal insulation connecting sleeve.

5. The mechanical standard static strain generator for a pure rolling rigid hinged beam according to claim 1, characterized in that, During room temperature experiments, when the device is loaded, once the pulse is positioned, the entire rigid hinge beam is in a state of static equilibrium in a rigid closed plane. If a stressed part or structure creeps or is interfered with by a certain factor, the displacement display will not repeat during several loading cycles, and the displacement display will not return to zero when returning to its original position, thus achieving process self-checking.

6. The pure rolling rigid hinge beam mechanical standard static strain generator according to claim 4, characterized in that, The device also includes a low-temperature room-temperature furnace, a high-temperature furnace, and a heat-insulating pad. The low-temperature room-temperature furnace and the high-temperature furnace are used to heat the Kt beam to a preset temperature. The heat-insulating connecting sleeve and the heat-insulating pad are used to insulate and heat-insulate the high-temperature furnace.

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