Suspension bridge sling pin joint connector pin shaft shearing test method and device

Abstract

The application discloses a kind of suspension bridge sling pin joint connecting piece pin shaft shearing test test method and device, comprising: first, according to the size of the shearing performance design test mould metal sheet of the pin shaft component to be tested;Second, cutting pin shaft component, to paste strain gauge and fix its rotation;Third, during the test process, the measured strain value is verified using staged loading, if the error is large, adjust test device in time;Finally, test pin shaft component appears obvious yield, directly loaded to fracture, data processing exports shear stress-shear strain curve.The application method is by optimizing shearing test mould, ensure that pin shaft occurs pure shear failure, the test method can verify test result in the test process, correct test device in time, reduce test error, obtain the curve of pin shaft component shear stress and shear strain in a more reliable way with high precision, to obtain pin shaft component real shear performance in a more accurate way.

Description

Technical Field

[0001] This invention relates to the field of mechanical property testing and detection technology for metallic materials, specifically to a shear strain test mold, test method and apparatus for sling pin joint components. Background Technology

[0002] A suspension bridge is a type of bridge where the main cable serves as the primary load-bearing component. Its superstructure mainly consists of stiffening girders, main cables, towers, suspenders, and anchorages. In suspension bridges, the pin-connection method between the main cable and suspenders is a common connection method, consisting of anchor heads, pin connectors, single-ear plates, forked-ear plates, and pins. The force transmission path is: suspender → pin connector → ear plate → main cable, with the connector and ear plate connected by pins. As a crucial load-bearing and variable-load-bearing component of a suspension bridge, the suspender's pin is a key force-transmitting component. Under normal operating conditions, the pin primarily bears shear force. To prevent shear failure of the pin under alternating loads, the shear performance of the pin component needs to be measured.

[0003] Existing testing devices for the shear performance of pins in sling connection systems are too bulky, making it difficult to ensure that the pin component only undergoes shear failure during the test. Furthermore, the pin is prone to rotation during the test, and misalignment can easily occur between the fixing plates, resulting in low test reliability. Currently, there is a lack of a direct and effective method for measuring the shear strain of sling pin components, making it difficult to intuitively and easily assess the pin's shear performance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the prior art. The present invention provides a method and apparatus for shear testing of pin shafts of suspension bridge cable-connecting components. This method can ensure that the pin shaft component only undergoes a single shear failure, and measures the shear strain of the pin shaft in a more effective and intuitive way to evaluate the shear performance of the pin shaft component.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A test method for shear test of pin shaft of suspension bridge cable connector includes the following steps: Step 1: Verify the width and thickness of the metal plate by using the dimensions of the tested pin shaft connector, and deduce that the tensile strength of the metal plate opening section is greater than the shear strength of the pin shaft; Step 2: Perform three cutting processes on the tested pin shaft to cut two planes for attaching strain gauges and a groove for fixing the pin shaft rotation; Step 3: Install the test component and connect the data acquisition instrument. The hydraulic servo testing system and dynamic signal acquisition system are simultaneously activated. The loading method is graded loading. Calculate the theoretical curve of strain change in the elastic stage of the pin shaft, and verify it during each loading process to ensure that the pin shaft achieves pure shear failure; Step 4: When the load-displacement curve output by the hydraulic servo testing system shows a clear yield stage during loading, stop the graded loading scheme and continue loading until the pin shaft fails in shear. Output the load-displacement curve and strain-time curve. After data analysis, obtain the final shear strain-shear stress curve.

[0007] As a further preferred embodiment of the present invention, in step 1, the shear stress τ required for shear failure of the pin is calculated based on the dimensions of the tested pin component. P The required load F is derived. Based on the preset fixed plate cross-sectional dimensions, the cross-sectional stress σ at the opening of the fixed plate is calculated. If the cross-sectional stress is greater than the allowable stress, i.e., σ>[σ], then the cross-sectional dimensions of the fixed plate are redesigned.

[0008] As a further preferred embodiment of the present invention, the root pin component in step 2 is cut three times. First, two through grooves are cut symmetrically on the circular cross-sections at both ends of the pin. Second, a through groove is cut perpendicular to the first two cut surfaces at the end near the pin. Finally, strain gauges are attached to the preset shear surface.

