Small displacement non-welding shear stress measurement system and method

Abstract

The application provides a small displacement non-welding shear stress measurement system and method, which comprises a parallel link structure, two probe fixing devices, an external frame and two differential pressure measurement devices; the parallel link structure comprises a top plate, a first target plate, a second target plate, a first bottom fixed plate and a plurality of circular links, the external frame comprises a structural frame, a hollow plate and two transparent acrylic plates, the probe fixing device comprises a displacement sensor with external threads, a first fixed nut, a second fixed nut and a sleeve with internal and external threads, and the two displacement sensors are used for measuring the first displacement of the first target plate in the first horizontal direction and the second displacement of the second target plate in the second horizontal direction respectively. The application simultaneously monitors the displacement of the parallel link structure in two directions by using two displacement sensors, and realizes shear stress measurement when the water flow direction changes.

Description

Technical Field

[0001] This application mainly relates to the field of shear stress measurement technology, specifically to a small displacement non-welding shear stress measurement system and method. Background Technology

[0002] Currently, shear stress measurement methods are divided into direct and indirect methods. Direct measurement primarily calculates shear stress by measuring the displacement of the shear stress plate under water flow. Indirect measurement derives shear stress by measuring the velocity distribution and Reynolds stress distribution near the wall. Indirect measurement methods are difficult to apply to situations where flow velocity changes over time, near-wall velocities exceed 1 m / s, or water depth is shallow. Direct measurement methods currently suffer from several drawbacks, including the use of welding to process the shear stress plate, which can cause plate deformation or protrusions, leading to significant errors in measurement. Furthermore, the large displacement of the shear stress plate during measurement can disturb the water flow, causing measurement deviations. Currently, direct measurement methods are mainly applied to shear stress measurement in one direction and cannot measure shear stress when the water flow direction changes. Summary of the Invention

[0003] This application provides a small displacement non-welding shear stress measurement system and method, which aims to solve the problem that the existing technology cannot measure the shear stress when the direction of water flow changes.

[0004] In a first aspect, this application provides a small displacement non-welded shear stress measurement system, which includes a parallel linkage structure, two probe fixing devices, an external frame, and two differential pressure measuring devices.

[0005] The parallel linkage structure includes a top plate, a first target plate, a second target plate, a first bottom fixing plate, and a plurality of circular links. The first target plate and the second target plate are fixed to the top plate. The surface of the first target plate is perpendicular to a first horizontal direction, the surface of the second target plate is perpendicular to a second horizontal direction, and the surface of the top plate is perpendicular to the vertical direction. The first horizontal direction, the second horizontal direction, and the vertical direction are perpendicular to each other. The two ends of the circular links are respectively connected to the top plate and the first bottom fixing plate.

[0006] The external frame includes a structural frame, a hollowed-out flat plate, and two transparent acrylic plates. The structural frame includes a second bottom fixing plate and a first side plate and a second side plate fixed on the second bottom fixing plate. The sides of the first side plate, the two transparent acrylic plates, and the second side plate are connected in sequence and enclosed to form a cavity to accommodate the parallel linkage structure. The hollowed-out flat plate is fixed to the top of the structural frame.

[0007] The first bottom fixing plate is fixed on the second bottom fixing plate. The hollow plate has a central hollow area. The top plate is located in the central hollow area. A gap of a preset width is left between the edge of the top plate and the inner wall of the central hollow area. The top surface of the top plate is flush with the top surface of the hollow plate. The top plate and the hollow plate are used to bear stress.

[0008] The probe fixing device includes a displacement sensor with external threads, a first fixing nut, a second fixing nut, and a threaded sleeve with internal and external threads. The displacement sensor is threaded into the inside of the threaded sleeve to screw in or out. Each of the first and second side plates has a fastening threaded hole. Two threaded sleeves on the two probe fixing devices are respectively threaded into the fastening threaded holes. The first fixing nut is sleeved on the outer wall of the displacement sensor and located within the structural frame, used to fix the displacement sensor. The second fixing nut is sleeved on the outer wall of the threaded sleeve and located outside the structural frame, used to fix the threaded sleeve. The two displacement sensors are respectively used to measure the first displacement of the first target plate in the first horizontal direction and the second displacement of the second target plate in the second horizontal direction.

