Micro-macro dynamic synchronous observation method for mechanical behaviors of ice sample

Abstract

The invention relates to a microscopic and macroscopic dynamic synchronous observation method for mechanical behaviors of an ice sample. Measurement equipment adopted by the method comprises a load measurement system, a displacement measurement system and a microscopic imaging system, comprising the following steps: (1) preparing an ice sample; (2) placing a microscopic imaging system and carrying out microscopic capturing; (3) macroscopic data processing: for a Brazilian disk tensile test, recording an external load borne by the ice sample in real time through a load measurement system; a force-time change curve is generated; for a uniaxial compression test, the load measurement system and the displacement measurement system work synchronously to generate a stress-strain curve; and (4) microscomic data analysis.

Description

Technical Field

[0001] The invention belongs to the technical field of experimental testing and relates to a fine-macro dynamic synchronous observation method of the mechanical behavior of an ice sample. Background Art

[0002] Naturally formed sea ice is a complex polycrystalline material. Under natural growth conditions, sea ice has a specific crystal shape and arrangement structure. In addition, due to the mixing of air and salt water during the phase change process, defects between crystals are formed in the sea ice. These characteristics give natural sea ice unique physical and mechanical properties. The academic community usually studies the mesostructure of ice by cutting the ice sample into thin slices (usually less than 1 mm thick) and placing it under cross-polarized light for ice crystal development. This method can only study the macroscopic indicators of crystals, such as the average grain size and the number of grains, on the macroscopic mechanical behavior of ice samples. In further research, some scholars used digital image correlation technology (DIC) to conduct experiments on polycrystalline ice to characterize the development process of intra-grain scale strain inhomogeneity during transient creep deformation. The main approach is to analyze the mesostructure of the ice sample slices before the test and spray some specific coatings on the surface of the ice sample to form speckles. During the test, the strain field obtained by DIC technology is superimposed with the mesostructure of the ice sample before the test to study the influence of the mesostructure on strain inhomogeneity. The DIC technique can provide the displacement and strain distribution of the entire surface of the ice sample, which can reveal the complex deformation behavior of the ice sample during the stress process. However, since the DIC technique relies on the speckle pattern on the sample surface, the smooth surface of ice prevents most conventional materials (paint, ink, etc.) used to make speckle patterns from adhering to the ice surface. Therefore, the sample surface must be specifically treated and speckles must be made with special materials, which may affect the formation of speckles and the accuracy of observation. Secondly, when the DIC technique is applied to ice materials, it relies on the assumption that the microstructure of the ice sample does not change before and after the test. However, the actual ice crystals will undergo crystal deformation, slip between grain boundaries, dynamic recrystallization and other microscopic behaviors under mechanical loading conditions, which cannot be observed by the DIC technique. In addition, the DIC technique is mainly used to observe the surface deformation of the sample. After the speckle layer is formed on the surface, it will be difficult to capture the impact of defects inside the ice sample on the mechanical behavior.

[0003] At present, the following two methods are mainly used to study the influence of defects in ice on the mechanical behavior of ice: X-ray computed tomography (CT scanning) and acoustic imaging. The CT scanning method mainly relies on the multi-angle scanning of ice samples by CT scanners to generate a series of cross-sectional images, which are reconstructed into three-dimensional images by computers to show the internal structure of the ice sample, including the distribution and morphology of pores. However, the scanning and image reconstruction process may take a long time, and the temperature of the ice sample needs to be kept constant during this time to avoid structural changes caused by melting or recrystallization, which will affect the results of mechanical tests. The acoustic imaging method mainly sends ultrasonic pulses to the ice sample through a transmitter, and the receiver records the sound wave signals reflected or penetrated by the ice sample. The speed, attenuation and reflection characteristics of sound wave propagation are used to evaluate the location and size of the pores inside the ice sample. However, the sound wave signal is easily interfered by noise, and ice will inevitably produce sound when it breaks, so data processing and interpretation require high specialization.