[0009] As a further preferred embodiment of the present invention, in step 3, the theoretical formula for calculating the shear strain of the pin shaft and the load is calculated, the relationship between the load and strain in the elastic stage is calculated, and the final value of the pre-set graded loading strain is obtained. The theoretical value ε is then used to calculate the final value of the load. p Compared with the measured value ε m When the error is less than ±5%, it indicates that the pin component has undergone pure shear deformation, thus verifying the purpose of the test.

[0010] As a further preferred embodiment of the present invention, in step 4, the required yield load F for the pin to undergo plastic deformation is calculated. y When the graded load is applied to near the preset yield load, carefully observe the load-displacement curve output by the hydraulic servo system. When a clear yield segment appears on the load-displacement curve, cancel the graded loading scheme and continue loading until the pin fails under shear. Analyze and process the test data to obtain the shear strain-shear stress curve.

[0011] As a further preferred embodiment of the present invention, the theoretical formula for calculating the shear strain of the pin and the load is derived. Since this experimental device is a double shear failure device, the shear surface load is half of the system output load, i.e. The theoretical strain value is ε p :

[0012]

[0013] In the formula, A s Let G be the cross-sectional area of ​​the pin; G is the shear modulus of the pin. The theoretical value of the shear strain ε is verified during the graded loading process. p Compared with the measured value ε m If the relative error is within ±5%, it is considered that the pin component has undergone pure shear failure.

[0014] A test device for shear testing of pin shafts of suspension bridge cable connectors includes an upper component, a lower component, fixing screws, clamping screws, and a fixed rotating metal plate. The upper component includes an upper metal fixing plate with a circular hole. The lower component includes three metal plates welded together, each with a corresponding circular hole. The three metal plates are a right metal clamping plate, a left metal clamping plate, and a lower metal fixing plate. The fixed rotating metal plate is mounted on the left and right metal clamping plates by fixing screws. The upper metal fixing plate, the left metal clamping plate, and the right metal clamping plate all have corresponding rectangular openings and are fixed with clamping screws to apply clamping force.

[0015] As a further preferred embodiment of the present invention, it also includes a hydraulic servo testing system, wherein an upper metal fixing plate and a lower metal fixing plate are used to fix the hydraulic servo testing system.

[0016] The present invention has the following beneficial effects:

[0017] The present invention provides a method for conducting shear tests on cable pin-type connecting components by designing an improved shear testing device and improving the testing method and device. Compared with the traditional shear testing method, this method can directly measure the shear strain of the pin component. The improved testing device can ensure that the pin component only undergoes single shear failure during the test. Furthermore, the testing method can verify the test results during the test to ensure that the pin only undergoes shear failure. Attached Figure Description

[0018] Figure 1 This is a flowchart of a shear strain test mold and test method for a suspension pin-type connection component;

[0019] Figure 2 This is a top view of a shear testing device consisting of four sets of metal plates and rotating fixed plates.

[0020] Figure 3 This is a side view of a shear test apparatus consisting of four sets of metal plates and rotating fixed plates.

[0021] Figure 4 This is a top view of the sling pin connection component after three cutting operations;

[0022] Figure 5 This is a side view of the sling pin connection component after three cuts.

[0023] It includes: 1. Upper metal fixing plate, 2. Right metal clamping plate, 3. Left metal clamping plate, 4. Lower metal fixing plate, 5. Round hole, 6. Fixing rotating metal piece, 7. Fixing screw, 8. Clamping screw, 9. Rectangular opening. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific preferred embodiments.

[0025] In the description of this invention, it should be understood that the terms "left side," "right side," "upper part," "lower part," 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 this 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. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of this invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of this invention.

[0026] like Figure 1-5 As shown, a test method for shear test of pin shaft of suspension bridge cable pin connector includes:

[0027] Step 1: Based on the dimensions of the tested pin-type connecting component, verify the design of the width and thickness of the metal plate, and deduce that the tensile strength of the metal plate opening section is greater than the shear strength of the pin; Based on the dimensions of the tested pin component, calculate the shear stress τ required for the pin to fail. P The required load F is derived. Based on the preset fixed plate cross-sectional dimensions, the cross-sectional stress σ at the opening of the fixed plate is calculated. If the cross-sectional stress is greater than the allowable stress, i.e., σ>[σ], then the cross-sectional dimensions of the fixed plate are redesigned.

