Impact crater high-precision quantitative analysis method based on three-dimensional laser scanning

Abstract

The invention relates to the technical field of shock crater quantification, discloses a shock crater high-precision quantitative analysis method based on three-dimensional laser scanning, and solves the technical problem of relatively large error in tangent plane two-dimensional measurement in the prior art. The analysis method comprises the following steps: step 100, performing mold reversing on an inner concave structure formed by a to-be-tested impact crater to form a to-be-tested crater convex mold with an outer convex structure matched with the inner concave structure; step 200, scanning and processing the to-be-tested crater male die by using a three-dimensional laser scanner to obtain three-dimensional grid data of the to-be-tested impact crater, and establishing a cylindrical coordinate system; step 300, analyzing the three-dimensional grid data in a cylindrical coordinate system, obtaining a crater section curve of the to-be-measured impact crater, and obtaining the crater depth and the crater diameter of the to-be-measured impact crater based on the crater section curve; and Step 400, inputting the three-dimensional grid data into three-dimensional visualization software, and obtaining the crater volume of the impact crater to be measured.

Description

Technical Field

[0001] The present invention relates to the technical field of impact crater quantification, and in particular to a high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning. Background Art

[0002] In the fields of aviation, aerospace and national defense, structural materials are inevitably subjected to impact loads, such as bird strikes, space debris impacts, precision strikes by weapons, etc. Under such impact loads, the failure mode of the material is completely different from that of quasi-static loading, and the related equipment may be catastrophically damaged in a very short time. Therefore, many scientists are paying attention to the high-speed impact response of structural materials.

[0003] Light gas guns are the main loading equipment for studying the high strain rate impact response of structural materials. Typical experiments are ballistic impact experiments, where the strain rate can reach 10 6 s -1 The parameters of the crater formed by high-speed impact (such as crater cross-section curve, crater depth, crater volume, crater diameter, etc.) can directly reflect the material's anti-penetration performance. The variation of crater parameters with the number of impacts and impact speed can also provide an important basis for the service safety assessment of structural materials in extreme environments.

[0004] In previous studies, the crater cross-sectional curve, crater depth, and crater diameter are usually obtained by cutting the crater and then performing two-dimensional measurement of the cross-section, while the crater volume is estimated based on the cross-sectional shape. However, in actual operation, the deviation of the cutting position and the loss during the cutting process will directly affect the two-dimensional measurement results, resulting in large errors in the estimation of the crater volume. Summary of the invention

[0005] The main purpose of the present invention is to provide a high-precision quantitative analysis method for impact craters based on three-dimensional laser scanning, so as to solve the technical problem of large errors in two-dimensional measurement of cross sections in the prior art.

[0006] In order to achieve the above object, the present invention provides a high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning, and the technical solution is as follows:

[0007] The high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning includes the following steps:

[0008] Step 100, performing inverted molding on the inner concave structure formed by the impact crater to be tested, to form a convex mold of the crater to be tested having an outer convex structure matching the inner concave structure;

[0009] Step 200, using a three-dimensional laser scanner to scan and process the crater punch to be tested, obtain three-dimensional grid data of the impact crater to be tested, and establish a cylindrical coordinate system;

[0010] Step 300, analyzing the three-dimensional grid data in a cylindrical coordinate system to obtain a crater cross-section curve of the impact crater to be measured, and obtaining a crater depth and a crater diameter of the impact crater to be measured based on the crater cross-section curve;

[0011] Step 400, input the three-dimensional grid data into three-dimensional visualization software to obtain the crater volume of the impact crater to be tested.

[0012] As a further improvement of the above-mentioned high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning: Step 100 includes the following steps:

[0013] Step 110, filling the casting liquid into the impact crater to be tested, so that the casting liquid completely covers the impact crater to be tested and is higher than the impact plane; preferably, the casting liquid is a mixture of liquid silicone and a curing agent;

[0014] Step 120, performing vacuum degassing treatment on the impact crater to be tested filled with the casting liquid before the casting liquid is solidified;

[0015] Step 130, after the casting liquid solidifies, the solidified model is taken out from the impact crater to be tested, so as to obtain the crater convex mold to be tested.