[0004] Although the above methods can reveal the influence of mesostructure on macroscopic mechanical properties to a certain extent, they cannot fully reflect the deformation dynamics of crystal structure and internal defects in the crystal during the test. Therefore, the present invention proposes a new synchronous observation technology, which combines polarized light imaging and laser transmission technology to dynamically and synchronously measure the mesostructure and macroscopic mechanical behavior of ice samples during mechanical tests. This technology can not only monitor the temporal evolution of the mesostructure of ice samples in real time, but also deeply explore the relationship between mesomechanisms and macroscopic properties, thereby providing a more comprehensive understanding of the mechanical properties of sea ice materials. Summary of the invention

[0005] The purpose of the present invention is to provide a method for dynamically and synchronously observing the macroscopic behavior between macroscopic indicators such as macroscopic loading force (stress), loading displacement (strain) and loading speed (strain rate) of ice samples and ice crystal texture and pore defects during the mechanical test of sea ice. To achieve this purpose, the present invention proposes a method for dynamically and synchronously observing the mechanical behavior of ice samples in microscopic and macroscopic ways, and the technical scheme is as follows:

[0006] A method for synchronous micro-macroscopic dynamic observation of the mechanical behavior of an ice sample, wherein the measuring equipment used comprises a load measuring system, a displacement measuring system and a microscopic imaging system; the load measuring system comprises a load sensor for measuring the external load on the ice sample during the test; the displacement measuring system comprises a displacement sensor arranged on a pressure plate on a testing machine for measuring the displacement of the upper surface of the ice sample during the test; the microscopic imaging system comprises a camera, a background light source with adjustable brightness, a polarizing plate and a laser line light source for displaying the microscopic structural information of the ice sample on the recording device; the method comprises the following steps:

[0007] (1) Preparation of ice samples;

[0008] (2) Placement of microscopic imaging system and microscopic capture

[0009] A background light source with infinite dimming is set up at a position highly parallel to the test area behind the test machine, and the distance between the background light source and the test area is not more than 30 cm; the prepared ice sample is placed on the test machine so that the plane where it is located is perpendicular to the light emitted by the background light source; a polarizer a is placed between the background light source and the ice sample, and a polarizer b is placed on the other side of the ice sample, and the planes where the two polarizers are located are parallel to each other; the polarization direction of the polarizer b is adjusted so that it is perpendicular to the polarization direction of the polarizer a; a camera is placed in front of the polarizer b;

[0010] A laser line light source is placed on one side of the ice sample, and the angle of the laser line light source is adjusted so that the "I"-shaped light beam it emits is parallel to the side edge of the ice sample; and the laser line light source is incident at a position half the thickness of the ice sample; during each test, either the background light source is used alone, or the laser line light source is used alone, or both light sources are used simultaneously;

[0011] (3) Macro data processing: For the Brazilian plate tensile test, the load measurement system records the external load on the ice sample in real time and generates a "force-time" curve; for the uniaxial compression test, the load measurement system and the displacement measurement system work synchronously to generate a stress-strain curve;

[0012] (4) Micro-data analysis

[0013] Synchronous image sequence export: The images captured by the camera during the test are exported as image sequences at the same frame rate as the test loading data collected by the load measurement system and displacement measurement system, ensuring that each frame of the image is synchronized with the test loading data;

[0014] Select analysis moments: According to the changes in macroscopic mechanical data, including the "force-time" curve or the "stress-strain" curve, select key moments for analysis; key moments include load peaks and stress mutation points;

[0015] Comprehensive analysis of meso data.

[0016] Furthermore, the laser line light source is a green laser.

[0017] Furthermore, the method for preparing the ice sample is as follows: prepare an ice sample with a thickness not exceeding 15 mm in order to obtain a better crystal texture and pore defect development effect; for the uniaxial compression test, cut it into a rectangular sample not exceeding 100 mm × 100 mm, and grind all the cut surfaces to keep them smooth and flat, and the two opposite surfaces are strictly parallel, and the adjacent two surfaces are strictly perpendicular; for the Brazilian disk test, cut a disk-shaped sample from the cylindrical ice core sample, grind it until the circular plane is smooth and parallel, and the thickness is reduced to less than 10 mm.

