A three-dimensional trajectory test method for deep penetration test

Abstract

The application provides a kind of deep penetration test three-dimensional trajectory test method, after the reduction trajectory of foaming material, the coordinates of each point on the deep penetration trajectory are accurately obtained by image processing method;It should be noted that the foaming material prepared by the present application has certain strength and toughness after solidification, even if it is subjected to impact and wear of concrete block / stone block during target sectioning, the structure will not be damaged, and the three-dimensional model of the trajectory formed by the foaming material can ensure the integrity of the trajectory track after being taken out, the model can keep the original crater morphology and three-dimensional state of the trajectory;As can be seen, the trajectory reduction technology of the present application solves the contradiction between target sectioning randomness and retaining the integrity of the trajectory line, greatly reduces the difficulty of target sectioning, and has the advantages of saving labor and time cost, simple and efficient.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of ballistic test, and particularly relates to a three-dimensional ballistic test method for deep penetration test. BACKGROUND

[0002] Concrete material is widely used in important infrastructure construction such as high dam, bridge, nuclear power station, airport runway, highway and other protection engineering due to its high compressive strength, abundant raw materials and good durability. It is of great significance to develop concrete, rock and other deep drilling earth penetrators to improve the penetration and attack on deep underground targets and the exploitation of underground resources. In scientific research, the penetration of concrete, rock and other targets has been a research hotspot at home and abroad. The penetration process is a complex mechanical process of interaction and mutual influence between a projectile and a target. Concrete is a typical multi-phase heterogeneous composite material mainly composed of coarse aggregate, cement hydrate and aggregate and cement mortar bonding zone, and the properties of each phase are quite different. Due to the inhomogeneity of the target material, the projectile will be subjected to asymmetric lateral force, resulting in the deviation of the initial velocity direction or the initial projectile axis direction during the penetration process, i.e. the deflection of the penetration trajectory. The penetration trajectory deflection is a universal and basic physical phenomenon. A large number of penetration tests show that the penetration trajectory may be deflected for concrete, rock, soil and other geological media. It is also found that even for nearly normal penetration, the penetration trajectory may also be greatly deflected.

[0003] In deep penetration tests of concrete / rock and the like, it is always a difficulty to obtain and measure the penetration trajectory. In the literature, high-speed photography is often used to measure the trajectory of a projectile penetrating a thin concrete target. However, for a thick or semi-infinite concrete target, the trajectory of the projectile in the target cannot be observed.

[0004] In actual test conditions, the penetration trajectory is often three-dimensional. The existing technical means for obtaining the trajectory are mostly to cut or section the concrete target. However, due to the inhomogeneity of the material composition of the concrete target and the inability to cut the large concrete block in an ideal way, it is difficult for the dissected concrete target to leave a complete trajectory, and the three-dimensional trajectory cannot be restored after the target is disintegrated into pieces.

[0005] Existing ballistic testing methods include the post-dissection photographing and ruler measurement method, the gelatin-filled ballistic testing method, and the target recovery box recording method. Among these, the post-dissection photographing and ruler measurement method involves dissecting a deep-penetrating concrete target and then photographing the trajectory and measuring its length and width with a ruler. Based on the existing angles after dissection, the approximate trajectory of the ballistics is reconstructed by processing the photographed images and measuring the trajectory length with a ruler. Its disadvantages are: (1) The error of reconstructing the ballistics based on taking pictures and measuring with a ruler is large; (2) The test method of taking pictures and measuring with a ruler can only reflect the motion characteristics within the cross section, which is actually a two-dimensional motion trajectory, making it impossible to accurately reconstruct the ballistic trajectory; (3) The impact of the projectile on the concrete target will cause the concrete material near the impact point to break and collapse, resulting in the phenomenon of concrete pitting. This method cannot determine the initial impact point coordinates and obtain the pitting morphology; (4) Due to the brittle characteristics of concrete materials, the formation and development of random cracks during the target cutting process will cause the target to break into blocks of different sizes and shapes, making it difficult to ensure the integrity of the ballistic trajectory. The ballistic trajectory may be scattered in different broken blocks, causing measurement difficulties and low target cutting efficiency.

