Lining pipeline interface contact pressure distribution testing device and method

Abstract

The invention discloses a lining pipeline interface contact pressure distribution testing device and method, relates to the technical field of pipeline detection, and aims at solving the problem that in the prior art, interface contact pressure distribution is difficult to represent in a lossless and quantitative mode. The device comprises a testing machine moving platform, an overground control moving platform, a lining pipe wall testing claw, an ultrasonic signal transceiver and a three-dimensional imaging module, the testing claw carries four curved-surface ultrasonic probes, and signals are collected in a one-transmitting-multiple-receiving mode controlled by an FPGA (Field Programmable Gate Array); according to the method, a contact pressure characterization model is constructed through self-adaptive positioning and signal excitation and processing, and interface pressure distribution visualization is achieved in combination with a three-dimensional imaging technology. The method does not need to damage the pipeline structure, can accurately capture the spatial distribution characteristics of the contact pressure, is adaptive to the conventional detection of long-distance pipelines, provides a scientific basis for lining repair quality evaluation and pipeline operation safety, and is convenient to operate and high in applicability.

Description

Technical Field

[0001] This invention relates to the field of pipeline inspection technology, and in particular to a device and method for testing the interface contact pressure distribution of lined pipelines. Background Technology

[0002] In urban drainage and municipal pipeline repair projects, the lining method has become the mainstream technology for structural reinforcement and functional restoration of aging pipelines due to its significant advantages such as trenchless construction, minimal disturbance to existing pipelines, and high repair efficiency. This technology creates a composite "pipe-in-pipe" structure by installing a lining pipe inside the original pipeline. Its long-term service performance and safety stability largely depend on the interface contact state between the lining pipe and the inner wall of the original pipeline. This core factor directly determines the rationality of the structural force transmission path, the reliability of seepage prevention performance, and the degree of local stress concentration, making it a key parameter for evaluating the quality of lining repair and the safety of pipeline service.

[0003] Engineering practice has confirmed that the interface between the liner and the original pipe is not a simple binary state of "complete fit" or "complete separation," but rather generally exhibits a non-uniform spatial distribution of contact pressure. For pressure pipelines, this non-uniformity of interface contact pressure accelerates fatigue damage to the liner under repeated media pressure, significantly shortening its service life. However, current engineering assessments of the liner interface condition still primarily rely on construction experience or theoretical calculations of pipe diameters before and after repair. There is a lack of effective technical means to achieve non-destructive and quantitative characterization of interface contact pressure distribution without damaging the pipeline structure, severely restricting the scientific rigor and accuracy of liner repair quality assessment.

[0004] Existing testing methods all have significant shortcomings and are difficult to meet actual engineering needs: Traditional methods such as visual inspection, CCTV inspection, endoscopic inspection and pressure test can only make qualitative judgments on the integrity and overall sealing of the lining structure or obtain overall indicators. They cannot capture the microscopic changes in interface contact pressure and its spatial distribution characteristics, making it difficult to achieve a refined characterization and imaging display of the interface state. While X-ray and CT imaging technologies have a certain penetrating ability and can obtain the geometric characteristics of hidden areas, they are expensive, have complex operating procedures, and pose significant radiation safety hazards. They are not suitable for routine inspection of long-distance pipelines, and cannot directly characterize the contact pressure between the liner pipe and the original pipe. Ultrasonic testing technology, due to its non-destructive nature and sensitivity to interface conditions, has promising applications in the field of multilayer structure and interface inspection. However, existing ultrasonic testing technologies are mostly based on analysis of a single propagation path or a single echo characteristic, focusing only on determining the presence of cavities and failing to reflect the continuous distribution characteristics of interface contact pressure. Especially in pipeline inspection, the probe posture, contact conditions, and interface state continuously change along the pipeline's axial and circumferential directions. A single ultrasonic response cannot fully describe the interface coupling characteristics, making it difficult to meet the requirements for accurate inspection.

