A free-field sensor fixing device and adjustment method for realizing three-axis adjustment

Abstract

The invention discloses a free-field sensor fixing device and an adjustment method for realizing three-axis adjustment, comprising a horizontal displacement adjustment fixture, a vertical displacement and horizontal azimuth adjustment fixture, a vertical pitch angle adjustment fixture, and a laser ranging and alignment fixture; the horizontal displacement adjustment fixture is used to adjust the horizontal displacement of the free-field sensor, the vertical displacement and horizontal azimuth adjustment fixture is used to adjust the vertical displacement and horizontal azimuth of the free-field sensor, the vertical pitch angle adjustment fixture is used to adjust the vertical pitch angle of the free-field sensor, and the laser ranging and alignment fixture is used to realize the measurement of the distance from the explosion center to the free-field sensor and the calibration of the direction of the free-field sensor. The invention can simply and quickly realize the adjustment functions of the horizontal distance, the vertical distance, the horizontal azimuth and the vertical pitch angle, overcomes the difficulties of uneven deployment site and the calibration of the distance and angle from the explosion center to the sensitive point of the sensor, and improves the efficiency of sensor deployment.

Description

Technical Field

[0001] The invention belongs to the technical field of damage testing, and in particular relates to a free-field sensor fixing device and an adjustment method for realizing three-axis adjustment. Background Art

[0002] With the rapid development of various energetic materials, obtaining free-field shock wave parameters is an important basis for evaluating the performance of energetic materials, constructing shock wave force fields, and predicting damage performance. At present, scholars often use free-field sensors to obtain the mechanical parameters of free-field shock waves, such as shock wave peak value, positive pressure action time, and specific impulse. When laying out free-field sensors, it is necessary to lay out sensors at different distances based on the characteristics of the problem. During the sensor deployment process, four key indicators must be guaranteed: 1) the overall level of the sensor, 2) the sensor points to the center of the explosion, 3) the sensor sensitive point is at the same level as the center of the explosion, and 4) the distance between the sensor sensitive point and the center of the explosion is the required value.

[0003] At present, free-field sensors are often fixed with pen-type fixtures. Although such devices can adjust the vertical height and horizontal distance, they still have shortcomings in three aspects: 1) Once the installation site is uneven, the existing pen-type fixtures often cause the free-field sensors to tilt and fail to maintain overall levelness; 2) Once the orientation of the sensor fixing bracket deviates, the sensor cannot point to the explosion center. At this time, the measured shock wave value is not the free-field shock wave, but the reflected field shock wave. 3) For the horizontal distance from the explosion center to the sensor sensitive point, the existing measurement methods often use conventional measuring instruments such as tape measures, which have defects in measurement accuracy and scope of application.

[0004] The above defects of the free-field sensor fixture not only lead to a long sensor deployment time, but more seriously lead to low sensor deployment accuracy, which leads to a decrease in the credibility of the shock wave measurement value and a decrease in usability. Therefore, it is urgent to design a three-axis adjustable free-field sensor fixture to solve this problem. Summary of the invention

[0005] Based on the above technical objectives, the present invention provides a free-field sensor fixing device and adjustment method for realizing three-axis adjustment, so as to solve the technical problems that the horizontal azimuth and vertical pitch angle of the existing free-field sensor cannot be adjusted and the distance and angle from the sensor sensitive point to the explosion center cannot be accurately calibrated.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A free-field sensor fixing device for realizing three-axis adjustment, comprising a horizontal displacement adjustment fixture, a vertical displacement and horizontal azimuth adjustment fixture, a vertical pitch angle adjustment fixture, and a laser ranging and alignment fixture;

[0008] The horizontal displacement adjustment fixture is used to adjust the horizontal displacement of the free field sensor, and the horizontal displacement adjustment fixture includes a first hollow column, the axis of the first center hole is along the horizontal direction, and the diameter of the first center hole matches the diameter of the free field sensor; a first threaded hole is opened on the side wall of the first hollow column, and a side opposite to the first threaded hole is cut by a vertical surface to expose the first center hole, and when the free field sensor is assembled in the first center hole, the sensitive surface of the free field sensor and the vertical surface of the first hollow column are located on the same plane;

[0009] The vertical displacement and horizontal azimuth adjustment fixture is used to adjust the vertical displacement and horizontal azimuth of the free field sensor. The vertical displacement and horizontal azimuth adjustment fixture includes a second hollow column, a second center hole along the vertical direction, and is used to connect the column of the mounting base; a second threaded hole is provided on the side wall of the second hollow column;

