Pipe joint three-dimensional photoelastic testing device and testing method

Abstract

The invention provides a pipe joint three-dimensional photoelastic testing device and method, and relates to the field of pipe joint model tests.The pipe joint three-dimensional photoelastic testing device comprises a transparent model box, two pipe joints which abut against each other are inserted into the model box, and the axis intersection angle of the two pipe joints is variable; the loading assembly is used for applying acting force to the pipe joints; the light detection assemblies are used for obtaining interference fringes of the two pipe joints respectively and comprise outer modules, inner modules and light sources, the light sources are arranged on the sides, away from the outside of the pipe joints, of the outer modules, the outer modules comprise outer polarizers and outer quarter-wave plates, the outer modules are semi-cylindrical, the axial directions of the outer modules are parallel to the corresponding pipe joints, and the inner modules are arranged on the inner sides of the outer modules. The inner module comprises a photosensitive screen, an inner polarization analyzer, an inner quarter-wave plate, an eyepiece and an objective lens, and the photosensitive screen, the inner polarization analyzer and the inner quarter-wave plate are all semi-cylindrical; according to the device and the method, the interference fringes of the pipe joint are obtained by adopting a three-dimensional curved surface photoelastic imaging mode, so that the analysis of the stress field of the pipe joint is realized.

Description

Technical Field

[0001] The invention relates to the field of pipe segment model testing, and in particular to a three-dimensional photoelastic testing device and a testing method for a pipe segment. Background Art

[0002] In recent years, with the acceleration of the development and utilization of underground space, the pipe jacking method, as a key trenchless technology, has been widely used. For pipe jacking projects under complex engineering geological conditions, the existing relevant theories are difficult to accurately predict the interaction between force and deformation, and simple field tests are often uncertain and random and difficult to repeat. Therefore, it is necessary to design indoor model tests to accurately grasp the law of force changes during pipe jacking and provide reference and guidance for actual construction.

[0003] The stress state in the existing jacking pipe model test device is mostly in three-dimensional form, and theoretical calculation and analysis are often complicated, especially some stress concentration problems in the components cannot be effectively analyzed. Therefore, the stress analysis of engineering components is mostly analyzed by photoelastic experimental methods. The commonly used photoelastic test method is usually tested on two-dimensional structures. For three-dimensional photoelastic tests and their tests, the stress freezing method is often used. The stress freezing method is to apply a load to the specimen, heat it to the freezing temperature of the specimen material under the condition that the load applied to the specimen remains unchanged, slowly cool it to room temperature, remove the external load, slice the specimen, and analyze the stress distribution by observing the interference fringes preserved on the slice. However, this method cannot fully obtain the stress distribution of the specimen, and the workload of multiple slicing is large, which does not meet the experimental conditions of various working conditions. At present, there are few direct imaging devices for three-dimensional curved surfaces, especially for larger model imaging devices, so a three-dimensional photoelastic test device and test method for pipe sections are proposed. Summary of the invention

[0004] The present invention provides a three-dimensional photoelastic testing device and a testing method for a pipe segment, the purpose of which is to provide a device based on photoelastic imaging of a three-dimensional curved surface to simplify the process and difficulty of stress field distribution research.

[0005] In order to achieve the above object, an embodiment of the present invention provides a three-dimensional photoelastic testing device for a pipe segment, comprising: A transparent model box, in which two pipe sections abutting each other end to end are inserted, and the intersection angle of the axes of the two pipe sections is variable; A loading assembly acts on one end of any pipe segment to apply a force; Two optical inspection components, respectively used to obtain interference fringes of two tube segments, the optical inspection components include an outer module, an inner module and a light source, the outer module is used to be arranged outside the two tube segments, the inner module is used to be arranged inside the two tube segments, the light source is arranged on the side of the outer module away from the outside of the tube segment, the outer module includes an outer polarizer and an outer quarter wave plate from the outside to the inside, the outer module is semi-cylindrical, the axial direction of the outer module is parallel to the corresponding tube segment, the inner module includes a photosensitive screen, an inner analyzer, an inner quarter wave plate, an eyepiece and an objective lens from the outside to the inside, and the photosensitive screen, the inner analyzer and the inner quarter wave plate are all semi-cylindrical; The recording system is used to obtain the interference fringes obtained by the photosensitive screen and the magnitude of the force applied by the loading component.

[0006] Preferably, the side wall of the model box is provided with a pipe penetration hole, the diameter of the pipe penetration hole is larger than the diameter of the pipe segment, and the pipe segments are respectively inserted through the pipe penetration holes and abutted in the model box.