[0005] Therefore, there is an urgent need for a new detection technology for the inspection of lined pipes during operation. This technology can construct the equivalent contact pressure distribution parameters of the interface through multi-source excitation and multi-path reception of piezoelectric ultrasonic coupling response, and further realize the three-dimensional imaging characterization of the interface state. This will break through the existing technical bottlenecks and improve the scientificity and reliability of the quality assessment of lined pipe repair. Summary of the Invention

[0006] The purpose of this invention is to provide a device and method for testing the interface contact pressure distribution of lined pipes, so as to achieve non-destructive quantitative characterization and three-dimensional imaging of the interface contact pressure distribution of lined pipes, and provide a scientific basis for pipeline repair quality assessment and operational safety.

[0007] To achieve the above objectives, the present invention provides a testing device for the interface contact pressure distribution of lined pipes, comprising a testing machine mobile platform, a ground control mobile platform, a mobile power supply system, a WiFi control module, and a three-dimensional imaging module; the testing machine mobile platform is equipped with a liner pipe wall testing claw and an ultrasonic signal transceiver; the ground control mobile platform integrates a host computer central control module, and establishes a control connection with the testing machine mobile platform through the WiFi control module; the mobile power supply system supplies power to each module; and the three-dimensional imaging module is communicatively connected to the ultrasonic signal transceiver.

[0008] Preferably, the test machine mobile platform is also equipped with: a multi-axis robotic arm and a laser calibration system. The bottom end of the multi-axis robotic arm is fixed in the center of the test machine mobile platform, the inner liner tube wall test claw is set at the top of the multi-axis robotic arm, and the laser calibration system cooperates with a calibration prism set outside the test machine mobile platform.

[0009] Preferably, the inner liner tube wall test claw includes a test claw support frame, four rotary joints, four electric telescopic rods, and four curved ultrasonic probes; the test claw support frame is cross-shaped, and a robotic arm mounting plate and a probe mounting plate are respectively set on the two sides of the center of the test claw support frame. The test claw support frame is connected to a multi-axis robotic arm through the robotic arm mounting plate, and a visual probe and an ultrasonic ranging probe are set on the probe mounting plate. The end of the test claw support extends outwards and is rotatably connected to one end of the rotary joint. The other end of the rotary joint is provided with a mounting hole. The middle part of the electric telescopic rod is fixed in the mounting hole. One end of the electric telescopic rod is provided with a curved ultrasonic probe. A pressure sensor is provided between the curved ultrasonic probe and the electric telescopic rod. The curved ultrasonic probe and the probe mounting plate are both located on the side away from the multi-axis robotic arm.

[0010] Preferably, the curved ultrasonic probe includes a piezoelectric element. A cylindrical groove is formed at the top of the piezoelectric element, and a curved rigid piezoelectric element protective shell, a high-density rubber gasket, a low-density rubber gasket, a hard alloy gasket, and a butterfly spring are arranged sequentially from top to bottom in the cylindrical groove. An ultrasonic probe sleeve is provided between the curved rigid piezoelectric element protective shell and the high-density rubber gasket. An ultrasonic transmission shielding wire is connected to the side of the piezoelectric element. A fixing hole is formed at the bottom of the piezoelectric element, and a pressure sensor is connected through the fixing hole. The pressure sensor is electrically connected to an ultrasonic signal transceiver.

[0011] Preferably, the ultrasonic transceiver is controlled by an FPGA. All four curved ultrasonic probes are electrically connected to the transceiver via shielded ultrasonic transmission wires. One probe is cyclically switched as the excitation end, and the other three as the receiving ends. The total received signal is recorded in matrix form as follows: (1) In the formula: For the test signal matrix; For each test, receive the signal. The receiving probe number, The transmitter probe is numbered.

