Lunar soil coring dynamic process simulation method based on FEM-SPH coupling

Abstract

The invention discloses a lunar soil coring dynamic process simulation method based on FEM-SPH coupling, and the method comprises the steps: building a three-dimensional geometric model of real lunar soil particles based on the scanning data of the real lunar soil particles; establishing a lunar soil discrete element model based on the three-dimensional geometric model; performing a virtual mechanical test on the lunar soil discrete element model, and calibrating lunar soil macromechanical parameters; constructing a drilling tool finite element model, and defining a contact relation between the drilling tool finite element model and the lunar soil; based on the calibrated lunar soil macromechanical parameters, establishing an SPH particle model of the lunar soil; coupling the drilling tool finite element model and the SPH particle model, and performing lunar soil coring dynamic process simulation based on the contact relationship to obtain bedding information disturbance and drilling tool sampling rate results. According to the method, accurate simulation of the dynamic process of lunar soil coring is achieved, and a sampling rate and bedding information disturbance quantitative basis is provided for optimization of drilling tool parameters and drilling working conditions.

Description

Technical Field

[0001] This invention relates to the field of numerical model research technology, and in particular to a simulation method for the dynamic process of lunar soil coring based on FEM-SPH coupling. Background Technology

[0002] In lunar exploration projects, to successfully conduct unmanned lunar surface drilling and astronaut-handled drilling of lunar regolith samples, it is essential to maintain the sampling rate and preserve the morphological characteristics of the lunar regolith profile and the stratigraphic information of the subsurface regolith during shallow sampling. This requires analyzing the interaction between the drilling equipment and the lunar regolith to design the parameters of the drill bit and drill rod, as well as the working conditions for the drilling equipment's forward speed, drill bit rotation speed, and drilling depth. Experimental studies alone cannot reveal the dynamic mechanical behavior and the degree of internal stratification disturbance in the subsurface and deep lunar regolith. Therefore, efficient simulation and analysis of the lunar regolith particle sampling process has become an urgent technical problem to be solved.

[0003] Currently, most existing methods for simulating lunar soil dynamics employ FEM (Finite Element Method) and DEM (Discrete Element Method). However, for large deformation problems in lunar soil drilling, the finite element method is prone to mesh distortion and deformation, affecting computational accuracy. The discrete element method calculates by tracking the motion and stress state of particles, typically solving for all particles within the computational domain. Due to the extremely small size and large number of lunar soil particles, simulation using the discrete element method is extremely time-consuming.

[0004] Among existing patent technologies, invention patent CN118981892A discloses a simulation analysis method and system for the dynamic influence of irregular large particles in lunar soil drilling. It establishes a lunar soil drilling model, designs different simulation control groups, including angular large particle conditions and elongated large particle conditions, analyzes the shape relationship between the drill bit and the large particles and their influence on the axial force, torsional torque, large particle trajectory, and sampling volume of the drill bit, and plots force-load curves for simulation analysis. This method considers, to some extent, the influence of irregular large particles in lunar soil on the drilling process. Invention patent CN119180107A discloses a method and system for predicting lunar soil drilling sampling volume based on multi-dimensional telemetry data. It collects drilling operation test data, classifies drilling operations into stable and disturbed stages, extracts load response characteristic signals, and constructs prediction models for the stable and disturbed sampling stages to predict the drilling sampling volume. This method is applicable to the field of drilling sampling volume prediction.

[0005] However, existing technologies still have significant shortcomings. While the scheme in publication CN118981892A simulates the impact of irregular large particles, its method primarily focuses on analyzing the influence of large particles of different shapes and sizes on the drilling process. It does not elaborate on how to construct a high-precision model of realistic lunar regolith materials, especially how to handle the dynamic behavior of numerous fine particles in the lunar regolith and their interaction with the drill bit. This makes it difficult to solve the problem of efficiently simulating the dynamic process of drilling and coring after the accumulation of massive amounts of lunar regolith particles. The scheme in publication CN119180107A focuses on using multidimensional telemetry data to estimate the sampling volume, but it does not fully consider the complex mechanical properties and particle characteristics of the lunar regolith itself on the drilling process. It lacks refined modeling and simulation of the dynamic process of lunar regolith coring and cannot provide detailed mechanical analysis of the interaction between the drill bit and the lunar regolith, making it difficult to comprehensively guide drill bit design and drilling scheme optimization.

[0006] Therefore, there is an urgent need to provide a technical solution to address the above problems. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a simulation method for the dynamic process of lunar soil coring based on FEM-SPH coupling.

[0008] In a first aspect, the present invention provides a simulation method for the dynamic process of lunar soil coring based on FEM-SPH coupling, the technical solution of which is as follows: Based on the scanning data of real lunar soil particles, a three-dimensional geometric model of the real lunar soil particles is constructed. Based on the aforementioned three-dimensional geometric model, a discrete element model of lunar soil is established; Virtual mechanical experiments were conducted on the discrete element model of lunar soil to calibrate the macroscopic mechanical parameters of lunar soil. Construct a finite element model of the drill bit and define the contact relationship between the finite element model of the drill bit and the lunar soil; Based on the calibrated macroscopic mechanical parameters of lunar soil, an SPH particle model of lunar soil was established. The finite element model of the drill bit is coupled with the SPH particle model, and the dynamic process of lunar soil coring is simulated based on the contact relationship to obtain the results of bedding information disturbance and drill bit sampling rate.

[0009] The beneficial effects of the simulation method for dynamic processes of lunar soil coring based on FEM-SPH coupling of the present invention are as follows: The method of this invention solves the problems of mesh distortion in the traditional finite element method and the computational time of the pure discrete element method. It makes up for the shortcomings of existing technologies in accurately simulating the dynamic behavior of massive lunar soil particles and bedding disturbances, realizes accurate simulation of the dynamic process of lunar soil coring, and provides a quantitative basis for sampling rate and bedding information disturbance for the optimization of drilling parameters and drilling conditions.

[0010] Based on the above scheme, the simulation method for dynamic process of lunar soil coring based on FEM-SPH coupling of the present invention can be further improved as follows.

[0011] In one alternative approach, the step of constructing a three-dimensional geometric model of the real lunar regolith particles based on scan data of the real lunar regolith particles includes: Obtain real lunar soil particle samples; The real lunar soil particle sample was scanned using a computed tomography (CT) scanner to generate the scan data of the real lunar soil particles. The scanned data is reconstructed using a 3D reconstruction algorithm to generate 3D volume data of the real lunar soil particles. The three-dimensional volume data is segmented and surface mesh is generated to obtain the three-dimensional geometric model of the real lunar soil particles.

