Temperature control device and method for optical measurement of tensile specimen profile of marine engineering material

Abstract

The application provides a temperature control device and method for optical measurement of a tensile specimen profile of a marine engineering material, the device comprising: a nitrogen protection cavity, a temperature control system, an illumination module, a tensile loading mechanism and an optical image acquisition system; the nitrogen protection cavity comprises a preheating chamber, a temperature adjusting chamber and a working chamber connected in sequence; the tensile loading mechanism extends into the working chamber through a specimen through hole on the wall of the working chamber, the illumination module is arranged in the working chamber and is distributed around the specimen through hole; the temperature control system is used for adjusting and controlling the temperature environment in the nitrogen protection cavity; during the test of the optical image acquisition system, the nitrogen environment is maintained in the nitrogen protection cavity throughout the process. The application can realize clear and real-time optical capture of the profile of the specimen during the whole tensile process at a minimum temperature of-180 DEG C, provides key test support for obtaining accurate stress-strain constitutive relationship and fracture strength in the stage of low-temperature large plastic deformation, significantly reduces the equipment cost, improves the test efficiency and is suitable for material performance evaluation in extreme environments.

Description

Technical Field

[0001] This invention relates to the field of mechanical property testing technology for metallic materials, and more specifically, to a temperature control device and method for optical measurement of the profile of a tensile specimen of marine engineering materials. Background Technology

[0002] In the study of the low-temperature mechanical properties of metallic materials, especially for extreme service environments such as deep-sea equipment, polar engineering, and liquefied natural gas storage and transportation systems, accurately obtaining the true stress-strain constitutive relationship of materials at low temperatures (e.g., −180℃) is crucial. Among these methods, tensile testing is the fundamental means of evaluating the plastic deformation capacity and fracture behavior of materials, while high-precision, in-situ, dynamic optical measurement of the profile morphology (e.g., minimum cross-sectional radius / diameter) of the large plastic deformation stage (e.g., necking region) is the core prerequisite for inverting the true stress-strain curve.

[0003] Currently, in-situ optical measurements of cryogenic tensile testing primarily rely on vacuum cryogenic chamber systems. High vacuum reduces water vapor partial pressure, suppressing condensation and frost formation. However, this approach has significant drawbacks: First, vacuum systems are expensive and place extremely stringent requirements on chamber sealing, material outgassing rates, and moving parts (such as the dynamic seal of the tensile rod). Second, vacuuming and breaking are time-consuming, significantly reducing testing efficiency. Third, conventional convection cooling / heating methods cannot be used in a vacuum environment, leading to difficulties in light source temperature control. LED backlights are prone to intensity decay and color shift due to low temperatures, and the quartz observation window and sample surface are still susceptible to frost formation due to residual moisture or moisture introduced during operation, causing image blurring, reduced contrast, and even measurement interruption. Furthermore, it is difficult to integrate large field-of-view, multi-angle optical observation windows into the vacuum chamber, limiting the accuracy of contour recognition and the robustness of the algorithm.

[0004] In addition, existing non-vacuum cryogenic optical measurement devices mostly use static cold screens or direct liquid nitrogen cooling, which lack a coordinated control mechanism for humidity and temperature fields. They cannot continuously suppress fogging and frost during long-term heat preservation (tens of minutes to several hours), which is especially prominent when the sample undergoes severe deformation and local heat / mass exchange is triggered.

[0005] Chinese patent CN105955348A discloses an environmental chamber for a universal testing machine, comprising a chamber body and a support frame. The chamber body is fixed to the support frame for easy displacement and height adjustment. A dry nitrogen purging system is composed of a vaporization radiator and a purging pipeline. A cooling and heating control system is composed of two Pt resistance temperature sensors, a temperature controller, a controller, a Dewar flask, and liquid nitrogen pipeline. It proposes two methods to solve the problems of low-temperature frosting and defogging: chamber micro-positive pressure control and dry gas purging. However, it still has shortcomings in optical measurement structure design and temperature control accuracy.