[0009] The perforated plate is provided with two first pressure measuring holes arranged in a first horizontal direction and two second pressure measuring holes arranged in a second horizontal direction. The differential pressure measuring device includes a pressure measuring tube and a differential pressure sensor disposed on the pressure measuring tube. The two ends of the pressure measuring tube of one differential pressure measuring device are respectively connected to the two first pressure measuring holes to measure the first differential pressure. The two ends of the pressure measuring tube of the other differential pressure measuring device are respectively connected to the two second pressure measuring holes to measure the second differential pressure.

[0010] Optionally, the small displacement non-welded shear stress measurement system further includes a stiffness calibration system. The stiffness calibration system is used to measure the stiffness of the parallel linkage structure. The stiffness calibration system includes a measurement platform, a fixed pulley, a hook, a weight, a flexible line, and a lifting platform. The measurement platform is used to support the external frame and the fixed pulley. One end of the flexible line is used to connect to the top plate, and the other end of the flexible line passes through the fixed pulley and is connected to the hook. The weight is hung on the hook. When one end of the flexible line is connected to the top plate, the portion of the flexible line located between the fixed pulley and the top plate is parallel to the surface of the top plate. The lifting platform is used to support the weight from the direction of gravity.

[0011] Optionally, the bottom of the top plate is provided with two elongated grooves that are perpendicular to each other. The first target plate and the second target plate are respectively inserted into the two elongated grooves and fixed with a mixed epoxy resin adhesive.

[0012] Optionally, the number of circular connecting rods is four. The bottom of the top plate and the top of the first bottom fixing plate are each provided with four circular grooves. The two ends of the circular connecting rods are respectively inserted into one circular groove on the top plate and one circular groove on the first bottom fixing plate, and are fixed by a mixed epoxy resin adhesive.

[0013] Optionally, the bottom of the first bottom fixing plate is provided with four threaded grooves, and the second bottom fixing plate is provided with fixing screw holes corresponding to the four threaded grooves. A countersunk screw is threaded through the fixing screw hole and threaded into the threaded groove to connect the first bottom fixing plate and the second bottom fixing plate.

[0014] Optionally, cleaning grooves are provided on the first side plate and the second side plate.

[0015] Optionally, the cleaning tank is fitted with a water-stopping plug.

[0016] Optionally, the first target plate and the second target plate are aluminum plates, the preset width is 0.5mm, and the thickness of the top plate is 0.8mm.

[0017] Optionally, the corners of the hollowed-out plate are provided with internal threaded grooves for fixing to external components.

[0018] Secondly, this application provides a method for measuring non-welded shear stress based on small displacement, the method comprising:

[0019] Shear stress was measured using a small displacement non-welding shear stress measurement system to obtain the first displacement of the first target plate in the first horizontal direction, the second displacement of the second target plate in the second horizontal direction, the first pressure difference, and the second pressure difference.

[0020] The first stiffness of the parallel linkage structure in the first horizontal direction, the second stiffness in the second horizontal direction, the first interval distance between the two first pressure measuring holes, the second interval distance between the two second pressure measuring holes, the volume of the top plate, and the area of ​​the top plate are obtained.

[0021] The shear stress measurement value is determined based on the first displacement, the second displacement, the first pressure difference, the second pressure difference, the first stiffness, the second stiffness, the first interval distance, the second interval distance, the volume of the top plate, and the area of ​​the top plate.