[0018] Further, the method of macro data processing is as follows:

[0019] In the Brazilian plate tensile test, the external load on the ice sample is recorded in real time through the load measurement system; during the test, the load sensor will record the force of the ice sample at different time points during the loading process and generate a "force-time" change curve;

[0020] In the uniaxial compression test, the load measurement system and the displacement measurement system work synchronously to record the external load of the ice sample and the compression displacement of the upper pressure plate in real time; and generate a stress-strain curve to analyze the mechanical characteristics of the stress peak and the fracture point.

[0021] Furthermore, the method for comprehensive analysis of mesoscopic data is as follows: through polarized light imaging technology, the mesoscopic information of crystal particle size and grain boundary characteristics of the ice sample can be obtained; and the addition of laser transmission technology allows the observation results to further observe the characteristics of the bubble distribution inside the ice sample and the brine discharge channel on the basis of crystal characteristics; through comparative analysis of the previous and next frame images, the nucleation position, expansion path and development speed of the crack are accurately observed; through observation of the crack propagation process, the role of grains, grain boundaries and bubble structures in crack generation and expansion is understood; combined with image data, the displacement changes and strain distribution of local areas of the ice sample are analyzed; the local deformation information of the focus area is used to explain the influence of different structural characteristics including grains and pores on local mechanical behavior.

[0022] As a method for synchronously observing the mechanical behavior of ice samples in micro- and macro-dynamics, the present invention has the following advantages:

[0023] 1. Synchronous data acquisition: This method ensures the precise correspondence between macroscopic mechanical behavior and microscopic structural changes by synchronously recording load data and high-definition images. This synchronous observation can provide more accurate data support for analyzing the mechanical properties and failure process of ice.

[0024] 2. Detailed texture analysis: Using polarized light transmission technology, this method can carefully observe the structural characteristics of ice crystals, such as crystal size, grain boundary characteristics, etc. Using laser transmission technology, this method can intuitively display the distribution of bubbles in the ice sample, the characteristics of the brine discharge channel, etc. This detailed structural analysis helps to deeply understand the impact of the internal structure of ice on its macroscopic mechanical behavior.

[0025] 3. Visual observation of crack behavior: Through polarized light and laser transmission technology and continuous capture by high-definition cameras, this method can visually observe the initiation and expansion process of cracks and their relationship with the microstructure, providing an important perspective on the failure mechanism of ice samples. This is of great significance for observing the crack nucleation mechanism and expansion mode of ice.

[0026] 4. Improved experimental design: By manually selecting key moments for detailed analysis, this method allows researchers to adjust the observation focus according to the purpose and needs of the experiment, thereby exploring the mechanics and failure behavior of ice more flexibly. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the arrangement of each device during the test.

[0028] Figure 2 This is a diagram showing the effects of the Brazilian disk sample under polarized light development, laser transmission, and the two placed together.

[0029] Figure 3 This is the macroscopic loading force-time curve during the Brazilian disk tensile test.

[0030] Figure 4 This is a photo of the test scene captured during the Brazilian plate tensile test.

[0031] Figure 5 is the macroscopic stress-strain curve of the thin section uniaxial compression test.

[0032] Figure 6 This is a photo of the test scene during the thin slice uniaxial compression test.

[0033] Figure 7 This is a photo of the test scene during the uniaxial compression test of a thicker ice sample.

[0034] In the figure: 1. Stepless dimming backlight; 2. Polarizer a; 3. Upper pressure plate of loading device; 4. Lower pressure plate of loading device; 5. "I"-shaped laser transmitter; 6. Ice sample; 7. Polarizer b; 8. High-definition camera. DETAILED DESCRIPTION

[0035] The present invention is described in detail below with reference to examples.