[0012] The advantages of adopting the above-mentioned optional methods are as follows: further obtaining the real geometric shape of lunar soil particles through computed tomography and 3D reconstruction technology, combined with image segmentation and surface mesh generation, provides an accurate geometric basis for subsequent discrete element modeling and improves the consistency between the model and the real lunar soil particle shape.

[0013] In one alternative approach, the step of establishing a discrete element model of lunar regolith based on the three-dimensional geometric model includes: The three-dimensional geometric model is discretized into multiple spherical particles using the multi-sphere approximation method; The plurality of spherical particles are filled into the interior of the three-dimensional geometric model to form a spherical model of lunar soil particles; Based on the spherical cluster model, and combined with the preset contact mechanics model and micromechanical parameters, the discrete element model of lunar soil is established.

[0014] The advantages of adopting the above-mentioned optional method are as follows: by further using the multi-sphere approximation method to discretize the complex particle shape into a spherical cluster model, the computational complexity is reduced while retaining the geometric features. By combining the contact mechanics model and the microscopic parameters to establish a discrete element model, an accurate description of the microscopic mechanical behavior of lunar soil can be achieved.

[0015] In one alternative approach, the step of conducting virtual mechanical experiments on the discrete element model of lunar regolith to calibrate the macroscopic mechanical parameters of lunar regolith includes: Based on the preset gradation distribution, a cylindrical particle pack sample is generated using the lunar soil discrete element model. A virtual triaxial compression test was performed on the cylindrical particle pile specimen, applying confining pressure and axial load to the cylindrical particle pile specimen; The peak axial stress of the cylindrical particle pack sample was obtained under various confining pressure conditions. Based on the various confining pressure conditions and the corresponding peak axial stress, the Mohr-Coulomb strength envelope is fitted to obtain the following: Based on the Mohr-Coulomb strength envelope, the internal friction angle and cohesion are calculated and used as the macroscopic mechanical parameters of the calibrated lunar soil.

[0016] The advantages of adopting the above-mentioned optional method are as follows: the peak axial stress under different confining pressures can be obtained through virtual triaxial compression tests, the internal friction angle and cohesion can be calculated by fitting the Mohr-Coulomb strength envelope, the correlation between microscopic parameters and macroscopic mechanical properties can be established, and reliable parameter input can be provided for the SPH model.

[0017] In one alternative approach, the step of constructing a finite element model of the drill bit and defining the contact relationship between the finite element model of the drill bit and the lunar regolith includes: A three-dimensional solid geometric model of the drill bit is constructed, and the three-dimensional solid geometric model is meshed using finite element methods to generate a finite element model of the drill bit. A contact pair is established between the drill bit surface of the finite element model of the drill bit and the equivalent layer of lunar soil, and normal contact behavior and tangential contact behavior are defined in the contact pair to determine the contact relationship between the finite element model of the drill bit and the lunar soil.

[0018] The advantages of adopting the above-mentioned optional methods are as follows: further constructing a three-dimensional solid finite element model of the drill bit and dividing it into meshes, establishing a contact pair between the drill bit surface and the equivalent layer of lunar soil, defining normal and tangential contact behaviors, accurately describing the interaction mechanism between the drill bit and the lunar soil, and providing a basis for contact force calculation for coupled simulation.

[0019] In one alternative approach, the step of establishing the SPH particle model of lunar soil based on the calibrated macroscopic mechanical parameters of lunar soil includes: SPH particles are generated based on the geometric boundaries of the drilling area; The calibrated macroscopic mechanical parameters of lunar soil are assigned to the SPH particles to obtain SPH particles with assigned parameters. Configure the neighborhood search algorithm and GPU parallel computing environment; Establish an SPH particle model of the lunar soil that includes the SPH particles with the assigned parameters, the neighborhood search algorithm, and the GPU parallel computing environment.

[0020] The advantages of adopting the above optional method are: further generating SPH particles based on the geometry of the drilling area and assigning them with calibrated macroscopic mechanical parameters, configuring a neighborhood search algorithm and a GPU parallel computing environment, improving the computational efficiency of large-scale particle models, and realizing the rapid solution of large deformation behavior of lunar soil.

[0021] In one alternative approach, the step of coupling the drill string finite element model with the SPH particle model and simulating the dynamic process of lunar soil coring based on the contact relationship to obtain the bedding information disturbance and drill string sampling rate results includes: The finite element model of the drill bit is coupled with the SPH particle model of the lunar soil using FEM-SPH coupling. During the coupled solution process, the interaction between the drill bit and the lunar soil is calculated based on the contact relationship. The neighborhood search algorithm and the GPU parallel computing environment are applied to update the motion state of the particles in the SPH particle model of the lunar soil and extract the displacement field and stress field data of the particles in the SPH particle model of the lunar soil. Based on the displacement field and stress field data, the perturbation of the bedding information and the sampling rate of the drill bit are determined.

[0022] The advantages of adopting the above-mentioned optional methods are as follows: further realizing the collaborative solution of the drill string and lunar soil through FEM-SPH coupling, applying neighborhood search and GPU parallel computing to update the particle motion state, extracting displacement field and stress field data, and accurately quantifying the degree of perturbation of bedding information and the sampling rate results of the drill string.

[0023] Secondly, this invention provides a simulation system for the dynamic process of lunar soil coring based on FEM-SPH coupling. The technical solution of this system is as follows: A construction module is used to construct a three-dimensional geometric model of the real lunar soil particles based on the scanning data of the real lunar soil particles; A module is established to build a discrete element model of lunar soil based on the three-dimensional geometric model. The calibration module is used to conduct virtual mechanical experiments on the lunar soil discrete element model and calibrate the macroscopic mechanical parameters of the lunar soil. A definition module is used to construct a finite element model of the drill bit and define the contact relationship between the finite element model of the drill bit and the lunar soil; The generation module is used to establish the SPH particle model of lunar soil based on the calibrated macroscopic mechanical parameters of lunar soil. The simulation module is used to couple the finite element model of the drill bit with the SPH particle model, and to simulate the dynamic process of lunar soil coring based on the contact relationship, so as to obtain the results of bedding information disturbance and drill bit sampling rate.

[0024] The beneficial effects of the FEM-SPH-based simulation system for dynamic processes of lunar soil coring according to the present invention are as follows: The system of this invention solves the problems of mesh distortion in the traditional finite element method and the computation time of the pure discrete element method. It makes up for the shortcomings of existing technologies in accurately simulating the dynamic behavior of massive lunar soil particles and bedding disturbances, realizes accurate simulation of the dynamic process of lunar soil coring, and provides a quantitative basis for sampling rate and bedding information disturbance for the optimization of drilling parameters and drilling conditions.

[0025] Thirdly, the technical solution of an electronic device according to the present invention is as follows: It includes a memory, a processor, and a program stored in the memory and running on the processor, wherein the processor executes the program to implement the steps of the simulation method for dynamic process of lunar soil coring based on FEM-SPH coupling as described in this invention.

