A test method and system for laser fragmentation of metallic asteroid mineral samples

Abstract

The application discloses a kind of test method and system of laser crushing metal small asteroid mineral sample, belong to extreme environment laser rock breaking technical field.The test method includes the following steps: S1, constructing test environment;S2, to mineral sample in test environment, apply preset laser loading condition, and obtain laser reflection power P b And laser loading time t, while obtaining the surface temperature field data of mineral sample and test environment temperature;S3, receive laser reflection power P b And laser loading time t, surface temperature field data of mineral sample and test environment temperature information, calculate and analyze the cracking state of mineral sample.The application is by synchronous collection environment temperature, laser reflection power and mineral surface temperature field, and establishes the calculation relationship between effective absorption power, highest temperature, environment correction, thermal stress and cracking index, to realize the unified quantitative evaluation to laser crushing process.

Description

Technical Field

[0001] This invention relates to the field of laser rock breaking technology in extreme environments, and in particular to a test method and system for laser breaking of metallic asteroid mineral samples. Background Technology

[0002] Metallic asteroids typically contain metallic components such as iron and nickel, and may also contain heterogeneous structures such as sulfides, silicate inclusions, and pores. With the development of research on in-situ utilization, sampling, and planetary defense of asteroid resources, it is necessary to study the energy absorption, temperature response, and cracking behavior of metallic asteroid materials under external energy loading. Since real asteroid materials are difficult to obtain, related research usually uses simulated mineral samples from metallic asteroids to conduct ground-based simulation experiments.

[0003] Compared to atmospheric pressure and room temperature environments, the environment surrounding asteroid surfaces or near-surface materials is characterized by low pressure, low temperature, and weaker confinement conditions. These environmental differences may affect the material's heat transfer process, thermal expansion behavior, thermal stress formation, and crack propagation. Therefore, it is difficult to comprehensively evaluate the thermal response and cracking behavior of mineral samples under vacuum and low temperature conditions based solely on laser loading test results under atmospheric pressure and room temperature conditions.

[0004] Laser loading offers advantages such as non-contact operation, concentrated energy, and controllable application area. It can induce temperature gradients and thermal stress in mineral samples through rapid local heating, thereby causing cracking or breakage. Existing laser fracture testing devices primarily focus on observing the laser loading or fracture results, making it difficult to simultaneously obtain information such as laser reflected power, mineral sample surface temperature field, and ambient temperature under controlled pressure and temperature conditions in a vacuum cryogenic environment. Furthermore, a unified quantitative evaluation method that correlates known laser incident power, effective absorbed power, temperature response, environmental influences, thermal stress, and cracking state is lacking. Summary of the Invention

[0005] The purpose of this invention is to provide a test method and system for laser-induced fracturing of metallic asteroid mineral samples, in order to address the lack of a unified quantitative evaluation of the thermally induced cracking process of simulated metallic asteroid mineral samples in the existing technology.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A test method for laser fragmentation of metallic asteroid mineral samples includes the following steps: S1. Construct the test environment; S2. Apply preset laser loading conditions to the mineral sample in the test environment and obtain the laser reflection power P. b Simultaneously, the surface temperature field data of the mineral sample and the ambient temperature of the test environment were obtained, along with the laser loading time t. S3, Received laser reflection power P b Using the laser loading time t, surface temperature field data of the mineral sample, and ambient temperature information, the cracking state of the mineral sample is calculated and analyzed, including the following steps: S3.1, Based on laser reflection power P b Combined with laser incident power P a Calculate the effective absorbed power P1 and absorption coefficient of the mineral sample. ; S3.2. Based on the temperature field model under the action of a laser heat source, combined with the thermophysical parameters of the mineral sample, effective absorption power P1, and absorption coefficient. Using the laser loading time t, the surface temperature field data of the mineral sample, and the temperature of the test environment, the highest temperature at the center of the laser spot on the surface of the mineral sample is calculated. S3.3 Determine the highest temperature at the center of the laser spot on the surface of the mineral sample according to the laser loading mode and correct the test environment accordingly; S3.4 Calculate the thermal stress of the mineral sample based on the highest temperature at the center of the spot on the surface of the corrected mineral sample. S3.5 Calculate the cracking index based on the thermal stress of the mineral sample, and determine the cracking state of the mineral sample based on the cracking index.

[0007] Furthermore, the calculation of the highest temperature at the center of the light spot on the mineral sample surface includes the following steps: If the laser beam acting on the surface of the mineral sample is a Gaussian beam, then its power density distribution... for:

[0008] Where: w is the Gaussian beam radius, and x and y are the surface coordinates of the mineral sample; For a beam traveling along the positive x-axis at a velocity v s The temperature field of the mineral sample at time t, obtained by scanning Gaussian laser, is as follows:

[0009]

[0010] in: Let t be the temperature of the region adjacent to the mineral sample. The initial temperature inside the test environment is z, where z is the coordinate of the mineral sample along the depth direction, and v is v. s For laser scanning speed, For integration time variable, ρ is the thermal diffusivity of the mineral sample, k is the thermal conductivity of the mineral sample, ρ is the density of the mineral sample, and c is the specific heat capacity of the mineral sample. When the laser's point of action is fixed and the scanning speed v is not considered s At that time, the highest temperature of the light spot on the mineral sample surface appeared in the central region of the light spot, taking x=y=z=v s =0, the highest temperature at the center of the light spot on the mineral sample surface. It is expressed as follows: .

[0011] Furthermore, determining the highest temperature at the center of the laser spot on the mineral sample surface based on the laser loading mode includes the following steps: For continuous lasers, the laser continuously outputs stable laser power during its action time, effectively absorbing power. It is expressed as follows:

[0012] The highest temperature at the center of the laser spot on the surface of the mineral sample under continuous laser irradiation is expressed as follows: .