[0036] The measuring equipment used in this method includes a load measurement system and a displacement measurement system. The load measurement system includes a load sensor for measuring the external load on the ice sample during the test. The displacement measurement system includes a displacement sensor distributed on the pressure plate of the testing machine for measuring the displacement of the upper surface of the ice sample during the test. The specific implementation steps are as follows:

[0037] 1. Preparation of Ice Samples

[0038] Prepare thin ice slice samples (thickness no more than 15 mm) to obtain better visualization of crystal texture and pore defects. For uniaxial compression tests, first use a cutter to cut an ice sample about 15 mm thick from a larger ice block, and then cut it into rectangular samples no larger than 100 mm × 100 mm. All cut surfaces are polished with sandpaper or a planer to keep them smooth and flat, and the two opposite surfaces are strictly parallel and the adjacent surfaces are strictly perpendicular. For the Brazilian disk test, a disc-shaped sample about 15 mm thick is cut from a cylindrical ice core sample and polished with sandpaper or a planer until the circular plane is smooth and parallel, and the thickness is reduced to less than 10 mm.

[0039] 2. Placement of the imaging device and microscopic capture

[0040] At the rear of the test machine, set up a background light source with infinite dimming at a position parallel to the height of the test area. The distance between the light source and the test area should not be greater than 30cm. Place the prepared ice sample on the test machine so that its plane is perpendicular to the light emitted by the light source. Then place a polarizer a between the light source and the ice sample, and place a polarizer b on the other side of the ice sample, and make the planes of the two polarized lights parallel to each other. Next, adjust the polarization direction of the polarizer b so that it is perpendicular to the polarization direction of the polarizer a, so as to ensure that the light passing through the polarized light a can hardly pass through the polarizer b after passing through the ice sample. Then place a high-definition camera in front of the polarizer b to capture the interaction between crystals during the loading process. At the same time, place a laser (green line light source) on one side of the ice sample, and adjust the angle of the laser so that the "I" shape emitted by the laser is parallel to the side edge of the ice sample, and the laser should be incident at exactly half the thickness of the ice sample. The specific arrangement is as follows: Figure 1 As shown. The above operations are all carried out in a low-temperature darkroom. After placing the above-mentioned developing device, adjust the brightness of the electrodeless light source until the ice sample has a good developing effect in the high-definition camera, and the developing device is placed. Note that during each test, the polarized light developing device and the laser transmission device can be used separately to explore the interaction between crystals and the pore mechanical behavior respectively.

[0041] 3. Macro data processing

[0042] 3.1 Brazilian plate tensile test

[0043] In the Brazilian disk tensile test, in order to simplify the stress state of the disk during loading into a quasi-two-dimensional problem, the diameter of the specimen is usually required to be much larger than its thickness. The tensile stress in the test can be calculated using the following formula:

[0044]

[0045] Among them, F t is the loading force during the Brazilian plate tensile test, D t is the diameter of the Brazilian plate, L t This is the thickness of the Brazilian plate.

[0046] 3.2 Uniaxial compression test

[0047] When conducting uniaxial compression tests, the testing machine adopts a constant speed (v constant) loading mode, and the macroscopic total strain is obtained through theoretical calculation:

[0048]

[0049] Among them, H c is the initial height of the sea ice sample, and H(t) is the corresponding sample height at time t.

[0050] The strain rate is calculated as follows:

[0051]

[0052] Where Δt is the time interval.

[0053] Calculation of the nominal compressive stress σ during the uniaxial compression test based on the loading force c =F c / A c , where F c is the loading force in uniaxial compression test, A c is the contact area.

[0054] 4. Mesoscopic Data Analysis

[0055] After completing the test, a key step of the present invention is to process and analyze the microscopic test data to reveal the mechanical behavior and structural changes of the ice sample. This process includes the following technical steps:

[0056] Synchronous export of images and data: First, the test video captured by the HD camera will be exported as a picture sequence at the same frame rate as the data recorded by the force sensor, ensuring complete synchronization of the image data with the mechanical data.

