A testing device for testing the weld strain of a steel bridge and a manufacturing method thereof

Abstract

The application discloses a kind of steel bridge weld seam strain test test device and its manufacturing method, it is related to steel bridge weld seam strain test technical field, its technical points are: insulation isolation layer, setting in the surface of steel bridge weld seam;Strain test conductive layer, setting in the surface of insulation isolation layer, the surface of strain test conductive layer is provided with first terminal and second terminal;Electric signal input device is used to input constant direct current to first terminal, when steel bridge weld seam is strained when being stressed, the resistance change between the second terminal of strain test conductive layer is reflected as voltage change;Electric signal acquisition processing device is used to collect the voltage value between second terminal in real time, according to the numerical relationship of voltage value, longitudinal piezoresistive sensitive coefficient of strain test conductive layer and strain value, obtains the strain value of steel bridge weld seam stress.This application solves the strain test problem of the position such as T-shaped joint right-angle weld, bevel weld in steel bridge.

Description

Technical Field

[0001] This invention relates to the field of strain testing technology for steel bridge welds, and more specifically, to a testing device for strain testing of steel bridge welds and its manufacturing method. Background Technology

[0002] Bridges are an important part of the transportation network. Steel bridges, as a type of bridge, are widely used due to their advantages such as light weight, high strength, high rigidity, and short construction period. However, during use, the disadvantages caused by the large number of welds in the structure have become increasingly prominent. Due to the complex stress and large deformation at the welds, fatigue problems are serious, posing a great safety hazard to steel bridges. Real-time strain monitoring of the weld locations of steel bridges is crucial to ensuring the safety of the structure.

[0003] Due to the complex shape of the weld, it is not easy to attach strain gauges or install fiber optic grating sensors. The existing strain testing method mainly involves attaching strain gauges within a millimeter range near the weld and calculating the stress-strain value at the weld location from the strain values ​​at the surrounding locations. The above method is acceptable, but the location and shape of the steel bridge weld are complex. Therefore, when using fiber optic grating sensors or attaching strain gauges to measure stress-strain values, inaccurate installation or attachment can lead to measurement errors.

[0004] Therefore, this application provides a testing device and its manufacturing method for testing the strain of steel bridge welds to overcome the shortcomings of the prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a testing device and its manufacturing method for strain testing of steel bridge welds. Utilizing the accompanying damage properties of the insulating layer, the piezoresistive characteristics of the strain testing conductive layer, and the accompanying damage properties, the strain of the steel bridge weld is obtained by testing the voltage change of the strain testing conductive layer. This invention is a flexible sensor, easy to manufacture and convenient to apply, and is used to solve the problem of strain testing at locations such as right-angle welds and bevel welds of T-joints in steel bridges where strain gauges are difficult to arrange.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A first aspect of this application provides a testing apparatus for strain testing of steel bridge welds, comprising a coating, an electrical signal input device, and an electrical signal acquisition and processing device. The coating includes an insulating layer and a strain testing conductive layer: An insulating layer is placed on the surface of the steel bridge weld to isolate the steel bridge weld. A strain test conductive layer is disposed on the surface of an insulating layer, and a first terminal and a second terminal are disposed on the surface of the strain test conductive layer; wherein, the first terminal is connected to an electrical signal input device, and the second terminal is externally connected to an electrical signal acquisition and processing device; The electrical signal input device is used to input a constant DC current to the first terminal, so that when the steel bridge weld is subjected to stress and strain occurs, the resistance change between the second terminals of the strain test conductive layer is reflected as a voltage change. The electrical signal acquisition and processing device is used to acquire the voltage value between the second terminals in real time. Based on the numerical relationship between the voltage value, the longitudinal piezoresistive sensitivity coefficient of the strain test conductive layer, and the strain value, the strain value of the steel bridge weld is obtained.

[0007] In some possible implementations, the coating further includes a protective layer disposed on the surface of the insulating layer and the strain test conductive layer, wherein the protective layer is disposed after the first and second terminals are attached to the strain test conductive layer.