[0007] Preferably, the loading assembly further comprises a reaction frame and a jack, wherein the jack is arranged on the reaction frame, the jack is arranged at one end of the pipe segment exposed outside the model box and acts on the end of the pipe segment, and a pressure sensor is arranged between the jack and the abutting pipe segment.

[0008] Preferably, the recording system includes a PC and a digital display, the digital display is used to obtain the loading force of the pressure sensor, and the digital display and the photosensitive screen are respectively connected to the PC signal.

[0009] Preferably, the pipe segment and the model box are both made of transparent material.

[0010] The present application also provides a three-dimensional photoelastic testing method for a pipe segment, using the aforementioned three-dimensional photoelastic testing device for a pipe segment, comprising: S10. Fix the two inner modules in the two pipe sections respectively; S20. Insert two pipe sections from one end of the model box into the model box and abut against each other, the two pipe sections form an axis intersection angle, fill the model box with transparent soil of a preset temperature, and apply different preset loads to the two pipe sections with the transparent soil; S30. The two outer modules and the light source are fixed outside the model box, respectively, and the bending directions of the inner module and the outer module of the same pipe segment are ensured to be opposite; S40. Turn on the loading assembly, apply a loading force to the end of the tube segment exposed outside the model box, and obtain interference fringes on the photosensitive screen for the first time; S50. Rotate the inner module and the outer module 180° inside and outside their respective tube segments, apply the same loading force to the same tube segment in S40, and obtain interference fringes on the photosensitive screen for the second time; S60. The interference fringes obtained twice are spliced ​​to obtain complete interference fringes, and the stress field distribution of the pipe segment is analyzed based on the complete interference fringes, loading force, load and temperature.

[0011] Preferably, the three-dimensional photoelastic testing method for pipe segments further comprises step S70, in which at least one of the axis angle, the load, the loading force and the temperature of the transparent soil is changed, and steps S10-S60 are repeated.

[0012] Preferably, the angle range of the axis intersection angle is 0-10°.

[0013] Preferably, transparent soil is added to the model box, and the transparent soil is buried to different depths of the pipe segments to form different loads.

[0014] The above scheme of the present invention has the following beneficial effects: The present application adopts three-dimensional surface photoelastic imaging to obtain the interference fringes of the pipe joint, and then realizes the analysis of the stress field of the pipe joint. The present application can completely obtain the stress distribution information of the pipe joint, and in the process of obtaining the stress distribution information, the operation process is more convenient and concise.

[0015] The optical inspection component solves the problems of low accuracy and poor adaptability of traditional photoelasticity instrument in cylindrical pipe segment testing through curved surface adaptive optical path design and double wave plate closed-loop polarization control.

[0016] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is an overall schematic diagram of this application; Figure 2 It is a schematic diagram of the intersection angle of the axes of the first pipe section and the second pipe section; Figure 3 is a schematic diagram of the optical inspection component; Figure 4 It is a schematic diagram of loading components; Figure 5 It is a flow chart of the test method.

[0018] [Description of Reference Numerals] 100-model box, 200-first pipe section, 300-second pipe section, 400-loading assembly, 410-reaction frame, 420-jack, 421-pressure sensor, 510-external module, 511-external polarizer, 512-external quarter wave plate, 520-internal module, 521-photosensitive screen, 522-internal quarter wave plate, 523-eyepiece, 524-objective lens, 525-internal analyzer 530-light source, 600-recording system, 610-PC terminal, 620-digital display instrument.

[0019] α-axis intersection angle. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0021] like Figure 1-Figure 4 As shown, an embodiment of the present invention provides a three-dimensional photoelastic testing device for pipe segments, including a model box 100, an optical inspection component, a loading component 400 and a recording system 600, wherein the model box 100 is used to penetrate two pipe segments and fill soil. The pipe segment includes a first pipe segment 200 and a second pipe segment 300, the first pipe segment 200 and the second pipe segment 300 respectively penetrate into the model box 100 from the side of the model box 100, and abut against each other in the model box 100, and the axis intersection angle α of the first pipe segment 200 and the second pipe segment 300 is variable. When the first pipe segment 200 and the second pipe segment 300 are penetrated, the second pipe segment 300 can be completely in the model box 100, or partially in the model box 100, one end of the first pipe segment 200 is located in the model box 100, and the other end is located outside the model box 100.

[0022] Preferably, the first pipe section 200 and the second pipe section 300 have the same pipe diameter.