[0006] Therefore, it is evident that a temperature control device and method are needed for optical measurement of the profile of tensile specimens of marine engineering materials to overcome the common technical bottleneck of "optical pathway instability" under low temperature and high humidity conditions. Summary of the Invention

[0007] The purpose of this invention is to provide a temperature control device and method for optical measurement of the profile of tensile specimens of marine engineering materials. It adopts a strategy of micro-positive pressure nitrogen protection combined with gradient temperature control. The device is simple in structure, reliable in operation, cost-controllable, and highly compatible, providing an experimental basis for modeling materials and assessing structural safety in extreme environments.

[0008] To achieve the above objectives, this invention provides a temperature control device and method for optical measurement of the profile of tensile specimens of marine engineering materials. The technical solution of this invention is implemented as follows:

[0009] A temperature control device for optical measurement of the profile of a tensile specimen of marine engineering materials includes: a nitrogen protection chamber, a temperature control system, an illumination module, a tensile loading mechanism, and an optical image acquisition system; the nitrogen protection chamber includes a preheating chamber, a temperature regulating chamber, and a working chamber connected in sequence; the tensile loading mechanism extends into the working chamber through a specimen through-hole on the wall of the working chamber; the illumination module is disposed in the working chamber and distributed around the specimen through-hole; the temperature control system is used to regulate the temperature environment inside the nitrogen protection chamber; during the testing process of the optical image acquisition system, a nitrogen environment is maintained throughout the nitrogen protection chamber.

[0010] Furthermore, the temperature control system includes dual liquid nitrogen pipelines: the first pipeline is a direct cooling liquid nitrogen pipeline, which is connected to the temperature regulating chamber to achieve rapid cooling; the second pipeline is a preheating liquid nitrogen pipeline, which is preheated to the target temperature in the preheating chamber before being introduced into the temperature regulating chamber to achieve nitrogen temperature gradient transition and stable intracavity pressure.

[0011] Furthermore, the preheating chamber includes a multi-stage heating system, each stage of which includes a temperature-controlled electric heating belt, a heat-conducting uniform temperature layer, and a temperature feedback sensor.

[0012] Furthermore, with the opening direction of the working chamber as the front, the lighting module is located near the rear side of the working chamber, including a sealing tube, a light source, and a hot air channel arranged around the sealing tube; the light source is located inside the sealing tube; the hot air channel is connected to an external hot air generator, which continuously blows the outer wall of the sealing tube in a directional manner, so that the surface temperature of the sealing tube is always higher than the dew point temperature inside the cavity.

[0013] Furthermore, the device also includes an observation window, which comprises a window body and an anti-settlement axial flow fan; the anti-settlement axial flow fan is located above the window body and continuously blows air.

[0014] Furthermore, the device also includes a cavity door and an observation window. The cavity door is located at the opening of the working chamber, and a groove is provided on the cavity door. The observation window is located at the bottom of the groove.

[0015] Furthermore, the acquisition head of the optical image acquisition system is disposed within the groove.

[0016] A method for optically measuring the profile of a tensile specimen of marine engineering materials, using the apparatus described above, includes the following steps:

[0017] S1, Installation of the sample and optical image acquisition system;

[0018] S2, temperature environment construction, maintaining a positive pressure nitrogen environment;

[0019] S3, optical measurement and tensile testing are performed simultaneously;

[0020] S4, Post-test processing.

[0021] Furthermore, step S2 includes the following steps:

[0022] S21, continuously supply hot air into the sealed tube containing the packaged light source;

[0023] S22, open the liquid nitrogen input pipeline, the solenoid valve is normally open, and the liquid nitrogen is rapidly cooled through the direct cooling liquid nitrogen pipeline;

[0024] S23, when the temperature of the working chamber deviates from the target temperature less than the set value, switch the control mode: simultaneously open the direct cooling liquid nitrogen pipeline and the preheating liquid nitrogen pipeline, and synchronously control the flow rate of direct cooling and preheating nitrogen.

[0025] Furthermore, in step S4, after the sample breaks, the liquid nitrogen input is turned off, and the working chamber and observation window are dried with hot air.