[0012] A method for testing the interfacial contact pressure distribution of lined pipes, comprising the following steps: S1. Deployment of the test system: Mount the inner liner tube wall test claw on the test machine mobile platform, complete the positioning and travel path planning of the test machine mobile platform and prism, and establish a communication connection between the host computer control module and the ultrasonic signal transceiver through the WiFi control module. S2. Measurement point positioning: Through the linkage between the multi-axis robotic arm and the test claw of the inner lining pipe wall, the pipeline axis positioning, pipeline section measurement point positioning and curved ultrasonic probe head are completed in sequence. Test sections are set at intervals along the pipeline direction, and multiple measurement points are arranged on each test section. S3. Calibration of standard contact pressure value: The pressure value with a preset guarantee rate of pipe wall contact pressure among multiple measuring points is taken as the standard value. ; S4. Single-point ultrasonic signal excitation and reception: The pressure sensor feedback data controls four curved adaptive ultrasonic probes to adhere to the inner liner tube wall with the same clamping force. The ultrasonic transceiver controls the use of a one-to-many mode, cyclically switching one probe as the excitation end and the other three as the receiving ends to carry out piezoelectric ultrasonic contact pressure test. The total received signal is recorded in matrix form and temporarily stored in the ultrasonic transceiver. S5. Ultrasonic signal processing and analysis: The ultrasonic transceiver transmits the temporarily stored received signal to the data processing unit of the three-dimensional imaging module, extracts the ultrasonic signal feature indicators to form a measurement point index matrix, represented as: (2) In the formula: For the test signal matrix; These are the characteristic index values ​​of each test signal. The receiving probe number, Number the transmitting probe; The 2-norm L of matrix D is calculated as the evaluation index for this measurement point; S6. Construction of contact pressure characterization model: Based on the piezoelectric ultrasonic coupling principle, assuming the interface is a one-dimensional elastic contact model, ignoring the nonlinear behavior of the material, a quantitative relationship between ultrasonic signal characteristic parameters and contact pressure is established, and the 0% contact pressure condition is used as the base value for normalization. S7. Complete pipe test: After the single test section test is completed, adjust the position of the test claw to cover all test points. The host computer control module commands the test machine mobile platform to automatically move to the next test section through the WiFi control module. Repeat steps S4-S6 to complete the complete pipe test and save the data. S8. Three-dimensional imaging characterization: The three-dimensional imaging module processes the test data of the entire pipe in a unified manner and converts it into a three-dimensional image through visualization software to realize the three-dimensional imaging characterization of the interface contact pressure distribution.

[0013] Preferably, in step S6, establishing a quantitative relationship between ultrasonic signal characteristic parameters and contact pressure specifically includes: The reflection coefficient R and transmission coefficient T of ultrasound at the interface are expressed as follows: (3) In the formula: and These are the acoustic impedances of the lining material and the original pipe material, respectively. , For material density, The speed of sound; When contact pressure exists at the interface, the change in acoustic impedance satisfies: (4) In the formula: For experimental calibration constants related to material properties, This refers to the contact pressure at the pipe wall interface. Define the contact pressure ratio as Using the 0% contact pressure condition as the baseline for normalization, a quantitative relationship is established through a fitting function, expressed as: (5) By finding the inverse function of the fitted function, the contact pressure at a single measuring point can be evaluated. (6) In the formula: The evaluation index is denoted by a, b, c, and d, which are the fitting parameters.

[0014] Preferably, the clamping force error in step S4 is controlled within a preset range, and the clamping force meets the test requirements; the excitation signal is a frequency sweep signal or a pulse signal, and the excitation and reception timing is synchronously controlled by an ultrasonic transceiver.

[0015] Preferably, the feature index in step S5 includes at least one of Shannon entropy, signal energy, time-reversed focused peak, and multi-scale sample entropy.