[0008] In some possible implementations, the longitudinal dimension of the strain test conductive layer is greater than the test range in the width direction of the steel bridge weld, and the transverse dimension of the strain test conductive layer is equal to the test range in the length direction of the steel bridge weld.

[0009] In some possible implementations, the numerical relationship between the voltage value, the longitudinal piezoresistive sensitivity coefficient of the strain test conductive layer, and the strain value is as follows: Where C represents the longitudinal piezoresistive sensitivity coefficient of the conductive layer in the strain test. U represents the initial voltage value, and U represents the voltage value corresponding to the strain generated by the weld seam of the steel bridge under stress. This represents the strain value of the weld seam of the steel bridge under stress.

[0010] A second aspect of this application provides a method for manufacturing a testing device for testing the strain of steel bridge welds, used to manufacture a testing device for testing the strain of steel bridge welds as described in the first aspect of this application, the method comprising: Determine the actual dimensions for testing the steel bridge welds; The structural parameters of the coating are determined based on the actual dimensions of the steel bridge weld test. Molds are made based on the structural parameters of the coating; An insulating layer is sprayed onto the weld seam of the steel bridge. A strain test conductive layer is made according to the mold and placed on the insulating layer. A first terminal and a second terminal are arranged on the strain test conductive layer. A protective layer is sprayed onto the strain test conductive layer and the insulating layer. Connect the first terminal to the electrical signal input device and the second terminal to the electrical signal acquisition and processing device.

[0011] In some possible implementations, the insulating layer is made of a flexible material prepared by mixing polyurethane resin, a drying agent, and additives.

[0012] In some possible implementations, the strain test conductive layer is characterized by being made of a flexible material obtained by mixing and stirring silver-plated copper powder, silane coupling agent, aqueous acrylic emulsion, additives, and water.

[0013] In some possible implementations, the specific fabrication process of the flexible material used to make the strain testing conductive layer is as follows: Prepare a first solution by mixing and stirring a silane coupling agent with silver-plated copper powder. Add the first solution and water to the aqueous acrylic emulsion, stir and emulsify to obtain the second solution; Additives are added to the second solution, and the mixture is stirred to obtain a flexible material for fabricating a conductive layer for strain testing.

[0014] In some possible implementations, the protective layer is characterized by being made of a flexible material prepared by mixing polyurethane resin, a drying agent, and additives.

[0015] In some possible implementations, the fabricated insulating layer, strain test conductive layer, and protective layer all need to be left to stand for 4 hours.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a testing device for strain testing of steel bridge welds. It utilizes the piezoresistive characteristics and associated damage of the strain test conductive layer to obtain the strain condition of the steel bridge weld by testing the voltage change of the strain test conductive layer. This invention is a flexible sensor, which is easy to manufacture and convenient to spray. It is used to solve the problem of strain testing at locations such as right-angle welds and bevel welds of T-shaped joints in steel bridges where strain gauges are difficult to place.

[0017] 2. The coating of the present invention can be of different thicknesses, sizes, aspect ratios, and shapes, and is flexible. It can be directly placed at the weld positions of T-shaped right angles and oblique angles of steel bridges, replacing strain gauges and directly testing the strain at complex positions, thereby improving testing efficiency. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings: Figure 1 A schematic diagram of the structure of a testing device for testing the strain of steel bridge welds provided in an embodiment of this application; Figure 2 A cross-sectional schematic diagram of the coating of a test device for testing the strain of steel bridge welds provided in an embodiment of this application; Figure 3This is a schematic diagram showing the actual application location of the coating of a test device for testing the strain of steel bridge welds provided in this application embodiment; Figure 4 This is a schematic flowchart illustrating the manufacturing method of a testing device for strain testing of steel bridge welds, as provided in an embodiment of this application.

[0019] The attached diagram shows the markings and corresponding component names: 1. Coating; 2. Electrical signal input device; 3. Electrical signal acquisition and processing device; 11. Insulating layer; 12. Strain test conductive layer; 13. Protective layer; 14. First terminal; 15. Second terminal. Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0021] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly or indirectly attached to that other component. When a component is referred to as being "connected to" another component, it can be directly or indirectly connected to that other component.