[0026] Fourthly, the technical solution of a computer-readable storage medium provided by the present invention is as follows: The computer-readable storage medium stores instructions that, when read, cause the computer-readable storage medium to perform the steps of the simulation method for dynamic processes of lunar soil coring based on FEM-SPH coupling of the present invention.

[0027] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0028] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a flowchart illustrating an embodiment of the simulation method for dynamic processes of lunar soil coring based on FEM-SPH coupling according to the present invention. Figure 2 This is a simulation flowchart; Figure 3 This is a schematic diagram of an embodiment of a simulation system for dynamic processes of lunar soil coring based on FEM-SPH coupling according to the present invention. Figure 4 This is a schematic diagram of an embodiment of an electronic device according to the present invention. Detailed Implementation

[0029] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0030] Figure 1This diagram illustrates a flowchart of an embodiment of a dynamic simulation method for lunar regolith coring based on FEM-SPH coupling provided by the present invention. This simulation method can be executed by electronic devices such as terminal devices or servers. The terminal device can be any fixed or mobile terminal, such as user equipment (UE), mobile device, user terminal, terminal, cellular phone, cordless phone, personal digital assistant (PDA), handheld device, computing device, vehicle-mounted device, or wearable device. The server can be a single server or a server cluster consisting of multiple servers. Any electronic device can implement the FEM-SPH coupling-based dynamic simulation method for lunar regolith coring by having its processor call computer-readable instructions stored in its memory. Figure 1 As shown, it includes the following steps: S1. Based on the scanning data of real lunar soil particles, construct a three-dimensional geometric model of the real lunar soil particles.

[0031] Among these, "real lunar regolith particles" refers to solid particles obtained from the lunar surface that retain their original morphology and mineral composition; for example, individual particles with a diameter ranging from 20 to 1000 micrometers, intact surface morphology, and sharp edges selected from lunar regolith samples obtained from lunar sample return missions. "Scanning data" refers to the raw data set obtained by scanning an object using scanning instruments, reflecting the object's internal structure or surface morphology; for example, a series of two-dimensional projection images acquired by using a high-precision micro-CT system to perform multi-angle rotational scanning of selected real lunar regolith particles. "Three-dimensional geometric model" refers to a digital model built in a computer that accurately describes the three-dimensional shape and contour of an object; for example, a model file generated after three-dimensional reconstruction and surface reconstruction of the lunar regolith particle scanning data, representing the particle's shape using a network of triangular facets.

[0032] S2. Based on the three-dimensional geometric model, establish a discrete element model of lunar soil.

[0033] Among them, the lunar soil discrete element model refers to a numerical model that discretizes the lunar soil medium into a series of independently moving and interacting particle units, and describes its overall mechanical behavior through inter-particle contact mechanics; for example, a particle cluster model is formed by filling and approximating a three-dimensional geometric model of a real lunar soil particle with hundreds of closely packed spherical units.

[0034] S3. Conduct virtual mechanical tests on the discrete element model of lunar soil to calibrate the macroscopic mechanical parameters of lunar soil.

[0035] Virtual mechanical testing refers to the numerical testing process of applying simulated mechanical loads and boundary conditions to an established numerical model in a computer simulation environment to obtain its mechanical response; for example, in discrete element method (DEM) software, simulated confining pressure and axial compressive loads are applied to a virtual cylindrical specimen composed of a lunar regolith discrete element model stacked at a specific scale. Macroscopic mechanical parameters of lunar regolith refer to key physical quantities used to characterize the overall mechanical behavior of lunar regolith materials under the assumption of a continuous medium; for example, the internal friction angle and cohesion obtained through virtual mechanical testing analysis, used to describe the shear strength of lunar regolith.

[0036] S4. Construct a finite element model of the drill bit and define the contact relationship between the finite element model of the drill bit and the lunar soil.

[0037] Among them, the finite element model of the drill bit refers to a numerical model that discretizes the solid structure of the drill bit into a mesh composed of nodes and elements for structural stress and deformation analysis; for example, a model containing hundreds of thousands of individual elements and assigned alloy steel material properties after meshing the three-dimensional solid of the drill bit. Lunar regolith refers to a model object that represents the weathered layer of the lunar surface in the simulation environment and is assigned specific physical and mechanical properties; for example, an aggregate composed of a large number of particles with mass and strength parameters that represents the object of the drill bit in the simulation. Contact relationship refers to the predefined rules of force and motion transmission that are followed when different components or models come into physical contact in numerical simulation; for example, when the drill bit surface comes into contact with the lunar regolith surface, the normal direction is not allowed to penetrate and can be separated, while the tangential direction adopts a slip model based on the friction coefficient.

[0038] S5. Based on the calibrated macroscopic mechanical parameters of lunar soil, establish the SPH particle model of lunar soil.

[0039] The calibrated macroscopic mechanical parameters of lunar regolith refer to a set of macroscopic mechanical parameters of lunar regolith that are ultimately adopted after the model's mechanical response is matched with the target characteristics through virtual mechanical experiments. For example, after parameter adjustment and virtual experimental verification, the final internal friction angle of lunar regolith used for simulation is determined to be 28°, and the cohesion is 1.2 kPa. The SPH particle model refers to a numerical model that uses the smoothed particle hydrodynamics method to discretize the continuous medium into a series of moving particles carrying physical properties such as mass, momentum, and energy, and calculates field variables through kernel function approximation. For example, 100,000 moving particles generated in a set drilling space, each carrying the calibrated lunar regolith density, internal friction angle, and other properties.

[0040] S6. Couple the finite element model of the drill bit with the SPH particle model, and simulate the dynamic process of lunar soil coring based on the contact relationship to obtain the results of bedding information disturbance and drill bit sampling rate.

[0041] The simulation of the lunar soil coring dynamic process refers to the numerical simulation of the entire process of the drill bit entering the lunar soil, the large deformation and flow of the lunar soil, and the sampling and collection. For example, the drill bit's rotation speed and feed rate are set to simulate the drilling into the lunar soil SPH particle model, and the particle motion, stress changes, and drill bit stress are calculated in real time. Bedding information disturbance refers to the quantitative degree of deformation, mixing, or destruction of the original layered structure of the lunar soil under mechanical action during drilling. For example, by comparing the positions of lunar soil particles at different depths before and after the simulation, the standard deviation of their vertical displacement is calculated as a quantitative indicator of bedding disturbance. The drill bit sampling rate result refers to the percentage of the actual volume of lunar soil samples obtained by the drill bit, calculated through simulation, relative to the theoretically accommodating volume of the drill bit. For example, after the simulation, the total volume of lunar soil particles successfully captured and retained in the coring tube is counted, and the sampling rate is calculated to be 85%.

