Fatigue test device and method suitable for space KK type pipe joint

Abstract

The invention discloses a fatigue test device and method suitable for a space KK type pipe joint in the technical field of civil and ocean engineering structure fatigue tests, and aims to solve the problem that a real stress state is difficult to simulate in the fatigue test of the space KK type pipe joint in the prior art. The system comprises a constraint module; the loading module comprises a first fatigue actuator set, a second fatigue actuator set, a third fatigue actuator set and a fourth fatigue actuator set, and the first ends of the first fatigue actuator set, the second fatigue actuator set, the third fatigue actuator set and the fourth fatigue actuator set are all connected with the constraint module; the second ends are respectively used for connecting four branch pipes of the space KK type pipe joint; and the electric control module is mounted on the restraining module and is electrically connected with the loading module. According to the invention, the real stress state of the space KK type pipe joint can be simulated and the fatigue test is carried out, the stability and simulation precision of the fatigue test are improved, and a basis is provided for safety evaluation and failure prevention.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of civil and ocean engineering structure fatigue test, and particularly relates to a fatigue test device and method suitable for a spatial KK type pipe joint. BACKGROUND

[0002] High strength and weight ratio makes steel one of the best structural materials in civil engineering construction, and good material mechanical properties make steel pipe components widely used in various engineering structures, and the connection of the steel pipe components is the pipe joint. The pipe joint can be divided into two categories: planar pipe joint and spatial pipe joint. The planar pipe joint refers to the pipe joint in which all the axes of the members are in the same plane, and the spatial pipe joint refers to the pipe joint in which the axes are not all in the same plane. In the past decade, with the wide application of steel pipe structures in large-scale engineering, the original planar pipe joint cannot meet the engineering requirements, and many forms of spatial pipe joints have emerged.

[0003] The spatial KK type steel pipe joint is a common spatial joint form, which is formed by welding the main pipe and two pairs of branch pipes. Due to its compact structure, clear force transmission path and high space utilization rate, it is increasingly used in practical engineering, such as gymnasium roof, offshore booster platform, wind turbine guide pipe rack foundation structure, etc., and various civil and ocean steel structures need to resist complex cyclic loads during the service period, such as wind load, wave load, current load, water level change, marine organism growth and scouring erosion, etc.

[0004] Therefore, fatigue safety evaluation is an important part of offshore wind turbine foundation structure design, and physical model test is the most reliable means to determine the fatigue life of the pipe joint. However, the conditions for carrying out the fatigue test of the spatial KK type pipe joint are very limited at present, it is difficult to simulate the real stress state of the structure, and therefore the fatigue limit and failure mechanism of the spatial KK type pipe joint under different working conditions cannot be accurately revealed. SUMMARY

[0005] The present application aims to provide a fatigue test device and method suitable for a spatial KK type pipe joint, which can simulate the real stress state of the spatial KK type pipe joint and perform fatigue test, and provide a basis for safety evaluation and failure prevention.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0007] In a first aspect, the present application provides a fatigue test device suitable for a spatial KK type pipe joint, comprising:

[0008] a constraint module;

[0009] The loading module comprises a first fatigue actuator group, a second fatigue actuator group, a third fatigue actuator group and a fourth fatigue actuator group, and the first ends of the first fatigue actuator group, the second fatigue actuator group, the third fatigue actuator group and the fourth fatigue actuator group are connected with the constraint module, and the second ends are respectively used for connecting four branch pipes of the spatial KK type pipe node;

[0010] The electric control module is installed on the constraint module and is electrically connected with the loading module.

[0011] According to the first aspect, the constraint module comprises a counterforce wall, a foundation, a counterforce frame group, a first support and a second support;

[0012] The counterforce wall and the foundation are connected with the counterforce frame group, the counterforce wall is further connected with the first ends of the third fatigue actuator group and the fourth fatigue actuator group, and the counterforce frame group is further connected with the first ends of the first fatigue actuator group and the second fatigue actuator group;

[0013] The first connecting end of the first support is used for connecting the first end of the main pipe in the spatial KK type pipe node, the first connecting end of the second support is used for connecting the second end of the main pipe in the spatial KK type pipe node, and the second connecting ends of the two supports are connected with the foundation.