[0022] This application provides a small-displacement non-welded shear stress measurement system and method. The small-displacement non-welded shear stress measurement system includes a parallel linkage structure, two probe fixing devices, an external frame, and two differential pressure measuring devices. The parallel linkage structure includes a top plate, a first target plate, a second target plate, a first bottom fixing plate, and multiple circular linkages. The first and second target plates are fixed to the top plate. The surface of the first target plate is perpendicular to a first horizontal direction, the surface of the second target plate is perpendicular to a second horizontal direction, and the surface of the top plate is perpendicular to the vertical direction. The first horizontal direction, the second horizontal direction, and the vertical direction are mutually perpendicular. The circular connecting rod has two ends connected to a top plate and a first bottom fixing plate, respectively. The outer frame includes a structural frame, a hollowed-out plate, and two transparent acrylic plates. The structural frame includes a second bottom fixing plate and a first side plate and a second side plate fixed to the second bottom fixing plate. The sides of the first side plate, the two transparent acrylic plates, and the second side plate are connected in sequence and enclose to form a cavity to accommodate the parallel connecting rod structure. The hollowed-out plate is fixed to the top of the structural frame. The first bottom fixing plate is fixed to the second bottom fixing plate. A central hollow area is opened on the hollowed-out plate, and the top plate is located in the central hollow area. A gap is left between the edge of the top plate and the inner wall of the central hollow area. A pre-defined gap is provided, with the top surface of the top plate flush with the top surface of the perforated plate. The top plate and perforated plate are used to bear stress. The probe fixing device includes a displacement sensor with external threads, a first fixing nut, a second fixing nut, and a threaded sleeve with internal and external threads. The displacement sensor is threaded into the inside of the threaded sleeve, allowing it to screw in or out. Each of the first and second side plates has a fastening threaded hole. Two threaded sleeves on the two probe fixing devices are respectively threaded into the fastening threaded holes. The first fixing nut is fitted onto the outer wall of the displacement sensor and located within the structural frame to fix the displacement sensor. The second fixing nut is fitted onto the outer wall of the threaded sleeve. Located outside the structural frame, it is used to fix the screw sleeve; two displacement sensors are used to measure the first displacement of the first target plate in the first horizontal direction and the second displacement of the second target plate in the second horizontal direction, respectively; the hollow plate is provided with two first pressure measuring holes arranged in the first horizontal direction and two second pressure measuring holes arranged in the second horizontal direction. The differential pressure measuring device includes a pressure measuring tube and a differential pressure sensor set on the pressure measuring tube. The two ends of the pressure measuring tube of one differential pressure measuring device are respectively connected to the two first pressure measuring holes to measure the first differential pressure, and the two ends of the pressure measuring tube of the other differential pressure measuring device are respectively connected to the two second pressure measuring holes to measure the second differential pressure. This application uses two displacement sensors to simultaneously monitor the displacement of the parallel linkage structure in two directions, realizing the measurement of shear stress when the direction of water flow changes.

[0023] Furthermore, this application employs a small-displacement non-welding shear stress measurement system, ensuring that the top plate of the parallel linkage structure exhibits no surface deformation after processing. This solves the problem of plate surface deformation or protrusion caused by the welding method used in traditional methods for processing shear stress plates. Experimental results also show that the shear stress plate structure using the non-welding fixing method has high structural strength and meets the experimental measurement conditions.

[0024] Furthermore, the top plate surface of the parallel link structure of this application can be processed to different roughnesses. Since the non-welding fixing method used will not cause any deformation to the top plate surface, this application realizes the measurement of shear stress under different roughness conditions.

[0025] Furthermore, this application uses an aluminum target plate to improve the measurement accuracy of the displacement sensor. That is, while meeting the same measurement accuracy as the traditional method, the displacement of the shear stress plate can be further reduced, thereby reducing the disturbance to the water flow and reducing the measurement deviation. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is an overall schematic diagram of the small displacement non-welding shear stress measurement system of this application;

[0028] Figure 2 This is an exploded view of the small displacement non-welding shear stress measurement system of this application;

[0029] Figure 3 This application relates to the explosion of the parallel linkage structure. Figure 1 ;

[0030] Figure 4 This application relates to the explosion of the parallel linkage structure. Figure 2 ;

[0031] Figure 5 This is a diagram of the probe fixing device of this application;