[0026] Compared with existing technologies, the temperature control device and method for optical measurement of the profile of a marine engineering material tensile specimen, as described in this invention, have the following advantages:

[0027] 1. Excellent environmental stability. Utilizing a low-temperature nitrogen micro-positive pressure mechanism (dual cooling pipelines working in tandem), it completely isolates the system from external humid air, thoroughly eliminating fogging in the cavity and frost formation on the sample / window / light source, ensuring long-term clear and stable optical path, and overcoming the bottleneck of image failure under low temperature and high humidity conditions.

[0028] 2. High temperature control accuracy. At extreme low temperatures of −180℃, the temperature control accuracy reaches ±3℃, meeting the testing requirements for the temperature sensitivity of phase transformation and plastic behavior of metallic materials, and ensuring data reliability.

[0029] 3. High optical compatibility. The backlight source is sealed inside a sealed tube and supplemented with hot air for constant temperature, achieving stable, uniform, and high-contrast light emission at low temperatures. This solves problems such as ultra-low temperature light source failure, color drift, and frosting of the sealed tube, supporting sub-pixel-level contour recognition and real-time diameter / radius extraction.

[0030] 4. Excellent engineering practicality. It abandons high-cost vacuum systems, eliminates the need for ultra-high sealing and complex gas extraction and release processes; its modular structure is divided into three temperature zones, resulting in low manufacturing costs, simple operation, and short testing cycles. Manufacturing costs are significantly reduced, testing efficiency is greatly improved, and it combines scientific research precision with engineering scalability. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the temperature control device for optical measurement of the profile of a marine engineering material tensile specimen as described in Embodiment 1 of the present invention;

[0032] Figure 2 This is a schematic diagram of the position of the built-in light source as described in Embodiment 1 of the present invention;

[0033] Figure 3 This is a profile optical test result of the EH40 steel round bar tensile specimen at -180℃ at a certain moment according to Embodiment 2 of the present invention.

[0034] Figure 4 This is a graph showing the test results of the contour radius of the EH40 steel round bar tensile specimen after diameter reduction at -180℃ according to Embodiment 2 of the present invention at a certain moment.

[0035] Figure 5 This is a plastic stress-strain curve of the EH40 steel round bar tensile specimen at -180℃ described in Example 2 of the present invention.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Liquid nitrogen input pipeline; 2. Direct-cooled liquid nitrogen pipeline; 3. Solenoid valve one; 4. Fan motor; 5. Heating resistor; 6. Temperature regulating chamber; 7. Temperature equalization fan; 8. Chamber; 9. Chamber door; 10. Groove; 11. Heating device; 12. Observation window; 13. Anti-settling fan; 14. Sample through hole; 15. Thermocouple one; 16. Sealing tube; 17. Light source; 18. Hot air blower; 19. Thermocouple two; 20. Preheating chamber; 21. Three-stage heating system; 22. Preheating liquid nitrogen pipeline; 23. Solenoid valve two. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are only some, not all, of the embodiments of this invention. The specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0039] Example 1

[0040] A temperature control device for optical measurement of the profile of a tensile specimen of marine engineering materials includes: a nitrogen-protected chamber, a temperature control system, an illumination module, a tensile loading mechanism, and an optical image acquisition system. The nitrogen-protected chamber comprises three temperature zones connected sequentially: a preheating chamber 20, a temperature regulating chamber 6, and a working chamber 8. These temperature zones are connected by controllable vent valves, and the entire chamber maintains a nitrogen environment throughout the cooling and testing process. The tensile loading mechanism extends into the working chamber 8 through a specimen through-hole 14 on the wall of the working chamber 8. The illumination module is located within the working chamber 8, distributed around the specimen through-hole 14. The temperature control system regulates the temperature environment within the nitrogen-protected chamber. Preferably, a slightly positive nitrogen pressure of 0.1~0.5 kPa is maintained to completely isolate the entry of external humid air, thoroughly preventing condensation and frost formation on the inner wall of the chamber, the specimen surface, the observation window 12, and the outer wall of the sealing tube 16, ensuring a consistently clear and stable optical measurement path.