[0014] According to the first aspect, the counterforce wall and the foundation are provided with a plurality of connecting holes for connecting the loading module and the constraint module.

[0015] According to the first aspect, the first fatigue actuator group, the second fatigue actuator group, the third fatigue actuator group and the fourth fatigue actuator group are respectively provided with a force sensor and a displacement sensor for monitoring the force and displacement of each branch pipe in the spatial KK type pipe node in real time during the experiment, and the force sensor and the displacement sensor are respectively electrically connected with the electric control module.

[0016] According to the second aspect, the present application further provides a fatigue test method suitable for a spatial KK type pipe node, which adopts the fatigue test device suitable for the spatial KK type pipe node in the first aspect, and comprises the following steps:

[0017] The extension lengths of the first fatigue actuator group, the second fatigue actuator group, the third fatigue actuator group and the fourth fatigue actuator group in the loading module are adjusted, and the angles thereof are rotated, so that the second ends of the first fatigue actuator group, the second fatigue actuator group, the third fatigue actuator group and the fourth fatigue actuator group are respectively connected with the four branch pipes of the spatial KK type pipe node after the four branch pipes are coaxial with the first fatigue actuator group, the second fatigue actuator group, the third fatigue actuator group and the fourth fatigue actuator group;

[0018] The electric control module is started, the loading module is started through the electric control module, and a control instruction is sent to the loading module;

[0019] Based on the control instruction, the loading module starts running, at this time, the single or multiple branch pipes of the spatial KK type pipe node are loaded, the force sensor and the displacement sensor on the loading module send the force and displacement data of each branch pipe in the spatial KK type pipe node to the electric control module;

[0020] After the electric control module receives the data monitored by the force and displacement sensor, it compares the data with the preset force and displacement threshold value to determine whether the detected force or displacement data exceeds the threshold value, and if so, the electric control module determines that the spatial KK type pipe node fails and sends a stop running instruction to the loading module;

[0021] Based on the stop running instruction, the loading module stops running, and the test ends.

[0022] In combination with the second aspect, optionally, the control instruction includes any one of a force control instruction and a displacement control instruction;

[0023] The force control instruction is used to control the loading module to apply a quantitative force to the single or multiple branch pipes of the spatial KK type pipe node, the force including at least one of a pulling force and a pushing force;

[0024] The displacement control instruction is used to control the loading module to contract or stretch along the axial direction of the single or multiple branch pipes of the spatial KK type pipe node to complete a quantitative displacement.

[0025] In combination with the second aspect, optionally, the force control instruction includes at least one of the following operation instructions:

[0026] The first operation instruction controls the corresponding fatigue actuator group of the loading module to continuously apply a force to the single or multiple branch pipes of the spatial KK type pipe node at a preset rate until a preset maximum force value is reached;

[0027] The second operation instruction controls the corresponding fatigue actuator group of the loading module to repeatedly apply a force to the single or multiple branch pipes of the spatial KK type pipe node for multiple times, and the size of the force changes periodically.

[0028] In combination with the second aspect, optionally, the displacement control instruction includes at least one of the following operation instructions:

[0029] The third operation instruction controls the corresponding fatigue actuator group of the loading module to continuously contract or stretch along the axial direction of the single or multiple branch pipes of the spatial KK type pipe node for a single time until a preset maximum displacement amount is reached;

[0030] The fourth operation instruction controls the corresponding fatigue actuator group of the loading module to repeatedly contract and expand along the axial direction of the single or multiple branch pipes of the spatial KK type pipe node, and the contraction and expansion amounts change periodically.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] The constraint module supports and fixes the electrical control module, loading module, and spatial K-block K-type tube node, playing a role in constraint and limitation. The electrical control module controls the loading module to apply force to the spatial KK-type tube node, which can simulate the actual stress state of the spatial KK-type tube node during use, making the fatigue test results closer to the actual failure state, the test results more accurate and have more reference value, and can provide a reliable basis for the actual manufacturing and application of spatial KK-type tube nodes.