[0013] Furthermore, determining the highest temperature at the center of the laser spot on the mineral sample surface based on the laser loading mode includes the following steps: For an ideal rectangular pulsed laser mode, the parameters of the pulsed laser include pulse width. Repetition frequency f, pulse energy E p Peak power P peak and average power P avg ; Energy of a single pulse It is expressed as follows:

[0014] Since it contains f pulses per unit time, the average power of the pulsed laser is... It is expressed as follows:

[0015] Effective absorption power of mineral sample surface under ideal rectangular pulsed laser irradiation It is expressed as follows:

[0016] The highest temperature at the center of the laser spot on the surface of a mineral sample under ideal rectangular pulse laser irradiation is expressed as follows: .

[0017] Furthermore, determining the highest temperature at the center of the laser spot on the mineral sample surface based on the laser loading mode includes the following steps: For the continuous preheating-pulse co-loading mode, the calculation of the highest temperature at the center of the light spot on the mineral sample surface is divided into two stages: The first stage is the continuous laser preheating stage. In this stage, the continuous laser first acts on the surface of the mineral sample, causing the temperature in the central region of the laser spot on the mineral sample surface to rise. When the continuous preheating duration is t1, the temperature at the center of the laser spot on the mineral sample surface is expressed as follows:

[0018] The second stage is the pulsed laser shock stage. Based on the temperature established by continuous laser preheating, a pulsed laser is applied to further increase the temperature in the central region of the laser spot on the mineral sample surface. Under the conditions that the loading interval between the two stages is negligible, the laser action position remains unchanged, the thermophysical parameters of the mineral sample are considered constant, and the temperature response satisfies linear superposition, the highest temperature at the center of the laser spot on the mineral sample surface when the total duration of the pulse sequence loading stage is t2 is expressed as follows:

[0019] Where: t1 is the duration of continuous preheating, and t2 is the total duration of the pulse sequence loading phase.

[0020] Furthermore, the test environment is corrected for the highest temperature at the center of the light spot on the mineral sample surface, including the following steps: An environmental correction factor is introduced to correct for the highest temperature at the center of the light spot on the mineral sample surface. After the environmental correction, the highest temperature at the center of the light spot on the mineral sample surface is expressed as follows:

[0021] in: This represents the highest temperature at the center of the light spot on the surface of the mineral sample after environmental correction. This refers to the highest temperature at the center of the laser spot on the mineral sample surface, determined according to the corresponding laser loading mode. F represents the initial temperature inside the test environment. v This is the environmental correction factor.

[0022] Furthermore, based on the same mineral sample and the same preset laser loading conditions: When the test environment is normal pressure and room temperature, the normal pressure and room temperature test is used as the baseline operating condition, and the environmental correction factor F is used. v =1; When the test environment is a vacuum cryogenic condition, the environmental correction factor is determined based on the ratio of the temperature rise caused by laser action in a vacuum cryogenic environment to that in a normal pressure and room temperature environment:

[0023] in: This refers to the highest temperature at the center of the laser spot on the surface of the mineral sample, determined according to the corresponding laser loading mode under vacuum cryogenic conditions. The initial temperature within the test environment under vacuum and low temperature conditions. This represents the highest temperature at the center of the laser spot on the mineral sample surface, determined according to the corresponding laser loading mode under normal pressure and room temperature conditions. The initial temperature is the temperature within the test environment at normal pressure and room temperature.

[0024] Furthermore, the thermal stress of the mineral sample is calculated based on the highest temperature at the center of the light spot on the corrected mineral sample surface, including the following steps: Temperature rise at the center of the light spot on the surface of the mineral sample It is expressed as follows:

[0025] in: This represents the highest temperature at the center of the light spot on the surface of the mineral sample after environmental correction. The initial temperature inside the test environment; Calculate the thermal stress of the mineral sample based on the thermal stress relationship under constrained thermal expansion conditions. The calculation formula is as follows:

[0026] Where: E is the elastic modulus of the mineral sample. denoted as the coefficient of linear expansion of the mineral sample, and v as the Poisson's ratio of the mineral sample.

[0027] Furthermore, based on the thermal stress of the mineral sample Calculate the cracking index The calculation formula is as follows:

[0028] in: This represents the tensile strength of the mineral sample. Based on cracking index Determining the crack state of a mineral sample includes the following steps: when When the thermal stress has not yet reached the tensile strength of the mineral sample, the mineral sample does not undergo obvious thermal cracking. when When the thermal stress reaches or exceeds the tensile strength of the mineral sample, it indicates that the mineral sample has undergone thermal cracking or breakage.

[0029] A test system for laser-induced fragmentation of metallic asteroid mineral samples includes a test environment simulation module, a laser loading module, a temperature acquisition module, and a data terminal; The test environment simulation module is used to construct the test environment; The laser loading module is used to apply preset laser loading conditions to the mineral sample in the test environment and to obtain the laser reflection power P. b and the laser loading time t; The temperature acquisition module is used to acquire surface temperature field data of mineral samples and ambient temperature during testing. The data terminal is used to receive laser reflection power P. b Using the laser loading time t, surface temperature field data of the mineral sample, and ambient temperature information, the cracking state of the mineral sample is calculated and analyzed. The data terminal is also used for: based on laser reflection power P b Combined with laser incident power P a Calculate the effective absorbed power P1 and absorption coefficient of the mineral sample. Based on the temperature field model under the action of a laser heat source, combined with the thermophysical parameters of the mineral sample, effective absorption power P1, and absorption coefficient... Based on the laser loading time t, the surface temperature field data of the mineral sample, and the temperature of the test environment, the highest temperature at the center of the laser spot on the surface of the mineral sample is calculated; the highest temperature at the center of the laser spot on the surface of the mineral sample is determined according to the laser loading mode and the test environment is corrected accordingly; the thermal stress of the mineral sample is calculated based on the corrected highest temperature at the center of the laser spot on the surface of the mineral sample; the cracking index is calculated based on the thermal stress of the mineral sample, and the cracking state of the mineral sample is determined based on the cracking index.