[0042] The technical solution of this embodiment solves the problems of mesh distortion in the traditional finite element method and the computation time of the pure discrete element method. It makes up for the shortcomings of existing technologies in accurately simulating the dynamic behavior of massive lunar soil particles and bedding disturbances, realizes accurate simulation of the dynamic process of lunar soil coring, and provides a quantitative basis for sampling rate and bedding information disturbance for the optimization of drilling parameters and drilling conditions.

[0043] In one alternative approach, S1 specifically includes: Obtain real lunar soil particle samples.

[0044] Among them, the real lunar soil particle sample refers to the physical lunar soil particle entity used for scanning to obtain the original morphological data; for example, several single lunar soil particles selected from lunar return samples and prepared to be placed on the sample stage of the scanning equipment.

[0045] The real lunar soil particle sample was scanned using a computed tomography (CT) scanner to generate the scan data of the real lunar soil particles.

[0046] Among them, computed tomography (CT) equipment refers to an instrument that can reconstruct a three-dimensional image of the internal structure of an object by emitting rays and receiving signals after the rays penetrate the object from multiple angles; for example, a micro-CT system used in the laboratory to perform high-resolution scanning of lunar soil particles.

[0047] The scanned data is reconstructed using a 3D reconstruction algorithm to generate 3D volume data of the real lunar soil particles.

[0048] Among them, the 3D reconstruction algorithm refers to the calculation method of reconstructing a series of two-dimensional projected image data of an object into three-dimensional spatial distribution data through mathematical transformation; for example, using a filtered back projection algorithm, the sequence of projected images of lunar soil particles from multiple angles can be calculated and restored into a three-dimensional grayscale data volume. 3D volume data refers to a three-dimensional discrete data field composed of voxels as basic units, where each voxel contains density or grayscale information; for example, after CT scanning and 3D reconstruction of lunar soil particles, a data block with 1000 voxels in length, width, and height, each voxel storing the material's X-ray absorption coefficient value, is obtained.

[0049] The three-dimensional volume data is segmented and surface mesh is generated to obtain the three-dimensional geometric model of the real lunar soil particles.

[0050] Image segmentation and surface mesh generation refers to the process of separating the target object region from three-dimensional volume data based on grayscale or gradient information, and extracting its surface geometric information to generate a continuous curved surface mesh. For example, using image processing software, a threshold segmentation algorithm is used to identify lunar soil particles from the background, and then a moving cube algorithm is used to generate a triangular mesh model of its surface.

[0051] In the above-mentioned optional methods, the real geometric morphology of lunar soil particles is further obtained through computed tomography and 3D reconstruction technology. Combined with image segmentation and surface mesh generation, it provides an accurate geometric basis for subsequent discrete element modeling and improves the consistency between the model and the real lunar soil particle shape.

[0052] In one alternative approach, S2 specifically includes: The three-dimensional geometric model is discretized into multiple spherical particles using the multi-sphere approximation method.

[0053] The multi-sphere approximation method refers to a mathematical approach that uses a set of multiple spherical units to approximate a complex geometric shape. For example, to simulate an irregular lunar regolith grain in the discrete element method, its surface mesh model is decomposed into a combination of 500 tightly packed spheres of different diameters. Multiple spherical grains refer to the various spherical basic units used in the multi-sphere approximation method to approximate the target shape; for example, 500 spheres used to fill and represent the shape of an angular lunar regolith grain, each sphere having a defined center coordinate and radius.

[0054] The multiple spherical particles are filled into the interior of the three-dimensional geometric model to form a spherical model of lunar soil particles.

[0055] Among them, the spherical cluster model refers to a model formed by the aggregation of multiple spherical particles through the multi-sphere approximation method, which is used to represent a single complex-shaped particle in the discrete element method; for example, a collection of 500 spherical particles bound together by internal connections to represent a soil particle.

[0056] Based on the spherical cluster model, and combined with the preset contact mechanics model and micromechanical parameters, the discrete element model of lunar soil is established.

[0057] In this context, the contact mechanics model refers to a constitutive model that quantitatively describes the relationship between the normal and tangential forces generated by the overlap between two contacting particles in the discrete element method (DEM). For example, the Hertz-Mundling contact model is used to calculate the elastic, frictional, and damping forces between two contacting lunar regolith spheres. Micromechanical parameters refer to the fundamental physical parameters that define the material properties of the particles themselves and the contact behavior between them in the discrete element particle model. For example, the Young's modulus and Poisson's ratio assigned to each spherical element in the lunar regolith cluster model, as well as the static friction coefficient and coefficient of restitution for inter-particle contact.

[0058] Among the above-mentioned alternative methods, the multi-sphere approximation method is further used to discretize the complex particle shape into a spherical cluster model, which reduces the computational complexity while preserving the geometric features. By combining the contact mechanics model and the microscopic parameters, a discrete element model is established to achieve an accurate description of the microscopic mechanical behavior of lunar soil.

[0059] In one alternative approach, S3 includes: Based on the preset gradation distribution, a cylindrical particle accumulation sample is generated using the lunar soil discrete element model.

[0060] The preset gradation distribution refers to the pre-defined plan for the quantity or mass proportion of particles of different sizes when generating the particle aggregate; for example, based on the particle size analysis report of lunar soil, it is set that when generating the particle bed, particles with a diameter of 20-50 micrometers account for 30%, particles with a diameter of 50-100 micrometers account for 40%, and so on. A cylindrical particle pack sample refers to a cylindrical model formed by randomly stacking discrete element particles in virtual space according to specified dimensions and gradation; for example, a lunar soil particle pack column with a height of 80 mm and a diameter of 30 mm used for virtual triaxial compression tests.

[0061] A virtual triaxial compression test was performed on the cylindrical particle pile specimen, applying confining pressure and axial load to the cylindrical particle pile specimen.

[0062] The virtual triaxial compression test refers to the process of simulating a standard triaxial test for soil and rock in a numerical simulation environment, applying a constant confining pressure and a gradually increasing axial load to a cylindrical specimen. For example, in discrete element software, a constant confining pressure of 100 kPa is first applied to a lunar soil cylindrical specimen, and then the upper and lower pressure plates are moved at a constant rate to apply axial compression. Applying confining pressure and axial load refers to simulating the uniform pressure loading on the side of the specimen and the compressive force loading on the end face of the specimen in the virtual triaxial test. For example, a confining pressure of 50 kPa is applied and maintained by a movable wall surrounding the side of the cylindrical specimen in the simulation; at the same time, an axial load is applied by the rigid pressure plate at the top moving downwards at a speed of 0.05 mm / s.

[0063] The peak axial stress of the cylindrical particle pack sample was obtained under various confining pressure conditions.