[0041] The temperature control system includes dual liquid nitrogen pipelines: the first is a direct-cooling liquid nitrogen pipeline 2, which is connected to the bottom of the conditioning chamber 6 via solenoid valve 3 for rapid cooling. Solenoid valve 3 controls the amount of liquid nitrogen entering the conditioning chamber 6. The second is a preheating liquid nitrogen pipeline 22, which is connected to the preheating chamber 20 via solenoid valve 23. Solenoid valve 23 controls the amount of liquid nitrogen entering the preheating chamber 20. After the nitrogen is preheated to the target temperature (e.g., 0±5℃) in the preheating chamber 20, it is then introduced into the conditioning chamber 6, achieving a nitrogen temperature gradient transition and stable internal pressure. The preheating chamber 20 includes a three-stage heating system 21, each stage of which includes a temperature-controlled electric heating belt, a thermally conductive heat spreader, and a temperature feedback sensor. The temperature-controlled electric heating belt is preferably a heating film made of nickel alloy and PTFE insulation; the thermally conductive heat spreader is preferably an aluminum plate; and the temperature feedback sensor is preferably a thermocouple 19.

[0042] The temperature control chamber 6 includes a temperature equalization fan 7 and a heating resistance wire 5. The fan motor 4 drives the temperature equalization fan 7 to force convection of gas within the nitrogen-protected chamber, significantly improving the uniformity of temperature distribution and dynamic stability, and ensuring the isothermal nature of the sample and its surrounding environment during optical measurements. The heating resistance wire 5 is activated after each test to dry the working chamber 8 with hot air, raising the temperature of the inner wall and the surface of the observation window 12, effectively suppressing condensation and frost caused by the cooling of external humid air when the door is opened for sample changes, and maintaining the clarity of the optical path.

[0043] The working chamber 8 houses the specimen and the tensile mechanism, and has a specimen through-hole 14. An illumination module is located at the rear of the working chamber 8. The specimen through-hole 14 is situated in the middle region of the upper and lower walls of the working chamber 8. Light sources 17 are distributed around the specimen through-hole 14, forming a multi-angle illumination structure. A cavity door 9 is located at the opening of the working chamber 8.

[0044] The lighting module includes a sealed tube 16, a light source 17, and a hot air channel surrounding the sealed tube 16. The hot air channel is connected to an external 50±2℃ constant temperature hot air generator, which continuously and directionally blows on the outer wall of the sealed tube 16, ensuring that the surface temperature of the sealed tube 16 is always above the dew point temperature inside the cavity. Preferably, the sealed tube 16 is made of quartz glass, and the light source 17 is a backlight source.

[0045] like Figure 1 As shown, two sets of light sources 17 are installed in the chamber 8. The light sources 17 use arrayed LED beads and are covered with a light-diffusing plate to ensure uniform backlighting. The light sources 17 are located inside a sealed tube 16, the bottom of which is connected to a hot air blower 18. During the test, the light sources 17 inside the sealed tube 16 are always kept in hot air at approximately 50°C to ensure stable operation and prevent fogging or frost formation on the surface of the sealed tube 16. A second thermocouple 15 is installed in the chamber 8 to monitor the temperature and provide feedback to the temperature control system. Sample through-holes 14 are provided on the upper and lower walls of the chamber 8 for sample installation. The arrayed LED beads are broadband white LEDs with a light-emitting surface uniformity ≥95%, an adjustable light intensity range of 100~5000 cd / m², and a light decay rate ≤3% / 100h across the entire temperature range of −180°C to 25°C.

[0046] like Figure 2 As shown, the two sets of light sources 17 are distributed at a 90° angle around the through hole 14 of the sample, forming a preferred multi-angle lighting structure.

