Deep sea environment biaxial loading in-situ test system and method for industrial CT

Abstract

The invention discloses a deep sea environment biaxial loading in-situ test system and method for industrial CT, the test system comprises a biaxial test bench, a deep sea environment box, a rotary table, a simulation seawater loop and an X-ray imaging unit, the deep sea environment box is arranged at the central position of the biaxial test bench, the biaxial test bench is arranged on the rotary table, the rotary table is arranged on the rotary table, and the X-ray imaging unit is arranged on the rotary table. And the X-ray imaging unit directly faces the biaxial test bench. In order to solve the problems that no effective means for simulating the complex stress and corrosion coupling environment of the deep sea environment exists at present, and key data such as chemical products in the corrosion process of marine materials under the complex stress cannot be obtained in situ, the invention provides a coupling biaxial in-situ loading device and a seawater corrosion environment simulation box. Simulation of a deep-sea complex stress state and a seawater corrosion environment is realized, a chemical product evolution rule in a stress corrosion process is obtained in situ based on a spectrum measuring instrument, and a technical foundation is laid for clarification of a corrosion failure mechanism of a material under a real deep-sea service condition.

Description

TECHNICAL FIELD

[0001] The application relates to a deep-sea environment biaxial loading in-situ test system for industrial CT and an application method thereof, and relates to the field of material microscopic characterization analysis. BACKGROUND

[0002] The deep sea refers to a sea area between 200 meters below the sea level and several kilometers on the seabed. The deep-sea high-pressure environment is extremely harsh, and materials resistant to high pressure and corrosion are required for ocean development and seabed exploration, so the research on deep-sea materials has become an important part of modern engineering technology.

[0003] There are two limitations in the existing deep-sea material performance test technology: firstly, the mechanical loading device is mostly designed as a single axis, for example, an in-situ ultrahigh-temperature tensile experimental device based on a computer tomography system disclosed in the prior art can only apply static or low-frequency load in a single direction, and cannot simulate the multi-axial complex stress actually borne by the deep-sea equipment material, such as tensile-shear coupling and biaxial in-plane tensile and compressive load; secondly, the existing device cannot truly simulate the deep-sea seawater environment, for example, a biaxial loading in-situ mechanical test microsystem disclosed in the prior art can only be used in a normal temperature, normal pressure and air environment, and cannot simulate the degradation of materials by deep-sea stress corrosion. The above prior art breaks the coupling of mechanical loading and environment simulation under real service conditions, leading to a significant deviation of experimental data from real conditions, and it is difficult to reveal the damage evolution mechanism of materials under complex deep-sea environment.

[0004] Therefore, it is urgent to develop an in-situ test system integrating multi-axial mechanical loading and multi-environment coupling. SUMMARY

[0005] The application provides a deep-sea environment biaxial loading in-situ test system for industrial CT. Specifically, in view of the problems that there is no effective means to simulate the complex stress and corrosion coupling environment of the deep-sea environment, and it is also impossible to obtain key data such as chemical products in the corrosion process of the marine material under complex stress, the application realizes the simulation of the deep-sea complex stress state and the seawater corrosion environment by coupling the biaxial in-situ loading device and the seawater corrosion environment simulation box, and in-situ obtains the chemical product evolution law in the stress corrosion process based on a Raman spectrum measuring instrument, thereby laying a technical foundation for clarifying the corrosion failure mechanism of materials under real service conditions in the deep sea.

[0006] To achieve the above application purposes, the technical scheme adopted by the application is as follows: A deep-sea environment biaxial loading in-situ test system for industrial CT comprises a biaxial test bed, a deep-sea environment box, a turntable, a simulated seawater loop and an X-ray imaging unit, the deep-sea environment box is arranged at the center position of the biaxial test bed, the biaxial test bed is arranged on the turntable, and the X-ray imaging unit is opposite to the biaxial test bed, The simulated seawater loop is arranged in the deep-sea environmental box, The biaxial test bench is provided with electric servo actuators arranged in quadrature, and the actuating cylinders of the electric servo actuators are inserted into the deep-sea environmental box. The deep-sea environmental box is provided with plexiglass windows around.

[0007] In the application, the actuating cylinders of the biaxial test bench are inserted into the deep-sea environmental box, and the two are connected through a conventional sealing structure; the simulated seawater loop is a pipeline, which is linked with the deep-sea environmental box, and the other end is communicated with an external seawater storage tank, and the dynamic control of the pressure and composition parameters in the environmental box is a conventional technology; the rotary table and the X-ray imaging unit are connected with the control host through a cable, and the control host controls the X-ray emission, detection and rotation of the rotary table; the rotary table and the biaxial test bench are connected through bolt fastening.