[0006] The ballistic test method using gelatin is a method for measuring the ballistic length in the test of a projectile penetrating a concrete target. The technical solution is to fill the hole in the recovered concrete target with gelatin after the test, and after cooling for 48 hours, cut open the target and measure the length of the solidified gelatin to reflect the penetration depth. Its disadvantages are: (1) Because this method is applied to the measurement of the ballistic length of concrete with small penetration depth and small ballistic deflection, the solidified gelatin is used to roughly reflect the penetration depth. (1) Gelatin has poor expansion properties and low strength after solidification, which means it cannot completely fill the bullet hole when solidified. It is easily affected by residual concrete fragments, resulting in a smaller diameter of the ballistic trajectory compared to the actual one, and it cannot reflect the width of the ballistic trajectory. (2) Gelatin material is soft and difficult to shape after solidification. After recycling, it is impossible to obtain the three-dimensional coordinates of each point on the trajectory, and it is impossible to record the trend and shape of the three-dimensional trajectory. (3) Gelatin is viscous and has poor fluidity. It is easy to form a blockage in the middle of the filling process, resulting in a shallow penetration depth. (4) Gelatin has low strength after solidification and is easy to break. It is easy to be cut by concrete fragments and easily damaged during the target cutting process, resulting in inaccurate measurement length or data loss, and poor reliability of the obtained trajectory parameters. (5) The solidification time of 48h is long, and the test and testing efficiency is low.

[0007] like Figure 1 As shown, the target box recording method involves designing target paper inside the target box and recording the penetration trajectory of the projectile by recording the perforation coordinates of different target papers. Its disadvantages are: (1) It can only record the trajectory of the projectile inside the target box, which is within the scope of the recovery and cannot reflect the trajectory of the projectile inside the deep-penetrating concrete / rock targets; (2) It can only obtain a small number of coordinates at interval positions and cannot obtain the three-dimensional trajectory.

[0008] Therefore, in deep penetration tests of concrete / rock materials, existing measurement methods cannot directly observe the trajectory of the projectile inside the target, making it difficult to obtain and measure the penetration trajectory. Furthermore, most existing methods involve directly dissecting the target and photographing the remaining trajectory, followed by ruler measurement. This method cannot preserve the complete trajectory, accurately obtain the coordinates of the penetration point, the coordinates on the deep penetration trajectory, and the projectile's roll angle, and cannot reconstruct the crater morphology. Summary of the Invention

[0009] To address the aforementioned problems, this invention provides a three-dimensional ballistic testing method for deep penetration tests, which can accurately obtain the three-dimensional trajectory coordinates in the ballistic trajectory and is simple to operate and easy to measure, significantly improving testing efficiency.

[0010] A three-dimensional ballistic testing method for deep penetration tests includes the following steps:

[0011] S1: The foamed material mixture is poured into the trajectory of the concrete / rock target. After the foamed material has completely solidified, the concrete / rock target is cut open to obtain the trajectory model formed by the foamed material.

[0012] S2: Obtain the three-dimensional trajectory diagram of the ballistic model. On the three-dimensional trajectory diagram, establish an XYZ three-axis rectangular coordinate system with the geometric center of the bullet hole at the impact point of the concrete / rock target as the origin, and keep one axis of the rectangular coordinate system horizontal.

[0013] S3: In the current Cartesian coordinate system, obtain the projections of the boundary of the 3D trajectory graph onto the YZ plane, XY plane, and XZ plane respectively. Each plane has two boundary lines projected onto it.

[0014] S4: Starting from the origin, extract a series of sampling points at a set distance on the two boundary lines belonging to the same plane, and sequentially number the sampling points on the two boundary lines starting from the origin.

[0015] S5: Take the midpoint of two sampling points with the same index on two boundary lines belonging to the same plane as the coordinates of the three-dimensional trajectory graph at the current plane and the sampling point with the current index;

[0016] S6: Integrate the coordinates of the three-dimensional trajectory graph on three planes to obtain the three-dimensional coordinates of each sampling point in the three-axis rectangular coordinate system, and reconstruct the ballistic trajectory based on the three-dimensional coordinates.