[0047] The device also includes an observation window 12, located at the front of the working chamber 8, for external observation of the internal state of the working chamber 8. The observation window 12 includes: a window body, a heating device 11, a thermal insulation layer, and an anti-settling fan 13. Preferably, the window body is made of multi-layer composite high-transmittance optical glass; the heating device 11 uses an embedded transparent conductive film to heat the glass and prevent frost from forming on the observation window 12 during testing; the thermal insulation layer is located at the edge of the window body; the anti-settling fan 13 is located above the window body, and continuously blows upwards to prevent the cold air escaping from the upper sample through-hole 14 from settling downwards due to its high density, thus affecting optical measurements. The heating device 11 has an adjustable operating temperature from −20℃ to +40℃, and the anti-settling fan 13 blows air parallel to the inner surface of the window body at a speed of 0.3~1.0 m / s to prevent condensed water vapor from settling and adhering.

[0048] The device also includes a cavity door 9, located at the opening of the working chamber 8. A groove 10 is provided on the cavity door 9, and an observation window 12 is provided at the bottom of the groove 10. In some embodiments, the observation window 12 is provided on the cavity door 9. The groove 10 has a depth of ≥20mm, and an optical lens mounting flange and an optical path calibration reference target are embedded in the groove to achieve in-situ lens mounting without disassembly and sub-pixel-level optical axis alignment.

[0049] To meet the optical requirements for synchronous measurement of the sample profile from both sides at 90°, and to ensure that the lateral dimension of the optical system (i.e., the distance between the two lenses) is proportional to the test focal length, the sample through-hole 14 is positioned adjacent to the cavity door 9. The farther the sample is from the optical image acquisition system, the larger the required lens distance, which in turn necessitates a wider lateral width for the observation window 12. However, limited by the physical spacing between the columns of the tensile testing machine, the minimum required thickness of the insulation layer, and the stringent requirements for temperature uniformity within the working chamber 8, the lateral width of the observation window 12 must be minimized. Therefore, this invention positions the sample through-hole 14 close to the cavity door 9 and employs a concave structural design on the cavity door 9, i.e., a groove 10, to embed the acquisition head of the optical image acquisition system. This significantly shortens the optical path distance, reduces the lens distance and the width of the observation window 12, and avoids interference with the insulation structure and temperature field uniformity, achieving a balance between compact layout and high-precision measurement.

[0050] The tensile loading mechanism uses a metal frame, with the loading axis perpendicular to the optical measurement axis and intersecting at the center of the sample. Both the loading head and the sample clamping end are equipped with low-temperature lubricated ceramic bearings and flexible heat insulation compensation sections to ensure a displacement accuracy of better than ±1μm at −180℃.

[0051] The optical image acquisition system includes a telecentric lens, a high-resolution industrial camera, a ring-shaped LED front illumination unit, and a real-time image processing terminal; the camera and lens undergo vacuum coating and low-temperature adaptation treatment.

[0052] Example 2

[0053] A method for optically measuring the profile of a tensile specimen of marine engineering materials, using the apparatus described in Example 1, includes the following steps:

[0054] S1, Installation of the sample and optical image acquisition system.

[0055] S11, the machined round bar-shaped tensile specimen is inserted into the working chamber 8 through the specimen through hole 14, and the center of the parallel section of the specimen is aligned with the height of the observation window 12. Specifically, the specimen is EH40 steel, with a parallel section diameter of 10mm and a length of 60mm, and the clamping end has M16 coarse threads.

[0056] S12, embed the optical image acquisition system into the groove 10 on the cavity door 9. Ensure that the optical axes of the two probes are at a 90° angle and are aligned with both sides of the parallel section of the sample, so as to achieve synchronous imaging of dual views in a 90° direction.

[0057] The sample through-hole 14 is close to the cavity door 9 and adopts a concave optical system layout, which significantly shortens the test focal length, reduces the lens spacing and the horizontal width of the observation window 12, and ensures compact integration of the optical system and high-resolution imaging while meeting the constraints of column spacing, insulation layer thickness requirements and temperature uniformity of the working chamber 8.

[0058] S2, temperature environment construction, maintaining a positive pressure nitrogen environment.