[0030] The beneficial effects of this invention are as follows: This invention provides a test method and system for laser fracturing of metallic asteroid mineral samples. It establishes a complete test and evaluation process, encompassing environmental simulation, laser energy input, energy absorption, temperature response, thermal stress evolution, and crack determination. By simultaneously acquiring ambient temperature, laser reflection power, and the mineral surface temperature field, and establishing calculation relationships between effective absorbed power, maximum temperature, environmental correction, thermal stress, and cracking index, a unified quantitative evaluation of the laser fracturing process is achieved. This provides an experimental basis for the study of the laser fracturing mechanism and parameter optimization of metallic asteroid minerals. 1. This invention constructs an ambient pressure and room temperature environment or a vacuum and low temperature environment through an experimental environment simulation module, and applies laser loading to mineral samples under controlled experimental conditions, providing unified experimental conditions for comparing the energy absorption, temperature response and cracking behavior of mineral samples under different environmental conditions; 2. This invention combines the known incident laser power with the collected laser reflected power to determine the effective absorption power and absorption coefficient of the mineral sample, and simultaneously acquires the surface temperature field of the mineral sample and the temperature of the test environment, thereby establishing the correlation between laser energy input, energy absorption and temperature response; 3. This invention introduces an environmental correction coefficient based on the temperature rise difference between normal pressure and room temperature environments and vacuum and low temperature environments, and further calculates the thermal stress and cracking index of mineral samples, so that the temperature response obtained under different test environments can be analyzed according to a unified method, providing a basis for the quantitative evaluation of the thermally induced cracking state of mineral samples. 4. This invention supports multiple laser loading modes, such as continuous laser, pulsed laser, and continuous preheating and pulsed impact combined loading, which facilitates comparison of the effects of different laser loading modes on the temperature rise, thermal stress and cracking behavior of mineral samples, and provides an experimental basis for the selection and optimization of laser loading parameters. Attached Figure Description

[0031] Figure 1 This is a schematic flowchart of a test method for laser fragmentation of metallic asteroid mineral samples according to the present invention. Figure 2 This is a flowchart illustrating the calculation and analysis of the cracking state of a mineral sample in a laser-based method for fracturing metallic asteroid mineral samples according to the present invention. Figure 3 This is a schematic diagram (from one perspective) of the experimental system for laser fragmentation of metallic asteroid mineral samples according to the present invention. Figure 4 This is a schematic diagram (from another perspective) of the test system for laser fragmentation of metallic asteroid mineral samples according to the present invention.

[0032] Annotation instructions: 10-Test chamber body; 11-Test chamber cover; 12-Stage; 13-Vacuum pump; 14-Evacuation pipe; 15-Vacuum gauge; 16-Liquid nitrogen storage tank; 17-Liquid nitrogen circulation pipeline; 171-Liquid supply pipeline; 172-Return pipeline; 173-Cooling coil; 18-Flange interface; 19-Cable hole; 20-Laser; 21-Laser incident window; 22-Laser power meter; 23-Mineral holder; 24-Mineral sample; 25-Laser reflection window; 26-Integrating sphere; 30-Infrared thermal imager; 31-Temperature sensor; 40-Data terminal. Detailed Implementation

[0033] 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 specific examples described herein are merely illustrative and not intended to limit the scope of the invention.

[0034] Example 1:

[0035] Please see Figures 1-2 As shown, a test method for laser fragmentation of metallic asteroid mineral samples includes the following steps: S1. Construct the test environment (e.g., normal pressure room temperature test environment or vacuum low temperature test environment). S2. Apply preset laser loading conditions to the mineral sample (mineral sample is short for metallic asteroid simulated mineral sample, which refers to a sample used to simulate the material composition and thermophysical properties of metallic asteroids) in the test environment, and obtain the laser reflection power P. b Simultaneously, the surface temperature field data of the mineral sample and the ambient temperature of the test environment were obtained, along with the laser loading time t. S3, Received laser reflection power P b The cracking state of the mineral sample was calculated and analyzed by combining the laser loading time t, the surface temperature field data of the mineral sample, and the ambient temperature information.

[0036] Calculate and analyze the crack state of the mineral sample, including the following steps: S3.1, Based on laser reflection power P b Combined with laser incident power P a (Based on a prior laser incident power calibration test), calculate the effective absorbed power P1 and absorption coefficient of the mineral sample. .

[0037] Specifically, under the condition that the thickness of the mineral sample is sufficient to make the transmitted power negligible, based on the laser incident power P... a With laser reflection power P b The difference between them yields the effective absorbed power P1 on the surface of the mineral sample:

[0038] Wherein, P1 is the effective absorbed power on the surface of the mineral sample; Define the absorption coefficient of a mineral sample to laser energy. for:

[0039] absorption coefficient Used to characterize the effective absorption capacity of mineral samples for incident laser energy.

[0040] S3.2. Based on the temperature field model under the action of a laser heat source, combined with the thermophysical parameters of the mineral sample, effective absorption power P1, and absorption coefficient. Using the laser loading time t, the surface temperature field data of the mineral sample, and the temperature of the test environment, the highest temperature at the center of the laser spot on the surface of the mineral sample is calculated.

[0041] Specifically, the energy provided by the laser beam is the main heat source for the temperature rise of the mineral sample, and the energy density distribution characteristics of the laser beam directly affect the temperature field distribution on the surface and near-surface region of the mineral sample. Since the energy density of commonly used laser beams usually exhibits a Gaussian distribution characteristic that gradually decreases from the center of the spot to the edge, this embodiment establishes the power density distribution relationship of the laser beam acting on the surface of the mineral sample based on the Gaussian distribution.