[0017] Furthermore, the method for injecting the foaming material mixture into the trajectory of the concrete / rock target is as follows:

[0018] Place the ballistic missile face down and clean up any remaining target debris in the trajectory.

[0019] Place the ball with the incoming side facing up, insert a wire into the ball hole, and pour a pre-prepared foaming material mixture into the ball hole, allowing the foaming material mixture to be poured along the wire or the inner wall of the ball hole.

[0020] Use iron wire to continuously stir and vibrate, so that the foam material mixture fills the bullet holes.

[0021] Furthermore, the wire remained inside the bullet hole after the filling was completed.

[0022] Furthermore, when the projectile has an elliptical cross-section, the roll angle α during deep penetration is calculated as follows:

[0023] Assuming the major semi-axis of the elliptical cross-section is a, the minor semi-axis is b, the ballistic width is L, the z-axis of the rectangular coordinate system remains horizontal, and the roll angle α is the angle by which the projectile rotates around its central axis during deep penetration, then the equation of the ellipse in the XY plane is as follows:

[0024]

[0025] Where x is the x-axis coordinate of the ellipse equation, and y is the y-axis coordinate of the ellipse equation;

[0026] The maximum value of y obtained based on the equation of the ellipse is as follows:

[0027]

[0028] At this point, y = L / 2, and the roll angle α is obtained as follows:

[0029]

[0030] Furthermore, 3D scanning technology or three-view photography methods are used to obtain a three-dimensional trajectory diagram of the ballistic model.

[0031] Furthermore, the foaming material mixture is a mixture of oil-based polyurethane coating and water, and the ratio of oil-based polyurethane coating to water is 2.8:1.

[0032] Beneficial effects:

[0033] 1. This invention provides a three-dimensional ballistic testing method for deep penetration tests. After reconstructing the ballistic trajectory using foamed material, image processing is employed to accurately obtain the coordinates of each point on the deep penetration trajectory. It should be noted that the foamed material prepared according to the formulation of this invention has certain strength and toughness after solidification. Even if it is subjected to impact and abrasion from concrete blocks / stones during the target cutting process, no structural damage will occur. The three-dimensional ballistic model formed by the foamed material can ensure the integrity of the ballistic trajectory after removal. The model can maintain the original pit morphology and the three-dimensional state of the ballistic trajectory. Thus, the ballistic trajectory reconstruction technology of this invention solves the contradiction between the randomness of target cutting and the preservation of the integrity of the ballistic trajectory, greatly reducing the difficulty of target cutting, and has the advantages of saving manpower and time costs, and being simple and efficient.

[0034] 2. This invention provides a three-dimensional ballistic test method for deep penetration tests, and gives a specific calculation method for the roll angle of deep penetration of non-circular cross-section / irregular projectiles, filling the gap in this technology.

[0035] 3. This invention provides a three-dimensional ballistic test method for deep penetration testing. The iron wire is left in the bullet hole after filling and can serve as a strength structure to prevent the foam material from breaking due to target cutting errors.

[0036] 4. This invention provides a three-dimensional ballistic testing method for deep penetration tests. The foaming material is polyurethane coating, which has better toughness and higher strength than gelatin material, is not easily damaged, and will not damage the ballistics when dissecting the target. The method is simple, convenient, and efficient.

[0037] 5. This invention provides a three-dimensional ballistic test method for deep penetration testing. Polyurethane coating and water are mixed in a ratio of 2.8:1 to form a slightly viscous liquid. After filling the bullet hole, it only needs to stand at room temperature for 30 minutes to completely solidify, which greatly improves the testing efficiency of ballistic tests. Attached Figure Description

[0038] Figure 1 A schematic diagram of a target box design for recording penetration trajectories in existing ballistic testing methods;

[0039] Figure 2 A flowchart of a three-dimensional ballistic test method for deep penetration testing provided by the present invention;

[0040] Figure 3 This is a schematic diagram showing the markings on the anti-ballistic surface of the present invention;

[0041] Figure 4 This is a schematic diagram of the three-dimensional ballistic trajectory of the present invention;

[0042] Figure 5 This is a schematic diagram of the ballistic trajectory image processing method of the present invention;

[0043] Figure 6This is a schematic diagram illustrating the calculation of the roll angle for the ballistic width according to the present invention. Detailed Implementation

[0044] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0045] The abbreviations and key terms used in this invention are defined as follows:

[0046] Deep penetration: The mechanical process by which a projectile uses its own kinetic energy to achieve deep penetration into a protected target.