[0028] Step 2: The tested pin is cut three times to create two flat surfaces for attaching the strain gauge and a groove for fixing the pin's rotation. The pin component is cut three times: First, two through grooves are symmetrically cut into the circular sections at both ends of the pin. Second, a through groove is cut perpendicular to the first two cut surfaces at the end closest to the pin. To facilitate attaching the strain gauge and prevent damage to the conductors during the test, a through groove is cut perpendicular to the first two cut surfaces at the end closest to the pin to accommodate the rotating and fixing of the strain gauge. Finally, the strain gauge is attached to the pre-cut surface. The top view of the cut pin is shown below. Figure 4 The front view is Figure 5 .

[0029] Step 3: Install the test component and connect the acquisition instrument. The hydraulic servo testing system and the dynamic signal acquisition system are turned on simultaneously. The loading method is graded loading. Calculate the theoretical curve of strain change in the elastic stage of the pin and verify it during each loading process to ensure that the pin achieves the goal of pure shear failure.

[0030] Step 3 involves calculating the theoretical formula for the shear strain of the pin shaft and the load, calculating the relationship between the load and strain in the elastic stage, obtaining the final strain value of the preset graded loading, and then applying the theoretical value ε. p Compared with the measured value ε m When the error is less than ±5%, it indicates that the pin component has undergone pure shear deformation, thus verifying the purpose of the test.

[0031] The theoretical formulas for calculating the shear strain of the pin and the load were derived. Since this experimental setup is a double-shear failure device, the shear surface load is half of the system output load, i.e. The theoretical strain value is ε p :

[0032]

[0033] In the formula, A s Let G be the cross-sectional area of ​​the pin; G be the shear modulus of the pin. The theoretical value of shear strain ε is verified during graded loading. p Compared with the measured value ε m If the relative error is within ±5%, it is considered that the pin component has undergone pure shear failure.

[0034] Step 4: When the load-displacement curve output by the hydraulic servo testing system shows a clear yield stage during the loading process, the graded loading scheme is stopped, and loading continues until the pin fails under shear. The load-displacement curve and strain-time curve are output. After data analysis, the final shear strain-shear stress curve is obtained.

[0035] Calculate the yield load F required for the pin to undergo plastic deformation.y When the graded load is applied to near the preset yield load, carefully observe the load-displacement curve output by the hydraulic servo system. When a clear yield segment appears on the load-displacement curve, cancel the graded loading scheme and continue loading until the pin fails under shear. Analyze and process the test data to obtain the shear strain-shear stress curve.

[0036] Step 4 involves calculating the required yield load F for the pin to undergo plastic deformation. y When the graded load is applied to near the preset yield load, carefully observe the load-displacement curve output by the hydraulic servo system. When a clear yield segment appears on the load-displacement curve, cancel the graded loading scheme and continue loading until the pin fails under shear. Analyze and process the test data to obtain the shear strain-shear stress curve.

[0037] A test device for shearing of pin shafts in suspension bridge cable connectors includes an upper component, a lower component, fixing screws 7, clamping screws 8, and a fixed rotating metal plate 6. The upper component includes an upper metal fixing plate 1 with a circular hole 5 for fixing to a hydraulic servo testing system. The lower component includes three metal plates welded together, each with a corresponding circular hole 5. The three metal plates are a right metal clamping plate 2, a left metal clamping plate 3, and a lower metal fixing plate 4. The circular holes 5 on the right and left metal clamping plates 2 and 3 are the same as those on the upper structure for inserting the pin shaft. The lower metal fixing plate 4 is used for fixing to the hydraulic servo testing system.

[0038] The fixed rotating metal plate 6 is mounted on the left metal clamping plate 3 and the right metal clamping plate 2 by fixing screws 7. The fixed rotating metal plate 6 is used to fix the rotation of the pin. The upper metal fixing plate 1, the left metal clamping plate 3 and the right metal clamping plate 2 are each provided with two rectangular openings 9 of corresponding length boxes, which are fixed with clamping screws 8 to apply clamping force.

[0039] The present invention provides a method for conducting shear tests on cable pin-type connecting components by designing an improved shear testing device and improving the testing method and device. Compared with the traditional shear testing method, this method can directly measure the shear strain of the pin component. The improved testing device can ensure that the pin component only undergoes single shear failure during the test. Furthermore, the testing method can verify the test results during the test to ensure that the pin only undergoes shear failure.