[0032] Figure 6 This is an exploded view of the probe fixing device of this application;

[0033] Figure 7 This is an overall schematic diagram of the external framework of this application;

[0034] Figure 8 This is an exploded view of the external framework of this application;

[0035] Figure 9 This is a schematic diagram of the differential pressure measuring device of this application;

[0036] Figure 10 This is a structural schematic diagram of the stiffness calibration system of this application;

[0037] Figure 11 This is an experimental setup diagram of an embodiment of this application;

[0038] Figure 12 This is a stiffness diagram in the first horizontal direction obtained by the stiffness calibration system of this application;

[0039] Figure 13 This is a graph showing the change of shear stress value over time after the gate is lifted according to an embodiment of this application.

[0040] The components in the diagram are labeled as follows:

[0041] 1—Parallel linkage structure, 1-1—Top plate, 1-2—Circular linkage, 1-31—First target plate, 1-32—Second target plate, 1-4—First bottom fixing plate, 1-5—Circular groove, 1-6—Elongated groove, 1-7—Threaded groove, 2—Probe fixing device, 2-1—Displacement sensor, 2-2—First fixing nut, 2-3—Second fixing nut, 2-4—Threaded sleeve, 3—Outer frame, 3-1—Hollowed-out plate, 3-2—Transparent acrylic plate, 3- 3—Cleaning groove, 3-4—Fastening threaded hole, 3-51—First pressure measuring hole, 3-52—Second pressure measuring hole, 3-6—Water stop plug, 3-7—Fixing screw hole, 3-8—Counterhead screw, 3-9—Structural frame, 3-10—Internal thread groove, 4—Differential pressure measuring device, 4-1—Differential pressure sensor, 4-2—Pressure measuring tube, 5-1—Flexible line, 5-2—Fixed pulley, 5-3—Measuring platform, 5-4—Hook, 5-5—Weight, 5-6—Lifting platform, First side plate, Second side plate. Detailed Implementation

[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0043] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0044] In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0045] This application provides a system and method for measuring non-welded shear stress based on small displacement, which will be described in detail below.

[0046] Please see Figures 1-13 In this embodiment of the application, the small displacement non-welded shear stress measurement system includes a parallel link structure 1, two probe fixing devices 2, an external frame 3, and two differential pressure measuring devices 4.

[0047] The parallel linkage structure 1 includes a top plate 1-1, a first target plate 1-31, a second target plate 1-32, a first bottom fixing plate 1-4, and multiple circular connecting rods 1-2. The first target plate 1-31 and the second target plate 1-32 are fixed to the top plate 1-1. The surface of the first target plate 1-31 is perpendicular to the first horizontal direction x, the surface of the second target plate 1-31 is perpendicular to the second horizontal direction y, and the surface of the top plate 1-1 is perpendicular to the vertical direction. The first horizontal direction x, the second horizontal direction y, and the vertical direction are mutually perpendicular. The two ends of the circular connecting rods 1-2 are connected to the top plate 1-1 and the first bottom fixing plate 1-4, respectively. The thickness of the top plate 1-1 is 0.8 mm.

[0048] In this embodiment, the bottom of the top plate 1-1 is provided with two mutually perpendicular elongated grooves 1-6. The first target plate 1-31 and the second target plate 1-32 are respectively inserted into the two elongated grooves 1-6 and fixed using a mixed epoxy resin adhesive. The surface of the top plate 1-1 can be treated to different roughnesses.

[0049] In this embodiment, there are four circular connecting rods 1-2. Four circular grooves 1-5 are provided on the bottom of the top plate 1-1 and the top of the first bottom fixing plate 1-4. The two ends of each circular connecting rod 1-2 are inserted into one circular groove 1-5 on the top plate 1-1 and one circular groove 1-5 on the first bottom fixing plate 1-4, respectively, and are fixed using a mixed epoxy resin adhesive. Experimental results show that the structure has high strength after fixing and meets the experimental measurement conditions.