[0059] S21, start the hot air blower 18 and continuously introduce constant temperature hot air of about 50°C into the quartz sealing tube 16 of the encapsulated light source 17, so that the light source 17 maintains a stable luminous intensity at low temperature and prevents frost from forming on the surface of the sealing tube 16.

[0060] S22, open the liquid nitrogen input pipeline 1, solenoid valve 3 is normally open, and achieve rapid cooling through the direct cooling liquid nitrogen pipeline 2; at the same time, start the temperature equalization fan 7 to promote airflow circulation in the temperature equalization chamber 6 and accelerate the uniform temperature drop of the working chamber 8.

[0061] S23, when the temperature measured by thermocouple 15 in chamber 8 deviates from the target temperature (e.g., −180℃) by ≤10℃, switch the control mode: open the dual liquid nitrogen pipeline, and simultaneously control the flow rate of direct cooling and preheating nitrogen. Solenoid valve 3 switches to intermittent opening and closing for precise temperature control; solenoid valve 23 is normally open, and the three-stage heating system 21 in preheating chamber 20 is started to perform gradient preheating of the nitrogen flowing through preheating liquid nitrogen pipeline 22, so that the temperature of the nitrogen entering the conditioning chamber 6 is close to the set value.

[0062] S24 continuously introduces temperature-controlled low-temperature nitrogen gas to establish and maintain a micro-positive pressure environment of ≥50Pa within chamber 8. The micro-positive pressure nitrogen gas flow completely isolates the intrusion of external humid air, thoroughly eliminating fogging in the chamber.

[0063] The hot air protection light source 17 works in conjunction with preheated nitrogen to ensure that the optical system can operate stably, frost-free, and with high contrast for a long time at extreme low temperatures, providing a reliable environmental basis for capturing clear contours.

[0064] S3, optical measurement and tensile testing are performed simultaneously.

[0065] S31. After the temperature of the chamber 8 stabilizes at the target value and is maintained at that temperature for the set time (e.g., 10 minutes), turn on the preheated and stabilized lighting module and dual-view optical image acquisition system. Start the temperature equalization fan 7, heating device 11, and anti-settlement fan 13 as needed. The start and stop of the temperature equalization fan 7 and heating device 11 are controlled by a closed-loop humidity sensor inside the chamber: when the relative humidity is detected to be greater than the rated threshold (e.g., >10%RH), the hot air temperature is automatically increased (e.g., 5℃) and the fan speed is increased (e.g., 10%); when the humidity is less than the rated threshold (e.g., <5%RH), the chamber enters an energy-saving steady-state mode.

[0066] S32, synchronously activate the tensile loading mechanism to apply a uniaxial tensile load to the specimen until it fractures, continuously acquiring specimen contour images in two orthogonal directions throughout the process, with a frame rate ≥30fps. Figure 3 As shown.

[0067] S33, based on image recognition algorithms, extracts the contour radius (or diameter) data of the parallel segment of the sample at each moment in real time, such as... Figure 4 As shown, the true stress and strain at each moment are calculated by combining the synchronously recorded load-displacement curves. The image acquisition trigger and the tensile displacement signal are timestamped through a hardware synchronization interface to ensure strict correspondence between deformation and image data.

[0068] In a stable, low-temperature environment with no fog, no frost, and uniform illumination, real-time optical capture and millisecond-level dynamic analysis of the entire necking process of a sample under extreme low temperatures were achieved, obtaining high-precision stress-strain constitutive relations for the entire plastic stage (including necking evolution), such as... Figure 5 As shown, this method overcomes the bottleneck of data loss in the low-temperature large deformation stage of traditional methods.

[0069] S4, Post-test processing and sample change preparation.

[0070] S41, after the sample breaks, the liquid nitrogen input is shut off, the power of the three-stage heating system 21 is increased, and the airflow of the hot air blower 18 is increased to dry the working chamber 8 and the optical window 12 with hot air. Active hot air drying effectively prevents water vapor from condensing and frosting on the surface of the low-temperature components when the door is opened, ensuring the cleanliness and transparency of the optical window and the reliability of repeated use of the equipment, and significantly improving the efficiency of multiple batches of low-temperature testing.