[0010] The vertical pitch angle adjustment fixture is used to adjust the vertical pitch angle of the free field sensor, and the vertical pitch angle adjustment fixture includes a vertical plate, and the vertical plate is connected between the first hollow column and the second hollow column; the vertical plate is provided with a third threaded hole and an oblong hole for installing bolts, and the oblong hole is an arc-shaped hole with the central axis of the vertical plate as the axis, and the positions of the third threaded hole and the oblong hole correspond to the position of the first threaded hole. The vertical plate is detachably connected to the first hollow column by bolts, and the vertical plate can rotate with the third threaded hole as the rotation center;

[0011] The laser distance measurement and alignment fixture is used to measure the distance from the explosion center to the free field sensor and calibrate the direction of the free field sensor. The laser distance measurement and alignment fixture includes a third hollow column, and the third hollow column is connected to the front end of the free field sensor.

[0012] Preferably, the first hollow column includes a truncated cone section and a cylindrical section, the truncated cone section and the cylindrical section are integrally processed, at least two first bolt holes are arranged on the side wall of the cylindrical section, and the first bolt holes are arranged in sequence along the axial direction of the cylindrical section.

[0013] Preferably, the second hollow column is a hollow cylinder, and the second bolt hole is arranged on a side opposite to the vertical plate.

[0014] Preferably, the vertical plate is welded to the outer wall of the second hollow column.

[0015] Preferably, the vertical plate is a disc structure.

[0016] Preferably, the angle range of the oblong hole is 105° to 255°.

[0017] The present invention also discloses a method for adjusting a free-field sensor based on the free-field sensor fixing device for realizing three-axis adjustment according to the present invention, comprising the following steps:

[0018] Step 1, fix the free field sensor in the first hollow column, fix the laser distance measurement and alignment fixture on the head of the free field sensor, and use laser distance measurement to measure the distance and angle from the explosion center to the measuring point of the free field sensor;

[0019] Step 2: Based on the measurement results, adjust the horizontal displacement adjustment fixture, the vertical displacement and horizontal azimuth adjustment fixture, and the vertical pitch angle adjustment fixture so that the distance from the free-field sensor measuring point to the explosion center is a specified value and the free-field sensor points to the explosion center.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The sensor fixing device of the present invention can not only realize the horizontal distance (X-axis distance) and vertical distance (Y-axis distance) adjustment functions of the existing sensor fixing device, but also can simply and quickly realize the horizontal azimuth angle (angle around the Y axis) and vertical pitch angle (angle around the Z axis) adjustment functions.

[0022] (2) The laser distance measurement and alignment fixture in the sensor fixing device of the present invention can realize the accurate calibration of the distance and angle from the sensitive point of the sensor to the explosion center, improve the accuracy of the measurement results, and overcome the defects of low measurement accuracy and narrow application range of conventional measurement methods.

[0023] (c) The sensor fixture of the present invention can be used in the field of free-field shock wave testing. The fixture of the present invention can quickly adjust the spatial position of the free-field sensor, overcome the difficulties of uneven deployment site, distance and angle calibration from the explosion center to the sensor sensitive point, and improve the efficiency of sensor deployment.

[0024] Other advantages of the present invention are described below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a front view of the fixing device recorded in the embodiment of the present invention.

[0026] Figure 2 It is a top view of the fixing device recorded in the embodiment of the present invention.

[0027] Figure 3 It is a side view of the fixing device according to the embodiment of the present invention.

[0028] Figure 4 It is the shock wave overpressure time history curve obtained from measuring points at different elevation differences with a constant horizontal distance from the explosion center.

[0029] Figure 5 It is a curve showing the change of the peak value of the shock wave overpressure with the elevation difference when the horizontal distance from the explosion center is constant.

[0030] Figure 6 It is a curve showing the change of shock wave arrival time with elevation difference when the horizontal distance from the explosion center is constant.

[0031] The meaning of the symbols in the accompanying drawings:

[0032] 1- horizontal displacement adjustment fixture, 2- vertical displacement and horizontal azimuth adjustment fixture, 3- vertical pitch angle adjustment fixture, 4- laser ranging and alignment fixture, 5- bolts, 6- free field sensor;

[0033] 11-first hollow column, 12-first center hole, 13-first threaded hole, 14-vertical surface;

[0034] 21-second hollow column, 22-second center hole, 23-second threaded hole;

[0035] 31-vertical plate, 32-third threaded hole, 33-long round hole;

[0036] 41 - third hollow column, 42 - third center hole. DETAILED DESCRIPTION

[0037] In the present invention, the center hole of the first hollow column is referred to as a first center hole, the center hole of the second hollow column is referred to as a second center hole, and the center hole of the third hollow column is referred to as a third center hole.