[0042] More specifically, calculating the highest temperature at the center of the light spot on the surface of the mineral sample includes the following steps: If the laser beam acting on the surface of the mineral sample is a Gaussian beam, then its power density distribution... for:

[0043] Where: w is the Gaussian beam radius, and x and y are the surface coordinates of the mineral sample; For a beam traveling along the positive x-axis at a velocity v s The temperature field of the mineral sample at time t, obtained by scanning Gaussian laser, is as follows:

[0044]

[0045] in: Let t be the temperature of the region adjacent to the mineral sample. The initial temperature inside the test environment is z, where z is the coordinate of the mineral sample along the depth direction, and v is v. s For laser scanning speed, For integration time variable, ρ is the thermal diffusivity of the mineral sample, k is the thermal conductivity of the mineral sample, ρ is the density of the mineral sample, and c is the specific heat capacity of the mineral sample. When the laser's point of action is fixed and the scanning speed v is not considered s At that time, the highest temperature of the light spot on the mineral sample surface appeared in the central region of the light spot, taking x=y=z=v s =0, the highest temperature at the center of the light spot on the mineral sample surface. It is expressed as follows:

[0046] S3.3 Determine the highest temperature at the center of the laser spot on the surface of the mineral sample according to the laser loading mode and correct the test environment accordingly.

[0047] Specifically, in order to establish the correlation between laser parameters and the temperature-stress response of mineral samples, this embodiment selects three laser action modes: continuous laser, pulsed laser, and continuous preheating-pulse impact synergistic loading, and corrects the highest temperature at the center of the laser spot on the surface of the mineral sample for each mode.

[0048] More specifically, determining the highest temperature at the center of the laser spot on the mineral sample surface based on the laser loading mode includes the following steps: For continuous lasers, the laser continuously outputs stable laser power during its action time, effectively absorbing power. It is expressed as follows:

[0049] The highest temperature at the center of the laser spot on the surface of the mineral sample under continuous laser irradiation is expressed as follows:

[0050] For an ideal rectangular pulsed laser mode, the parameters of the pulsed laser include pulse width. Repetition frequency f, pulse energy E p Peak power P peak and average power P avg ; Energy of a single pulse It is expressed as follows:

[0051] Since it contains f pulses per unit time, the average power of the pulsed laser is... It is expressed as follows:

[0052] Effective absorption power of mineral sample surface under ideal rectangular pulsed laser irradiation It is expressed as follows:

[0053] The highest temperature at the center of the laser spot on the surface of a mineral sample under ideal rectangular pulse laser irradiation is expressed as follows:

[0054] For the continuous preheating-pulse co-loading mode, the calculation of the highest temperature at the center of the light spot on the mineral sample surface is divided into two stages: The first stage is the continuous laser preheating stage. In this stage, the continuous laser first acts on the surface of the mineral sample, causing the temperature in the central region of the laser spot on the mineral sample surface to rise. When the continuous preheating duration is t1, the highest temperature at the center of the laser spot on the mineral sample surface is expressed as follows:

[0055] The second stage is the pulsed laser shock stage. Based on the temperature established by continuous laser preheating, a pulsed laser is applied to further increase the temperature in the central region of the laser spot on the mineral sample surface. Under the conditions that the loading interval between the two stages is negligible, the laser action position remains unchanged, the thermophysical parameters of the mineral sample are considered constant, and the temperature response satisfies linear superposition, the highest temperature at the center of the laser spot on the mineral sample surface when the total duration of the pulse sequence loading stage is t2 is expressed as follows:

[0056] Where: t1 is the duration of continuous preheating, and t2 is the total duration of the pulse sequence loading phase.

[0057] Specifically, due to the significant differences between the initial temperature and ambient pressure of the chamber in a vacuum cryogenic environment and those in an atmospheric pressure / room environment, the temperature and heat dissipation characteristics of the mineral samples will also change during laser irradiation. Therefore, to further consider the influence of environmental conditions on the maximum surface temperature of the mineral samples, this step introduces an environmental correction coefficient F based on the obtained correction results for different laser modes. v The temperature rise caused by the laser action is used as the correction target.

[0058] More specifically, the experimental environment is corrected for the highest temperature at the center of the light spot on the mineral sample surface, including the following steps: An environmental correction factor is introduced to correct for the highest temperature at the center of the light spot on the mineral sample surface. After the environmental correction, the highest temperature at the center of the light spot on the mineral sample surface is expressed as follows:

[0059] in: This represents the highest temperature at the center of the light spot on the surface of the mineral sample after environmental correction. This refers to the highest temperature at the center of the laser spot on the mineral sample surface, determined according to the corresponding laser loading mode. F represents the initial temperature inside the test environment. v This is the environmental correction factor.

[0060] Based on the same mineral sample and the same preset laser loading conditions: When the test environment is normal pressure and room temperature, the normal pressure and room temperature test is used as the baseline operating condition, and the environmental correction factor F is used. v =1, then the highest temperature at the center of the light spot on the surface of the mineral sample after environmental correction is:

[0061] When the test environment is a vacuum cryogenic condition, the environmental correction factor is determined based on the ratio of the temperature rise caused by laser action in a vacuum cryogenic environment to that in a normal pressure and room temperature environment:

[0062] in: This refers to the highest temperature at the center of the laser spot on the surface of the mineral sample, determined according to the corresponding laser loading mode under vacuum cryogenic conditions. The initial temperature within the test environment under vacuum and low temperature conditions. This represents the highest temperature at the center of the laser spot on the mineral sample surface, determined according to the corresponding laser loading mode under normal pressure and room temperature conditions. The initial temperature is the temperature within the test environment at normal pressure and room temperature.