[0047] Ballistics: The trajectory formed inside a target as the projectile penetrates it.

[0048] Pit creation: The impact of a projectile on a concrete target causes the concrete material near the target point to break and collapse, creating a pit-like appearance.

[0049] Roll angle: (mostly used in projectiles with non-circular cross-sections) refers to the angle generated by the projectile's rotation around its axis during penetration.

[0050] Impact surface: The surface of the target or test object that is impacted by the projectile.

[0051] like Figure 2 As shown, a three-dimensional ballistic test method for deep penetration testing includes the following steps:

[0052] S1: The foamed material mixture is poured into the trajectory of the concrete / rock target. After the foamed material has completely solidified, the concrete / rock target is cut open to obtain the trajectory model formed by the foamed material.

[0053] It should be noted that the concrete target's impact surface needs to be marked with lines before the deep penetration test. Before the test, after the concrete target is placed in the predetermined position, the impact point of the projectile can be determined using infrared aiming. Then, a reference coordinate system is established with the impact point as the origin, and horizontal and vertical marks are made on the target's impact surface using a marking method, such as... Figure 3 As shown, an initial reference is set up to reconstruct the three-dimensional spatial trajectory of the deep penetration test.

[0054] Following the deep penetration test, ballistic reconstruction was conducted. First, the concrete / rock target was recovered, placed face down, and any remaining target debris was removed from the trajectory. Then, the target was placed face up, and a pre-prepared foaming material mixture was poured into the cavity. During filling, a thin wire was inserted into the cavity to guide the mixture along the wire or the inner wall of the cavity (the wire also acts as a guide). The mixture was continuously stirred and vibrated with the wire to ensure it filled the cavity. After approximately 30 minutes, the foaming material solidified completely. Finally, the concrete target was dissected to obtain a clear ballistic trajectory. Additionally, before the foaming material solidified, a hard flat surface such as a wooden board could be used to cover the crater area, allowing the solidified foaming material to fill the crater and reveal the damaged morphology.

[0055] It should be noted that foamed materials refer to fluids with high initial fluidity and permeability that react quickly upon contact with water and air to form porous solids with high strength, hardness, and plasticity, and are easily spliced ​​and adhered after breakage. This includes, but is not limited to, the following materials: The foamed material can be a mixture of oil-based polyurethane coating and water. If necessary, a dye can be added for color adjustment. After thorough mixing, it is slowly poured into the bullet holes along the sidewall or with a wire. The polyurethane coating used in this invention is a single-component polyurethane with MDI as the main raw material and a pH value between 6.7 and 7.3. This material expands rapidly upon contact with water, producing foam and clogging the pores. Mixing the polyurethane coating with water at a ratio of 2.8:1 forms a slightly viscous liquid. After filling the bullet holes, it will completely solidify after standing at room temperature for 30 minutes. The ratio of polyurethane coating to water needs to be precise; too high or too low a ratio will result in the foamed material not solidifying or a prolonged solidification time, affecting experimental efficiency.

[0056] Furthermore, the wire used is a thinner steel wire, which can act as a guide during the filling of the foaming material. Continuous stirring and vibration with the wire during filling ensures the mixture flows fully to fill the entire cavity. After filling, the wire remains inside the cavity as a structural support, preventing the foaming material from breaking due to target misfires.

[0057] It should be noted that in concrete deep penetration tests, the concrete target has high strength, large volume and weight, and cannot be cut according to a regular shape. Therefore, it is difficult to use cutting machines of various sizes when dissecting the target. The common method is to chisel and pry along the cracks on the target to destructively dissect it. Therefore, foamed materials are harder and stronger than gelatin materials, and are not easily damaged. They will not damage the trajectory when dissecting the target, and are simple, convenient and efficient to operate.