[0016] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: (1) This invention effectively overcomes the limitations of existing technologies for detecting interface contact pressure in lined pipes, and achieves non-destructive and quantitative characterization of interface contact pressure distribution. Existing technologies mostly rely on empirical judgment or indirect calculation, making it difficult to accurately obtain the actual stress state of the interface. However, this invention is based on the piezoelectric ultrasonic coupling principle and constructs a quantitative relationship between contact pressure and ultrasonic signal characteristic parameters through multi-source excitation and multi-path reception of signal responses. It can capture the spatial distribution characteristics of interface contact pressure without damaging the pipe structure, filling the technical gap in refined detection in this field.

[0017] (2) The testing system has strong adaptability to working conditions and is easy to operate, meeting the routine testing needs of long-distance pipelines. The adaptive positioning design of the testing claw can accurately adapt to the curved shape of the pipeline, ensuring stable contact between the ultrasonic probe and the pipe wall. Combined with the autonomous walking and measuring point positioning functions of the testing machine's moving platform, it can effectively cope with the complex changes in the axial and circumferential interface state inside the pipeline. Compared with the problems of expensive, complex operation and safety hazards of traditional X-ray, CT and other technical equipment, the present invention has a simple structure, flexible control, and does not require complex on-site deployment, significantly reducing the testing threshold and application cost.

[0018] (3) This invention achieves intuitive visualization of the detection results through three-dimensional imaging technology, providing a scientific basis for engineering decision-making. Through the collaborative work of various modules, the scattered measurement point data are integrated into a complete three-dimensional pressure distribution image, clearly showing the microscopic changes and overall distribution law of the interface contact pressure, solving the defect that traditional qualitative detection cannot quantify the interface state. This technology can not only accurately assess the quality of lining repair, but also predict potential structural safety risks in advance, providing reliable protection for the long-term service safety of pipelines, and promoting the development of lining pipeline repair quality assessment towards a more scientific and precise direction.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of an embodiment of the interface contact pressure distribution testing device for lined pipes according to the present invention. Figure 2 (a) is a schematic diagram of the inner liner tube wall test claw structure according to an embodiment of the present invention; (b) is a schematic diagram of the front structure; Figure 3 This is a schematic diagram of the connection structure between the electric telescopic rod and the curved ultrasonic probe according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the cross-sectional structure of the curved ultrasonic probe according to an embodiment of the present invention; Figure 5 This is a flowchart of a method for testing the interface contact pressure distribution of an inner-lined pipe according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the calibration inside the pipeline of the test machine moving platform according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the inner cross-section of the test machine mobile platform pipe in an embodiment of the present invention. (a) is a diagram of the travel position of the test machine mobile platform; (b) is a diagram of the distribution of measuring points. Figure 8 This is a flowchart illustrating the signal processing of an embodiment of the present invention. Figure 9 This is a schematic diagram of the one-transmitter-multiple-receiver mode of the curved ultrasonic probe according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the signal measured at a single measurement point according to an embodiment of the present invention; Figure 11 This is a graph showing the multi-scale entropy as a function of the contact pressure ratio in an embodiment of the present invention. Figure 12 This is a schematic diagram of normalization processing and curve fitting in an embodiment of the present invention; Figure 13 This is a schematic diagram of the three-dimensional imaging results of the pipe wall contact pressure in an embodiment of the present invention.

[0022] Figure Labels 10. Testing machine moving platform; 11. Inner liner tube wall testing claw; 111. Testing claw support frame; 112. Rotary joint; 113. Curved surface ultrasonic probe; 114. Electric telescopic rod; 115. Probe mounting plate; 116. Robotic arm mounting plate; 117. Vision probe; 118. Ultrasonic ranging probe; 119. Pressure sensor; 120. Piezoelectric element; 121. Curved surface rigid piezoelectric element protective shell; 122. Ultrasonic probe sleeve; 123. High-density rubber gasket; 124. Low-density rubber gasket; 125. Hard alloy gasket; 126. Cylindrical groove; 127. Butterfly spring; 128. Fixing hole; 129. Ultrasonic transmission shielded wire; 12. Laser calibration system; 13. Multi-axis robotic arm; 14. Ultrasonic signal transceiver; 20. Ground control mobile platform; 21. Mobile power supply system; 22. Host computer central control module; 23. Wiring roller; 30. Calibration prism. Detailed Implementation

[0023] 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] Example like Figure 1 As shown, a test device for the interface contact pressure distribution of an inner-lined pipe includes a test machine mobile platform 10, a ground control mobile platform 20, a mobile power system 21, a WiFi control module, and a three-dimensional imaging module.