[0023] The optical inspection component includes a light source 530 for emitting light, an outer module 510 for being arranged outside the tube segment, and an inner module 520 for being arranged inside the tube segment. The outer module 510 includes an outer polarizer 511 and an outer quarter wave plate 512 which are sequentially attached from the outside to the inside. In this application, the center of the tube segment is defined as the inner side, and the directions extending from the center of the circle to the outside are all the outer sides. The outer polarizer 511 and the outer quarter wave plate 512 are both semi-cylindrical, and the diameters of the outer polarizer 511 and the outer quarter wave plate 512 are both larger than the diameter of the tube segment. The axial direction of the outer module 510 is parallel to the axial directions of the first tube segment 200 and the second tube segment 300. The inner module 520 includes a photosensitive screen 521, an inner polarizer 525, an inner quarter wave plate 522, an eyepiece 523, and an objective lens 524, which are sequentially attached from outside to inside. The photosensitive screen 521, the inner polarizer 525, and the inner quarter wave plate 522 are all semi-cylindrical, and the eyepiece 523 and the objective lens 524 are plate-shaped. The light source 530 is arranged on the outside of the outer module 510, that is, on the side of the outer module 510 away from the tube segment.

[0024] In the present application, the light emitted by the light source 530 passes through the external polarizer 511, the external quarter wave plate 512, the tube segment, the objective lens 524, the eyepiece 523, the inner quarter wave plate 522, and the inner analyzer 525 in sequence, and is received by the photosensitive screen 521. In the process of light penetration, plane polarized light is generated by the action of the external polarizer 511, and the plane polarized light is converted into circular polarized light by the external quarter wave plate 512. The tube segment is a force model in the jacking process. The circular polarized light is received by the objective lens 524 after passing through the tube segment and forms a real image. The eyepiece 523 amplifies the real image, and the inner quarter wave plate 522 restores the circular polarized light of the real image to plane polarized light. The plane polarized light generates interference fringes after passing through the inner analyzer 525. The interference fringes are received by the photosensitive screen 521 to realize three-dimensional curved surface imaging. At the same time, the setting of the eyepiece 523 and the objective lens 524 ensures that the light passing through the tube segment is reduced by equal times, and ensures that the photosensitive screen 521 can obtain the complete stress field of the tube segment.

[0025] The outer quarter wave plate 512 is located outside the tube segment, and after receiving the plane polarized light generated by the external polarizer 511, it converts it into circularly polarized light. This conversion can ensure that the circularly polarized light produces a birefringence effect when passing through the tube segment, forming an optical path difference related to the stress distribution. The outer quarter wave plate 512 adopts a semi-cylindrical shape and has a diameter larger than the tube segment, which solves the problem of matching the optical path of the tube segment curved surface and avoids the phase error caused by the incident angle deviation of the edge light. The outer quarter wave plate 512 and the inner quarter wave plate 522 form a closed-loop optical path, which can suppress the interference of ambient light and improve the contrast of interference fringes.

[0026] The coordinated magnification of the eyepiece 523 and the objective lens 524 enables the photosensitive screen 521 to completely receive the stress stripes of the tube segment, thereby improving the spatial resolution.

[0027] The loading assembly 400 is disposed at one end of the pipe segment and applies a loading force thereto, thereby simulating the jacking of the pipe segment.

[0028] The recording system 600 is used to obtain the interference fringes obtained by the photosensitive screen 521 and the magnitude of the loading force applied by the loading component 400.

[0029] Preferably, in the present application, the outer polarizer 511 is formed by bonding a plurality of small polarizers to form a semi-cylindrical shape, and the outer quarter-wave plate 512 is formed by bonding a plurality of small quarter-wave plates to form a semi-cylindrical shape. Similarly, the inner analyzer 525 and the inner quarter-wave plate 522 are formed by bonding the corresponding analyzers and quarter-wave plates.

[0030] The aforementioned tube section is made of a transparent material, and in this embodiment, it is made of epoxy resin material. The light source 530 has white and yellow single colors, which is convenient for switching the light color to form clearer interference fringes.

[0031] Furthermore, in the present application, the side wall of the model box 100 is detachable, and a pipe hole is provided on one side wall of the model box 100. The diameter of the pipe hole is larger than the diameter of the pipe section, so that the axial angle between the first pipe section 200 and the second pipe section 300 can be changed.

[0032] The aforementioned loading assembly 400 includes a reaction frame 410, on which a jack 420 is disposed, and the jack 420 has a telescopic end, and the telescopic end is extended and retracted to realize applying different loading forces to the end of the pipe segment exposed to the model box 100 to simulate jacking. A pressure sensor 421 is also disposed at the telescopic end of the jack 420, and the pressure sensor 421 is located between the telescopic end of the jack 420 and the end of the pipe segment to obtain the loading force of the jack 420.