[0022] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention 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. Therefore, they should not be construed as limitations on the present invention.

[0023] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] Bridges are an important part of the transportation network. Steel bridges, as a type of bridge, are widely used due to their advantages such as light weight, high strength, high rigidity, and short construction period. However, during use, the disadvantages caused by the large number of welds in the structure have become increasingly prominent. Due to the complex stress and large deformation at the welds, fatigue problems are serious, posing a great safety hazard to steel bridges. Real-time strain monitoring of the weld locations of steel bridges is crucial to ensuring the safety of the structure.

[0025] Due to the complex shape of the weld, it is not easy to attach strain gauges or install fiber optic grating sensors. The existing strain testing method mainly involves attaching strain gauges within a millimeter range near the weld and calculating the stress-strain value at the weld location from the strain values ​​at the surrounding locations. The above method is acceptable, but the location and shape of the steel bridge weld are complex. Therefore, when using fiber optic grating sensors or attaching strain gauges to measure stress-strain values, inaccurate installation or attachment can lead to measurement errors.

[0026] To address the aforementioned problems, this application provides a testing device and its manufacturing method for strain testing of steel bridge welds. Utilizing the inherent damage properties of the insulating layer, the piezoresistive characteristics of the strain testing conductive layer 12, and the inherent damage properties, the strain of the steel bridge weld is obtained by testing the voltage change of the strain testing conductive layer 12. This invention is a flexible sensor, easy to manufacture and convenient to apply, and is used to solve the problem of strain testing at locations such as right-angle welds and bevel welds of T-joints in steel bridges where strain gauges are difficult to arrange. The following is a detailed description in conjunction with the accompanying drawings.

[0027] Please refer to Figure 1 As shown, Figure 1 A schematic diagram of the structure of a testing device for testing the strain of steel bridge welds provided in an embodiment of this application; like Figure 1 As shown, the testing device includes a coating 1, an electrical signal input device 2, and an electrical signal acquisition and processing device 3. The coating 1 includes an insulating layer 11 and a strain testing conductive layer 12: An insulating layer 11 is disposed on the surface of the steel bridge weld to isolate the steel bridge weld. The strain test conductive layer 12 is disposed on the surface of the insulating layer 11. The surface of the strain test conductive layer 12 is provided with a first terminal 14 and a second terminal 15. The first terminal 14 is connected to the electrical signal input device 2, and the second terminal 15 is externally connected to the electrical signal acquisition and processing device 3. The electrical signal input device 2 is used to input a constant DC current to the first terminal 14, so that when the steel bridge weld is subjected to stress and strain occurs, the resistance change between the second terminals 15 of the strain test conductive layer 12 is reflected as a voltage change. The electrical signal acquisition and processing device 3 is used to acquire the voltage value between the second terminals 15 in real time. Based on the numerical relationship between the voltage value, the longitudinal piezoresistive sensitivity coefficient of the strain test conductive layer 12, and the strain value, the strain value of the steel bridge weld is obtained.

[0028] Specifically, it's important to understand that since the material is applied to the surface of the steel bridge weld where strain values ​​need to be tested via spraying, a pneumatic spray gun can be used for this purpose, and the air pressure can be controlled at 8-10 kg / cm².2 The gun holding distance is 18-23cm, the spray width is controlled between 12-19cm, and the paint spraying volume is 160ml / min.

[0029] The insulating isolation layer 11 is disposed on the surface of the strain test position of the steel bridge weld. It deforms synchronously with the test position and isolates the steel bridge weld, ensuring that its conductivity does not affect the potential distribution of the strain test conductive layer 12. It is understood that the size of the insulating isolation layer 11 should be slightly larger than that of the strain test conductive layer 12 to ensure complete isolation between the steel bridge structure and the conductive layer. The resistance of the structure will not affect the potential distribution of the conductive layer, and the excessive size of the insulating isolation layer 11 will not cause damage to itself or the accompanying strain test conductive layer 12.