[0064] The confining pressure condition refers to the constant lateral pressure applied in the triaxial test; for example, three different confining pressure values ​​of 50 kPa, 100 kPa, and 150 kPa are set in the virtual test. The peak axial stress refers to the maximum value reached by the axial stress of the specimen as strain increases during triaxial compression; for example, under a confining pressure of 100 kPa, the axial stress of the lunar soil specimen reaches a maximum of 280 kPa when the strain increases by 20%, and this 280 kPa is the peak axial stress.

[0065] Based on the various confining pressure conditions and the corresponding peak axial stress, the Mohr-Coulomb strength envelope is obtained by fitting.

[0066] The Mohr-Coulomb strength envelope refers to the common tangent of the Mohr stress circles corresponding to material failure under different confining pressures, used to determine the shear strength parameters of the material. For example, the peak strengths obtained under three confining pressures are plotted on the normal stress-shear stress plane to obtain three Mohr circles, and a common tangent is drawn for them.

[0067] Based on the Mohr-Coulomb strength envelope, the internal friction angle and cohesion are calculated and used as the macroscopic mechanical parameters of the calibrated lunar soil.

[0068] The internal friction angle refers to the angle corresponding to the tangent of the angle between the strength envelope and the normal stress axis in the Mohr-Coulomb strength criterion, characterizing the frictional properties of the material. Cohesion refers to the intercept of the strength envelope on the shear stress axis in the Mohr-Coulomb strength criterion, characterizing the bond strength of the material.

[0069] In the above-mentioned optional methods, the peak axial stress under different confining pressures is further obtained through virtual triaxial compression tests. The internal friction angle and cohesion are calculated by fitting the Mohr-Coulomb strength envelope, and the correlation between microscopic parameters and macroscopic mechanical properties is established, providing reliable parameter input for the SPH model.

[0070] In one alternative approach, S4 specifically includes: A three-dimensional solid geometric model of the drilling tool is constructed, and the three-dimensional solid geometric model is meshed using finite element methods to generate the finite element model of the drilling tool.

[0071] Finite element mesh generation refers to the process of decomposing a continuous geometric structure into a set of regularly shaped small units (such as tetrahedrons and hexahedrons) that are interconnected by nodes. For example, an imported 3D solid model of a drill bit can be automatically meshed to generate a finite element mesh containing approximately 500,000 tetrahedral units.

[0072] A contact pair is established between the drill bit surface of the finite element model of the drill bit and the equivalent layer of lunar soil, and normal contact behavior and tangential contact behavior are defined in the contact pair to determine the contact relationship between the finite element model of the drill bit and the lunar soil.

[0073] In this context, "drill bit surface" refers to the set of element surfaces in the finite element model of the drill bit that directly contact and interact with the lunar regolith medium; for example, in the finite element mesh of the drill bit, these element surfaces represent the drill bit cutting edge, chip flute surface, and part of the drill pipe outer wall. "Lunar regolith equivalent layer" refers to the model boundary used to represent the lunar regolith medium region interacting with the drill bit when defining contact; for example, in a coupled simulation setup, the leading edge particle boundary near the drill bit in the SPH particle model is equivalently defined as a continuous geometric surface. "Contact pair" refers to a pre-specified combination of a controlling surface and a subordinate surface that may interact in finite element or coupled analysis; for example, defining the drill bit surface element group as the controlling surface and the lunar regolith equivalent layer geometric surface as the subordinate surface constitutes a complete contact pair.

[0074] The normal contact behavior refers to defining the mechanical response rules of the contact pair in the normal direction at the contact point, mainly controlling penetration and separation. For example, the normal behavior of the contact pair can be defined as "hard contact," which strictly prohibits mutual penetration between the master and slave surfaces and allows separation after contact. The tangential contact behavior refers to defining the mechanical response rules of the contact pair in the tangential direction at the contact point, mainly controlling friction and slippage. For example, the tangential behavior of the contact pair can be defined as a "penalty function" model based on Coulomb friction, with a friction coefficient of 0.3.

[0075] In the above-mentioned optional methods, a three-dimensional solid finite element model of the drill bit is further constructed and meshed, a contact pair between the drill bit surface and the equivalent layer of lunar soil is established, the normal and tangential contact behaviors are defined, the interaction mechanism between the drill bit and the lunar soil is accurately described, and the contact force calculation basis is provided for coupled simulation.

[0076] In one alternative approach, S5 specifically includes: SPH particles are generated based on the geometric boundaries of the drilling area.

[0077] The geometric boundary of the drilling area refers to the spatial region outline used to define the initial generation range of lunar soil SPH particles in the simulation space; for example, a cuboid region with dimensions of 50mm × 50mm × 60mm located directly below the drill bit. An SPH particle is a basic computational unit in the smoothed particle hydrodynamics method, a discrete point carrying physical properties such as mass, position, velocity, and stress; for example, within the defined cuboid drilling area, 120,000 discrete points uniformly spaced at an initial interval of 0.5mm each constitute an SPH particle.

[0078] The calibrated macroscopic mechanical parameters of lunar soil are assigned to the SPH particles to obtain SPH particles with assigned parameters.

[0079] Here, the SPH particles with assigned parameters refer to SPH particles whose macroscopic mechanical parameters have been assigned; for example, after the SPH particles are generated, each particle is uniformly assigned a calibrated lunar regolith density of 1800 kg / m³. 3 Properties include an internal friction angle of 28° and a cohesive force of 1.2 kPa.

[0080] Configure the neighborhood search algorithm and GPU parallel computing environment.

[0081] Neighborhood search algorithms, in particle-based methods, refer to algorithms used to efficiently find all neighboring particles within the influence domain of each particle. For example, the entire computational domain is divided into uniform grid cells, and particles are assigned to corresponding grids based on their coordinates. Each particle only needs to determine its neighbors with particles in the same and adjacent grids. GPU parallel computing environments refer to hardware and software configurations that utilize graphics processing unit (GPU) hardware and its parallel computing architecture to accelerate large-scale computational tasks. For example, all SPH particle data is transferred to the GPU's video memory, and parallel computing kernel functions are written to utilize tens of thousands of threads to simultaneously calculate the interaction forces between particles.

[0082] Establish an SPH particle model of the lunar soil that includes the SPH particles with the assigned parameters, the neighborhood search algorithm, and the GPU parallel computing environment.

[0083] In the above-mentioned optional methods, SPH particles are further generated based on the geometry of the drilling area and assigned calibrated macroscopic mechanical parameters. A neighborhood search algorithm and a GPU parallel computing environment are configured to improve the computational efficiency of large-scale particle models and achieve rapid solution of large deformation behavior of lunar soil.

[0084] In one alternative approach, S6 specifically includes: The finite element model of the drill bit is coupled with the SPH particle model of the lunar soil using FEM-SPH coupling.