[0033] The recording system 600 includes a PC terminal 610 and a digital display 620 . The digital display 620 is connected to the pressure sensor 421 by signal and transmits the recorded loading force information to the PC terminal 610 . The PC terminal 610 is also connected to the photosensitive screen 521 by signal.

[0034] Reference Figure 5 The present application also provides a three-dimensional photoelastic testing method for a pipe segment, which is based on the aforementioned three-dimensional photoelastic testing device for a pipe segment and is used to simulate the change of the stress field of the pipe segment during the jacking process, and includes the following steps: S10. Fix the two inner modules 520 in the first pipe section 200 and the second pipe section 300 respectively.

[0035] In this step, two inner modules 520 are fixed in the first pipe section 200 and the second pipe section 300 by using a detachable clamp, and the circumference of the inner module 520 is half of the circumference of the pipe section.

[0036] S20. The first pipe segment 200 and the second pipe segment 300 are respectively inserted into the model box 100 from one side of the model box 100 and abutted against each other, the first pipe segment 200 and the second pipe segment 300 form an axial intersection angle, and transparent soil of a preset temperature is filled into the model box 100. The transparent soil applies different preset loads to the first pipe segment 200 and the second pipe segment 300.

[0037] In this step, the first pipe segment 200 and the second pipe segment 300 having the inner module 520 are respectively inserted into the model box 100 and abutted against each other, and the first pipe segment 200 and the second pipe segment 300 form different axis intersection angles according to the test requirements.

[0038] Preferably, the axis intersection angle ranges from 0 to 10°.

[0039] The transparent soil is heated to a temperature higher than a preset temperature, and the heated transparent soil is filled into the model box 100 while keeping the axis angle unchanged. The transparent soil is buried to different depths of the first pipe section 200 and the second pipe section 300, thereby applying different preset loads to the first pipe section 200 and the second pipe section 300.

[0040] Preferably, during the filling process, the transparent soil can be buried to the entire, half, one third, one quarter, etc. of the pipe section height, thereby simulating different preset loads such as full load, one half load, etc.

[0041] S30. Fix the two outer modules 510 and the light source 530 outside the model box 100 respectively, and ensure that the bending directions of the inner module 520 and the outer module 510 in the same pipe section are opposite.

[0042] In this step, two outer modules 510 are set up outside the model box 100, each outer module 510 is installed corresponding to the inner module 520 in the pipe section, and two light sources 530 are respectively arranged on the outer sides of the two outer modules 510, that is, on the side away from the model box 100. The light emitted by each light source 530 can pass through the outer module 510, the pipe section and the inner module 520 in sequence, and be received by the photosensitive screen 521 of the inner module 520.

[0043] The inner module 520 is bent to the right, and the outer module 510 is bent to the left, forming a spatial pattern in which the inner module 520 and the outer module 510 are bent in opposite directions.

[0044] S40. Turn on the loading assembly 400, apply a loading force to one of the tube segments, and first obtain the interference fringes on the photosensitive screen 521.

[0045] In this step, when the temperature of the transparent soil is reduced to a preset temperature, a loading force is applied to the end of the first pipe section 200 that is not located in the model box 100, and interference fringes captured by the photosensitive screen 521 are obtained for the first time. In this embodiment, the interference fringes obtained by the photosensitive screen 521 for the first time reflect the stress field changes on the right side of the first pipe section 200 and the second pipe section 300.

[0046] S50. Rotate the inner module 520 and the outer module 510 180 degrees inside and outside their respective tube segments, apply the same loading force to the same tube segment, and obtain interference fringes on the photosensitive screen 521 for the second time.

[0047] In this step, the inner module 520 is rotated 180° so that the bending direction of the inner module 520 is to the left, and the outer module 510 and the light source 530 are arranged on the other side of the first pipe section 200 and the second pipe section 300, forming a spatial pattern in which the bending direction of the inner module 520 is to the left and the bending direction of the outer module 510 is to the right. After applying the same loading force to the same pipe section in step S50, the interference fringes obtained by the photosensitive screen 521 reflect the stress field changes on the left side of the first pipe section 200 and the second pipe section 300.

[0048] S60. The interference fringes obtained twice are spliced ​​to obtain complete interference fringes, and the stress field distribution of each pipe segment is analyzed based on the complete interference fringes, loading force, load and temperature.

[0049] In step S40 and step S50, interference fringes on one side of the first pipe section 200 and the second pipe section 300 are obtained respectively, and the interference fringes of the first pipe section 200 and the second pipe section 300 are spliced ​​to obtain complete interference fringes of the first pipe section 200 and the second pipe section 300. Based on the complete interference fringes, the loading force of the loading assembly 400, the load of the transparent soil, and the temperature, the stress field changes of the first pipe section 200 and the second pipe section 300 are analyzed.