[0008] The seawater storage tank, control host and the like mentioned in the application are conventional components, and their positional relationship and experimental method follow common sense, which does not affect the understanding of the technical effects of the application by those skilled in the art.

[0009] The application discloses a method for deep-sea environmental biaxial loading in-situ testing of a sample by using the deep-sea environmental biaxial loading in-situ testing system for industrial CT, and the method comprises the following steps: placing the sample on the chuck at the end of the actuating cylinder of the electric servo actuator in the deep-sea environmental box; then injecting simulated seawater and pressurizing; then starting the electric servo actuator and the X-ray source; the X-ray detection device collects signals and reconstructs three-dimensional images in the computer, thereby realizing deep-sea environmental biaxial loading in-situ testing of the sample.

[0010] In a further technical solution, four electric servo actuators are started to form quadrature load loading.

[0011] In a further technical solution, the deep-sea environmental box is provided with a pressure sensor, a salinity sensor and a temperature sensor.

[0012] In a further technical solution, the rotary table is a magnetic coupling wireless rotary table, which is used for supporting 360° continuous rotation of the biaxial table and avoiding cable winding interference with CT imaging.

[0013] In a further technical solution, the X-ray imaging unit comprises an X-ray emitting device and an X-ray detection device; and the biaxial test bench is located between the X-ray emitting device and the X-ray detection device.

[0014] In a further technical solution, the shell of the deep-sea environmental box is a titanium alloy shell.

[0015] In a further technical solution, the thickness of the plexiglass window is 8-12 mm, and the pressure bearing capacity is 30-45 MPa; for example, the thickness of the plexiglass window is 10 mm, and the pressure bearing capacity is 40 MPa.

[0016] Further technical solutions, the displacement control precision of the electric servo actuator is 0.1 mu m, the biaxial centering error is less than or equal to 0.1 mu m, and the loading frequency is between 0.1 and 5 Hz.

[0017] Further technical solutions, the rotating speed of the rotary table is between 0.1 and 5 degrees per second.

[0018] In the technical solution of the application, the deep-sea environmental box does not leak under pressure conditions, that is, no leakage is detected.

[0019] Further technical solutions, the frame of the biaxial test bed is a carbon fiber frame.

[0020] In the technical solution of the application, the maximum loading force of the electric servo actuator is 20kN, the frequency is 5Hz, the displacement resolution is 0.1 mu m, and the biaxial displacement synchronization and centering error are less than or equal to 0.1 mu m through closed-loop control.

[0021] In the technical solution of the application, the simulated seawater loop dynamically adjusts the seawater pressure range of 0.1-30MPa, the temperature range of 0-20℃, and the pH value range of 3-11.

[0022] In the technical solution of the application, the X-ray unit includes a 160kV micro-focus source with a spatial resolution of less than or equal to 5 mu m, a 450kV high-energy source, a flat panel detector, and a linear array detector, which are corrected by a multi-layer medium optical path algorithm for the attenuation and refraction distortion of organic glass and seawater to X-rays.

[0023] In the technical solution of the application, the multi-layer medium optical path algorithm is a continuous three-dimensional reconstruction algorithm based on FDK back-projection optimization, specifically the Feldkamp-Davis-Kress back-projection algorithm.

[0024] In the technical solution of the application, the end of the electric servo actuator is provided with a corrosion-resistant chuck for clamping the sample to be tested, and the chuck adopts a silicon carbide coating + aluminum alloy substrate composite process; the corrosion-resistant clamp is located at the end of the electric servo actuator in the environmental box and is used to clamp the biaxial sample, which can stably serve in a 0.35% salinity seawater environment for more than 3000 hours.

[0025] Due to the use of the above technical solutions, the application has the following advantages compared with the prior art: 1.The application reduces the X-ray average attenuation rate to 15% of the traditional metal structure by combining the carbon fiber frame with the organic glass window, ensures high signal-to-noise ratio imaging, precise displacement control of the dual-axis servo actuator and cable-free design of the turntable, eliminates mechanical interference and motion artifacts, and improves crack propagation observation accuracy to the 5μm level; the corrosion-resistant chuck adopts a silicon carbide coating and aluminum alloy composite process, and the service life is extended to more than 3 times that of the conventional chuck; the gradient sealing structure of the deep sea environment box has almost zero leakage rate under 30MPa pressure, ensuring long-term experimental stability.