[0026] The testing machine mobile platform 10 is equipped with an inner liner pipe wall testing claw 11, an ultrasonic signal transceiver 14, a multi-axis robotic arm 13, and a laser calibration system 12. The bottom end of the multi-axis robotic arm 13 is fixed to the center of the testing machine mobile platform 10, and the inner liner pipe wall testing claw 11 is located at the top of the multi-axis robotic arm 13. The laser calibration system 12 includes a distance recording device and a laser deviation calibration device, which cooperate with the calibration prism 30 located outside the testing machine mobile platform 10 to calibrate the travel path of the testing machine mobile platform 10, so that the testing machine mobile platform 10 travels along the central axis of the pipe.

[0027] The ground control mobile platform 20 integrates the host computer control module 22, establishes a control connection with the test machine mobile platform 10 through the WiFi control module, the mobile power system 21 supplies power to each module, and the three-dimensional imaging module communicates with the ultrasonic signal transceiver 14.

[0028] like Figure 2 As shown, the inner liner tube wall test claw 11 includes a test claw support frame 111, four rotary joints 112, four electric telescopic rods 114, and four curved ultrasonic probes 113. The test claw support frame 111 is cross-shaped, and a robotic arm mounting plate 116 and a probe mounting plate 115 are respectively arranged on the two sides of the center of the test claw support frame 111. The test claw support frame 111 is connected to the multi-axis robotic arm 13 through the robotic arm mounting plate 116. A vision probe 117 and an ultrasonic ranging probe 118 are arranged on the probe mounting plate 115. The two ultrasonic ranging probes 118 are located on both sides of the vision probe 117.

[0029] The test claw support frame 111 extends outwards and is rotatably connected to one end of the rotating joint 112. The other end of the rotating joint 112 is provided with a mounting hole, and the middle part of the electric telescopic rod 114 is fixed in the mounting hole.

[0030] like Figure 3 As shown, a curved ultrasonic probe 113 is provided at one end of the electric telescopic rod 114, and a pressure sensor 119 is provided between the curved ultrasonic probe 113 and the electric telescopic rod 114. The curved ultrasonic probe 113 and the probe mounting plate 115 are both located on the side away from the multi-axis robotic arm 13.

[0031] like Figure 4As shown, the curved ultrasonic probe 113 includes a piezoelectric element 120. A cylindrical groove 126 is formed at the top of the piezoelectric element 120. Within the cylindrical groove 126, from top to bottom, are arranged a curved rigid piezoelectric element protective shell 121, a high-density rubber gasket 123, a low-density rubber gasket 124, a hard alloy gasket 125, and a disc spring 127. An ultrasonic probe sleeve 122 is positioned between the curved rigid piezoelectric element protective shell 121 and the high-density rubber gasket 123. An ultrasonic transmission shielded wire 129 is connected to the side of the piezoelectric element 120 to achieve signal connection with the ultrasonic signal transceiver 14.

[0032] A fixing hole 128 is provided at the bottom end of the piezoelectric sheet 120, and it is connected to the pressure sensor 119 through the fixing hole 128. The pressure sensor 119 is electrically connected to the ultrasonic signal transceiver 14.

[0033] like Figure 5 As shown, a method for testing the interface contact pressure distribution of an inner-lined pipe includes the following steps: (1) Build a test system and construct a test claw for the inner lining pipe wall based on piezoelectric ultrasonic coupling. Building such Figure 1 The test system shown consists of a mobile test platform 10, an ultrasonic transceiver 14, a ground control mobile platform 20, a mobile power supply system 21, wiring rollers 23, and a WiFi control module. The test system integrates testing, control, and signal processing. (The last sentence appears to be incomplete and possibly refers to a different system.) Figure 3 The inner lining pipe wall test claw 11 shown is programmed with an adaptive control program to achieve autonomous and precise positioning and autonomous correction.