[0033] Furthermore, since the control commands issued by the electronic control module can be either force control commands or displacement control commands; it can control the loading module to apply force to a single branch of the spatial KK-type pipe node, or to apply force to multiple branches simultaneously; when applying force, it can apply gradually increasing force in a single operation, or apply force repeatedly in a cyclical manner. The above-mentioned flexible control methods make the stress conditions of the spatial KK-type pipe node simulated by this invention more varied and realistic, and can conduct targeted tests to fit different working conditions of the spatial KK-type pipe node. Therefore, the test results are more valuable for reference. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a three-dimensional schematic diagram of a fatigue testing device suitable for spatial KK-type pipe joints according to the present invention;

[0036] Figure 2 This is a front view schematic diagram of the loading module and the constraint module in this invention;

[0037] Figure 3 This is a top view of the loading module and constraint module in this invention;

[0038] Figure 4 This is a side view of the loading module and constraint module in this invention;

[0039] Explanation of reference numerals in the attached figures:

[0040] 1-Reaction wall; 2-Foundation; 3-First reaction frame; 4-Second reaction frame; 5-Third reaction frame; 6-Fourth reaction frame; 7-Fifth reaction frame; 8-First support; 9-Second support; 10-Spatial KK-type pipe joint; 11-First fatigue actuator group; 12-Second fatigue actuator group; 13-Third fatigue actuator group; 14-Fourth fatigue actuator group; 15-Hydraulic oil source; 16-Distribution cabinet; 17-Electrical control console. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use.

[0042] Example 1

[0043] like Figure 1 As shown, this embodiment provides a fatigue testing device suitable for spatial KK-type pipe nodes, including: a constraint module; and a loading module, including a first fatigue actuator group 11, a second fatigue actuator group 12, a third fatigue actuator group 13, and a fourth fatigue actuator group 14. The first ends of the first fatigue actuator group 11, the second fatigue actuator group 12, the third fatigue actuator group 13, and the fourth fatigue actuator group 14 are all connected to the constraint module, and the second ends are respectively used to connect to the four branch pipes of the spatial KK-type pipe node 10. In the specific implementation process, the displacement loading range of the fatigue actuator group is -25mm≤X (i.e., displacement loading value)≤25mm, the load loading range is 0~1000kN, and the loading frequency is 0~5Hz. Here, loading refers to applying a load to the test specimen, and the load can be either force or displacement.

[0044] An electrical control module is installed on the constraint module and electrically connected to the loading module. In specific implementation, the electrical control module is arranged on the side of the constraint system, providing power to the loading module and controlling its operation. It can control the loading module to apply a single load or a combination of loads based on the actual stress state of the test specimen. The electrical control system includes a hydraulic oil source 15, a power distribution cabinet 16, and an electrical control console 17. The connections and coordination relationships between the hydraulic oil source 15, the power distribution cabinet 16, and the electrical control console 17, as well as their connections and coordination relationships with other components in the fatigue testing device, are disclosed in the prior art.

[0045] The above technical solution, with the synergistic effect of the constraint module, can simulate the actual stress state of the spatial KK-type tube node during use, making the fatigue test results closer to the actual failure state and the test results more accurate.

[0046] In one specific embodiment of this example, the constraint module includes a reaction wall 1, a foundation 2, a reaction frame assembly, a first support 8, and a second support 9.