[0057] Selection and analysis of key moments: According to the macroscopic force-time curve or stress-strain curve, several moments that need to be focused on are manually selected. These moments usually correspond to key mechanical events in the test, such as load peaks or mutation points.

[0058] Analysis of crystal interactions and pore effects: Analyze the images before and after the selected time to observe and record how the interactions between crystals and bubble pores and brine drainage channels affect the mechanical behavior of ice samples. This analysis relies on polarized light and laser transmission development photos, from which detailed information including crystal size, total number of crystals, grain boundary characteristics, bubble distribution, brine channel characteristics can be obtained. Based on the pictures of the previous and next frames, the displacement and local strain of the focus area can also be analyzed.

[0059] Observation of crack behavior: Images obtained through polarized light and laser transmission technology can further observe and analyze the crack nucleation location and its propagation path.

[0060] The test process is further described below in conjunction with the embodiments.

[0061] Example 1: Brazilian plate tensile test scenario

[0062] 1. Use a slicer to cut out a 15mm thick ice disc sample from the sea ice core. Then use sandpaper to grind the cut surface of the ice disc sample to make it smooth and flat. Then, measure the geometric dimensions of the processed sample and place it on the loading device for preparation.

[0063] 2. According to Figure 1 The configuration shown in the figure adjusts the angle between the two polarized lights, the incident direction of the laser, and the intensity of the backlight source to achieve the best imaging effect, such as Figure 2 The advantage of this configuration method is that it provides a certain degree of flexibility: if you only need to pay attention to the deformation of the crystal structure, you can use the polarized light development system alone; if you only need to pay attention to the effects of bubbles and brine pores on mechanical behavior, you can use the laser transmission device alone.

[0064] 3. Use the testing machine to apply load to the Brazilian disk sample until the sample cracks. The relationship between macroscopic loading force and time is Figure 3 According to the maximum force value (655N) and the size of the sample (diameter 90mm, thickness 9mm), the tensile strength of the ice sample can be calculated as 0.51MPa according to Formula 1.

[0065] 4. Analyze the micro data. Figure 4 The development of the ice sample at several key moments corresponding to the loading curve is shown. Figure 4a shows that before the test, the green highlighted area on the right side of the specimen is more obvious than that on the left side, indicating that there are more bubbles and pores on the right side. Figure 4 b shows that during the loading process, the highlighted area on the right becomes more obvious, indicating that microcracks begin to form in this area, and obvious green microcracks appear at the contact point between the ice sample and the lower pressure plate, indicating that stress is concentrated here. Figure 4 c is the situation after the sample is broken, which shows that although many microcracks are formed in the right area, the existence of bubbles and pores hinders the expansion of macro cracks to a certain extent, and the final macro crack is along the Figure 4 The extension in the direction of the grain boundary marked in b indicates that during the Brazilian disk test, when the specimen is under tensile stress, the macro crack is more likely to extend in a position parallel to the grain boundary.

[0066] Example 2: Thin slice uniaxial compression test scenario

[0067] 1. First, use a slicer to cut a rectangular ice slice with a thickness of about 15 mm and a cross-sectional shape of 50 mm × 100 mm from the sea ice sample. Next, use sandpaper to grind the cut surface of the ice slice until it is smooth and flat, and measure its geometric dimensions for subsequent tests.

[0068] 2. Follow Figure 1 Set up the test device according to the instructions, adjust the polarizer angle of the cross-polarized light, the incident direction of the laser and the intensity of the backlight source to ensure the best imaging effect.

[0069] 3.Use the testing machine to carry out uniaxial compression test, and record the data of force sensor and displacement sensor in real time to calculate the macro stress, strain and strain rate of ice sample. The macro stress-strain curve is shown in Figure 5 middle.