[0034] (2) Measurement point positioning: The multi-axis robotic arm 13 is linked with the inner lining pipe wall test claw 11 to sequentially complete the positioning of the pipe axis, the positioning of the pipe cross-section measurement points, and the precise positioning of the curved surface ultrasonic probe. The pipe axis positioning is achieved by the laser calibration system 12 and the calibration prism 30 in the moving platform 10 of the testing machine. Figure 6 and Figure 7 As shown in (a), the test machine mobile platform 10 travels along the central axis of the pipe.

[0035] The testing machine moving platform 10 allows the testing device to move along the entire pipeline, and the multi-axis robotic arm 13 is used to adjust the position and angle of the test claws on the pipe wall to ensure the accurate positioning of the test points within the pipeline cross-section. Test sections are set at intervals along the pipeline direction according to the diameter of the test pipeline. Multiple test points a, ~, g, ... are evenly arranged circumferentially on each test section, as shown in the diagram. Figure 7 As shown in (b) of the diagram. Figure 7 In the cross-section of the pipe, from the inside out, the pipe consists of an inner liner, the original pipe, and the outermost layer is the pipe cover.

[0036] (3) Standard value of contact pressure between the inner liner and the original pipe wall Measurement The pressure value with a 95% guarantee rate for pipe wall contact pressure is selected from 100 measuring points. The typical value for one type of pipeline is 0.5 MPa.

[0037] (4) Single-point signal excitation and reception During the test, a one-to-many test mode was adopted. Figure 9 As shown, one of the ultrasonic probes is used for excitation, and the emitted signal is... The remaining three probes are used to receive signals, and the excitation probes are changed cyclically. The total received signal is written in matrix form, as shown in equation (1). In this embodiment, the excitation signal is a linear frequency sweep signal with a sweep range of 100kHz to 2MHz. The signal of a single test at a single measurement point is as follows: Figure 10 As shown.

[0038] (5) Processing and analysis of single-point ultrasonic signals In this embodiment, the signal testing metric selected is multi-scale sample entropy. Substitute the test index into equation (2) to solve for the 2-norm of the multi-signal multi-scale sample entropy. In the calculation of the multi-scale sample entropy, the number of time scales is 5, the signal embedding dimension is 2, and the similarity tolerance is 0.0326. Local pipe walls with different interfacial contact pressures P are tested according to the contact pressure ratio (0%, 10%, 20%...80%, 90%, 100%). As the contact pressure increases, the transmitted wave signal is enhanced, the reflected wave signal is suppressed, the signal energy remaining in the inner liner tube will decrease, and the entropy value will increase. The relationship between the loss rate of different contact pressures and the 2-norm of the multi-signal Shannon entropy is tested. The typical curve is a monotonically increasing curve, such as Figure 11 As shown.

[0039] (6) Construction of contact pressure characterization model, signal processing process as follows Figure 8 As shown. The test data were normalized, the test curve was fitted, and a contact pressure distribution characterization model was established. The case with a contact pressure loss rate of 0% was used as the base value for normalization. The typical fitting function between the void area and the evaluation index is shown in Equation (6). The fitting curve and fitting parameters are as follows. Figure 12 As shown.

[0040] (7) Three-dimensional imaging of pipe inspection and pipeline test indicators By having all modules work together, a test is conducted every 20cm along the pipeline direction to accurately characterize the contact pressure distribution at the interface of the lining pipeline.

[0041] (8) Three-dimensional imaging characterization: The three-dimensional imaging module processes the test data of the entire pipe in a unified manner, and the visualization software converts the processed data into intuitive three-dimensional images, showing the distribution information of the contact pressure at the interface of the inner lining pipe, such as... Figure 13 As shown.