[0063] From the above, we can see that F v This reflects the degree of influence of the vacuum low-temperature environment on the temperature rise caused by laser irradiation of mineral samples. When F v When F > 1, it indicates that the surface temperature of the mineral sample rises above that under normal pressure and room temperature conditions in a vacuum low-temperature environment; when F v When the value is less than 1, it indicates that the surface temperature rise of the mineral sample is suppressed to a certain extent under vacuum low-temperature environment. Through the above correction, the highest surface temperature of the mineral sample that simultaneously considers the effects of laser loading mode and vacuum low-temperature environment can be obtained, and it can be used for subsequent thermal stress calculation and thermal cracking criterion analysis.

[0064] S3.4 Calculate the thermal stress of the mineral sample based on the highest temperature at the center of the light spot on the corrected mineral sample surface.

[0065] Specifically, the thermal stress of the mineral sample is calculated based on the highest temperature at the center of the light spot on the corrected surface, including the following steps: Temperature rise at the center of the light spot on the surface of the mineral sample It is expressed as follows:

[0066] in: This represents the highest temperature at the center of the light spot on the surface of the mineral sample after environmental correction. The initial temperature inside the test environment; Calculate the thermal stress of the mineral sample based on the thermal stress relationship under constrained thermal expansion conditions. The calculation formula is as follows:

[0067] Where: E is the elastic modulus of the mineral sample. denoted as the coefficient of linear expansion of the mineral sample, and v as the Poisson's ratio of the mineral sample.

[0068] S3.5 Calculate the cracking index based on the thermal stress of the mineral sample, and determine the cracking state of the mineral sample based on the cracking index.

[0069] Specifically, based on the thermal stress of the mineral sample Calculate the cracking index The calculation formula is as follows:

[0070] in: This represents the tensile strength of the mineral sample. Based on cracking index Determining the crack state of a mineral sample includes the following steps: when When the thermal stress has not yet reached the tensile strength of the mineral sample, the mineral sample does not undergo obvious thermal cracking. when When the thermal stress reaches or exceeds the tensile strength of the mineral sample, it indicates that the mineral sample has undergone thermal cracking or breakage.

[0071] Example 2:

[0072] Please see Figures 3-4 As shown, a test system for laser-induced fragmentation of metallic asteroid mineral samples includes a test environment simulation module, a laser loading module, a temperature acquisition module, and a data terminal, wherein: The test environment simulation module is used to construct test environments (e.g., ambient pressure and room temperature test environment or vacuum and low temperature test environment). The laser loading module is used to apply preset laser loading conditions to the mineral sample 24 in the test environment and to obtain the laser reflection power P. b and the laser loading time t; The temperature acquisition module is used to acquire surface temperature field data of mineral sample 24 and ambient temperature. The data terminal is used to receive laser reflection power P b Using the laser loading time t, surface temperature field data of mineral sample 24, and ambient temperature information, the cracking state of mineral sample 24 was calculated and analyzed. The data terminal is also used for: based on laser reflection power P b Combined with laser incident power P a (Based on a prior laser incident power calibration test), the effective absorbed power P1 and absorption coefficient of mineral sample 24 were calculated. Based on the temperature field model under the action of a laser heat source, combined with the thermophysical parameters of mineral sample 24, effective absorption power P1, and absorption coefficient... Using the laser loading time t, the surface temperature field data of mineral sample 24, and the temperature of the test environment, the highest temperature at the center of the laser spot on the surface of the mineral sample is calculated; the highest temperature at the center of the laser spot on the surface of the mineral sample is determined according to the laser loading mode and corrected for the test environment; the thermal stress of mineral sample 24 is calculated based on the corrected highest temperature at the center of the laser spot on the surface of the mineral sample; the cracking index is calculated based on the thermal stress of mineral sample 24, and the cracking state of mineral sample 24 is determined based on the cracking index.

[0073] Specifically, the structural design of the experimental system is as follows: The test environment simulation module includes: test chamber 10, test chamber cover 11, stage 12, vacuum pump 13, evacuation pipe 14, vacuum gauge 15, liquid nitrogen storage tank 16, and liquid nitrogen circulation pipeline 17.

[0074] The test chamber 10 is cylindrical, and is equipped with a flange interface 18, a laser incident window 21, and a laser reflection window 25.

[0075] The laser incident window 21 is used to allow external laser light to pass through and enter the interior of the test chamber 10 while maintaining the chamber's airtightness. The laser incident window 21 is made of an optical material with high laser transmittance and heat resistance, preferably quartz glass.

[0076] The laser reflection window 25 is used to allow the laser light reflected from the surface of the mineral sample 24 inside the chamber to pass through and exit the chamber while maintaining the airtightness of the test chamber 10. The laser reflection window 25 is the same as the laser incident window 21, and is preferably made of quartz glass.

[0077] The test chamber cover 11 is located at the top opening of the test chamber 10 and is sealed to the test chamber 10 by a sealing ring to ensure that the required vacuum level can be maintained inside the chamber during the test.

[0078] The stage 12 is located at the bottom of the test chamber 10 and is used to support the mineral holder 23 and the mineral sample 24.

[0079] The mineral holder 23 is mounted on the stage 12 to fix the mineral sample 24 and maintain its stable position during laser irradiation, preventing movement due to thermal shock, vibration, or localized breakage. The mineral holder 23 can be adjusted according to the size of the mineral sample 24 to accommodate mineral samples 24 of different shapes and sizes. The specific shape of the mineral sample 24 is not limited, as long as its size allows it to be placed on the stage 12 and stably held by the mineral holder 23.

[0080] A vacuum pump 13 is installed on the outside of the test chamber 10 and connected to the flange interface 18 on the test chamber 10 via a vacuum pipe 14. It is used to evacuate the air inside the chamber to bring the pressure inside the chamber to a preset vacuum condition. The vacuum pipe 14 is a hollow sealed pipe.

[0081] The vacuum gauge 15 is installed inside the test chamber 10 to monitor the internal pressure of the chamber in real time.