[0016] As a further improvement of the above-mentioned high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning, Step 200 includes the following steps:

[0017] Step 210, using a 3D laser scanner to collect surface data of the crater punch to be tested, to form 3D point cloud data;

[0018] Step 220, after meshing the three-dimensional point cloud data, three-dimensional mesh data is obtained;

[0019] Step 230, determine the y-axis direction by the normal vector of the impact plane, determine the y-axis position by the principle of minimum rotational inertia, and then determine the y-axis of the coordinate system;

[0020] Step 240, define the intersection of the impact plane and the y-axis of the coordinate system as the coordinate origin, and select a ray starting from the origin in the impact plane as the x-axis of the coordinate system;

[0021] Step 250, determine the cylindrical coordinate system x-θ-y, where θ is the angle between the projection of the spatial point on the xy plane and the x-axis of the coordinate system.

[0022] Preferably, in Step 210, blue light is selected as the light source of the three-dimensional laser scanner; the crater punch to be measured is placed on a rotating table with the raised portion facing upward; during the scanning process of the three-dimensional laser scanner, the rotating table is in a rotating state.

[0023] As a further improvement of the above-mentioned high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning, Step 300 includes the following steps:

[0024] Step 310, representing each point in the three-dimensional grid data as a point (x, θ, y) in a cylindrical coordinate system, extracting the (x, y) coordinates of all points (x, θ, y), and drawing a scatter plot on a two-dimensional plane;

[0025] Step 320, determine the value range in the x-axis direction of the coordinate system and set the step size. Within each step size range, calculate the average value of the x value and the y value of all data points to obtain a new data point;

[0026] Step 330, connecting all the obtained new data points with a smooth curve, that is, forming a crater cross-section curve of the impact crater to be tested;

[0027] Step 340, on the crater cross-section curve, find the minimum y value, and its absolute value is the crater depth; on the crater cross-section curve, find the point with the y value closest to 0, and the corresponding 2 times of the x value is the crater diameter.

[0028] As a further improvement of the above-mentioned high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning, Step 400 includes the following steps:

[0029] Step 410, inputting the three-dimensional mesh data into a three-dimensional visualization software to display it as a spatial surface, cutting the spatial surface with a plane that coincides with the impact plane, and identifying the portion below the impact plane as a crater;

[0030] Step 420, extracting the crater portion by cropping, converting the 3D grid data of the crater portion into voxels, and then setting the side length of the voxels;

[0031] Step 430, counting the total number of converted hoxels, and calculating the crater volume of the impact crater to be tested according to the side length and the total number of hoxels, wherein the crater volume is equal to the cube of the side length of the hoxel multiplied by the total number of hoxels.

[0032] As a further improvement of the above-mentioned high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning: in Step 100, the impact crater to be tested is obtained through a ballistic impact experiment, specifically: first, the surface of the sample is ground and polished to obtain the sample to be tested; then, a light gas gun system is used as a ballistic loading device, and the sample to be tested is placed in the target chamber of the ballistic loading device, and the surface of the sample to be tested is made perpendicular to the impact axis and impact direction of the projectile; then, the projectile is launched to impact the surface of the sample to be tested, that is, a test impact crater with a concave structure is formed on the surface of the sample to be tested.

[0033] As a further improvement of the above-mentioned high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning:

[0034] The sample to be tested of the same material is impacted multiple times at the same impact speed, and the three-dimensional grid data of the crater is obtained after each impact, and the crater depth, crater diameter and crater volume after each impact are calculated respectively;

[0035] The changing trends of crater depth, crater diameter and crater volume with the number of impacts are analyzed, a relationship model between crater size parameters and the number of impacts is established, and quantitative analysis results of impact craters are generated.