[0050] In this embodiment of the application, the bottom of the first bottom fixing plate 1-4 is provided with four threaded grooves 1-7, and the second bottom fixing plate is provided with fixing screw holes 3-7 corresponding to the four threaded grooves 1-7. The countersunk screws 3-8 are threaded through the fixing screw holes 3-7 and threaded to the threaded grooves 1-7 to connect the first bottom fixing plate 1-4 and the second bottom fixing plate.

[0051] In this embodiment, the outer frame 3 includes a structural frame 3-9, a hollowed-out flat plate 3-1, and two transparent acrylic plates 3-2. The structural frame 3-9 includes a second bottom fixing plate and a first side plate and a second side plate fixed to the second bottom fixing plate. The sides of the first side plate, the two transparent acrylic plates 3-2, and the second side plate are connected in sequence and enclosed to form a cavity to accommodate the parallel connecting rod structure 1. The hollowed-out flat plate 3-1 is fixed to the top of the structural frame 3-9.

[0052] The first bottom fixing plate 1-4 is fixed on the second bottom fixing plate. The hollow plate 3-1 has a central hollow area. The top plate 1-1 is located in the central hollow area. A gap of a preset width is left between the edge of the top plate 1-1 and the inner wall of the central hollow area. The top surface of the top plate 1-1 is flush with the top surface of the hollow plate 3-1. The top plate 1-1 and the hollow plate 3-1 are used to bear stress.

[0053] The probe fixing device 2 includes a displacement sensor 2-1 with external threads, a first fixing nut 2-2, a second fixing nut 2-3, and a threaded sleeve 2-4 with internal and external threads. The displacement sensor 2-1 is threaded into the inside of the threaded sleeve 2-4 to screw in or out of the threaded sleeve 2-4. Each of the first and second side plates is provided with a fastening threaded hole 3-4. The two threaded sleeves 2-4 on the two probe fixing devices 2 are respectively threaded into the fastening threaded holes 3-4. The first fixing nut 2-2 is sleeved on the outer wall of the displacement sensor 2-1 and located inside the structural frame 3-9 for fixing the displacement sensor 2-1. The second fixing nut 2-3 is sleeved on the outer wall of the threaded sleeve 2-4 and located outside the structural frame 3-9 for fixing the threaded sleeve 2-4. The two displacement sensors 2-1 are respectively used to measure the first displacement of the first target plate 1-31 in the first horizontal direction x and the second displacement of the second target plate 1-32 in the second horizontal direction y.

[0054] The perforated plate 3-1 is provided with two first pressure measuring holes 3-51 arranged in the first horizontal direction x and two second pressure measuring holes 3-52 arranged in the second horizontal direction y. The differential pressure measuring device 4 includes a pressure measuring tube 4-2 and a differential pressure sensor 4-1 disposed on the pressure measuring tube 4-2. The two ends of the pressure measuring tube 4-2 of one differential pressure measuring device 4 are respectively connected to the two first pressure measuring holes 3-51 to measure the first differential pressure. The two ends of the pressure measuring tube 4-2 of the other differential pressure measuring device 4 are respectively connected to the two second pressure measuring holes 3-52 to measure the second differential pressure.

[0055] In this embodiment, the small displacement non-welded shear stress measurement system further includes a stiffness calibration system. The stiffness calibration system is used to measure the stiffness of the parallel linkage structure 1. The stiffness calibration system includes a measurement platform 5-3, a fixed pulley 5-2 set on the measurement platform 5-3, a hook 5-4, a weight 5-5, a flexible line 5-1, and a lifting platform 5-6. The measurement platform 5-3 is used to support the external frame 3 and the fixed pulley 5-2. One end of the flexible line 5-1 is used to connect to the top plate 1-1, and the other end of the flexible line 5-1 passes through the fixed pulley 5-2 and is connected to the hook 5-4. The weight 5-5 is hung on the hook 5-4. When one end of the flexible line 5-1 is connected to the top plate 1-1, the portion of the flexible line 5-1 located between the fixed pulley 5-2 and the top plate 1-1 is parallel to the surface of the top plate 1-1. The lifting platform 5-6 is used to support the weight 5-5 from the direction of gravity.