[0058] Furthermore, clamps or other devices can be used to keep the trajectory starting point horizontal, restoring the attitude of the foamed material in the concrete target. 3D scanning technology or three-view photography can be used to obtain a three-dimensional trajectory diagram of the ballistic model. After testing, a schematic diagram of the three-dimensional ballistic trajectory formed by the foamed material can be obtained, as shown below. Figure 4 As shown, the projectile's penetration depth, roll angle, and three-dimensional trajectory can then be obtained by taking and processing the images.

[0059] S2: Obtain the three-dimensional trajectory diagram of the ballistic model. On the three-dimensional trajectory diagram, establish an XYZ three-axis rectangular coordinate system with the geometric center of the bullet hole at the impact point of the concrete / rock target as the origin, and keep one axis of the rectangular coordinate system horizontal.

[0060] S3: In the current Cartesian coordinate system, obtain the projections of the boundary of the 3D trajectory graph onto the YZ plane, XY plane, and XZ plane respectively. Each plane has two boundary lines projected onto it.

[0061] For example, such as Figure 5 As shown, two boundary lines are obtained on the YZ plane along the trajectory length direction.

[0062] S4: Starting from the origin, extract a series of sampling points at a set distance on the two boundary lines belonging to the same plane, and sequentially number the sampling points on the two boundary lines starting from the origin.

[0063] S5: Take the midpoint of two sampling points with the same index on two boundary lines belonging to the same plane as the coordinates of the three-dimensional trajectory graph at the current plane and the sampling point with the current index.

[0064] S6: Integrate the coordinates of the three-dimensional trajectory graph on three planes to obtain the three-dimensional coordinates of each sampling point in the three-axis rectangular coordinate system, and reconstruct the ballistic trajectory based on the three-dimensional coordinates.

[0065] It should be noted that when obtaining the coordinates of the ballistic trajectory sampling points on the 3D trajectory diagram according to steps S3 to S6, it is necessary to ensure that the bullet hole attitude at the impact point is consistent with the projectile's impact attitude, keep the tangent direction of the ballistic trajectory at the impact point horizontal, and establish a coordinate system with the geometric center of the bullet hole at the impact point as the origin, such as... Figure 5 As shown, on the two boundary lines of the ballistic trajectory in the YZ plane, a certain number of sampling points, such as P1, P2, ..., P, are taken at equal intervals. n ;Q1,Q2,…Q n For two points with the same subscript on the two boundary lines (such as P...), n and Q nThe midpoint is the coordinate of the nth sampling point of the trajectory in the YZ plane, and the larger the value of n, the more accurate the obtained trajectory. The same algorithm is used to obtain the coordinates of each sampling point of the trajectory in the XY and XZ planes. By combining the coordinates of the three planes, the (x, y, z) coordinates of each point of the trajectory can be obtained, and then the three-dimensional trajectory of the deep penetration trajectory can be reconstructed.

[0066] Furthermore, in scientific research, the penetration problem of projectiles with non-circular cross-sections / irregular structures has gradually become a hot topic. However, a testing method for obtaining the roll angle of non-circular cross-section projectiles during deep penetration remains a gap. This invention proposes an algorithm for obtaining the roll angle of an elliptical cross-section projectile based on the width of the trajectory in a ballistic trajectory view, as follows:

[0067] First, using the same point division method as in steps S3 to S5, the ballistic width L at different points is obtained.

[0068] Subsequently, the relationship between the ballistic width L and the roll angle α was calculated. Figure 6 Taking the elliptical cross-section projectile as an example, Figure 6 Assuming the projectile has a quarter-elliptical cross-section, with the major semi-axis of the ellipse being 'a', the minor semi-axis being 'b', and the ballistic half-width being 'l' (2l = L), and the projectile rotates about its axis 'o' (i.e., the z-axis in a rectangular coordinate system) by an angle 'α', the equation of the ellipse on the XY cross-section can be obtained as follows:

[0069]

[0070] Where x is the x-axis coordinate of the ellipse equation, and y is the y-axis coordinate of the ellipse equation;

[0071] The maximum value of y obtained based on the equation of the ellipse is as follows:

[0072]

[0073] Let l = y, L = 2l, then we obtain the relationship between α and L:

[0074]

[0075] Where α is the roll angle during the deep penetration of the projectile, and L is the trajectory width in the ballistic view.