[0036] As a further improvement of the above-mentioned high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning:

[0037] Single impacts are respectively performed on multiple samples to be tested at multiple different impact velocities, three-dimensional grid data of craters formed at each impact velocity are obtained, and crater depths, crater diameters, and crater volumes at different impact velocities are respectively calculated;

[0038] The changing trends of crater depth, crater diameter and crater volume with impact velocity are analyzed, a relationship model between crater size parameters and impact velocity is established, and quantitative analysis results of impact craters are generated.

[0039] Compared with the traditional two-dimensional section measurement method, the high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning of the present invention has the following advantages:

[0040] (1) High-precision measurement: Traditional methods rely on two-dimensional slice measurement, which can easily produce large errors; the three-dimensional laser scanning used in the present invention is an advanced non-contact high-precision measurement technology, which can quickly and accurately obtain the surface information of the crater punch and provide more accurate three-dimensional morphology data, thereby significantly improving the measurement accuracy; and the cylindrical coordinate system used in the present invention is based on the cylinder, which can conveniently describe the position and coordinates of cylindrically symmetrical objects in three-dimensional space, and facilitate the processing and analysis of three-dimensional grid data; further, the present invention uses three-dimensional visualization software to process and analyze three-dimensional grid data, which has powerful processing capabilities and can convert three-dimensional grid data into intuitive images, thereby more intuitively displaying the crater shape.

[0041] (2) Completeness and comprehensiveness: The data obtained by the present invention through three-dimensional laser scanning technology covers the complete shape of the entire crater, rather than just the information of a certain section, ensuring the comprehensiveness and accuracy of the analysis; in particular, if the crater is directly subjected to three-dimensional laser scanning, there are likely to be blind spots that cannot be scanned. The present invention cleverly uses the inverted mold technology to convert the concave structure of the crater into a convex mold with an external convex structure, providing a convenient shape for subsequent three-dimensional laser scanning.

[0042] (3) Reducing human errors: Traditional methods require manual measurement and recording of cross-sections, which is prone to introducing human errors; the three-dimensional laser scanning and automatic data processing used in the present invention greatly reduce manual operations, reduce the error rate, and make the entire process more efficient and reliable.

[0043] (4) Non-destructive measurement: The traditional method uses incision measurement, which will destroy the crater structure and cause a large error between the measured result and the actual result. The three-dimensional laser scanning used in the present invention is a non-destructive method that can maintain the original state of the crater, and the calculated result is closer to the actual result.

[0044] (5) Efficient and fast: The three-dimensional laser scanning of the present invention can obtain a large amount of high-precision data in a short time, which is more efficient than the traditional step-by-step measurement method, saving time and human resources.

[0045] (6) Data visualization and analysis capabilities: The present invention inputs the acquired 3D mesh data into 3D visualization software to provide an intuitive 3D model, which facilitates further analysis and research and helps to better understand the formation and characteristics of the crater.

[0046] (7) Adaptability to Complex Shapes: The three-dimensional laser scanning utilized in the present invention can accurately capture complex shapes and surface details and is applicable to craters of various shapes, no matter how complex their shapes are.

[0047] In summary, the high-precision quantitative analysis method of craters based on three-dimensional laser scanning of the present invention is simple to operate, and has significant advantages in terms of accuracy, efficiency, comprehensiveness and data processing capabilities. It can greatly improve the quality and efficiency of quantitative research and measurement of impact craters, and effectively solve the technical problem of large errors in two-dimensional measurement of cross-sections in the prior art. It can not only be used for experimental research to provide an important basis for the service safety assessment of structural materials in extreme environments, but also has good practical application value, and can directly perform refined quantitative processing on existing craters.

[0048] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. Additional aspects and advantages of the present invention will be partially given in the following description, partially become apparent from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The drawings constituting a part of the present invention are used to assist in understanding the present invention. The contents provided in the drawings and their related descriptions in the present invention can be used to explain the present invention, but do not constitute improper limitations on the present invention. In the drawings:

[0050] Figure 1It is a top view of the impact crater to be tested at a certain impact speed in an embodiment of the present invention.