[0050] S70. Change at least one of the axis angle, loading force, load and temperature of the transparent soil, and repeat steps S10-S60 to obtain the correspondence between multiple sets of interference fringes and different factors, and analyze the correspondence between the stress field distribution of the first pipe section 200 and the second pipe section 300 and different factors.

[0051] The correspondence between stress field distribution and different factors can be trained using existing data models, such as using a physical neural network algorithm to establish a physical-data dual-driven stress PINN prediction model, thereby obtaining the stress field distribution of the pipe section under different factors.

[0052] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A three-dimensional photoelastic testing device for pipe segments, characterized in that: include: A transparent model box, in which two pipe sections abutting each other end to end are inserted, and the intersection angle of the axes of the two pipe sections is variable; A loading assembly acts on one end of any pipe segment to apply a force; Two optical inspection components, respectively used to obtain interference fringes of two tube segments, the optical inspection components include an outer module, an inner module and a light source, the outer module is used to be arranged outside the two tube segments, the inner module is used to be arranged inside the two tube segments, the light source is arranged on the side of the outer module away from the outside of the tube segment, the outer module includes an outer polarizer and an outer quarter wave plate from the outside to the inside, the outer module is semi-cylindrical, the axial direction of the outer module is parallel to the corresponding tube segment, the inner module includes a photosensitive screen, an inner analyzer, an inner quarter wave plate, an eyepiece and an objective lens from the outside to the inside, and the photosensitive screen, the inner analyzer and the inner quarter wave plate are all semi-cylindrical; The recording system is used to obtain the interference fringes obtained by the photosensitive screen and the magnitude of the force applied by the loading component.

2. The three-dimensional photoelastic testing device for pipe segments according to claim 1, characterized in that: The side wall of the model box is provided with a pipe penetration hole, the diameter of the pipe penetration hole is larger than the diameter of the pipe section, and the pipe sections are respectively inserted through the pipe penetration holes and abutted in the model box.

3. The three-dimensional photoelastic testing device for pipe segments according to claim 1, characterized in that: The loading assembly also includes a reaction frame and a jack. The jack is arranged on the reaction frame. The jack is arranged at one end of the pipe segment exposed outside the model box and acts on the end of the pipe segment. A pressure sensor is arranged between the jack and the abutting pipe segment.

4. The three-dimensional photoelastic testing device for pipe segments according to claim 3, characterized in that: The recording system includes a PC and a digital display, wherein the digital display is used to obtain the loading force of the pressure sensor, and the digital display and the photosensitive screen are respectively connected to the PC signal.

5. The three-dimensional photoelastic testing device for pipe segments according to claim 1, characterized in that: The pipe section and the model box are both made of transparent materials.

6. A three-dimensional photoelastic testing method for a pipe segment, using the three-dimensional photoelastic testing device for a pipe segment according to claim 1, characterized in that: include: S10. Fix the two inner modules in the two pipe sections respectively; S20. Insert two pipe sections from one end of the model box into the model box and abut against each other, the two pipe sections form an axis intersection angle, fill the model box with transparent soil of a preset temperature, and apply different preset loads to the two pipe sections with the transparent soil; S30. The two outer modules and the light source are fixed outside the model box, respectively, and the bending directions of the inner module and the outer module of the same pipe segment are ensured to be opposite; S40. Turn on the loading assembly, apply a loading force to the end of the tube segment exposed outside the model box, and obtain interference fringes on the photosensitive screen for the first time; S50. Rotate the inner module and the outer module 180° inside and outside their respective tube segments, apply the same loading force to the same tube segment in S40, and obtain interference fringes on the photosensitive screen for the second time; S60. The interference fringes obtained twice are spliced ​​to obtain complete interference fringes, and the stress field distribution of the pipe segment is analyzed based on the complete interference fringes, loading force, load and temperature.

7. The three-dimensional photoelastic testing method for pipe segments according to claim 6, characterized in that: The three-dimensional photoelastic testing method for pipe segments also includes step S70, in which at least one of the axis angle, the load, the loading force and the temperature of the transparent soil is changed, and steps S10-S60 are repeated.

8. The three-dimensional photoelastic testing method for pipe segments according to claim 6, characterized in that: The angle range of the axis intersection angle is 0-10°.

9. The three-dimensional photoelastic testing method for pipe segments according to claim 6, characterized in that: Transparent soil is added into the model box, and the transparent soil is buried to different depths of the pipe sections to form different loads.

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