[0085] FEM-SPH coupling refers to the technique of combining the finite element method with the smoothed particle fluid dynamics method in the same simulation, so that the two can work together to solve the dynamic problems of different components. For example, the structural dynamics of the drill is solved by the finite element method, while the large deformation flow of lunar soil is solved by the smoothed particle fluid dynamics method. The two exchange forces and motion information through the contact interface.

[0086] During the coupled solution process, the interaction between the drill bit and the lunar soil is calculated based on the contact relationship. The neighborhood search algorithm and the GPU parallel computing environment are applied to update the motion state of the particles in the SPH particle model of the lunar soil and extract the displacement field and stress field data of the particles in the SPH particle model of the lunar soil.

[0087] The coupled solution process refers to the alternating or synchronous execution of calculation steps by the finite element solver and the smoothed particle hydrodynamics solver, and the advancement of the transient dynamic evolution of the entire system through data transfer. For example, within each time step, the force exerted by the drill bit on the lunar soil particles is first calculated based on the contact state, and the particle motion is updated. Then, the reaction force of the lunar soil particles is applied to the drill bit mesh nodes, and the drill bit motion is updated. The interaction between the drill bit and the lunar soil refers to the mutual forces and torques generated by the finite element model of the drill bit and the lunar soil model through the defined contact relationship in the coupled simulation. For example, the cutting edge of the drill bit presses against the lunar soil particles in front, generating normal contact force and tangential friction force. At the same time, the lunar soil particles generate equal and opposite reaction forces and drag torques on the drill bit. The motion state refers to the set of kinematic information possessed by the objects or particles in the model at a certain moment in the simulation. For example, at a certain calculation time point, the three-dimensional coordinates, velocity vector, and acceleration vector of a certain SPH particle together describe its current motion state. Displacement field refers to the spatial distribution of displacement vectors generated by all particles or nodes within the spatial region covered by the model at a certain moment or time interval; for example, after the drilling simulation, the spatial distribution map composed of the displacement data of all lunar soil SPH particles relative to their initial positions. Stress field data refers to the spatial distribution information of the stress tensor borne by all particles or elements within the spatial region covered by the model; for example, during the drilling process, the hydrostatic pressure and deviatoric stress data borne by lunar soil SPH particles can be used to analyze the compaction state and shear failure zone of lunar soil.

[0088] Based on the displacement field and stress field data, the perturbation of the bedding information and the sampling rate of the drill bit are determined.

[0089] In the above-mentioned optional methods, FEM-SPH coupling is further used to achieve collaborative solution between the drill string and lunar soil. Neighborhood search and GPU parallel computing are applied to update the particle motion state, extract displacement field and stress field data, and accurately quantify the degree of perturbation of bedding information and the sampling rate of the drill string.

[0090] To better illustrate the technical solution of this embodiment, the following complete example is used for explanation, such as... Figure 2 As shown, specifically: 1) Sample Processing Steps: Particles with typical mineral composition characteristics were screened from real lunar soil samples. The specific process included mechanically dispersing aggregated particles and separating single-particle samples with a particle size distribution ranging from 20 μm to 1000 μm using a dry sieving method. Damaged particles were removed by secondary sieving using an optical microscope, retaining single-particle samples with intact surface morphology and clear angular features. All samples underwent surface dust removal pretreatment in a constant temperature and humidity environment.

[0091] 2) Computed tomography (CT) scans were performed on real lunar soil particle samples. Scanning parameters were set to a spatial resolution of 0.5 μm, tube voltage of 80 kV, and exposure time of 1.5 s / frame, with 3600 projection images acquired for each sample. A dual-axis rotary stage was used to achieve full-angle three-dimensional coverage during the scanning process. Phase contrast imaging mode was activated for specific mineral compositions.

[0092] 3) The 3D reconstruction algorithm processes the scanned data to generate 3D volumetric data of real lunar soil particles. Subsequently, image segmentation and surface mesh generation are performed to obtain a high-fidelity 3D surface mesh model, which can be exported in STL and OBJ formats. The resulting model records multiple morphological parameters of the particles, including edge curvature, cavity depth, and specific surface area.

[0093] 4) The discrete element method for constructing the lunar regolith model employs a multi-sphere approximation method. This method decomposes the three-dimensional geometric model of real lunar regolith particles into a set of sphere clusters, minimizing the geometric deviation between the target particle surface and the sphere cluster envelope. The implementation process involves dividing the envelope of the geometric model into a uniform cubic mesh, generating candidate spheres within each mesh cell. Through mesh generation and sphere arrangement, spherical filling is achieved, approximating the irregular shape of the lunar regolith particles. The minimum radius of the generated spheres is approximately 1 / 50th of the particle size, and the coverage is optimized by merging adjacent spheres.

[0094] The contact mechanics model employs the Hertz-Mindlin interaction model. The model assumes the particles are elastic and isotropic materials. The normal force is based on Hertz theory. Among them, normal stiffness for: Equivalent Young's modulus for: equivalent radius for: The normal overlap is (m). Elastic modulus (Pa); is the particle geometric radius (m); Let be Poisson's ratio. The normal damping force is: equivalent quality for: Damping coefficient for: Normal and tangential stiffness for: The coefficient of recovery, The relative velocity normal component (m / s). Based on Mindlin theory, the tangential force... for: It is the equivalent shear modulus (Pa). ; Let be the static friction coefficient. The tangential damping force is: Let be the tangential component of the relative velocity (m / s). Rolling friction is: The coefficient of rolling friction; The distance from the contact point to the center of mass (m); This is the unit angular velocity vector at the point of contact.

[0095] The initial assumption for the microscopic parameters of lunar soil particles is: Poisson's ratio. The elastic modulus is 0.25. The static friction coefficient is 70-110 GPa. The rolling friction coefficient is 0.8. The coefficient of recovery is 0.3. It is 0.1.

[0096] 5) The particle aggregate is generated according to a preset gradation distribution. The particle bed is divided into regular cubic units, and efficiency is optimized through a segmented material generation and stacking method. The size of the segmented materials meets the requirements. , The maximum particle size is defined. Particles within a single material block are randomly distributed according to a preset volume fraction, and a Poisson disk sampling algorithm is used to ensure minimum spacing. The material blocks are then re-stacking from cubic units, layer by layer, along the direction of gravity.

[0097] 6) Virtual triaxial compression test to calibrate the macroscopic mechanical parameters of lunar soil. A cylindrical granular aggregate specimen with a height of 80 mm and a diameter of 30 mm was generated. A constant confining pressure was applied to the sides of the specimen during the test. Rigid walls at the top and bottom acted as loading plates to apply axial pressure at a loading rate of 0.05 m / s. Peak axial stresses under various confining pressure conditions were obtained, and the Mohr stress circle was plotted and its envelope fitted.