[0051] Figure 2 1 and 2 are a top view (a) and an oblique view (b) of a crater punch to be tested formed at a certain impact speed in an embodiment of the present invention.

[0052] Figure 3 1 and 2 are a top view (a) and an oblique view (b) of a cylindrical coordinate system of an impact crater to be measured formed at a certain impact velocity in an embodiment of the present invention.

[0053] Figure 4 It is a crater cross-section curve of the impact crater to be measured formed at a certain impact speed in an embodiment of the present invention.

[0054] Figure 5 1 is a curve showing the variation of crater depth with impact velocity in an embodiment of the present invention.

[0055] Figure 6 1 is a curve showing the change of crater diameter with impact velocity in an embodiment of the present invention.

[0056] Figure 7 1 and 2 are a whole-voxel image (a) and a local magnified image (b) of an impact crater to be tested at a certain impact velocity in an embodiment of the present invention.

[0057] Figure 8 1 is a curve showing the change of crater volume with impact velocity in an embodiment of the present invention. DETAILED DESCRIPTION

[0058] The present invention is described clearly and completely below in conjunction with the accompanying drawings. A person skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly noted that:

[0059] The technical solutions and technical features provided in each part of the present invention, including the following description, may be combined with each other if there is no conflict.

[0060] In addition, the embodiments of the present invention involved in the following description are generally only a part of the embodiments of the present invention, rather than all the embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0061] About the terms and units in the present invention: The terms "include", "have" and any variations thereof in the description and claims of the present invention and related parts are intended to cover non-exclusive inclusions.

[0062] The specific implementation of the impact crater high-precision quantitative analysis method based on three-dimensional laser scanning of the present invention includes the following steps Step 100-400, which are as follows:

[0063] Step 100, performing inverted molding on the inner concave structure formed by the impact crater to be tested, to form a convex mold of the crater to be tested having an outer convex structure matching the inner concave structure;

[0064] Step 200, using a three-dimensional laser scanner to scan and process the crater punch to be tested, obtain three-dimensional grid data of the impact crater to be tested, and establish a cylindrical coordinate system;

[0065] Step 300, analyzing the three-dimensional grid data in a cylindrical coordinate system to obtain a crater cross-section curve of the impact crater to be measured, and obtaining a crater depth and a crater diameter of the impact crater to be measured based on the crater cross-section curve;

[0066] Step 400, input the three-dimensional grid data into three-dimensional visualization software to obtain the crater volume of the impact crater to be tested.

[0067] Wherein, Step 100 includes the following steps:

[0068] Step 110, filling the casting liquid into the impact crater to be tested, so that the casting liquid completely covers the impact crater to be tested and is higher than the impact plane; the casting liquid is preferably, but not limited to, a mixture of liquid silicone and a curing agent, and the curing agent is at least one of a tin catalyst, a platinum catalyst, an aminosilane crosslinking agent, a vinylsiloxane crosslinking agent, and an organic peroxide catalyst; the impact plane refers to the surface of the sample that is first impacted;

[0069] Step 120, before the casting liquid is solidified, the impact crater to be tested filled with the casting liquid is subjected to vacuum degassing treatment; the vacuum degassing treatment can prevent bubbles from forming cavities or defects in the punch of the crater to be tested that affect the accuracy and quality of the punch;

[0070] Step 130, after the casting liquid solidifies, the solidified model is taken out from the impact crater to be tested, so as to obtain the crater convex mold to be tested.

[0071] Step 200 includes the following steps:

[0072] Step 210, using a three-dimensional laser scanner to collect surface data of the crater punch to be measured to form three-dimensional point cloud data; preferably, blue light is selected as the light source of the three-dimensional laser scanner, which can provide higher resolution and more accurate measurement results than red light; the crater punch to be measured is placed on a rotating table with the raised part facing upward; during the scanning process of the three-dimensional laser scanner, the rotating table is in a rotating state.