[0030] The strain testing conductive layer 12 is disposed on the surface of the insulating layer 11. A first terminal 14 is provided on the layer to arrange measuring points and connect a constant DC current. An electrical signal input device 2 is connected to the first terminal 14 through a wire to provide a constant DC current, such as a DC current source. Since the steel bridge weld deforms due to stress, both the insulating layer 11 and the strain testing conductive layer 12 will deform synchronously. Due to the good attached damage resistance of the insulating layer 11 material and the good attached damage resistance and piezoresistive characteristics of the strain testing conductive layer 12 material, the good piezoresistive characteristics of the materials are used to test the strain. When the coating 1 is subjected to stress and strain, its resistance will change significantly, which is reflected as a change in the voltage between the measuring points of the conductive layer. According to the correspondence between the voltage of the coating 1 and the strain value, the strain value can be obtained. Therefore, in application, the strain value of the steel bridge weld can be obtained by testing the voltage between the measuring points. A second terminal 15 is also provided on the layer, connected to the electrical signal acquisition and processing device 3, to acquire the voltage value generated by synchronous deformation. The electrical signal acquisition device can be a computer terminal, so that the real-time acquired voltage value can be displayed and recorded. Based on the numerical relationship between the voltage value, the longitudinal piezoresistive sensitivity coefficient of the strain test conductive layer, and the strain, the strain value of the steel bridge weld under stress can be obtained. For example, a circuit is formed by connecting the first terminal 14, the second terminal 15, and the wire to the strain test conductive layer 12; the first terminal 14 and the second terminal 15 are bonded to the strain test conductive layer 12 with ALTECOL-Z84 adhesive to form an integral whole, and are both arranged on the same side of the surface of the strain test conductive layer 12. It should be noted that since a circuit must be formed to input current and output voltage, the number of the first terminal 14 and the second terminal 15 is at least two. The number of terminals can be appropriately increased according to the actual situation, but the number should be an even number.

[0031] The first terminal 14 is located outside the test range of the strain test conductive layer 12 and is used to connect to the electrical signal input device 2 to input a constant DC current. The second terminal 15 on the inner side is close to the outside of the strain test range of the conductive layer and serves as a measuring point. It is connected to the electrical signal acquisition and processing device 3 to acquire the voltage value generated by the deformation of the strain test conductive layer 12. The voltage value is then processed to test the strain value of the steel bridge weld.

[0032] In one embodiment, the coating 1 further includes a protective layer 13 disposed on the surface of the insulating isolation layer 11 and the strain test conductive layer 12, wherein the protective layer 13 is disposed after the first terminal 14 and the second terminal 15 are attached to the strain test conductive layer 12.

[0033] Specifically, such as Figure 2 As shown, the protective layer 13 is disposed on the surface of the insulating layer 11 and the strain test conductive layer 12. It is sprayed after the first terminal 14 and the second terminal 15 are attached, and is used to protect the insulating layer 11 and the strain test conductive layer 12 from damage and failure. It should be noted that the size of the protective layer 13 should be slightly larger than the insulating layer 11 to provide good protection for the remaining two layers.

[0034] In one embodiment, the longitudinal dimension of the strain test conductive layer 12 is greater than the test range in the width direction of the steel bridge weld, and the transverse dimension of the strain test conductive layer 12 is equal to the test range in the length direction of the steel bridge weld.

[0035] Specifically, such as Figure 3 As shown, when applied to actual weld testing, since the steel bridge weld is mainly subjected to longitudinal bending compressive stress, the strain along the length direction of the weld can be ignored compared with the strain along the width direction of the weld. Therefore, it is only necessary to determine the test position along the length direction of the weld and test the strain along the width direction of the weld within the test range at this position. Therefore, in this embodiment, the longitudinal dimension of the strain testing conductive layer 12 is larger than the test range along the width direction of the steel bridge weld, and the transverse dimension of the strain testing conductive layer 12 is equal to the test range along the length direction of the steel bridge weld.