[0038] In the description of the invention, unless otherwise clearly specified and limited, the terms such as "set" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or an integrated connection; it can be a direct connection or an indirect connection, etc. For ordinary technicians in this field, the specific meanings of the above terms in this technical solution can be understood according to the specific circumstances. In the absence of any contrary instructions, the directional words used, such as "upper, lower, bottom, top", are usually defined based on the drawings of the corresponding drawings, and "inside and outside" are defined based on the outline of the corresponding drawings.

[0039] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that the terms "include" and "have" and any variation thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0040] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0041] A free-field sensor fixing device for realizing three-axis adjustment is disclosed in a specific embodiment of the present invention, such as Figures 1 to 3 As shown, it includes a horizontal displacement adjustment fixture 1, a vertical displacement and horizontal azimuth adjustment fixture 2, a vertical pitch angle adjustment fixture 3, and a laser ranging and alignment fixture 4;

[0042] The horizontal displacement adjustment fixture 1 is used to adjust the horizontal displacement of the free field sensor. The horizontal displacement adjustment fixture 1 of this embodiment includes a first hollow column 11, the first hollow column 11 is a horizontal hollow column as a whole, the axis of the first center hole 12 is along the horizontal direction, the diameter of the first center hole 12 matches the diameter of the free field sensor, and the free field sensor 6 is fixed in the first center hole 12 by a bolt 5.

[0043] The first hollow column 11 includes a truncated cone section and a cylindrical section, and the first center hole 12 runs through the truncated cone section and the cylindrical section. The purpose of providing the truncated cone section is to minimize the interference with the shock wave. The truncated cone section and the cylindrical section of this embodiment are integrated, and two first bolt holes 13 are provided on the side wall of the cylindrical section. The two first bolt holes 13 are sequentially arranged along the axial direction of the cylindrical section.

[0044] A vertical surface is cut on the first hollow column 11 on one side opposite to the first threaded hole 13 to expose the first center hole 12, so that the pressure sensitive surface of the free field sensor 6 is not blocked after installation, ensuring an ideal speed measurement environment. When the free field sensor is assembled in the first center hole 12, the sensitive surface of the free field sensor is on the same plane as the vertical surface 14 of the first hollow column 11, so as to improve the measurement accuracy.

[0045] The vertical displacement and horizontal azimuth adjustment fixture 2 is used to adjust the vertical displacement and horizontal azimuth of the free field sensor. The vertical displacement and horizontal azimuth adjustment fixture 2 of this embodiment includes a second hollow column 21, which is a hollow circular column arranged vertically, and a second center hole 22 is along the vertical direction. The diameter of the second center hole 22 matches the diameter of the column of the existing mounting base, and is used to connect the column of the mounting base. A second threaded hole 23 is provided on the side wall of the second hollow column 21, and the second hollow column 21 is fixed to the column by a bolt 5. The second hollow column 21 can move up and down along the column and rotate around the column to achieve the adjustment of the vertical displacement and horizontal azimuth of the free field sensor 6.

[0046] The vertical pitch angle adjustment fixture 3 is used to adjust the vertical pitch angle of the free field sensor. The vertical pitch angle adjustment fixture 3 of this embodiment includes a vertical plate 31, which is connected between the first hollow column 11 and the second hollow column 21, wherein the vertical plate 31 is welded to the outer wall of one side of the second hollow column 21, and the second bolt hole 23 is arranged on the second hollow column 21 on a side opposite to the vertical plate 31.

[0047] The vertical plate 31 of this embodiment is preferably a disc structure. Compared with other shapes, the disc shape can minimize the interference with the shock wave, and the diameter of the disc is substantially consistent with the length of the cylindrical section in the first hollow column 11. The angle range of the oblong hole 33 is 105° to 255°, and the pitch angle adjustment within the range of 105° to 255° can be achieved.

[0048] The vertical plate 31 is provided with a third threaded hole 32 and an oblong hole 33 for installing the bolt 5. The oblong hole 33 is a circular arc with the central axis of the vertical plate as the axis. The positions of the third threaded hole 32 and the oblong hole 33 correspond to the positions of the two first threaded holes 13. The vertical plate 3 is detachably connected to the first hollow column 11 by the bolt 5, and the vertical plate 3 can be rotated with the third threaded hole 32 as the rotation center to adjust the vertical pitch angle of the free field sensor 6. When the vertical pitch angle needs to be adjusted, the bolt 5 between the vertical plate 3 and the first hollow column 11 is loosened, and the first hollow column 11 is rotated with the bolt in the third threaded hole 32 as the rotation center. When it is rotated to the desired position, the bolt is tightened again.