[0073] Step 220, after meshing the three-dimensional point cloud data, three-dimensional mesh data is obtained;

[0074] Step 230, determine the y-axis direction by the normal vector of the impact plane, determine the y-axis position by the principle of minimum rotational inertia, and then determine the y-axis of the coordinate system;

[0075] Step 240, define the intersection of the impact plane and the y-axis of the coordinate system as the coordinate origin, and select a ray from the origin in the impact plane as the x-axis of the coordinate system; the x-axis starting from the origin specifies the lateral position measurement of the point in the plane, and is perpendicular to the y-axis. The two together build an accurate coordinate framework for the geometric characteristics and quantitative analysis of the crater;

[0076] Step 250, determine the cylindrical coordinate system x-θ-y, where θ is the angle between the projection of the spatial point on the xy plane and the x-axis of the coordinate system;

[0077] The cylindrical coordinate system is a commonly used three-dimensional coordinate system, which consists of three parameters: radius, angle, and height. The radius represents the distance from the spatial point to the x-axis, the angle represents the angle between the projection of the spatial point on the plane and the x-axis, and the height is the coordinate value of the spatial point along the y-axis. By representing the points in the three-dimensional space with the coordinate values ​​in the cylindrical coordinate system, subsequent data calculation and analysis can be more convenient.

[0078] Step 300 includes the following steps:

[0079] Step 310, representing each point in the three-dimensional grid data as a point (x, θ, y) in a cylindrical coordinate system, extracting the (x, y) coordinates of all points (x, θ, y), and drawing a scatter plot on a two-dimensional plane;

[0080] The (x, y) coordinates are a specific parameter combination related to the two-dimensional plane in the cylindrical coordinate system. The (x, y) coordinate points extracted are plotted one by one as scatter plots on the two-dimensional plane using drawing tools. The distribution and arrangement of these scatter points on the scatter plot can preliminarily present the characteristics and laws of the three-dimensional grid data from a specific two-dimensional plane perspective. The general distribution trend of the data can be intuitively observed through the scatter plot, providing important visual reference and basic information for subsequent more in-depth data analysis and interpretation;

[0081] Step 320, determine the value range in the x-axis direction of the coordinate system and set the step size. Within each step size range, calculate the average value of the x value and the y value of all data points to obtain a new data point;

[0082] By analyzing the coordinate values ​​of all data points on the x-axis, a specific value that is obviously larger than the diameter of the crater is found. This value determines the value range of the x-axis direction of the coordinate system. Then, a sufficiently small step size is reasonably set according to factors such as the distribution characteristics of the data, the accuracy requirements of the analysis, and the complexity of the subsequent calculations. The size of the step size will determine the degree of refinement of the data interval division. Then, according to the set step size, the value range of the x-axis is divided into several intervals. For each data point within the step range, its corresponding x value and y value are collected. The sum of these x values ​​and the sum of y values ​​are calculated respectively, and then the sum is divided by the number of data points within the step range, so as to obtain the average value of the x value and the average value of the y value within the step range. In this way, each step range corresponds to a new set of data points containing the average value of the x value and the average value of the y value. These new data points are a summary and refinement of the original data within a specific interval. They more concisely reflect the changing trend of the data within different x-axis intervals.

[0083] Step 330, connecting all the obtained new data points with a smooth curve, that is, forming a crater cross-section curve of the impact crater to be tested;

[0084] In the order of data points, adjacent data points are connected with smooth curve segments to obtain the crater cross-section curve, which can intuitively show the shape and change law of the crater cross-section on the two-dimensional plane, and provide an important visualization basis for further analysis of the geometric characteristics and physical properties of the crater. In some cases, in order to obtain a smoother curve, the data points can be fitted according to the characteristics of the data and actual needs.