[0042] The remaining technical features in the above embodiments can be flexibly selected by those skilled in the art to meet different specific practical needs according to actual circumstances. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims. In the above description, numerous specific details have been set forth to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to implement the present invention. In other instances, to avoid obscuring the present invention, well-known techniques, such as specific construction details, operating conditions, and other technical conditions, have not been specifically described.

[0043] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A device for testing the interface contact pressure distribution of an inner-lined pipe, characterized in that: The system includes a mobile testing platform, a ground control mobile platform, a mobile power system, a WiFi control module, and a 3D imaging module. The mobile testing platform is equipped with a pipe wall testing claw and an ultrasonic signal transceiver. The ground control mobile platform integrates a host computer control module and establishes a control connection with the mobile testing platform through the WiFi control module. The mobile power system supplies power to each module, and the 3D imaging module is communicatively connected to the ultrasonic signal transceiver.

2. The device for testing the interface contact pressure distribution of an inner-lined pipe according to claim 1, characterized in that: The test machine mobile platform is also equipped with a multi-axis robotic arm and a laser calibration system. The bottom end of the multi-axis robotic arm is fixed in the center of the test machine mobile platform. The inner liner tube wall test claw is set at the top of the multi-axis robotic arm. The laser calibration system works in conjunction with a calibration prism set outside the test machine mobile platform.

3. The device for testing the interface contact pressure distribution of an inner-lined pipe according to claim 1, characterized in that: The inner liner tube wall test claw includes a test claw support frame, four rotary joints, four electric telescopic rods, and four curved ultrasonic probes. The test claw support frame is cross-shaped, with a robotic arm mounting plate and a probe mounting plate respectively located on the two sides of the center of the test claw support frame. The test claw support frame is connected to a multi-axis robotic arm through the robotic arm mounting plate, and a visual probe and an ultrasonic ranging probe are installed on the probe mounting plate. The end of the test claw support extends outwards and is rotatably connected to one end of the rotary joint. The other end of the rotary joint is provided with a mounting hole. The middle part of the electric telescopic rod is fixed in the mounting hole. One end of the electric telescopic rod is provided with a curved ultrasonic probe. A pressure sensor is provided between the curved ultrasonic probe and the electric telescopic rod. The curved ultrasonic probe and the probe mounting plate are both located on the side away from the multi-axis robotic arm.

4. The device for testing the interface contact pressure distribution of an inner-lined pipe according to claim 3, characterized in that: The curved ultrasonic probe includes a piezoelectric element. A cylindrical groove is formed at the top of the piezoelectric element. From top to bottom, a curved rigid piezoelectric element protective shell, a high-density rubber gasket, a low-density rubber gasket, a hard alloy gasket, and a disc spring are arranged in the cylindrical groove. An ultrasonic probe sleeve is placed between the curved rigid piezoelectric element protective shell and the high-density rubber gasket. An ultrasonic transmission shielding wire is connected to the side of the piezoelectric element. A fixing hole is formed at the bottom of the piezoelectric element, through which a pressure sensor is connected. The pressure sensor is electrically connected to an ultrasonic signal transceiver.

5. The device for testing the interface contact pressure distribution of an inner-lined pipe according to claim 4, characterized in that: The ultrasonic transceiver is controlled by an FPGA. Four curved ultrasonic probes are electrically connected to the transceiver via shielded ultrasonic transmission wires. One probe is cyclically used as the excitation end, and the other three as the receiving ends. The total received signal is recorded in matrix form as follows: （1） In the formula: For the test signal matrix; For each test, receive the signal. The receiving probe number, The transmitter probe is numbered.