[0082] The liquid nitrogen storage tank 16 is located outside the test chamber 10. The liquid nitrogen circulation pipeline 17 includes a supply pipeline 171, a return pipeline 172, and a cooling coil 173. One end of the supply pipeline 171 is connected to the liquid nitrogen storage tank 16, and the other end passes through the flange interface 18 of the test chamber 10 and connects to the cooling coil 173 inside the chamber. One end of the return pipeline 172 passes through the flange interface 18 of the test chamber 10 and connects to the cooling coil 173 inside the chamber, and the other end is connected to the liquid nitrogen storage tank 16.

[0083] During the experiment, liquid nitrogen enters the cooling coil 173 inside the test chamber 10 from the liquid nitrogen storage tank 16 via the supply pipeline 171. The cooling coil 173 is located near the inner wall of the test chamber 10. As the liquid nitrogen flows within the cooling coil 173, it absorbs heat from the stage 12 and the internal environment of the chamber, lowering the internal temperature to a set value. The heat-exchanged liquid nitrogen returns to the liquid nitrogen storage tank 16 via the return pipeline 172, thus achieving continuous cooling of the internal environment of the chamber.

[0084] The environmental simulation module can switch between ambient pressure and room temperature control mode and vacuum low temperature simulation mode: In the normal pressure and room temperature control mode, the vacuum pump 13 and the liquid nitrogen circulation pipeline 17 are in the closed state, and the interior of the chamber is maintained at normal pressure and room temperature. In the vacuum cryogenic simulation mode, the vacuum pump 13 evacuates the air from the inside of the chamber, and the liquid nitrogen circulation pipeline 17 cools the inside of the chamber to create a preset vacuum cryogenic environment.

[0085] The laser loading module includes a laser 20, a laser power meter 22, and an integrating sphere 26.

[0086] The laser 20 is located outside the test chamber 10 and can realize continuous laser, pulsed laser, and continuous preheating-pulse impact combined loading. The laser emitted by the laser 20 enters the chamber through the laser incident window 21 opened on the side wall of the test chamber 10 and acts on the surface of the mineral sample 24.

[0087] The laser power meter 22 is movable and positioned on the stage 12 to calibrate the actual incident power reaching the surface of the mineral sample 24 before the formal test. After calibration, the laser power meter 22 is moved out of the optical path, and the mineral sample 24 is placed in the same position to conduct the laser irradiation test.

[0088] The integrating sphere 26 is positioned outside the laser reflection window 25 and is used to measure the laser power reflected from the surface of the mineral sample 24.

[0089] More specifically, both the laser incident window 21 and the laser reflection window 25 are disposed on the side wall of the test chamber 10, and arranged according to the laser incident light path and the reflected light path of the mineral sample 24 surface: the laser incident window 21 is located on the propagation path of the output beam of the laser 20, so that the laser can pass through the laser incident window 21 and irradiate the preset action area on the surface of the mineral sample 24; the laser reflection window 25 is disposed on the propagation path of the reflected light from the surface of the mineral sample 24, so that the laser reflected from the surface of the mineral sample 24 can exit the test chamber 10 through the laser reflection window 25. The integrating sphere 26 is disposed outside the laser reflection window 25, and the entrance of the integrating sphere 26 is located on the reflected light path of the mineral sample 24.

[0090] The temperature acquisition module includes an infrared thermal imager 30 and a temperature sensor 31.

[0091] The test chamber cover 11 has light-transmitting properties. The infrared thermal imager 30 is arranged above the test chamber 10 and is aligned with the surface of the mineral sample 24 through the light-transmitting test chamber cover 11. This is used to obtain the temperature field evolution information of the surface of the mineral sample 24 during the laser action without damaging the airtightness of the chamber.

[0092] More specifically, the test chamber cover 11 is provided with an infrared temperature measurement window, which is made of an infrared transparent material with a preset transmittance within the working band of the infrared thermal imager 30. The infrared thermal imager 30 is aligned with the surface of the mineral sample through the infrared temperature measurement window.

[0093] Temperature sensor 31 is located above stage 12 and is used to monitor changes in ambient temperature inside the cabin in real time.

[0094] The data terminal 40 is used to receive data from the vacuum gauge 15, laser power meter 22, integrating sphere 26, infrared thermal imager 30 and temperature sensor 31, and to record and store information such as cabin pressure, laser incident power, laser reflected power, temperature field and ambient temperature.

[0095] The test chamber 10 is equipped with a cable hole 19, which is sealed to ensure that the cable does not damage the airtightness of the test chamber 10 during cable installation. The signal lines of the vacuum gauge 15, laser power meter 22, integrating sphere 26 and temperature sensor 31 are sealed and led out through the cable hole 19 and connected to the data terminal 40.

[0096] The data terminal 40 is also used to calculate the effective absorbed power, maximum temperature, thermal stress, and cracking index to achieve a quantitative evaluation of the temperature response and thermally induced cracking state of the mineral sample 24 during laser treatment.

[0097] In this embodiment, taking a vacuum cryogenic test environment as an example, the process of constructing the test environment and performing laser loading is as follows: First, the laser incident power is calibrated. The test chamber cover 11 is opened, and the laser power meter 22 is placed in the center of the stage 12, aligning its measurement position with the laser action position on the surface of the subsequent mineral sample 24. The test chamber cover 11 is then closed to ensure the test chamber 10 is airtight. The vacuum pump 13 is started to evacuate the test chamber 10, and the internal pressure is monitored in real time using a vacuum gauge 15 until it stabilizes at the preset vacuum condition. The liquid nitrogen storage tank 16 is opened, allowing liquid nitrogen to enter the cooling coil 173 inside the test chamber 10 via the supply line 171. The liquid nitrogen exchanges heat with the internal environment of the chamber through the cooling coil 173 until the internal temperature decreases and stabilizes at the preset low temperature condition. The cooled liquid nitrogen returns to the liquid nitrogen storage tank 16 via the return line 172, thus achieving low-temperature circulating heat exchange. Once the internal pressure and temperature of the chamber have reached the preset conditions, the laser 20 is activated and outputs a preset laser mode, allowing the laser to irradiate the laser power meter 22 through the laser incident window 21. After a preset action time t, the laser 20 is turned off, and the actual incident power P fed back by the laser power meter 22 is read. a .