[0085] Step 340, on the crater cross-section curve, find the minimum y value, and its absolute value is the crater depth; on the crater cross-section curve, find the point whose y value is closest to 0, and the corresponding x value twice is the crater diameter;

[0086] Among them, the absolute value of the minimum y value is taken as the crater depth, which can eliminate the direction of the value and only focus on its magnitude to obtain the sinking depth of the crater relative to the impact plane;

[0087] Step 400 includes the following steps:

[0088] Step 410, inputting the three-dimensional mesh data into a three-dimensional visualization software to display it as a spatial surface, cutting the spatial surface with a plane that coincides with the impact plane, and identifying the portion below the impact plane as a crater;

[0089] The three-dimensional visualization software may be, but is not limited to, Avizo;

[0090] The setting of the side length is determined according to actual needs and the characteristics of the data. Generally, the smaller the side length is, the closer the final result is to the real result. However, setting the side length too small will increase the amount of computer calculations, so comprehensive consideration is required.

[0091] Step 420, extracting the crater portion by cropping, converting the 3D grid data of the crater portion into voxels, and then setting the side length of the voxels;

[0092] The crater part can be accurately extracted by cropping, so as to focus on the crater area and exclude the interference of other irrelevant parts.

[0093] Step 430, counting the total number of converted hoxels, and calculating the crater volume of the impact crater to be tested according to the side length and the total number of hoxels, wherein the crater volume is equal to the cube of the side length of the hoxel multiplied by the total number of hoxels;

[0094] The total number of hoxels reflects the number of spatial units occupied by the crater under the hoxel representation. Since each hoxel is a small cube, the total volume of the crater is equal to the sum of the volumes of all hoxels, that is, the volume of the crater is equal to the cube of the hoxel side length multiplied by the total number of hoxels. Through this calculation method, the volume of the crater can be obtained more accurately, providing an important quantitative indicator for further evaluating the characteristics of the crater and related physical analysis.

[0095] The present invention can be used for analyzing existing craters and can also be used for experimental research. When used for experimental research, in Step 100, the impact crater to be tested is obtained through a ballistic impact experiment, specifically: first, the sample surface is polished to obtain the sample to be tested; then, a light gas gun system is used as a ballistic loading device, and the sample to be tested is placed in the target chamber of the ballistic loading device, and the surface of the sample to be tested is perpendicular to the impact axis and impact direction of the projectile; then, the projectile is launched to impact the surface of the sample to be tested, that is, a test impact crater with a concave structure is formed on the surface of the sample to be tested.

[0096] One application of the experimental research is: impact the sample to be tested of the same material multiple times at the same impact speed, obtain the three-dimensional grid data of the crater after each impact, and calculate the crater depth, crater diameter and crater volume after each impact; analyze the changing trends of the crater depth, crater diameter and crater volume with the number of impacts, establish a relationship model between the crater size parameters and the number of impacts, and generate quantitative analysis results of the impact crater.

[0097] Another application of the experimental research is: to perform a single impact on multiple samples to be tested at multiple different impact velocities, obtain the three-dimensional grid data of the crater formed at each impact velocity, and calculate the crater depth, crater diameter and crater volume at different impact velocities; analyze the changing trends of the crater depth, crater diameter and crater volume with the impact velocity, establish a relationship model between the crater size parameters and the impact velocity, and generate quantitative analysis results of the impact crater.

[0098] The beneficial effects of the present invention are described below by way of examples.

[0099] Example 1

[0100] Step 100:

[0101] A first-stage light gas gun loading system was used to impact the sample to be tested, which was made of equiatomic ratio CrCoNi alloy. The projectile used was SS304 stainless steel with a diameter of 5 mm. The flight distance of the projectile after leaving the barrel was set to about 2 m. The projectile was launched to impact the surface of the sample to be tested at different impact speeds (311 m / s, 500 m / s, 807 m / s, and 1040 m / s respectively). The impact axis and impact direction of the projectile were perpendicular to the surface of the sample to be tested, and the impact craters formed at various impact speeds were obtained; among them, Figure 1 It is a top view of the impact crater to be tested at a certain impact velocity.