[0056] Furthermore, the stiffness calibration system is used to measure the stiffness of the parallel link structure 1. The stiffness of the parallel link structure 1 includes stiffness k1 and stiffness k2.

[0057] The operating steps are as follows: Place the weight on the hook, then slowly lower the lifting platform until the hook leaves the platform surface, and record the applied force and the displacement value measured by displacement sensor 2-1; raise the lifting platform until the flexible wire 5-1 is completely slack, and record the displacement value measured by displacement sensor 2-1 when the applied force is zero. Repeat the above steps, and perform linear fitting on the obtained series of known forces F and displacement values ​​Δx according to the formula F=kΔx to obtain the stiffness k. Placing the flexible wire 5-1 parallel to the first horizontal direction x and performing the above experiment yields the stiffness k1, and placing the flexible wire 5-1 parallel to the second horizontal direction y and performing the above experiment yields the stiffness k2. The stiffness diagram of the first horizontal direction x measured by the stiffness calibration system is shown below. Figure 11 As shown.

[0058] In this embodiment, cleaning grooves 3-3 are provided on the first and second side plates. The cleaning grooves 3-3 are used to drain deposits from the structural frame 3-9.

[0059] In this embodiment of the application, a water-stop plug 3-6 is inserted into the cleaning tank 3-3. The water-stop plug 3-6 is used to stop the water from entering the cleaning tank 3-3.

[0060] In this embodiment of the application, the first target plate 1-31 and the second target plate 1-32 are aluminum plates with a preset width of 0.5mm.

[0061] In this embodiment of the application, the corner of the top plate 1-1 is provided with an internal threaded groove 3-10 for fixing to an external component.

[0062] Furthermore, this application provides a method for measuring non-welded shear stress based on small displacement. The method for measuring non-welded shear stress based on small displacement includes:

[0063] (1) Shear stress is measured using a small displacement non-welding shear stress measurement system to obtain the first displacement of the first target plate in the first horizontal direction x and the second displacement of the second target plate in the second horizontal direction y, the first pressure difference and the second pressure difference.

[0064] (2) Obtain the first stiffness of the parallel link structure in the first horizontal direction x, the second stiffness in the second horizontal direction y, the first interval distance between the two first pressure measuring holes, the second interval distance between the two second pressure measuring holes, the volume of the top plate 1-1, and the area of ​​the top plate 1-1.

[0065] (3) Determine the shear stress measurement value based on the first displacement, the second displacement, the first pressure difference, the second pressure difference, the first stiffness, the second stiffness, the first interval distance, the second interval distance, the volume of the top plate 1-1, and the area of ​​the top plate 1-1.

[0066] The formula for calculating the measured shear stress τ is as follows:

[0067]

[0068] Wherein, △x1 is the first displacement of the first target plate in the first horizontal direction x measured by displacement sensor 2-1, △x2 is the second displacement of the second target plate in the second horizontal direction y measured by displacement sensor 2-1, k1 and k2 are the first stiffness of the parallel link structure in the first horizontal direction x and the second stiffness in the second horizontal direction y, respectively, △P1 and △P2 are the first and second differential pressures measured by differential pressure sensors in the first and second horizontal directions x and y, l1 is the first interval distance between the two first pressure measuring holes, l2 is the second interval distance between the two second pressure measuring holes, V is the volume of the top plate of the parallel link structure, and A is the upper surface area of ​​the top plate of the parallel link structure.

[0069] This application is based on a small displacement non-welded shear stress measurement system and method. It uses two displacement sensors to simultaneously monitor the displacement of a parallel link structure in two directions, obtains the pressure gradient through a differential pressure measurement system, and processes the displacement values ​​and pressure gradients at different times to determine the shear stress at any time.