[0026] 2.The application first realizes in-situ correlation analysis of deep-sea multi-axial stress-corrosion-damage evolution, providing an effective tool for deep-sea material design and life prediction.

[0027] 3.During the operation of the system, the sample is placed in the environmental box, the dual-axis loading and CT scanning are performed synchronously, the millisecond-level time alignment of mechanical-damage-imaging data is realized, and the four-dimensional visualization of damage evolution is realized by combining the continuous three-dimensional reconstruction algorithm. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a structural schematic diagram of the deep-sea environmental biaxial loading in-situ test system for industrial CT according to the application; Figure 2 is a structural schematic diagram of the deep-sea environmental biaxial loading in-situ test system for industrial CT according to the application; Figure 3 is a structural schematic diagram of the deep-sea environmental biaxial loading in-situ test system for industrial CT according to the application; Wherein: the biaxial test bench 1, the deep-sea environmental box 2, the turntable 3, the simulated seawater loop 4, the X-ray emitting device 5, the X-ray detecting device 6, the electric servo actuator 11, the frame 12 of the biaxial test bench, the actuator cylinder 13 of the electric servo actuator, the organic glass window 21, the corrosion-resistant chuck 14, the pressure sensor 22, the salinity sensor 23, and the temperature sensor 24. DETAILED DESCRIPTION

[0029] The application provides a deep-sea environmental biaxial loading in-situ test system for industrial CT. Specifically, in view of the problem that there is no effective means to simulate the complex stress and corrosion coupling environment of deep-sea environment, and it is also impossible to obtain key data such as chemical products in the corrosion process of marine materials under complex stress, the application couples a biaxial in-situ loading device and a seawater corrosion environment simulation box to realize deep-sea complex stress state and seawater corrosion environment simulation, and based on a Raman spectrum measuring instrument, the chemical product evolution law in the stress corrosion process is obtained in-situ, which lays a technical foundation for elucidating the corrosion failure mechanism of materials under deep-sea real service conditions.

[0030] The utility model discloses a kind of deep-sea environment biaxial loading in-situ test system for industrial CT, including biaxial test bench, deep-sea environment box, rotary table, simulated seawater loop and X-ray imaging unit, the deep-sea environment box is located in the central position of biaxial test bench, the biaxial test bench is located on rotary table, X-ray imaging unit is opposite biaxial test bench, The simulated seawater loop is arranged in the deep-sea environment box, The biaxial test bench is provided with electric servo actuators arranged orthogonally, and the actuator cylinders of the electric servo actuators are inserted into the deep-sea environment box. The deep-sea environment box is provided with an organic glass window around the shell. The deep-sea environment box adopts a conventional sealing structure, which is a multilayer O-ring + hydraulic self-tightening flange, and the environment box is provided with a warehouse door and other conventional components, which are common sense.

[0031] In the utility model, the actuator cylinders of the biaxial test bench are inserted into the deep-sea environment box, and the two are connected through a conventional sealing structure; the simulated seawater loop is a pipeline connected with the deep-sea environment box, and the other end is communicated with an external seawater storage tank to dynamically control the pressure and composition parameters in the environment box, which is a conventional technology; the rotary table and the X-ray imaging unit are connected with a control host through a cable, and the control host controls the X-ray emission, detection and rotation of the rotary table, which is a conventional technology; the rotary table and the biaxial test bench are connected by bolt fastening.

[0032] In the utility model, the sample is placed on the chuck at the end of the actuator cylinder of the electric servo actuator in the deep-sea environment box; then simulated seawater is injected and pressurized; then the electric servo actuator and the X-ray source are started; the X-ray detection device collects signals and reconstructs three-dimensional images in the computer to realize in-situ testing of the sample under deep-sea biaxial loading.

[0033] The components used in the following description of the utility model with reference to the drawings and examples are existing products, and the specific connection method and use method are conventional technologies.