[0040] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A test method for shear test of pin shaft of suspension bridge cable pin connector, characterized in that: Step 1: Verify the width and thickness of the metal plate by using the dimensions of the pin-type connecting component measured in the experiment, and deduce that the tensile strength of the metal plate opening section is greater than the shear strength of the pin. Specifically, based on the dimensions of the tested pin component, calculate the shear stress required for the pin to undergo shear failure. The required load at this time is derived. Based on the preset cross-sectional dimensions of the fixing plate, calculate the cross-sectional stress at the opening of the fixing plate. If the cross-sectional stress is greater than the allowable stress, that is, If so, the cross-sectional dimensions of the fixing plate should be redesigned; Step 2: Perform three cutting processes on the tested pin shaft to cut out two planes for attaching the strain gauge and a groove for fixing the pin shaft's rotation. The three cutting processes on the pin shaft component are as follows: First, symmetrically cut two through grooves on the circular cross-sections at both ends of the pin shaft; second, cut a through groove perpendicular to the first two cutting surfaces at the end closest to the pin shaft; finally, attach the strain gauge to the preset shear surface. Step 3: Install the test component and connect the acquisition instrument. The hydraulic servo testing system and the dynamic signal acquisition system are turned on simultaneously. The loading method is graded loading. Calculate the theoretical curve of strain value change in the elastic stage of the pin. Verify it during each loading process to ensure that the pin achieves the goal of pure shear failure. Step 4: When the load-displacement curve output by the hydraulic servo testing system shows a clear yield stage during the loading process, the graded loading scheme is stopped, and loading continues until the pin fails under shear. The load-displacement curve and strain-time curve are output. After data analysis, the final shear strain-shear stress curve is obtained.

2. The test method for shear test of pin shaft of suspension bridge cable pin connector according to claim 1, characterized in that: In step 3, the theoretical formulas for the shear strain of the pin and the load are calculated, the relationship between the load and strain in the elastic stage is calculated, and the final strain value of the preset graded loading is obtained. The theoretical value is then... Compared with measured values When the error is less than ±5%, it indicates that the pin component has undergone pure shear deformation, thus achieving the purpose of the verification test.

3. The test method for shear test of pin shaft of suspension bridge cable pin connector according to claim 1, characterized in that: In step 4, the yield load required for the pin to undergo plastic deformation is calculated. When the graded load is applied to near the preset yield load, carefully observe the load-displacement curve output by the hydraulic servo system. When a clear yield segment appears on the load-displacement curve, cancel the graded loading scheme and continue loading until the pin fails under shear. Analyze and process the test data to obtain the shear strain-shear stress curve.

4. The test method for shear test of pin shaft of suspension bridge cable pin connector according to claim 2, characterized in that: The theoretical formulas for calculating the shear strain of the pin and the load were derived. Since this experimental setup is a double-shear failure device, the shear surface load is half of the system output load, i.e. The theoretical strain value is : ； In the formula, Let be the cross-sectional area of ​​the pin. The shear modulus of the pin is used to verify the theoretical value of shear strain during graded loading. Compared with measured values If the relative error is within ±5%, it is considered that the pin component has undergone pure shear failure.

5. A test apparatus for shear testing of pin shafts of suspension bridge cable-stayed connectors according to any one of claims 1-4, characterized in that: It includes an upper component, a lower component, a fixing screw (7), a clamping screw (8), and a fixing rotating metal plate (6). The upper component includes an upper metal fixing plate (1) with a round hole (5). The lower component includes three metal plates welded together, namely a right metal clamping plate (2), a left metal clamping plate (3), and a lower metal fixing plate (4). The left and right metal clamping plates have corresponding round holes (5). The fixed rotating metal plate (6) is installed on the left metal clamping plate (3) and the right metal clamping plate (2) by fixing screws (7). The upper metal fixing plate (1), the left metal clamping plate (3) and the right metal clamping plate (2) are all provided with corresponding rectangular openings (9), which are fixed with clamping screws (8) and clamping force is applied.

6. The test device for shear test of pin shaft of suspension bridge cable pin connector according to claim 5, characterized in that: It also includes a hydraulic servo testing system, with an upper metal fixing plate (1) and a lower metal fixing plate (4) for fixing to the hydraulic servo testing system.

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