[0047] like Figure 1 As shown, both the reaction wall 1 and the foundation 2 are connected to the reaction frame assembly. The reaction wall 1 is also connected to the first ends of the third fatigue actuator assembly 13 and the fourth fatigue actuator assembly 14. The reaction frame assembly is also connected to the first ends of the first fatigue actuator assembly 11 and the second fatigue actuator assembly 12. In the specific implementation process, the second ends of the four fatigue actuator assemblies are respectively connected to the four branch pipes of the spatial KK-type pipe node 10. The first ends of the third fatigue actuator assembly 13 and the fourth fatigue actuator assembly 14 are fixed to the reaction wall 1 with bolts, and the first ends of the first fatigue actuator assembly 11 and the second fatigue actuator assembly 12 are connected to the reaction wall 1. The reaction frame is fixed to the reaction frame assembly by bolts. The reaction frame assembly includes a first reaction frame 3, a second reaction frame 4, a third reaction frame 5, a fourth reaction frame 6, and a fifth reaction frame 7. The first reaction frame 3 and the second reaction frame 4 are longitudinal beams, with their bottoms fixed to the foundation 2. The third reaction frame 5, the fourth reaction frame 6, and the fifth reaction frame 7 are transverse beams. One end of the fourth reaction frame 6 and the fifth reaction frame 7 is connected and fixed to the reaction wall 1, and the other end is connected to the two longitudinal beams respectively. The third reaction frame 5 is located between the two longitudinal beams. The longitudinal beams and the transverse beams can be connected and fixed by welding or bolts to construct a sturdy and reliable support to constrain the loading module.

[0048] The first connecting end of the first support 8 is used to connect to the first end of the main pipe in the spatial KK-type pipe node 10, and the first connecting end of the second support 9 is used to connect to the second end of the main pipe in the spatial KK-type pipe node 10. The second connecting ends of both are connected to the foundation 2. In the specific implementation process, both the reaction wall 1 and the foundation 2 are reinforced concrete shear walls with a thickness of 1000mm, which have extremely high strength and rigidity. In normal tests, they can be regarded as rigid bodies and are used to fix the reaction frame assembly, the first support 8, the second support 9, and the loading module, etc. The reaction frame assembly is fixed to the reaction wall and the foundation by bolts and is used to install the loading module.

[0049] In the above technical solution, the constraint module can support and fix the electronic control module, the loading module, and the spatial KK-type tube node, playing a role in constraint and limiting. The electronic control module controls the loading module to apply force to the spatial KK-type tube node.

[0050] In one specific embodiment of this invention, both the reaction wall 1 and the foundation 2 are provided with a plurality of connection holes for connecting the loading module and the constraint module. In practice, the connection holes can be configured as a plurality of bolt holes with a spacing of 500 mm and a diameter of 50 mm.

[0051] In one specific embodiment of this example, the first fatigue actuator group 11, the second fatigue actuator group 12, the third fatigue actuator group 13 and the fourth fatigue actuator group 14 are all equipped with displacement sensors to monitor in real time the displacement of each branch pipe in the spatial KK-type pipe node 10 during the experiment. The displacement sensors are electrically connected to the electronic control module.

[0052] Example 2

[0053] This embodiment provides a fatigue testing method suitable for spatial KK-type pipe joints, using the fatigue testing apparatus for spatial KK-type pipe joints described in Embodiment 1, and includes the following steps:

[0054] Adjust the extension and retraction lengths of the first fatigue actuator group 11, the second fatigue actuator group 12, the third fatigue actuator group 13, and the fourth fatigue actuator group 14 in the loading module and rotate their angles so that they are coaxial with the four branch pipes of the spatial KK-type pipe node 10 respectively. Then connect the second ends of the first fatigue actuator group 11, the second fatigue actuator group 12, the third fatigue actuator group 13, and the fourth fatigue actuator group 14 to the four branch pipes of the spatial KK-type pipe node 10 respectively.