[0036] In one embodiment, the numerical relationship between the voltage value, the longitudinal piezoresistive sensitivity coefficient of the strain test conductive layer, and the strain value is as follows: Where C represents the longitudinal piezoresistive sensitivity coefficient of the conductive layer in the strain test. U represents the initial voltage value, and U represents the voltage value corresponding to the strain generated by the weld seam of the steel bridge under stress. This represents the strain value of the weld seam of the steel bridge under stress.

[0037] The above embodiments are coatings 1 with specific shapes, sizes, thicknesses, and aspect ratios to adapt to the specific weld test locations. The size of the terminals is not a unique value. This invention does not impose specific limitations. Embodiments that modify the parameters of coating 1, the position and size of the first terminal 14 and the second terminal 15, and the number of the first terminal 14 and the second terminal 15 are all within the scope of this invention.

[0038] In another embodiment, based on the same inventive concept, this application also provides a method for manufacturing a testing device for testing the strain of steel bridge welds, used to manufacture the testing device for testing the strain of steel bridge welds described in the above embodiments, such as... Figure 4 As shown, the method includes: Step S110: Determine the actual dimensions of the steel bridge weld test.

[0039] Specifically, the test location can be determined based on finite element analysis or existing actual bridge test data to identify locations with high stress and strain, or within the weld range where fatigue cracking is likely to occur in the steel bridge. For example, taking the longitudinal rib-top plate weld location of an orthotropic steel bridge deck as an example, a finite element model of the orthotropic steel bridge deck requiring strain testing is established. The strain (stress) distribution at the longitudinal rib-top plate weld is extracted, the location of high strain (stress) is identified, and the location and size of coating 1 are determined.

[0040] Step S120: Determine the structural parameters of coating 1 based on the actual dimensions of the steel bridge weld test.

[0041] In this embodiment, based on step S110, it is assumed that the actual size of the test location is 10mm×2mm; therefore, according to the terminal arrangement position, the size of the strain test conductive layer 12 on the top plate and longitudinal rib on both sides of the weld bend is set to 3mm×2mm; the insulating isolation layer 11 should be slightly larger than the strain test conductive layer 12, and each side is widened by the same width.

[0042] Step S130: Make a mold according to the structural parameters of coating 1.

[0043] In this embodiment, the mold can be manufactured using 3D printing. The specific manufacturing method is existing technology and will not be explained here. It should be noted that the mold is made to prevent the 12-layer conductive layer from being difficult to lay out manually during strain testing, and to ensure the structural accuracy of coating 1.

[0044] Step S140: Spray an insulating isolation layer 11 onto the weld seam of the steel bridge, fabricate a strain test conductive layer 12 according to the mold and place the strain test conductive layer 12 on the insulating isolation layer 11, arrange a first terminal and a second terminal on the strain test conductive layer 12, and spray a protective layer 13 onto the strain test conductive layer 12 and the insulating isolation layer 11.

[0045] In this embodiment, the insulating layer is fabricated according to the structural parameters; the mold can be a custom-made sticker template of the corresponding shape and size, which is directly applied to the insulating layer. After the strain test conductive layer 12 is sprayed, the template can be carefully peeled off. Then, the first terminal 14 and the second terminal 15 are bonded to the strain test conductive layer 12, and finally, a protective layer 13 is sprayed to separate the insulating layer and the strain test conductive layer 12.

[0046] Step S160: Connect the first terminal 14 to the electrical signal input device 2 and the second terminal 15 to the electrical signal acquisition and processing device 3.

[0047] Specifically, the first terminal 14 and the second terminal 15 can be connected to the electrical signal input device 2 and the electrical signal acquisition and processing device 3 respectively via wires, so as to input electrical signals and acquire voltage signals.

[0048] In one embodiment, the insulating layer 11 is made of a flexible material prepared by mixing polyurethane resin, a drying agent, and additives.