[0076] Furthermore, given that the function of the projectile's cross-sectional profile is available, the above-mentioned ideas can also be applied to calculate the deep penetration roll angle of projectiles with non-circular / irregular cross-sections, such as elliptical variable cross-sections, non-circular cross-sections, and non-circular variable cross-sections.

[0077] Thus, this invention provides a method for testing the roll angle of non-circular cross-section / irregular projectiles (i.e., elliptical cross-section projectiles) in deep penetration tests, filling a technological gap.

[0078] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A method of three-dimensional trajectory testing for deep penetration testing, characterized in that, The method comprises the following steps: S1: filling the foaming material mixture into the trajectory of the concrete or rock target, after the foaming material is completely solidified, the concrete or rock target is cut open to obtain a trajectory model formed by the foaming material; S2: obtaining a three-dimensional trajectory graph of the trajectory model, establishing an XYZ three-axis rectangular coordinate system with the geometric center of the impact hole at the impact point of the concrete or rock target as the origin on the three-dimensional trajectory graph, and one axis coordinate direction of the rectangular coordinate system remains horizontal; S3: obtaining the projections of the boundaries of the three-dimensional trajectory graph on the Y-Z plane, the X-Y plane and the X-Z plane in the current rectangular coordinate system respectively, wherein two boundary lines are projected on each plane; S4: extracting a series of sampling points on the two boundary lines belonging to the same plane according to the set distance from the origin as the starting point, and sequentially numbering the sampling points on the two boundary lines from the origin as the starting point; S5: taking the midpoint of the two sampling points with the same serial number on the two boundary lines belonging to the same plane as the coordinate of the three-dimensional trajectory graph at the sampling point of the current plane and the current serial number; S6: integrating the coordinates of the three-dimensional trajectory graph on the three planes to obtain the three-dimensional coordinates of each sampling point in the three-axis rectangular coordinate system, and restoring the trajectory of the trajectory according to the three-dimensional coordinates.

2. A method of three-dimensional ballistic testing for deep penetration testing as in claim 1, wherein, The method for filling the foaming material mixture into the trajectory of the concrete or rock target comprises the following steps: placing the impact surface downward, cleaning the residual target debris in the trajectory; placing the impact surface upward, selecting an iron wire to extend into the impact hole, and pouring the pre-configured foaming material mixture into the impact hole, so that the foaming material mixture flows along the iron wire or the inner wall of the impact hole; continuously stirring and vibrating the iron wire to make the foaming material mixture fill the impact hole.

3. A method of three-dimensional ballistic testing for deep penetration testing as in claim 2, wherein, The iron wire is retained in the impact hole after the filling is completed.

4. A method of three-dimensional ballistic testing for deep penetration testing as in claim 1, wherein, When the projectile is an elliptical cross-section projectile, the calculation method of the roll angle a in the deep penetration process is as follows: assuming that the long semi-axis of the elliptical cross-section is a, the short semi-axis is b, the trajectory width is L, the direction of the Z axis of the rectangular coordinate system remains horizontal, the roll angle a is the angle of rotation of the projectile around the central axis of the projectile in the deep penetration process, the X axis points to the long semi-axis direction, and the Y axis points to the short semi-axis direction, then the elliptical equation on the X-Y plane is as follows: wherein x is the X axis coordinate of the elliptical equation, and y is the Y axis coordinate of the elliptical equation; the maximum value of y is obtained based on the elliptical equation as follows: at this time, y=L / 2, and the roll angle a is obtained as follows:

5. A method of three-dimensional trajectory testing for deep penetration testing as claimed in any one of claims 1 to 4, wherein, the three-dimensional trajectory graph of the trajectory model is obtained by using the 3D scanning technology or the three-view photographing method.

6. A method of three-dimensional trajectory testing for deep penetration testing as claimed in any one of claims 1 to 4, wherein, The foaming material mixture is a mixed liquid formed by mixing oil-based polyurethane paint and water, and the ratio of the oil-based polyurethane paint to water is 2.8:1.

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