[0098] internal friction angle Calculated according to the Mohr-Coulomb criterion: For axial stress, Confining pressure. Cohesion. The calculation formula is: The model solution based on the SPH particle method uses the particle motion equations: For particle velocity, This is a smooth kernel function.

[0099] 7) Apply a neighborhood search algorithm to reduce computational complexity. Divide the computational domain into a uniform grid, and particles are mapped to grid cells according to their coordinates. Only particles in adjacent cells participate in interactive computation. The neighbor particle index is updated periodically to reduce search overhead.

[0100] 8) GPU parallel computing allocates particle data to video memory and uses parallel thread blocks to process particle search and force calculation. Resources are dynamically allocated based on particle density, and an artificial viscosity term is introduced and the smoothing length is dynamically adjusted to maintain numerical stability.

[0101] Figure 3 This diagram illustrates a structural schematic of an embodiment of a simulation system 200 for dynamic processes of lunar soil coring based on FEM-SPH coupling provided by the present invention. Figure 3 As shown, the simulation system 200 for the dynamic process of lunar soil coring based on FEM-SPH coupling includes: The construction module 201 is used to construct a three-dimensional geometric model of the real lunar soil particles based on the scanning data of the real lunar soil particles; Module 202 is used to establish a discrete element model of lunar soil based on the three-dimensional geometric model; Calibration module 203 is used to conduct virtual mechanical tests on the lunar soil discrete element model and calibrate the macroscopic mechanical parameters of the lunar soil; Module 204 is defined to construct a finite element model of the drill bit and to define the contact relationship between the finite element model of the drill bit and the lunar soil. The generation module 205 is used to establish the SPH particle model of lunar soil based on the calibrated macroscopic mechanical parameters of lunar soil. The simulation module 206 is used to couple the finite element model of the drill bit with the SPH particle model, and to simulate the dynamic process of lunar soil coring based on the contact relationship, so as to obtain the results of bedding information disturbance and drill bit sampling rate.

[0102] In one alternative approach, It should be noted that the beneficial effects of the lunar regolith core sampling dynamic process simulation system 200 based on FEM-SPH coupling provided in the above embodiments are the same as those of the lunar regolith core sampling dynamic process simulation method based on FEM-SPH coupling, and will not be repeated here. Furthermore, the system provided in the above embodiments is only illustrated by the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the system can be divided into different functional modules according to the actual situation to complete all or part of the functions described above. In addition, the system and method embodiments provided in the above embodiments belong to the same concept, and their specific implementation process is detailed in the method embodiments, and will not be repeated here.

[0103] The FEM-SPH-coupled dynamic process simulation system 200 for lunar soil coring of the present invention can be a computer program (including program code) running on a computer device. For example, the FEM-SPH-coupled dynamic process simulation system 200 for lunar soil coring of the present invention is an application software that can be used to execute the corresponding steps in the FEM-SPH-coupled dynamic process simulation method for lunar soil coring of the present invention.

[0104] In some embodiments, the FEM-SPH-coupled lunar core sampling dynamic process simulation system 200 of the present invention can be implemented in a combination of hardware and software. As an example, the FEM-SPH-coupled lunar core sampling dynamic process simulation system 200 of the present invention can be a processor in the form of a hardware decoding processor, which is programmed to execute the FEM-SPH-coupled lunar core sampling dynamic process simulation method of the present invention. For example, the processor in the form of a hardware decoding processor can be one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), or other electronic components.

[0105] The modules described in the embodiments of this invention can be implemented in software or hardware. The names of the modules are not, in some cases, limiting the scope of the module itself.

[0106] An electronic device according to an embodiment of the present invention includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements any of the above-mentioned simulation methods for dynamic processes of lunar regolith extraction based on FEM-SPH coupling. That is, an electronic device according to an embodiment of the present invention may include, but is not limited to: a processor and a memory; the memory is used to store the computer program; the processor is used to execute the simulation method for dynamic processes of lunar regolith extraction based on FEM-SPH coupling shown in any embodiment of the present invention by calling the computer program.

[0107] In one alternative embodiment, an electronic device is provided, such as Figure 4 As shown, Figure 4 The illustrated electronic device 4000 includes a processor 4001 and a memory 4003. The processor 4001 and the memory 4003 are connected, for example, via a bus 4002. Optionally, the electronic device 4000 may further include a transceiver 4004, which can be used for data interaction between the electronic device and other electronic devices, such as sending and / or receiving data. It should be noted that in practical applications, the transceiver 4004 is not limited to one type, and the structure of the electronic device 4000 does not constitute a limitation on the embodiments of the present invention.

[0108] Processor 4001 may be a CPU (Central Processing Unit), a general-purpose processor, a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this invention. Processor 4001 may also be a combination that implements computational functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc.

[0109] Bus 4002 may include a path for transmitting information between the aforementioned components. Bus 4002 may be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. Bus 4002 can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 4 The bus 4002 is represented by only one thick line, but this does not mean that there is only one bus or one type of bus.

[0110] The memory 4003 may be ROM (Read Only Memory) or other types of static storage devices capable of storing static information and instructions, RAM (Random Access Memory) or other types of dynamic storage devices capable of storing information and instructions, or EEPROM (Electrically Erasable Programmable Read Only Memory), CD-ROM (Compact Disc Read Only Memory) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto.

[0111] The memory 4003 stores application code (computer program) for executing the present invention, and its execution is controlled by the processor 4001. The processor 4001 executes the application code stored in the memory 4003 to implement the content shown in the foregoing method embodiments.

[0112] Among them, electronic devices can also be terminal devices. A terminal device can be any terminal device that can install applications and access web pages through applications, including at least one of smartphones, tablets, laptops, desktop computers, smart speakers, smartwatches, smart TVs, and smart in-vehicle devices.

[0113] It should be noted that, Figure 4 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of the embodiments of the present invention.

[0114] An embodiment of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements any of the above-mentioned simulation methods for dynamic processes of lunar soil coring based on FEM-SPH coupling.

[0115] Alternatively, the computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a compact disc read-only memory (CD-ROM), magnetic tape, a floppy disk, and an optical data storage device, etc.

[0116] In an exemplary embodiment, a computer program product or computer program is also provided, which includes computer instructions stored in a computer-readable storage medium. A processor of an electronic device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the electronic device to perform the aforementioned simulation method for dynamic processes of lunar soil coring based on FEM-SPH coupling.

[0117] Computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0118] It should be understood that the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of methods and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0119] The computer-readable storage medium provided in this invention can be, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this invention, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0120] The aforementioned computer-readable storage medium carries one or more programs, which, when executed by the electronic device, cause the electronic device to perform the method shown in the above embodiments.

[0121] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this invention is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-disclosed concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this invention.