[0049] The laser distance measurement and alignment fixture 4 is used to measure the distance from the center of the explosion to the free field sensor and calibrate the direction of the free field sensor. The laser distance measurement and alignment fixture of this embodiment includes a third hollow column 41, and the third hollow column 41 is connected to the front end of the free field sensor 6. The diameter of the third center hole 42 of the third hollow column 41 matches the diameter of the free field sensor 6. The length of the third hollow column 41 is about 5 mm longer than the conical section of the free field sensor. When the third hollow column 41 is installed on the head of the free field sensor 6, the front end of the free field sensor 6 is located in the third hollow column 41. When in use, the third hollow column 41 is fixed to the head of the free field sensor 5 to achieve accurate measurement of the distance from the center of the explosion to the free field sensor 5 and accurate calibration of the direction of the free field sensor, thereby improving the accuracy of the measurement unit.

[0050] When the bolts are connected in the present invention, the bolts and spring washers cooperate with each other, which is convenient to disassemble and not easy to fall off, thereby preventing the screws from directly contacting the surface of the free field sensor.

[0051] The installation sequence of the sensor fixing device of this embodiment is:

[0052] ① Insert the vertical rod of the mounting base into the second center hole 22 of the vertical displacement and horizontal azimuth adjustment fixture 2, and fix them together with bolts;

[0053] ② Align the two first threaded holes 13 of the horizontal displacement adjustment fixture 1 with the third threaded hole 32 and the oblong hole 33 of the vertical pitch angle adjustment fixture 3, and fix them together with bolts 5;

[0054] ③ Insert the free field sensor 6 into the first central hole 12 of the first hollow column 11 and fix them together with bolts.

[0055] The present invention also discloses a method for adjusting a free-field sensor using the free-field sensor fixing device described in the above embodiment, which specifically comprises the following steps:

[0056] Step 1, fix the free field sensor in the first hollow column 11, fix the laser ranging and alignment fixture 4 on the head of the free field sensor; measure the distance and angle from the explosion center to the measuring point of the free field sensor based on the laser ranging method;

[0057] When measuring the distance from the explosion center to the free field sensor measuring point, first measure the distance from the explosion center to the laser ranging and alignment fixture 4, and then add the distance from the laser ranging and alignment fixture to the free field sensor measuring point to get the distance from the explosion center to the free field sensor measuring point.

[0058] Step 2: Based on the measurement results, adjust the horizontal displacement adjustment fixture, the vertical displacement and horizontal azimuth adjustment fixture, and the vertical pitch angle adjustment fixture so that the distance from the free-field sensor measuring point to the explosion center is a specified value and the free-field sensor points to the explosion center.

[0059] The specific adjustment idea is: adjust the position of the free-field sensor on the first hollow column 11 to ensure that the distance between the sensor measuring point and the explosion center is the specified value; adjust the vertical position of the second hollow column 21 to achieve the vertical height adjustment of the free-field sensor 6 to ensure that the free-field sensor measuring point and the explosion center are at the same horizontal height; adjust the vertical plate 31 to achieve the horizontal layout of the free-field sensor 6 to ensure its overall level; rotate the second hollow column 21 to ensure that the free-field sensor 6 points to the explosion center.

[0060] It should be noted that after adjusting the vertical plate 31 of the vertical pitch angle adjustment fixture, the vertical height of the free field sensor measuring point may change in some cases. At this time, the vertical position of the second hollow column 21 needs to be adjusted again to ensure that the sensor measuring point is at the same horizontal height as the explosion center.

[0061] After the above adjustments are completed, testing work can be carried out.

[0062] During the deployment of the free-field sensor 6 of the present invention, the sensor is required to point to the explosion center, and the sensitive surface of the sensor is at the same elevation as the explosion center. In order to quantify the influence of the elevation difference on the free-field shock wave monitoring results, a numerical simulation study was carried out. The measuring points were deployed at a horizontal distance of dh = 150 cm from the explosion center, and the elevation difference Δh was from -10 cm to 0 cm to obtain the shock wave time history curve and related mechanical quantities. A negative elevation difference indicates that the elevation of the measuring point is lower than the elevation of the explosion center.