[0034] In the utility model, the rotary table is a magnetic coupling wireless rotary table, and during in-situ imaging, after one rotation of imaging is completed, loading is continued to the next strain characteristic point for another rotation of imaging; the shell of the deep-sea environment box is a titanium alloy shell; the frame of the biaxial test bench is a carbon fiber frame; the thickness of the organic glass window is 10 mm, and the bearing pressure is 30 MPa; the displacement control accuracy of the electric servo actuator is 0.1 μm, the biaxial centering error is less than or equal to 0.1 μm, and the loading frequency is between 0.1 and 5 Hz; the rotation speed of the rotary table is between 0.1 and 5 ° / s; the leakage rate of the deep-sea environment box under 30 MPa is almost zero, and no detection is made.

[0035] In the technical scheme of the present application, the end of the electric servo actuator is provided with a corrosion-resistant chuck for clamping the sample to be tested. The chuck has a conventional structure and adopts a silicon carbide coating + aluminum alloy base composite process. The specific process is a conventional technology. The corrosion-resistant chuck is located at the end of the electric servo actuator in the environmental chamber and is used for clamping the biaxial sample. It can stably serve in a 0.35% salinity seawater environment for more than 3000 hours. Embodiment one

[0036] Referring to Figure 1 , Figure 2 as shown in the figure: A deep-sea environment biaxial loading in-situ test system for industrial CT includes a biaxial test bench 1, a deep-sea environment chamber 2, a rotary table 3, a simulated seawater circuit 4, and an X-ray imaging unit. The deep-sea environment chamber is located at the center of the biaxial test bench. The biaxial test bench is located on the rotary table. The X-ray imaging unit is opposite to the biaxial test bench. The X-ray imaging unit includes an X-ray emitting device 5 and an X-ray detecting device 6. The biaxial test bench is located between the X-ray emitting device and the X-ray detecting device. The simulated seawater circuit is located on the deep-sea environment chamber and is used for simulating the inlet and outlet of seawater. The biaxial test bench is provided with orthogonally arranged electric servo actuators 11, which are conventionally installed on the frame 12 of the biaxial test bench. The actuator cylinders 13 of the electric servo actuators are inserted into the deep-sea environment chamber. The deep-sea environment chamber is provided with an organic glass window 21 around it. The deep-sea environment chamber adopts a gradient sealing structure. The end of the electric servo actuator is provided with a corrosion-resistant chuck 14 for clamping the sample to be tested. The chuck is mounted on the actuator cylinder and located in the deep-sea environment chamber.

[0037] As common sense, the specific shape of the frame of the biaxial test bench is not limited, as long as it can fix the four electric servo actuators arranged orthogonally.

[0038] As common sense, the simulated seawater circuit is conventionally connected to the simulated seawater storage tank.

[0039] As common sense, the test system further includes a power supply, a control host and other common components. The rotary table and the X-ray imaging unit are connected to the control host through cables. The control host controls the X-ray emission, detection and rotation of the rotary table, which is a conventional technology. Embodiment two

[0040] In this embodiment, one or more of a pressure sensor 22, a salinity sensor 23, and a temperature sensor 24 are provided in the deep-sea environment chamber, as shown in Figure 3 ; the rest refers to embodiment one. Embodiment three

[0041] The deep-sea environment biaxial loading in-situ test system for industrial CT of Example 2 is used, and the deep-sea environment box is provided with a pressure sensor, a salinity sensor and a temperature sensor.

[0042] A carbon fiber composite biaxial cross specimen with a size of 5 mm x 5 mm x 2 mm is selected and installed on a corrosion-resistant chuck in the environment box of the test system, artificial seawater is injected and pressurized to 20 MPa, and the temperature is set to 4 DEG C.

[0043] The biaxial test bench applies an axial alternating load with an amplitude of 8 kN, a frequency of 3 Hz and a force value of 10 kN; a 160 kV microfocus X-ray source is started synchronously, the sample is rotated by steps of 0.5 DEG, and a flat panel detector collects projection data at 40 frames per second. After three-dimensional reconstruction by a conventional method, the propagation path of the internal microcrack (width 3 μm) of the specimen after 1000 cycles is clearly observed, the spatial resolution is 4.6 μm, and the high sensitivity of the system to micro-damage is verified.

[0044] Comparative example Before the deep-sea environment biaxial loading in-situ test system for industrial CT is proposed in the application, the prior art cannot realize in-situ CT characterization during the biaxial loading process in the seawater high-pressure environment, the system for simulating marine environment stress and corrosion coupling test is first proposed in the application, and the spatial resolution is high. Example 4

[0045] The deep-sea environment biaxial loading in-situ test system for industrial CT of Example 2 is used, and the deep-sea environment box is provided with a pressure sensor, a salinity sensor and a temperature sensor.