[0122] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and represent a limitation on a specific order or sequence. Where appropriate, the order of use for similar objects can be interchanged so that the embodiments of this application described herein can be implemented in an order other than that shown or described.

[0123] Those skilled in the art will recognize that this invention can be implemented as a system, method, or computer program product. Therefore, this invention can be specifically implemented in the following forms: it can be entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software, generally referred to herein as a "circuit," "module," or "system." Furthermore, in some embodiments, this invention can also be implemented as a computer program product contained in one or more computer-readable media, which includes computer-readable program code.

[0124] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A simulation method for the dynamic process of lunar soil coring based on FEM-SPH coupling, characterized in that, include: Based on the scanning data of real lunar soil particles, a three-dimensional geometric model of the real lunar soil particles is constructed. Based on the aforementioned three-dimensional geometric model, a discrete element model of lunar soil is established; Virtual mechanical experiments were conducted on the discrete element model of lunar soil to calibrate the macroscopic mechanical parameters of lunar soil. Construct a finite element model of the drill bit and define the contact relationship between the finite element model of the drill bit and the lunar soil; Based on the calibrated macroscopic mechanical parameters of lunar soil, an SPH particle model of lunar soil was established. The finite element model of the drill bit is coupled with the SPH particle model, and the dynamic process of lunar soil coring is simulated based on the contact relationship to obtain the results of bedding information disturbance and drill bit sampling rate.

2. The simulation method for dynamic processes of lunar soil coring based on FEM-SPH coupling according to claim 1, characterized in that, The step of constructing a three-dimensional geometric model of the real lunar soil particles based on the scanning data of the real lunar soil particles includes: Obtain real lunar soil particle samples; The real lunar soil particle sample was scanned using a computed tomography (CT) scanner to generate the scan data of the real lunar soil particles. The scanned data is reconstructed using a 3D reconstruction algorithm to generate 3D volume data of the real lunar soil particles. The three-dimensional volume data is segmented and surface mesh is generated to obtain the three-dimensional geometric model of the real lunar soil particles.

3. The simulation method for dynamic processes of lunar soil coring based on FEM-SPH coupling according to claim 2, characterized in that, The steps for establishing a discrete element model of lunar soil based on the three-dimensional geometric model include: The three-dimensional geometric model is discretized into multiple spherical particles using the multi-sphere approximation method; The plurality of spherical particles are filled into the interior of the three-dimensional geometric model to form a spherical model of lunar soil particles; Based on the spherical cluster model, and combined with the preset contact mechanics model and micromechanical parameters, the discrete element model of lunar soil is established.

4. The simulation method for dynamic processes of lunar soil coring based on FEM-SPH coupling according to claim 3, characterized in that, The steps of conducting virtual mechanical experiments on the discrete element model of lunar soil and calibrating the macroscopic mechanical parameters of lunar soil include: Based on the preset gradation distribution, a cylindrical particle pack sample is generated using the lunar soil discrete element model. A virtual triaxial compression test was performed on the cylindrical particle pile specimen, applying confining pressure and axial load to the cylindrical particle pile specimen; The peak axial stress of the cylindrical particle pack sample was obtained under various confining pressure conditions. Based on the various confining pressure conditions and the corresponding peak axial stress, the Mohr-Coulomb strength envelope is fitted to obtain the following: Based on the Mohr-Coulomb strength envelope, the internal friction angle and cohesion are calculated and used as the macroscopic mechanical parameters of the calibrated lunar soil.

5. The simulation method for dynamic processes of lunar soil coring based on FEM-SPH coupling according to any one of claims 1 to 4, characterized in that, The steps of constructing a finite element model of the drill bit and defining the contact relationship between the finite element model of the drill bit and the lunar regolith include: A three-dimensional solid geometric model of the drill bit is constructed, and the three-dimensional solid geometric model is meshed using finite element methods to generate a finite element model of the drill bit. A contact pair is established between the drill bit surface of the finite element model of the drill bit and the equivalent layer of lunar soil, and normal contact behavior and tangential contact behavior are defined in the contact pair to determine the contact relationship between the finite element model of the drill bit and the lunar soil.

6. The simulation method for dynamic processes of lunar soil coring based on FEM-SPH coupling according to claim 5, characterized in that, The steps for establishing the SPH particle model of lunar soil based on the calibrated macroscopic mechanical parameters include: SPH particles are generated based on the geometric boundaries of the drilling area; The calibrated macroscopic mechanical parameters of lunar soil are assigned to the SPH particles to obtain SPH particles with assigned parameters. Configure the neighborhood search algorithm and GPU parallel computing environment; Establish an SPH particle model of the lunar soil that includes the SPH particles with the assigned parameters, the neighborhood search algorithm, and the GPU parallel computing environment.

7. The simulation method for dynamic processes of lunar soil coring based on FEM-SPH coupling according to claim 6, characterized in that, The steps of coupling the drill string finite element model with the SPH particle model and simulating the dynamic process of lunar soil coring based on the contact relationship to obtain the bedding information disturbance and drill string sampling rate results include: The finite element model of the drill bit is coupled with the SPH particle model of the lunar soil using FEM-SPH coupling. During the coupled solution process, the interaction between the drill bit and the lunar soil is calculated based on the contact relationship. The neighborhood search algorithm and the GPU parallel computing environment are applied to update the motion state of the particles in the SPH particle model of the lunar soil and extract the displacement field and stress field data of the particles in the SPH particle model of the lunar soil. Based on the displacement field and stress field data, the perturbation of the bedding information and the sampling rate of the drill bit are determined.

8. A simulation system for the dynamic process of lunar soil coring based on FEM-SPH coupling, characterized in that, include: A construction module is used to construct a three-dimensional geometric model of the real lunar soil particles based on the scanning data of the real lunar soil particles; A module is established to build a discrete element model of lunar soil based on the three-dimensional geometric model. The calibration module is used to conduct virtual mechanical experiments on the lunar soil discrete element model and calibrate the macroscopic mechanical parameters of the lunar soil. A definition module is used to construct a finite element model of the drill bit and define the contact relationship between the finite element model of the drill bit and the lunar soil; The generation module is used to establish the SPH particle model of lunar soil based on the calibrated macroscopic mechanical parameters of lunar soil. The simulation module is used to couple the finite element model of the drill bit with the SPH particle model, and to simulate the dynamic process of lunar soil coring based on the contact relationship, so as to obtain the results of bedding information disturbance and drill bit sampling rate.

9. An electronic device, characterized in that, The electronic device includes a processor coupled to a memory, the memory storing at least one computer program, which is loaded and executed by the processor to enable the electronic device to implement the simulation method for dynamic process of lunar soil coring based on FEM-SPH coupling as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one computer program, which, when executed by a processor, implements the simulation method for dynamic process of lunar soil coring based on FEM-SPH coupling as described in any one of claims 1 to 7.

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