[0102] A casting liquid with a volume ratio of 100:2 of liquid silicone and tin catalyst was used to mold the impact craters formed at various impact speeds. After vacuum degassing and curing, the silicone model was taken out from the impact crater to be tested, and the convex mold images of the craters to be tested formed at various impact speeds were obtained. The top view and oblique view of the convex mold of the crater to be tested formed at a certain impact speed are shown in Figure 1. Figure 2 (a) and Figure 2 (b) as shown.

[0103] Step200:

[0104] Using the PRINCE-335 3D laser scanner of Scan Technology, blue light is used as the light source, and the scanning resolution is set to 0.05mm. The above-mentioned crater punch is scanned and processed to obtain the 3D grid data of the impact crater to be tested, and a cylindrical coordinate system is established. Among them, the top view and oblique view of the cylindrical coordinate system of the impact crater to be tested formed at a certain impact speed are shown as follows: Figure 3 (a) and Figure 3 (b) as shown.

[0105] Step300:

[0106] In the cylindrical coordinate system, the three-dimensional grid data of each crater punch to be tested is analyzed, and the step size is set to 0.05 mm to obtain the crater cross-section curve of the impact crater to be tested formed at each impact speed. Among them, the crater cross-section curve of the impact crater to be tested formed at a certain impact speed is as follows: Figure 4 shown.

[0107] Based on the crater cross-section curve, the crater depth and crater diameter of the impact crater to be tested at each impact speed are obtained. Then, according to the crater depth and crater diameter calculated at each impact speed, the curves of the crater depth and crater diameter changing with the impact speed are obtained as follows: Figure 5 and Figure 6 shown.

[0108] Step 400:

[0109] Using the 3D visualization software Avizo, the 3D grid data of the crater part was converted into voxels, and the side length of the voxel was set to 0.01 mm to obtain the voxel image of the impact crater to be tested at various impact velocities. Among them, the voxel overall image and the local magnified image of the impact crater to be tested at a certain impact velocity are shown as follows: Figure 7 (a) and Figure 7 (b) as shown.

[0110] According to the length and total number of voxels, the crater volume of the impact crater to be tested formed at each impact speed is calculated. Then, according to the crater volume at each impact speed, the curve of the crater volume changing with the number of impacts is obtained as follows: Figure 8 shown.

[0111] The above is a description of the relevant contents of the present invention. A person skilled in the art will be able to implement the present invention based on these descriptions. Based on the above contents of the present invention, all other embodiments obtained by a person skilled in the art without creative work shall fall within the scope of protection of the present invention.

Claims

1. A high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning, characterized by: The following steps are involved: Step 100, performing inverted molding on the inner concave structure formed by the impact crater to be tested, to form a convex mold of the crater to be tested having an outer convex structure matching the inner concave structure; Step 200, using a three-dimensional laser scanner to scan and process the crater punch to be tested, obtain three-dimensional grid data of the impact crater to be tested, and establish a cylindrical coordinate system; Step 300, analyzing the three-dimensional grid data in a cylindrical coordinate system to obtain a crater cross-section curve of the impact crater to be measured, and obtaining a crater depth and a crater diameter of the impact crater to be measured based on the crater cross-section curve; Step 400, input the three-dimensional grid data into three-dimensional visualization software to obtain the crater volume of the impact crater to be tested.

2. The high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning according to claim 1, characterized in that: Step 100 includes the following steps: Step 110, filling the impact crater to be tested with the casting liquid, so that the casting liquid completely covers the impact crater to be tested and is higher than the impact plane; Step 120, performing vacuum degassing treatment on the impact crater to be tested filled with the casting liquid before the casting liquid is solidified; Step 130, after the casting liquid solidifies, the solidified model is taken out from the impact crater to be tested, so as to obtain the crater convex mold to be tested.

3. The high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning according to claim 2, characterized in that: The casting liquid is a mixture of liquid silicone and a curing agent.