[0063] Figure 4 is the shock wave time history curve at different elevation differences. Figure 5 is the curve of the peak value of shock wave overpressure changing with the height difference. Figure 6 It is the curve of the shock wave arrival time changing with the elevation difference. As can be seen from the figure, there are obvious differences in the shock wave data at different elevation differences. When the elevation difference decreases from 0cm to -10cm, the shock wave arrival time increases by 6.36% and the shock wave overpressure decreases by 3.43%. Therefore, establishing a free field sensor fixing device that realizes three-axis adjustment can improve the layout accuracy of the free field sensor and improve the accuracy of the shock wave monitoring results.

Claims

1. A free-field sensor fixing device for realizing three-axis adjustment, characterized in that: It comprises a horizontal displacement adjustment fixture (1), a vertical displacement and horizontal azimuth adjustment fixture (2), a vertical pitch angle adjustment fixture (3), and a laser distance measurement and alignment fixture (4); The horizontal displacement adjustment fixture (1) is used to adjust the horizontal displacement of the free field sensor, and comprises a first hollow column (11), the axis of the first center hole (12) is along the horizontal direction, and the diameter of the first center hole (12) matches the diameter of the free field sensor; a first threaded hole (13) is provided on the side wall of the first hollow column (11), and a side opposite to the first threaded hole (13) is cut by a vertical surface to expose the first center hole (12), and when the free field sensor is assembled in the first center hole (12), the sensitive surface of the free field sensor and the vertical surface (14) of the first hollow column (11) are located on the same plane; The vertical displacement and horizontal azimuth adjustment fixture (2) is used to adjust the vertical displacement and horizontal azimuth of the free field sensor, and the vertical displacement and horizontal azimuth adjustment fixture (2) comprises a second hollow column (21), a second center hole (22) along the vertical direction, and is used to connect to a column of the mounting base; a second threaded hole (23) is provided on the side wall of the second hollow column (21); The vertical pitch angle adjustment fixture (3) is used to adjust the vertical pitch angle of the free-field sensor. The vertical pitch angle adjustment fixture (3) comprises a vertical plate (31), wherein the vertical plate (31) is connected between the first hollow column (11) and the second hollow column (21); the vertical plate (31) is provided with a third threaded hole (32) and an oblong hole (33) for mounting a bolt (5); the oblong hole (33) is in the shape of an arc with a central axis of the vertical plate as an axis; the positions of the third threaded hole (32) and the oblong hole (33) correspond to the position of the first threaded hole (13); the vertical plate (31) is detachably connected to the first hollow column (11) by means of the bolt (5), and the vertical plate (31) can rotate with the third threaded hole (32) as a rotation center; the angle range of the oblong hole (33) is 105° to 255°; The laser distance measurement and alignment fixture (4) is used to measure the distance from the explosion center to the free field sensor and calibrate the direction of the free field sensor. The laser distance measurement and alignment fixture comprises a third hollow column (41), and the third hollow column (41) is connected to the front end of the free field sensor. The first hollow column (11) comprises a truncated cone section and a cylindrical section, the truncated cone section and the cylindrical section are integrally processed, at least two first threaded holes (13) are arranged on the side wall of the cylindrical section, and the first threaded holes (13) are arranged in sequence along the axial direction of the cylindrical section.

2. The free-field sensor fixing device for realizing three-axis adjustment as claimed in claim 1, characterized in that: The second hollow column (21) is a hollow cylinder, and the second threaded hole (23) is arranged on a side opposite to the vertical plate (31).

3. The free-field sensor fixing device for realizing three-axis adjustment according to claim 1 or 2, characterized in that: The vertical plate (31) is welded to the outer wall of the second hollow column (21).

4. The free-field sensor fixing device for realizing three-axis adjustment according to claim 1, characterized in that: The vertical plate (31) is a disc structure.

5. A method for adjusting a free-field sensor based on the free-field sensor fixing device for realizing three-axis adjustment according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1, fixing a free-field sensor in the first hollow column (11), fixing a laser distance measurement and alignment fixture (4) on the head of the free-field sensor, and measuring the distance and angle from the explosion center to the measurement point of the free-field sensor by laser distance measurement; Step 2, based on the measurement results, by adjusting the horizontal displacement adjustment fixture (1), the vertical displacement and horizontal azimuth adjustment fixture (2), and the vertical pitch angle adjustment fixture (3), the distance from the free-field sensor measurement point to the explosion center is set to a specified value and the free-field sensor points to the explosion center.

Images