[0055] Start the electronic control module, then start the loading module through the electronic control module, and send control commands to the loading module;

[0056] Based on the control command, the loading module starts to run. At this time, one or more branch pipes of the spatial KK type pipe node 10 are loaded. The force sensor and displacement sensor on the loading module send the force and displacement data of each branch pipe in the spatial KK type pipe node 10 to the electronic control module.

[0057] After receiving the data monitored by the force and displacement sensors, the electronic control module compares it with the preset force and displacement thresholds. When the detected force or displacement data exceeds the threshold, the electronic control module determines that the space KK type tube node 10 has failed and sends a stop operation command to the loading module.

[0058] Based on the stop command, the loading module stopped running, and the experiment ended.

[0059] In the specific implementation process, the spatial KK-type pipe node 10 is fixed on the constraint module and connected to the corresponding loading module. The electrical control module is started first, and a trial run is conducted with one-tenth of the design load. The readings of each sensor are observed. After the trial run is completed, the formal test begins, that is, the formal test is started according to the design load value. The design load is: the quantitative force applied to one or more branch pipes of the spatial KK-type pipe node 10, or the quantitative displacement of the loading module along the axial direction of one or more branch pipes in the spatial KK-type pipe node 10 towards the spatial KK-type pipe node 10.

[0060] After the test, displacement-time history curves and force-time history curves of the four branch pipe ends of the spatial KK-type pipe node 10 can be obtained. The test personnel can also observe the failure process and final failure state of the spatial KK-type pipe node 10 during the test.

[0061] In one specific embodiment of this example, the control command includes either a force control command or a displacement control command;

[0062] The force control command is used to control the loading module to apply a quantitative force to one or more branch pipes of the spatial KK-type pipe node 10, the force including at least one of tension and thrust.

[0063] The displacement control command is used to control the loading module to contract or stretch along the axial direction of one or more branch pipes in the spatial KK-type pipe node 10, thereby completing a quantitative displacement.

[0064] In one specific embodiment of this invention, the force control command includes at least one of the following operating commands:

[0065] The first running instruction controls the fatigue actuator group corresponding to the loading module to continuously apply force to one or more branch pipes of the spatial KK-type pipe node 10 at a preset rate until the preset maximum force value is reached.

[0066] The second operating instruction controls the fatigue actuator group corresponding to the loading module to repeatedly apply force to one or more branch pipes of the spatial KK-type pipe node 10, and the magnitude of the force changes periodically.

[0067] In one specific embodiment of this example, the displacement control command includes at least one of the following operating commands:

[0068] The third operating instruction controls the fatigue actuator group corresponding to the loading module to continuously contract or stretch along the axial direction of one or more branch pipes in the spatial KK-type pipe node 10 until the preset maximum displacement is reached.

[0069] The fourth operating command controls the fatigue actuator group corresponding to the loading module to repeatedly extend and retract along the axial direction of one or more branch pipes of the spatial KK-type pipe node 10, and the amount of extension and retraction changes periodically.

[0070] In the description of this invention, it should be understood that the terms "first," "second," etc., 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. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0071] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A fatigue testing device suitable for spatial KK-type pipe joints, characterized in that, include: Constraint module; The loading module includes a first fatigue actuator group (11), a second fatigue actuator group (12), a third fatigue actuator group (13), and a fourth fatigue actuator group (14). The first ends of the first fatigue actuator group (11), the second fatigue actuator group (12), the third fatigue actuator group (13), and the fourth fatigue actuator group (14) are all connected to the constraint module, and the second ends are respectively used to connect the four branches of the spatial KK type pipe node (10). An electrical control module is installed on the constraint module and is electrically connected to the loading module.

2. The fatigue testing device for spatial KK-type pipe joints according to claim 1, characterized in that, The constraint module includes a reaction wall (1), a foundation (2), a reaction frame assembly, a first support (8), and a second support (9); The reaction wall (1) and the foundation (2) are both connected to the reaction frame assembly. The reaction wall (1) is also connected to the first end of the third fatigue actuator assembly (13) and the fourth fatigue actuator assembly (14). The reaction frame assembly is also connected to the first end of the first fatigue actuator assembly (11) and the second fatigue actuator assembly (12). The first connecting end of the first support (8) is used to connect the first end of the main pipe in the spatial KK type pipe node (10), and the first connecting end of the second support (9) is used to connect the second end of the main pipe in the spatial KK type pipe node (10). The second connecting ends of both are connected to the foundation (2).