[0098] Because the laser experiences transmission loss as it passes through the laser incident window 21, the output power P0 displayed on the laser unit 20 panel cannot accurately represent the actual laser power acting on the surface of the mineral sample 24. Therefore, in this embodiment, a laser power meter 22 is used to measure the actual incident power P that reaches the surface of the mineral sample 24 after passing through the laser incident window 21. a This refers to the preliminary laser incident power calibration test.

[0099] It should be noted that laser incident power calibration is not required before every experiment; it can be arranged reasonably according to the progress of the experiment.

[0100] After completing the laser incident power calibration, the test chamber cover 11 is opened, the laser power meter 22 is moved out of the laser action position, and the mineral sample 24 is placed in the center of the stage 12, so that the preset action area on the surface of the mineral sample 24 corresponds to the measurement position of the aforementioned laser power meter 22. Then, the mineral sample 24 is fixed using the mineral holder 23, and the test chamber cover 11 is closed to ensure the airtightness of the test chamber 10. Following the same method as the incident power calibration, the vacuum pump 13 and liquid nitrogen circulation system are started to stabilize the internal pressure and ambient temperature of the chamber to the preset vacuum low-temperature conditions. After the test environment stabilizes, the laser 20 is started and outputs the same preset laser mode, so that the laser shines through the laser incident window 21 onto the preset action area on the surface of the mineral sample 24. The laser, reflected by the surface of the mineral sample 24, exits the test chamber 10 along the reflected light path through the laser reflection window 25 and is received by the integrating sphere 26 located on the reflected light path. After a preset action time t, the laser 20 is turned off, and the reflected power P fed back by the integrating sphere 26 is read. b .

[0101] This invention is not limited to the specific embodiments described above. Those skilled in the art can implement this invention using various other specific embodiments based on the content disclosed herein. Therefore, any design that adopts the design structure and concept of this invention and makes some simple changes or modifications falls within the scope of protection of this invention.

Claims

1. A test method for laser fragmentation of metallic asteroid mineral samples, characterized in that: Includes the following steps: S1. Construct the test environment; S2. Apply preset laser loading conditions to the mineral sample in the test environment and obtain the laser reflection power P. b Simultaneously, the surface temperature field data of the mineral sample and the ambient temperature of the test environment were obtained, along with the laser loading time t. S3, Received laser reflection power P b Using the laser loading time t, surface temperature field data of the mineral sample, and ambient temperature information, the cracking state of the mineral sample is calculated and analyzed, including the following steps: S3.1, Based on laser reflection power P b Combined with laser incident power P a Calculate the effective absorbed power P1 and absorption coefficient of the mineral sample. ; S3.

2. Based on the temperature field model under the action of a laser heat source, combined with the thermophysical parameters of the mineral sample, effective absorption power P1, and absorption coefficient. Using the laser loading time t, the surface temperature field data of the mineral sample, and the temperature of the test environment, the highest temperature at the center of the laser spot on the surface of the mineral sample is calculated. S3.3 Determine the highest temperature at the center of the laser spot on the surface of the mineral sample according to the laser loading mode and correct the test environment accordingly; S3.4 Calculate the thermal stress of the mineral sample based on the highest temperature at the center of the spot on the surface of the corrected mineral sample. S3.5 Calculate the cracking index based on the thermal stress of the mineral sample, and determine the cracking state of the mineral sample based on the cracking index.

2. The test method for laser fragmentation of metallic asteroid mineral samples according to claim 1, characterized in that: Calculating the highest temperature at the center of the light spot on the surface of the mineral sample includes the following steps: If the laser beam acting on the surface of the mineral sample is a Gaussian beam, then its power density distribution... for: Where: w is the Gaussian beam radius, and x and y are the surface coordinates of the mineral sample; For a beam traveling along the positive x-axis at a velocity v s The temperature field of the mineral sample at time t, obtained by scanning Gaussian laser, is as follows: in: Let t be the temperature of the region adjacent to the mineral sample at time t. The initial temperature inside the test environment is z, where z is the coordinate of the mineral sample along the depth direction, and v is v. s For laser scanning speed, For integration time variable, ρ is the thermal diffusivity of the mineral sample, k is the thermal conductivity of the mineral sample, ρ is the density of the mineral sample, and c is the specific heat capacity of the mineral sample. When the laser's point of action is fixed and the scanning speed v is not considered s At that time, the highest temperature of the light spot on the mineral sample surface appeared in the central region of the light spot, taking x=y=z=v s =0, the highest temperature at the center of the light spot on the mineral sample surface. It is expressed as follows: 。 3. The test method for laser fragmentation of metallic asteroid mineral samples according to claim 2, characterized in that: Determining the highest temperature at the center of the laser spot on the surface of the mineral sample based on the laser loading mode includes the following steps: For continuous lasers, the laser continuously outputs stable laser power during its action time, effectively absorbing power. It is expressed as follows: The highest temperature at the center of the laser spot on the surface of the mineral sample under continuous laser irradiation is expressed as follows: 。 4. The test method for laser fragmentation of metallic asteroid mineral samples according to claim 2, characterized in that: Determining the highest temperature at the center of the laser spot on the surface of the mineral sample based on the laser loading mode includes the following steps: For an ideal rectangular pulsed laser mode, the parameters of the pulsed laser include pulse width. Repetition frequency f, pulse energy E p Peak power P peak and average power P avg ; Energy of a single pulse It is expressed as follows: Since it contains f pulses per unit time, the average power of the pulsed laser is... It is expressed as follows: Effective absorption power of mineral sample surface under ideal rectangular pulsed laser irradiation It is expressed as follows: The highest temperature at the center of the laser spot on the surface of a mineral sample under ideal rectangular pulse laser irradiation is expressed as follows: 。 5. The test method for laser fragmentation of metallic asteroid mineral samples according to claim 2, characterized in that: Determining the highest temperature at the center of the laser spot on the surface of the mineral sample based on the laser loading mode includes the following steps: For the continuous preheating-pulse co-loading mode, the calculation of the highest temperature at the center of the light spot on the mineral sample surface is divided into two stages: The first stage is the continuous laser preheating stage. In this stage, the continuous laser first acts on the surface of the mineral sample, causing the temperature in the central region of the laser spot on the mineral sample surface to rise. When the continuous preheating duration is t1, the highest temperature at the center of the laser spot on the mineral sample surface is expressed as follows: The second stage is the pulsed laser shock stage. A pulsed laser is applied on top of the temperature established by continuous laser preheating, causing the temperature in the central region of the laser spot on the mineral sample surface to continue to rise. Under the conditions that the loading interval between the two stages is negligible, the laser action position remains unchanged, the thermophysical parameters of the mineral sample are considered constant, and the temperature response satisfies linear superposition, the highest temperature at the center of the laser spot on the mineral sample surface when the total duration of the pulse sequence loading stage is t2 is expressed as follows: Where: t1 is the duration of continuous preheating, and t2 is the total duration of the pulse sequence loading phase.