[0046] A 5 mm x 5 mm x 2 mm TC4 titanium alloy biaxial cross specimen is selected for testing, the pressure of the environment box is adjusted to 15 MPa, and the biaxial loading is set to axial 10 kN static compression and lateral 2 kN dynamic bending (frequency 1 Hz). A 450 kV high-energy X-ray source and a linear array detector are enabled, and the turntable completes 360 DEG scanning in a continuous rotation mode (rotation speed 1 DEG / s), and the single-cycle imaging time is shortened to 6 minutes. Through a conventional large-field reconstruction algorithm, a pore distribution map (field of view covering 80 mm x 80 mm) in the full length of the pipe is obtained, and a hole defect with a diameter of 20 μm at the weld is detected, meeting the rapid detection requirements of engineering large components.

[0047] In view to the problem that there is no effective means to simulate the complex stress and corrosion coupling environment of deep sea environment at present, and the key data such as chemical products in the corrosion process of the material for ocean use under complex stress cannot be obtained in situ, the application realizes the simulation of deep sea complex stress state and seawater corrosion environment by coupling the biaxial in-situ loading device and the seawater corrosion environment simulation box, and based on the spectrum measuring instrument, the chemical product evolution law in the stress corrosion process is obtained in situ, which lays a technical foundation for elucidating the corrosion failure mechanism of the material under the real service working condition of deep sea.

Claims

1. A biaxial loading in-situ testing system for industrial CT in a deep-sea environment, characterized in that: The system includes a biaxial test rig, a deep-sea environment chamber, a turntable, a simulated seawater circuit, and an X-ray imaging unit. The deep-sea environment chamber is located at the center of the biaxial test rig, which is situated on the turntable. The X-ray imaging unit is positioned directly opposite the biaxial test rig. The simulated seawater circuit is located inside a deep-sea environment tank. The biaxial test bench is equipped with orthogonally arranged electric servo actuators, and the actuator cylinders of the electric servo actuators are inserted into the deep-sea environment chamber. The deep-sea environment tank is equipped with plexiglass windows on all four sides.

2. The deep-sea environment biaxial loading in-situ testing system for industrial CT according to claim 1, characterized in that: The deep-sea environment chamber is equipped with a pressure sensor, a salinity sensor, and a temperature sensor.

3. The deep-sea environment biaxial loading in-situ testing system for industrial CT according to claim 1, characterized in that: The turntable is a magnetically coupled wireless turntable; the shell of the deep-sea environment chamber is a titanium alloy shell; and the frame of the biaxial test bench is a carbon fiber frame.

4. The deep-sea environment biaxial loading in-situ testing system for industrial CT according to claim 1, characterized in that: The X-ray imaging unit includes an X-ray emitting device and an X-ray detection device; the biaxial test bench is located between the X-ray emitting device and the X-ray detection device.

5. The deep-sea environment biaxial loading in-situ testing system for industrial CT according to claim 1, characterized in that: The displacement control accuracy of the electric servo actuator is 0.08μm to 0.12μm, the dual-axis alignment error is ≤0.1μm, and the loading frequency is between 0.1 and 5Hz.

6. The deep-sea environment biaxial loading in-situ testing system for industrial CT according to claim 1, characterized in that: The rotational speed of the turntable is between 0.1 and 5° / s.

7. The deep-sea environment biaxial loading in-situ testing system for industrial CT according to claim 1, characterized in that: The end of the actuating cylinder is equipped with a chuck.

8. A method for conducting biaxial loading in-situ testing of samples in a deep-sea environment using the deep-sea environment biaxial loading in-situ testing system for industrial CT as described in claim 1, characterized in that, Includes the following steps: The sample is placed in the clamp at the end of the actuator cylinder of the electric servo actuator, in a deep-sea environment chamber; then simulated seawater is injected and pressurized; the electric servo actuator and X-ray source are then turned on; the X-ray detection device collects signals and reconstructs them into a three-dimensional image in the computer, realizing the in-situ dual-axis loading test of the sample in the deep-sea environment.

9. The method for performing biaxial loading in-situ testing of samples in a deep-sea environment using the deep-sea environment biaxial loading in-situ testing system for industrial CT according to claim 8, characterized in that: Four electric servo actuators are activated to form an orthogonal load.

10. The application of the deep-sea environment biaxial loading in-situ testing system for industrial CT as described in claim 1 in deep-sea environment biaxial loading in-situ testing.

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