[0070] A brief description of how this solution works:

[0071] The experimental setup provided in this embodiment is as follows: Figure 11 The experiment mainly consists of an upstream water tank 6-1, a gate 6-2, an experimental water tank, a return water system 6-3, and a small-displacement non-welded shear stress measurement system. The experimental water tank is 20m long, 0.5m wide, and 0.5m high, with a bottom plate made of plexiglass. The small-displacement non-welded shear stress measurement system is installed on the downstream bottom plate 6-4 of the experimental water tank. During the experiment, the upstream water tank 6-1 is filled to 300mm, and the gate 6-2 is quickly removed to simulate the movement of a dam-break flood. The variation of shear stress over time measured by the small-displacement non-welded shear stress measurement system during the experiment is shown in the appendix. Figure 13 As shown.

[0072] The advantages and positive effects of this application are as follows:

[0073] 1. This application uses a small displacement non-welding shear stress measurement system, and the top plate of the parallel linkage structure has no surface deformation after processing. This solves the problem of plate surface deformation or protrusion caused by the welding method used in traditional methods. Moreover, the experimental results show that the shear stress plate structure using the non-welding fixing method has high strength and meets the experimental measurement conditions.

[0074] 2. The top plate surface of the parallel linkage structure of this application can be processed to different roughnesses. Since the non-welding fixing method is adopted, it will not cause any deformation to the top plate surface. Therefore, this application realizes the measurement of shear stress under different roughness conditions.

[0075] 3. This application uses an aluminum target plate to improve the measurement accuracy of the displacement sensor. That is, while meeting the same measurement accuracy as the traditional method, the displacement of the shear stress plate can be further reduced, thereby reducing the disturbance to the water flow and reducing the measurement deviation.

[0076] 4. This application uses two displacement sensors to simultaneously monitor the displacement of the parallel linkage structure in two directions, realizing the measurement of shear stress when the direction of water flow changes.

[0077] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

[0078] The foregoing has provided a detailed description of a small displacement non-welding shear stress measurement system and method provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A small-displacement non-welding shear stress measurement system, characterized in that, The small displacement non-welding shear stress measurement system includes a parallel linkage structure, two probe fixing devices, an external frame, and two differential pressure measuring devices. The parallel linkage structure includes a top plate, a first target plate, a second target plate, a first bottom fixing plate, and a plurality of circular links. The first target plate and the second target plate are fixed to the top plate. The surface of the first target plate is perpendicular to a first horizontal direction, the surface of the second target plate is perpendicular to a second horizontal direction, and the surface of the top plate is perpendicular to the vertical direction. The first horizontal direction, the second horizontal direction, and the vertical direction are perpendicular to each other. The two ends of the circular links are respectively connected to the top plate and the first bottom fixing plate. The external frame includes a structural frame, a hollowed-out flat plate, and two transparent acrylic plates. The structural frame includes a second bottom fixing plate and a first side plate and a second side plate fixed on the second bottom fixing plate. The sides of the first side plate, the two transparent acrylic plates, and the second side plate are connected in sequence and enclosed to form a cavity to accommodate the parallel linkage structure. The hollowed-out flat plate is fixed to the top of the structural frame. The first bottom fixing plate is fixed on the second bottom fixing plate. The hollow plate has a central hollow area. The top plate is located in the central hollow area. A gap of a preset width is left between the edge of the top plate and the inner wall of the central hollow area. The top surface of the top plate is flush with the top surface of the hollow plate. The top plate and the hollow plate are used to bear stress. The probe fixing device includes a displacement sensor with external threads, a first fixing nut, a second fixing nut, and a threaded sleeve with internal and external threads. The displacement sensor is threaded into the inside of the threaded sleeve to screw in or out. Each of the first and second side plates has a fastening threaded hole. Two threaded sleeves on the two probe fixing devices are respectively threaded into the fastening threaded holes. The first fixing nut is sleeved on the outer wall of the displacement sensor and located within the structural frame, used to fix the displacement sensor. The second fixing nut is sleeved on the outer wall of the threaded sleeve and located outside the structural frame, used to fix the threaded sleeve. The two displacement sensors are respectively used to measure the first displacement of the first target plate in the first horizontal direction and the second displacement of the second target plate in the second horizontal direction. The hollow plate is provided with two first pressure measuring holes arranged in a first horizontal direction and two second pressure measuring holes arranged in a second horizontal direction. The differential pressure measuring device includes a pressure measuring tube and a differential pressure sensor disposed on the pressure measuring tube. The two ends of the pressure measuring tube of one differential pressure measuring device are respectively connected to the two first pressure measuring holes to measure the first differential pressure. The two ends of the pressure measuring tube of the other differential pressure measuring device are respectively connected to the two second pressure measuring holes to measure the second differential pressure. The bottom of the top plate has two elongated grooves that are perpendicular to each other. The first target plate and the second target plate are respectively inserted into the two elongated grooves and fixed with a mixed epoxy resin adhesive.