[0070] 4. After the test, select key time points for microscopic data analysis, such as stress mutation points and peak points during the rise of the stress-strain curve. Figure 6 a shows the imaging effect of the ice sample under polarized light and laser transmission before the experiment. As the experiment progresses, Figure 6 b shows microcracks at a recrystallization site; these cracks start from the pore-dense locations and propagate along the brine drainage channels inside the crystal parallel to the loading direction, as shown in Figure 2. Figure 6 c. At this time, the generation of macro cracks causes a sudden drop in stress in the stress-strain curve. When loading continues, Figure 6 d shows that a new microcrack has initiated at the triple grain boundary, but due to the obstruction of the crystal grain boundary below, the crack failed to develop downward. Figure 6 The highlighted area in e shows that a large number of microcracks were generated on the right half of the specimen. Figure 6In f, these highlighted areas eventually formed macro cracks that crossed multiple grain boundaries, and the stress reached a peak at this time. Although the sample was not completely damaged in the subsequent process and still had a certain bearing capacity, this was mainly attributed to the loading strain rate of 5×10 -4 s -1 , the main deformation of ice sample is creep.

[0071] Example 3: Thick specimen uniaxial compression test scenario

[0072] For thicker sea ice samples, they cannot be visualized under cross-polarized light due to their physical properties, but the effect of pores can be analyzed using laser transmission technology. The operation steps of steps 1 to 3 are similar to those of Example 2 and will not be described in detail here.

[0073] This example focuses on describing the synchronous changes of macroscopic experimental phenomena and microscopic pore structure. The initiation and concentration of microcracks were first observed in the salt water pores inside the crystals and the bubble pores between the crystals. The formation of these microcracks is manifested in the specimen as enhanced green light development areas, such as Figure 7 a and Figure 7 As shown in Fig. 2b, the developed area of ​​the latter is significantly increased compared with the former. The green and bright white developed areas represent the microcracks in the brine pores and bubble pores, respectively. As the stress increases, the microcracks continue to expand, cross and eventually form macro cracks, such as Figure 7 c. The area marked by the red arrow in this figure shows a significant difference in laser transmittance, indicating the presence of macro cracks. The formation path of these cracks is hindered by micro cracks in multiple directions, showing an uneven crack interface. Figure 7 The area marked by the white arrow in c shows the ductile damage area formed by the extension of microcracks caused by brine pores. Before the formation of macro cracks, the stress reaches the maximum value, marking the maximum uniaxial compressive strength of the sea ice sample at this strain rate. Then the stress-strain curve enters the descending stage. After the formation of macro cracks, slip and dislocation occur in the local area of ​​the sample along the crack interface, resulting in obvious expansion of the sample in the lateral direction, as shown in Figure 2. Figure 7 As shown in d.

[0074] The micro- and macro-dynamic synchronous observation method of the mechanical behavior of ice samples of the present invention can realize the synchronous monitoring of the macroscopic mechanical properties of sea ice and the microscopic crystal interaction process and the deformation process of pore defects, and can be used for research on the mechanical properties of sea ice.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the operating procedures of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the essence of the principles and technical solutions of the present invention, the technical solutions of the present invention can still be improved, or some of the technical features therein can be replaced by equivalents. These improvements and replacements should also be regarded as the scope of protection of the present invention.