6. A test method for laser fragmentation of metallic asteroid mineral samples according to any one of claims 3 to 5, characterized in that: The experimental environment is corrected for the highest temperature at the center of the light spot on the surface of the mineral sample, including the following steps: An environmental correction factor is introduced to correct for the highest temperature at the center of the light spot on the mineral sample surface. After the environmental correction, the highest temperature at the center of the light spot on the mineral sample surface is expressed as follows: in: This represents the highest temperature at the center of the light spot on the surface of the mineral sample after environmental correction. This refers to the highest temperature at the center of the laser spot on the mineral sample surface, determined according to the corresponding laser loading mode. F represents the initial temperature inside the test environment. v This is the environmental correction factor.

7. The test method for laser fragmentation of metallic asteroid mineral samples according to claim 6, characterized in that: Based on the same mineral sample and the same preset laser loading conditions: When the test environment is normal pressure and room temperature, the normal pressure and room temperature test is used as the baseline operating condition, and the environmental correction factor F is used. v =1; When the test environment is a vacuum cryogenic condition, the environmental correction factor is determined based on the ratio of the temperature rise caused by laser action in a vacuum cryogenic environment to that in a normal pressure and room temperature environment: in: This refers to the highest temperature at the center of the laser spot on the surface of the mineral sample, determined according to the corresponding laser loading mode under vacuum cryogenic conditions. The initial temperature within the test environment under vacuum and low temperature conditions. This represents the highest temperature at the center of the laser spot on the mineral sample surface, determined according to the corresponding laser loading mode under normal pressure and room temperature conditions. The initial temperature is the temperature within the test environment at normal pressure and room temperature.

8. The test method for laser fragmentation of metallic asteroid mineral samples according to claim 7, characterized in that: The thermal stress of the mineral sample is calculated based on the highest temperature at the center of the light spot on the corrected surface, including the following steps: Temperature rise at the center of the light spot on the surface of the mineral sample It is expressed as follows: in: This represents the highest temperature at the center of the light spot on the surface of the mineral sample after environmental correction. The initial temperature inside the test environment; Calculate the thermal stress of the mineral sample based on the thermal stress relationship under constrained thermal expansion conditions. The calculation formula is as follows: Where: E is the elastic modulus of the mineral sample. denoted as the coefficient of linear expansion of the mineral sample, and v as the Poisson's ratio of the mineral sample.

9. The test method for laser fragmentation of metallic asteroid mineral samples according to claim 8, characterized in that: Based on the thermal stress of the mineral sample Calculate the cracking index The calculation formula is as follows: in: This represents the tensile strength of the mineral sample. Based on cracking index Determining the crack state of a mineral sample includes the following steps: when When the thermal stress has not yet reached the tensile strength of the mineral sample, the mineral sample does not undergo obvious thermal cracking. when When the thermal stress reaches or exceeds the tensile strength of the mineral sample, it indicates that the mineral sample has undergone thermal cracking or breakage.

10. A test system for laser fragmentation of metallic asteroid mineral samples, characterized in that: It includes a test environment simulation module, a laser loading module, a temperature acquisition module, and a data terminal; The test environment simulation module is used to construct the test environment; The laser loading module is used to apply preset laser loading conditions to the mineral sample in the test environment and to obtain the laser reflection power P. b and the laser loading time t; The temperature acquisition module is used to acquire surface temperature field data of mineral samples and ambient temperature during testing. The data terminal is used to receive laser reflection power P. b Using the laser loading time t, surface temperature field data of the mineral sample, and ambient temperature information, the cracking state of the mineral sample is calculated and analyzed. The data terminal is also used for: based on laser reflection power P b Combined with laser incident power P a Calculate the effective absorbed power P1 and absorption coefficient of the mineral sample. Based on the temperature field model under the action of a laser heat source, combined with the thermophysical parameters of the mineral sample, effective absorption power P1, and absorption coefficient... Based on the laser loading time t, the surface temperature field data of the mineral sample, and the temperature of the test environment, the highest temperature at the center of the laser spot on the surface of the mineral sample is calculated; the highest temperature at the center of the laser spot on the surface of the mineral sample is determined according to the laser loading mode and the test environment is corrected accordingly; the thermal stress of the mineral sample is calculated based on the corrected highest temperature at the center of the laser spot on the surface of the mineral sample; the cracking index is calculated based on the thermal stress of the mineral sample, and the cracking state of the mineral sample is determined based on the cracking index.

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