2. The small-displacement non-welding shear stress measurement system according to claim 1, characterized in that, The small-displacement non-welded shear stress measurement system also includes a stiffness calibration system. The stiffness calibration system is used to measure the stiffness of the parallel linkage structure. The stiffness calibration system includes a measurement platform, a fixed pulley, a hook, a weight, a flexible line, and a lifting platform. The measurement platform is used to support the external frame and the fixed pulley. One end of the flexible line is used to connect to the top plate, and the other end of the flexible line passes through the fixed pulley and is connected to the hook. The weight is hung on the hook. When one end of the flexible line is connected to the top plate, the portion of the flexible line located between the fixed pulley and the top plate is parallel to the surface of the top plate. The lifting platform is used to support the weight from the direction of gravity.

3. The small-displacement non-welding shear stress measurement system according to claim 1, characterized in that, The number of circular connecting rods is 4. The bottom of the top plate and the top of the first bottom fixing plate are provided with four circular grooves. The two ends of the circular connecting rods are respectively inserted into one circular groove on the top plate and one circular groove on the first bottom fixing plate, and are fixed with mixed epoxy resin adhesive.

4. The small-displacement non-welding shear stress measurement system according to claim 1, characterized in that, The bottom of the first bottom fixing plate is provided with four threaded grooves, and the second bottom fixing plate is provided with fixing screw holes corresponding to the four threaded grooves. A countersunk screw is threaded through the fixing screw hole and threaded into the threaded groove to connect the first bottom fixing plate and the second bottom fixing plate.

5. The small displacement non-welding shear stress measurement system according to claim 1, characterized in that, The first side plate and the second side plate are provided with cleaning grooves.

6. The small-displacement non-welding shear stress measurement system according to claim 5, characterized in that, The cleaning tank is filled with a water-stopping plug.

7. The small-displacement non-welding shear stress measurement system according to claim 1, characterized in that, The first target plate and the second target plate are aluminum plates, the preset width is 0.5mm, and the thickness of the top plate is 0.8mm.

8. The small displacement non-welding shear stress measurement system according to claim 1, characterized in that, The perforated flat plate has internal threaded grooves at its corners for fixing to external components.

9. A method for measuring non-welded shear stress based on small displacement, characterized in that, The method for measuring non-welding shear stress based on small displacement includes: Shear stress is measured using a small displacement non-welding shear stress measurement system to obtain the first displacement of the first target plate in the first horizontal direction, the second displacement of the second target plate in the second horizontal direction, the first pressure difference, and the second pressure difference, wherein the small displacement non-welding shear stress measurement system is the small displacement non-welding shear stress measurement system according to any one of claims 1-8; The first stiffness of the parallel linkage structure in the first horizontal direction, the second stiffness in the second horizontal direction, the first interval distance between the two first pressure measuring holes, the second interval distance between the two second pressure measuring holes, the volume of the top plate, and the area of ​​the top plate are obtained. The shear stress measurement value is determined based on the first displacement, the second displacement, the first pressure difference, the second pressure difference, the first stiffness, the second stiffness, the first interval distance, the second interval distance, the volume of the top plate, and the area of ​​the top plate.

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