Claims

1. A method for synchronous micro- and macroscopic dynamic observation of the mechanical behavior of an ice sample, wherein the measuring equipment used comprises a load measurement system, a displacement measurement system and a microscopic imaging system; the load measurement system comprises a load sensor for measuring the external load on the ice sample during the test; the displacement measurement system comprises a displacement sensor arranged on a pressure plate on a testing machine for measuring the displacement of the upper surface of the ice sample during the test; the microscopic imaging system comprises a camera, a background light source with adjustable brightness, a polarizer and a laser line light source for displaying the microscopic structural information of the ice sample on the recording device; the method comprises the following steps: (1) Preparation of ice samples; (2) Placement of microscopic imaging system and microscopic capture A background light source with infinite dimming is set up at a position highly parallel to the test area behind the test machine, and the distance between the background light source and the test area is not more than 30 cm; the prepared ice sample is placed on the test machine so that the plane where it is located is perpendicular to the light emitted by the background light source; a polarizer a is placed between the background light source and the ice sample, and a polarizer b is placed on the other side of the ice sample, and the planes where the two polarizers are located are parallel to each other; the polarization direction of the polarizer b is adjusted so that it is perpendicular to the polarization direction of the polarizer a; a camera is placed in front of the polarizer b; Place a laser line light source on one side of the ice sample and adjust the angle of the laser line light source so that the "I"-shaped light beam it emits is parallel to the side edge of the ice sample; and the laser line light source is incident at a position half the thickness of the ice sample; in each test, either the background light source alone, the laser line light source alone, or both light sources are used simultaneously; (3) Macro data processing: For the Brazilian plate tensile test, the external load on the ice sample is recorded in real time through the load measurement system; Generate a "force-time" curve; for uniaxial compression tests, the load measurement system and displacement measurement system work synchronously to generate a stress-strain curve; (4) Micro-data analysis Synchronous image sequence export: The images captured by the camera during the test are exported as image sequences at the same frame rate as the test loading data collected by the load measurement system and displacement measurement system, ensuring that each frame of the image is synchronized with the test loading data; Select analysis moments: According to the changes in macroscopic mechanical data, including "force-time" curves or "stress-strain" curves, select key moments for analysis; Critical moments include load peaks and stress mutation points; Comprehensive analysis of meso data.

2. The method for synchronous micro- and macroscopic dynamic observation of the mechanical behavior of ice samples according to claim 1 is characterized in that: The laser line light source is a green laser.

3. The method for synchronous micro- and macroscopic dynamic observation of the mechanical behavior of ice samples according to claim 1 is characterized in that: The method for preparing ice samples is as follows: prepare ice samples with a thickness of no more than 15 mm to obtain better crystal texture and pore defect visualization effects; for uniaxial compression tests, cut into rectangular samples not exceeding 100 mm × 100 mm, grind all cut surfaces to keep them smooth and flat, and the two opposite surfaces are strictly parallel and the adjacent surfaces are strictly perpendicular; for Brazilian disk tests, cut disc-shaped samples from cylindrical ice core samples, grind until the circular planes are smooth and parallel, and the thickness is reduced to less than 10 mm.

4. The method for synchronous micro- and macroscopic dynamic observation of the mechanical behavior of ice samples according to claim 1 is characterized in that: The method of macro data processing is as follows: In the Brazilian plate tensile test, the external load on the ice sample is recorded in real time through the load measurement system; during the test, the load sensor records the force of the ice sample at different time points during the loading process and generates a "force-time" curve; In the uniaxial compression test, the load measurement system and the displacement measurement system work synchronously to record the external load of the ice sample and the compression displacement of the upper platen in real time; Generate stress-strain curves for analyzing the mechanical characteristics of stress peaks and fracture points.

5. The method for synchronous micro- and macroscopic dynamic observation of the mechanical behavior of ice samples according to claim 1 is characterized in that: The method for comprehensive analysis of mesoscopic data is as follows: through polarized light imaging technology, the crystal particle size and grain boundary characteristics of the ice sample can be obtained; and the addition of laser transmission technology allows the observation results to further observe the bubble distribution inside the ice sample and the characteristics of the brine discharge channel based on the crystal characteristics; through comparative analysis of the previous and next frame images, the nucleation position, expansion path and development speed of the crack are accurately observed; through observation of the crack propagation process, the role of grains, grain boundaries and bubble structures in crack generation and expansion is understood; combined with image data, the displacement changes and strain distribution of local areas of the ice sample are analyzed; the local deformation information of the focus area is used to explain the influence of different structural characteristics including grains and pores on local mechanical behavior.

Images