[0049] Specifically, the insulating layer 11 is made of polyurethane resin, drier, and additives. It is red. After determining the position, shape, size, thickness, and other parameters of this layer, it is sprayed onto the test position of the orthotropic steel bridge deck with a pneumatic spray gun. The thickness is 20~40μm, and it is left to stand for 4 hours.

[0050] In one embodiment, the strain test conductive layer 12 is made of a flexible material obtained by mixing and stirring silver-plated copper powder, silane coupling agent, aqueous acrylic emulsion, additives, and water.

[0051] In this embodiment, the additives include dispersants, defoamers, and leveling agents. The dispersant is a polyisobutylene polysuccinimide ashless additive, which has good dispersibility and excellent high-temperature stability. The defoamer reduces surface tension, inhibits foam generation, or eliminates existing foam, preventing foaming of the insulating layer 11 and affecting deformation transfer. The leveling agent promotes the formation of a smooth, uniform coating film during the drying process, effectively reducing the surface tension of the coating liquid and improving its leveling and uniformity.

[0052] After preparation, the spraying area is arranged, and the coating is sprayed onto the insulating layer 11 using a pneumatic spray gun or by spraying based on the above-mentioned mold. The thickness of the strain test conductive layer is 20-40μm. The layer is left to stand for 4 hours to ensure that the strain test conductive layer is completely dry and formed, so as to avoid damage to the conductive layer caused by the subsequent bonding of the first terminal 14 and the second terminal 15.

[0053] The material used in the strain test conductive layer 12 after preparation has a volume conductivity greater than 5 × 10⁻⁶. 4It has a high conductivity (S / m); after being placed in an environment with a temperature of 60°C and a relative humidity of 100% for 1000 hours, its volume resistivity increases by less than 20%, indicating stable conductivity; its longitudinal piezoresistive sensitivity coefficient is greater than 19.020, and its resistance changes greatly with strain, exhibiting good piezoresistive characteristics.

[0054] In one embodiment, the specific fabrication process of the flexible material used to make the strain testing conductive layer 12 is as follows: Prepare a first solution by mixing and stirring a silane coupling agent with silver-plated copper powder. Add the first solution and water to the aqueous acrylic emulsion, stir and emulsify to obtain the second solution; Additives are added to the second solution, and the mixture is stirred to obtain a flexible material for fabricating the conductive layer 12 for strain testing.

[0055] It should be understood that when preparing the flexible material for the sprayed strain test conductive layer 12, it is necessary to follow the manufacturing process of this embodiment.

[0056] Specifically, in the first step of the manufacturing process, existing technology can be used to prepare the silane coupling agent, which will not be explained in detail here. The silane coupling agent is mixed with silver-plated copper powder to ensure the conductivity of the flexible material used to make the conductive layer for strain testing.

[0057] In the second step of the manufacturing process, adding water-based acrylic emulsion and performing emulsification is to ensure the adhesion of the flexible material.

[0058] In the third step of the production process, the additives include dispersants, defoamers, and leveling agents. The specific functions and effects of the additives have been explained in detail above and will not be explained here.

[0059] In one embodiment, the protective layer 13 is made of a flexible material prepared by mixing polyurethane resin, a drying agent, and additives.

[0060] Specifically, the flexible material of the sprayed protective layer 13 is made of polyurethane resin, drying agent and additives. It has good waterproof, corrosion-resistant and high temperature resistant properties. It is sprayed on the insulating isolation layer 11 and the strain test conductive layer 12 using a pneumatic spray gun. The thickness is 10-20μm. It is left to stand for 4 hours to ensure that the coating 1 is completely dry and formed.

[0061] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is 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 should be included within the scope of protection of the present invention.

Claims

1. A testing device for strain testing of steel bridge welds, characterized in that, Includes coating, electrical signal input device, and electrical signal acquisition and processing device: The coating includes an insulating layer and a strain testing conductive layer: An insulating layer is placed on the surface of the steel bridge weld to isolate the steel bridge weld. A strain test conductive layer is disposed on the surface of an insulating layer. The surface of the strain test conductive layer is provided with a first terminal and a second terminal. The first terminal is connected to an electrical signal input device, and the second terminal is connected to an external electrical signal acquisition and processing device. The strain test conductive layer is made of a flexible material obtained by mixing and stirring silver-plated copper powder, silane coupling agent, water-based acrylic emulsion, additives, and water. The longitudinal piezoresistive sensitivity coefficient of the strain test conductive layer is greater than 19.