4. The high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning according to claim 1, characterized in that: Step 200 includes the following steps: Step 210, using a 3D laser scanner to collect surface data of the crater punch to be tested, to form 3D point cloud data; Step 220, after meshing the three-dimensional point cloud data, three-dimensional mesh data is obtained; Step 230, determine the y-axis direction by the normal vector of the impact plane, determine the y-axis position by the principle of minimum rotational inertia, and then determine the y-axis of the coordinate system; Step 240, define the intersection of the impact plane and the y-axis of the coordinate system as the coordinate origin, and select a ray starting from the origin in the impact plane as the x-axis of the coordinate system; Step 250, determine the cylindrical coordinate system x-θ-y, where θ is the angle between the projection of the spatial point on the xy plane and the x-axis of the coordinate system.

5. The high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning according to claim 4, characterized in that: In Step 210, blue light is selected as the light source of the three-dimensional laser scanner; the crater punch to be tested is placed on a rotating table with the raised portion facing upward; during the scanning process of the three-dimensional laser scanner, the rotating table is in a rotating state.

6. The high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning according to claim 1, characterized in that: Step 300 includes the following steps: Step 310, representing each point in the three-dimensional grid data as a point (x, θ, y) in a cylindrical coordinate system, extracting the (x, y) coordinates of all points (x, θ, y), and drawing a scatter plot on a two-dimensional plane; Step 320, determine the value range in the x-axis direction of the coordinate system and set the step size. Within each step size range, calculate the average value of the x value and the y value of all data points to obtain a new data point; Step 330, connecting all the obtained new data points with a smooth curve, that is, forming a crater cross-section curve of the impact crater to be tested; Step 340, on the crater cross-section curve, find the minimum y value, and its absolute value is the crater depth; on the crater cross-section curve, find the point with the y value closest to 0, and the corresponding 2 times of the x value is the crater diameter.

7. The high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning according to claim 1, characterized in that: Step 400 includes the following steps: Step 410, inputting the three-dimensional mesh data into three-dimensional visualization software to display it as a spatial surface, cutting the spatial surface with a plane that coincides with the impact plane, and identifying the portion below the impact plane as a crater; Step 420, extracting the crater portion by cropping, converting the 3D grid data of the crater portion into voxels, and then setting the side length of the voxels; Step 430, counting the total number of converted hoxels, and calculating the crater volume of the impact crater to be tested according to the side length and the total number of hoxels, wherein the crater volume is equal to the cube of the side length of the hoxel multiplied by the total number of hoxels.

8. The high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning according to claim 1, characterized in that: In Step 100, the impact crater to be tested is obtained through a ballistic impact experiment, specifically: first, the surface of the sample is ground and polished to obtain the sample to be tested; then, a light gas gun system is used as a ballistic loading device, the sample to be tested is placed in the target chamber of the ballistic loading device, and the surface of the sample to be tested is made perpendicular to the impact axis and impact direction of the projectile; then, the projectile is launched to impact the surface of the sample to be tested, that is, a test impact crater with a concave structure is formed on the surface of the sample to be tested.

9. The high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning according to claim 8, characterized in that: The sample to be tested of the same material is impacted multiple times at the same impact speed, and the three-dimensional grid data of the crater is obtained after each impact, and the crater depth, crater diameter and crater volume after each impact are calculated respectively; The changing trends of crater depth, crater diameter and crater volume with the number of impacts are analyzed, a relationship model between crater size parameters and the number of impacts is established, and quantitative analysis results of impact craters are generated.

10. The high-precision quantitative analysis method of impact craters based on three-dimensional laser scanning according to claim 8, characterized in that: Single impacts are respectively performed on multiple samples to be tested at multiple different impact velocities, three-dimensional grid data of craters formed at each impact velocity are obtained, and crater depths, crater diameters, and crater volumes at different impact velocities are respectively calculated; The changing trends of crater depth, crater diameter and crater volume with impact velocity are analyzed, a relationship model between crater size parameters and impact velocity is established, and quantitative analysis results of impact craters are generated.

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