[0071] S42. When the temperature rises to above -30°C and the humidity inside the chamber drops below the dew point, open the chamber door 9, replace the sample with a new one, and then repeat the above steps for the next round of testing.

[0072] It should be noted that all terms used in this invention to indicate direction and position, such as "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "inner", "outer", "top", "lower", "tail end", "head end", "center", etc., are only used to explain the relative positional relationship and connection between components in a specific state. They are only for the convenience of describing this invention and do not require that this invention must be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0073] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0074] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A temperature control device for optical measurement of the profile of a tensile specimen of marine engineering materials, characterized in that, include: The nitrogen protection chamber includes a temperature control system, an illumination module, a tensile loading mechanism, and an optical image acquisition system. The nitrogen protection chamber comprises a preheating chamber (20), a temperature regulating chamber (6), and a working chamber (8) connected in sequence. The tensile loading mechanism extends into the working chamber (8) through a sample through-hole (14) on the wall of the working chamber (8). The illumination module is located in the working chamber (8) and distributed around the sample through-hole (14). The temperature control system is used to regulate the temperature environment inside the nitrogen protection chamber.

2. The apparatus according to claim 1, characterized in that, The temperature control system includes a dual liquid nitrogen pipeline: the first pipeline is a direct cooling liquid nitrogen pipeline (2), which is connected to the temperature regulating chamber (6); the second pipeline is a preheating liquid nitrogen pipeline (22), which is preheated to the target temperature through the preheating chamber (20) and then connected to the temperature regulating chamber (6).

3. The apparatus according to claim 1, characterized in that, The preheating chamber (20) includes a multi-stage heating system, each stage of which includes a temperature-controlled electric heating belt, a heat-conducting uniform temperature layer, and a temperature feedback sensor.

4. The apparatus according to claim 1, characterized in that, With the opening direction of the working chamber (8) as the front, the lighting module is located near the rear side of the working chamber (8), including a sealing tube (16), a light source (17) and a hot air channel arranged around the sealing tube (16); the light source (17) is located inside the sealing tube (16); the hot air channel is connected to an external hot air generator to continuously blow the outer wall of the sealing tube (16) in a directional manner.

5. The apparatus according to claim 1, characterized in that, The device also includes an observation window (12), which includes a window body and an anti-settlement axial flow fan; the anti-settlement axial flow fan is located above the window body and blows air continuously.

6. The apparatus according to claim 1, characterized in that, The device also includes a cavity door (9) and an observation window (12). The cavity door (9) is located at the opening of the working chamber (8). A groove (10) is provided on the cavity door (9), and the observation window (12) is located at the bottom of the groove (10).

7. The apparatus according to claim 6, characterized in that, The acquisition head of the optical image acquisition system is located in the groove (10).

8. A method for optical measurement of the profile of a tensile specimen of marine engineering materials, characterized in that, The measurement using the apparatus described in any one of claims 1 to 7 includes the following steps: S1, Installation of the sample and optical image acquisition system; S2, temperature environment construction, maintaining a positive pressure nitrogen environment; S3, optical measurement and tensile testing are performed simultaneously; S4, Post-test processing.

9. The method according to claim 8, characterized in that, Step S2 includes the following steps: S21, hot air is continuously introduced into the sealing tube (16) of the packaged light source (17); S22, open the liquid nitrogen input pipeline (1), solenoid valve 1 (3) is normally open, and the liquid nitrogen is cooled down quickly through the direct cooling liquid nitrogen pipeline (2); S23, when the temperature of the working chamber (8) deviates from the target temperature less than the set value, switch the control mode: simultaneously open the direct cooling liquid nitrogen pipeline (2) and the preheating liquid nitrogen pipeline (22), and synchronously control the flow rate of direct cooling and preheating nitrogen.

10. The method according to claim 8, characterized in that, In step S4, after the sample breaks, the liquid nitrogen input is turned off, and the working chamber (8) and observation window (12) are dried with hot air.

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