6. A method for testing the interfacial contact pressure distribution of lined pipes, using the interfacial contact pressure distribution testing device for lined pipes as described in any one of claims 1-5, characterized in that, The steps are as follows: S1. Deployment of the test system: Mount the inner liner tube wall test claw on the test machine mobile platform, complete the positioning and travel path planning of the test machine mobile platform and prism, and establish a communication connection between the host computer control module and the ultrasonic signal transceiver through the WiFi control module. S2. Measurement point positioning: Through the linkage between the multi-axis robotic arm and the test claw of the inner lining pipe wall, the pipeline axis positioning, pipeline section measurement point positioning and curved ultrasonic probe head are completed in sequence. Test sections are set at intervals along the pipeline direction, and multiple measurement points are arranged on each test section. S3. Calibration of standard contact pressure value: The pressure value with a preset guarantee rate of pipe wall contact pressure among multiple measuring points is taken as the standard value. ; S4. Single-point ultrasonic signal excitation and reception: The pressure sensor feedback data controls four curved adaptive ultrasonic probes to adhere to the inner liner tube wall with the same clamping force. The ultrasonic transceiver controls the use of a one-to-many mode, cyclically switching one probe as the excitation end and the other three as the receiving ends to carry out piezoelectric ultrasonic contact pressure test. The total received signal is recorded in matrix form and temporarily stored in the ultrasonic transceiver. S5. Ultrasonic signal processing and analysis: The ultrasonic transceiver transmits the temporarily stored received signal to the data processing unit of the three-dimensional imaging module, extracts the ultrasonic signal feature indicators to form a measurement point index matrix, represented as: （2） In the formula: For the test signal matrix; These are the characteristic index values ​​of each test signal. The receiving probe number, Number the transmitting probe; The 2-norm L of matrix D is calculated as the evaluation index for this measurement point; S6. Construction of contact pressure characterization model: Based on the piezoelectric ultrasonic coupling principle, assuming the interface is a one-dimensional elastic contact model, ignoring the nonlinear behavior of the material, a quantitative relationship between ultrasonic signal characteristic parameters and contact pressure is established, and the 0% contact pressure condition is used as the base value for normalization. S7. Complete pipe test: After the single test section test is completed, adjust the position of the test claw to cover all test points. The host computer control module commands the test machine mobile platform to automatically move to the next test section through the WiFi control module. Repeat steps S4-S6 to complete the complete pipe test and save the data. S8. Three-dimensional imaging characterization: The three-dimensional imaging module processes the test data of the entire pipe in a unified manner and converts it into a three-dimensional image through visualization software to realize the three-dimensional imaging characterization of the interface contact pressure distribution.

7. The method for testing the interface contact pressure distribution of an inner-lined pipe according to claim 6, characterized in that: In step S6, a quantitative relationship is established between the characteristic parameters of the ultrasonic signal and the contact pressure, specifically including: The reflection coefficient R and transmission coefficient T of ultrasound at the interface are expressed as follows: （3） In the formula: and These are the acoustic impedances of the lining material and the original pipe material, respectively. , For material density, The speed of sound; When contact pressure exists at the interface, the change in acoustic impedance satisfies: （4） In the formula: For experimental calibration constants related to material properties, This refers to the contact pressure at the pipe wall interface. Define the contact pressure ratio as Using the 0% contact pressure condition as the baseline for normalization, a quantitative relationship is established through a fitting function, expressed as: （5） By finding the inverse function of the fitted function, the contact pressure at a single measuring point can be evaluated. （6） In the formula: The evaluation index is denoted by a, b, c, and d, which are the fitting parameters.

8. The method for testing the interface contact pressure distribution of an inner-lined pipe according to claim 6, characterized in that: In step S4, the clamping force error is controlled within a preset range, and the clamping force meets the test requirements; the excitation signal is a frequency sweep signal or a pulse signal, and the excitation and reception timing is synchronously controlled by an ultrasonic transceiver.

9. The method for testing the interface contact pressure distribution of an inner-lined pipe according to claim 6, characterized in that: The feature indicators mentioned in step S5 include at least one of Shannon entropy, signal energy, time-reversed focused peak, and multi-scale sample entropy.

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