020. The electrical signal input device is used to input a constant DC current to the first terminal, so that when the steel bridge weld is subjected to stress and strain occurs, the resistance change between the second terminals generated by the strain test conductive layer based on the piezoresistive characteristics is reflected as a voltage change. The electrical signal acquisition and processing device is used to acquire the voltage value between the second terminals in real time. Based on the numerical relationship between the voltage value, the longitudinal piezoresistive sensitivity coefficient of the strain test conductive layer, and the strain value, the strain value of the steel bridge weld is obtained.

2. The testing device for strain testing of steel bridge welds according to claim 1, characterized in that, The coating also includes a protective layer disposed on the surface of the insulating layer and the strain test conductive layer, wherein the protective layer is disposed after the first terminal and the second terminal are attached to the strain test conductive layer.

3. The testing device for strain testing of steel bridge welds according to claim 1, characterized in that, The longitudinal dimension of the strain test conductive layer is larger than the longitudinal test range of the steel bridge weld, and the transverse dimension of the strain test conductive layer is equal to the transverse test range of the steel bridge weld.

4. The testing device for strain testing of steel bridge welds according to claim 1, characterized in that, Based on the numerical relationship between voltage value, longitudinal piezoresistive sensitivity coefficient of the conductive layer, and strain value, the following is established: Where C represents the longitudinal piezoresistive sensitivity coefficient of the conductive layer in the strain test. U represents the initial voltage value, and U represents the voltage value corresponding to the strain generated by the weld seam of the steel bridge under stress. This represents the strain value of the weld seam of the steel bridge under stress.

5. A method for manufacturing a testing device for strain testing of steel bridge welds, used to manufacture the testing device for strain testing of steel bridge welds as described in claims 1 to 4, characterized in that, The methods include: Determine the actual dimensions for testing the steel bridge welds; The structural parameters of the coating are determined based on the actual dimensions of the steel bridge weld test. Molds are made based on the structural parameters of the coating; An insulating layer is sprayed onto the weld seam of the steel bridge. A strain test conductive layer is made according to the mold and placed on the insulating layer. A first terminal and a second terminal are arranged on the strain test conductive layer. A protective layer is sprayed onto the strain test conductive layer and the insulating layer. Connect the first terminal to the electrical signal input device and the second terminal to the electrical signal acquisition and processing device.

6. A method for manufacturing a testing device for strain testing of steel bridge welds according to claim 5, characterized in that, The insulating layer is made of a flexible material prepared by mixing polyurethane resin, a drying agent, and additives.

7. A method for manufacturing a testing device for strain testing of steel bridge welds according to claim 5, characterized in that, The conductive layer for strain testing is made of a flexible material obtained by mixing and stirring silver-plated copper powder, silane coupling agent, aqueous acrylic emulsion, additives, and water.

8. A method for manufacturing a testing device for strain testing of steel bridge welds according to claim 7, characterized in that, The specific fabrication process of the flexible material used to create the strain test conductive layer is as follows: Prepare a first solution by mixing and stirring a silane coupling agent with silver-plated copper powder. Add the first solution and water to the aqueous acrylic emulsion, stir and emulsify to obtain the second solution; Additives are added to the second solution, and the mixture is stirred to obtain a flexible material for fabricating a conductive layer for strain testing.

9. A method for manufacturing a testing device for strain testing of steel bridge welds according to claim 5, characterized in that, The protective layer is made of a flexible material prepared by mixing polyurethane resin, a drying agent, and additives.

10. A method for manufacturing a testing device for strain testing of steel bridge welds according to claim 5, characterized in that, The insulating layer, strain test conductive layer, and protective layer that have been fabricated all need to be left to stand for 4 hours.

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