3. The fatigue testing device for spatial KK-type pipe joints according to claim 2, characterized in that, Both the reaction wall (1) and the foundation (2) are provided with several connection holes for connecting the loading module and the constraint module.

4. The fatigue testing apparatus for spatial KK-type pipe joints according to claim 1, characterized in that, The first fatigue actuator group (11), the second fatigue actuator group (12), the third fatigue actuator group (13) and the fourth fatigue actuator group (14) are all equipped with force sensors and displacement sensors to monitor in real time the force and displacement of each branch pipe in the spatial KK type pipe node (10) during the experiment. The force sensors and displacement sensors are electrically connected to the electronic control module.

5. A fatigue testing method applicable to spatial KK-type pipe joints, characterized in that, The fatigue testing apparatus for spatial KK-type tube joints as described in claims 1 to 4 includes the following steps: Adjust the extension length and rotate the angle of the first fatigue actuator group (11), the second fatigue actuator group (12), the third fatigue actuator group (13) and the fourth fatigue actuator group (14) in the loading module so that they are coaxial with the four branches of the spatial KK type pipe node (10) respectively. Then connect the second ends of the first fatigue actuator group (11), the second fatigue actuator group (12), the third fatigue actuator group (13) and the fourth fatigue actuator group (14) to the four branches of the spatial KK type pipe node (10) respectively. Start the electronic control module, then start the loading module through the electronic control module, and send control commands to the loading module; Based on the control command, the loading module starts to run. At this time, one or more branches of the spatial KK type pipe node (10) are loaded. The force sensor and displacement sensor on the loading module send the force and displacement data of each branch in the spatial KK type pipe node (10) to the electrical control module. After receiving the data monitored by the force and displacement sensors, the electronic control module compares it with the preset force and displacement thresholds. When the detected force or displacement data exceeds the threshold, the electronic control module determines that the space KK type pipe node (10) is faulty and sends a stop operation command to the loading module. Based on the stop command, the loading module stopped running, and the experiment ended.

6. The fatigue testing method for spatial KK-type tube joints according to claim 5, characterized in that, The control command includes either a force control command or a displacement control command; The force control command is used to control the loading module to apply a quantitative force to one or more branch pipes of the spatial KK-type pipe node (10), the force including at least one of tension and thrust; The displacement control command is used to control the loading module to contract or stretch along the axial direction of one or more branch pipes in the spatial KK-type pipe node (10) to complete a quantitative displacement.

7. The fatigue testing method for spatial KK-type tube joints according to claim 6, characterized in that, The force control command includes at least one of the following operating commands: The first running instruction controls the fatigue actuator group corresponding to the loading module to continuously apply force to one or more branch pipes of the spatial KK-type pipe node (10) at a preset rate until the preset maximum force value is reached. The second running instruction controls the fatigue actuator group corresponding to the loading module to repeatedly apply force to one or more branch pipes of the spatial KK-type pipe node (10), and the magnitude of the force changes periodically.

8. The fatigue testing method for spatial KK-type tube joints according to claim 6, characterized in that, The displacement control command includes at least one of the following operation commands: The third running instruction controls the fatigue actuator group corresponding to the loading module to continuously contract or stretch along the axial direction of one or more branch pipes in the spatial KK-type pipe node (10) until the preset maximum displacement is reached. The fourth operating instruction controls the fatigue actuator group corresponding to the loading module to repeatedly extend and retract along the axial direction of one or more branch pipes of the spatial KK-type pipe node (10), and the amount of extension and retraction changes periodically.

Images