Plastic pressure measuring device and method for rigid wall surface shock wave pressure measurement

Abstract

The invention discloses a plastic pressure measuring structure for rigid wall surface shock wave pressure measurement and a testing method. The device comprises a base, a diaphragm bearing cover and a conical surface fixing ring, the diaphragm bearing cover is assembled on a base mounting cylinder, an impact cavity is formed in the mounting cylinder, and the cross section area of an impact through hole is smaller than that of the impact cavity; the diaphragm bearing cover is sleeved with the conical surface fixing ring, the upper fixing ring is fixedly connected with the diaphragm bearing cover through threads, and meanwhile the axial height of the conical surface fixing ring is the same as the height of the diaphragm bearing cover. According to the method disclosed by the invention, the plastic pressure measuring structure is fixed on the wall surface to measure the shock wave pressure peak value of the area, and the shock wave pressure peak value of the area is obtained according to the maximum deformation depth of the diaphragm to be measured. According to the invention, the diaphragm is closer to ideal constraint, and the measurement error is reduced; the conical surface fixing structure can effectively reduce the measurement error of the skim wave, and is suitable for wall surface pressure measurement.

Description

Technical Field

[0001] This invention belongs to the field of shock wave pressure testing, specifically relating to a plastic pressure measuring device and method for measuring shock wave pressure on rigid walls. Background Technology

[0002] Plastic pressure testing, as a shock wave testing method, is based on the principle of using the maximum depth of the indentation generated by a peripherally fixed circular diaphragm under the action of a shock wave, i.e., the deformation deflection, to measure the shock wave pressure. It has the advantages of being easy to use, low cost, sensitive to shock waves, and able to effectively avoid parasitic effects during the explosion process. It is a relatively scientific, economical and effective method for testing the damage performance of explosion shock waves.

[0003] Plastic pressure measuring devices have various structures and installation methods. Existing technology "201711286128.9, An effect target device suitable for measuring shock wave pressure in a dynamic blast field" designs a strip-shaped plastic pressure measuring structure with five diaphragm response areas of different ranges. However, this device is heavy (9kg) and bulky, and its assembly and disassembly (connected by 26 screws) are complex, making field use time-consuming and labor-intensive. Existing technology "201811541060.9, A modular effect target device suitable for measuring shock wave pressure in a dynamic blast field" designs a cylindrical plastic pressure measuring structure that can simultaneously install two diaphragms, significantly reducing structural size and weight, and is fixed with six screws.

[0004] The aforementioned plastic pressure testing targets involve complex diaphragm installation and replacement operations, and the current plastic pressure testing structures are not well-suited for measuring pressure on rigid walls (rigid walls refer to rigid objects with flat surfaces, including cement floors, walls, and boards). Firstly, the structures are too heavy and difficult to fix to rigid walls. Secondly, the pressure measured by the diaphragm differs significantly from the actual pressure, resulting in substantial testing errors. Summary of the Invention

[0005] In view of the defects or deficiencies of the prior art, the present invention provides a plastic pressure measuring device for measuring the shock wave pressure of a rigid wall.

[0006] Therefore, the plastic pressure measuring device provided by the present invention includes a base, a diaphragm support cover, and a conical fixing ring; The base is provided with an installation cylinder; the top surface of the diaphragm support cover is provided with a diaphragm installation groove and an impact through hole, the cross-sectional area of ​​the impact through hole is smaller than the bottom area of ​​the diaphragm installation groove and the impact through hole is located at the center of the diaphragm installation groove; the main body of the conical fixing ring is a cone structure, and the cone structure is hollow. At the same time, the top part of the cone structure is cut off. Along the axial direction of the cone structure, the top of the hollow structure is the upper fixing ring and the bottom of the hollow structure is the lower fixing ring. The diaphragm support cover is assembled on the mounting cylinder, and the diaphragm support cover is threadedly connected to the base mounting cylinder. At the same time, the diaphragm support cover does not extend radially beyond the base. An impact cavity is formed inside the mounting cylinder, and the cross-sectional area of ​​the impact through hole is smaller than the cross-sectional area of ​​the impact cavity. The conical fixing ring is fitted onto the outside of the diaphragm support cover, wherein the upper fixing ring is fixedly connected to the diaphragm support cover by threads, and the axial height of the conical fixing ring is the same as the height of the diaphragm support cover.

[0007] An alternative approach is that the shape and size of the diaphragm mounting groove are determined according to the diaphragm to be tested, wherein the diaphragm to be tested is a circular structure with a thickness of 0.2mm-0.5mm.

[0008] An alternative is to ensure that the diameter of the diaphragm mounting groove is at least twice the diameter of the impact through hole, so as to ensure sufficient adhesive force and that the bonded part of the diaphragm will not undergo relative displacement during deformation.

[0009] An alternative is that the bottom surface of the base has a rough structure to facilitate fixing it to the wall surface being tested with adhesive.

[0010] An alternative approach is to have the diameter of the impact orifice be the same as the diameter of the pressure-loaded region of the diaphragm under test.

[0011] An alternative is to use an impact hole diameter of 10mm to 30mm.

[0012] An alternative is that the cone angle of the conical fixing ring is 5° to 30°.

[0013] Alternatively, the base, diaphragm support cover, and conical fixing ring may all be made of aluminum alloy, magnesium alloy, or titanium-aluminum alloy.

[0014] The present invention also provides a method for measuring shock wave pressure, the method being used to measure the impact pressure on a rigid wall surface, the method comprising: Diaphragms with different pressure-loaded region diameters were selected for testing. Shock tube dynamic calibration or explosion tests were used to calibrate the diaphragms with different pressure-loaded region diameters, establishing the peak shock wave pressure for diaphragms of different diameters. P 0 and the maximum deformation depth of the diaphragm w max Relationship model; The diaphragm to be tested is fixed in the diaphragm mounting slot of the above device, and then the above device is fixed to the rigid wall surface by the bottom surface of the base and the lower fixing ring of the conical fixing ring. The shock wave acts on the diaphragm to be tested in a direction perpendicular to the diaphragm to be tested. After the impact, the maximum deformation depth of the diaphragm under test is measured. w max , to the maximum deformation depth w maxSubstitution P 0- w max The peak pressure of the shock wave was calculated from the relational model.

[0015] This invention simplifies the installation structure and method, and the replaceable structural components are suitable for different tests. It can be used to quickly and accurately obtain the pressure peak value of wall shock waves to meet testing requirements.

[0016] The diaphragm installation method in this invention approximates ideal constraints, resulting in small measurement errors. Installation is simple and disassembly is convenient. Appropriate structural components can be selected according to different testing scenarios. The use of edge ramps can reduce measurement errors caused by height differences when measuring swept waves. It is particularly suitable for measuring the impact pressure of vertical rigid walls perpendicular to the ground.

[0017] The test method of this invention can quickly obtain the peak value of the shock wave pressure in the measuring area by reading the maximum deformation of the circular diaphragm after the shock wave action. This can meet the needs of troops in combat exercises, dynamite explosions and other situations that require rapid installation and deployment and rapid data acquisition. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the plastic pressure testing structure of the present invention; the numbers in the figure are: 1-diaphragm to be tested, 2-base, 3-diaphragm support cover, 4-conical fixing ring. Detailed Implementation

[0019] Unless otherwise specified, the scientific and technical terms used in this article are intended for understanding by those skilled in the art.

[0020] The axial, radial, top, bottom, and other directional or orientational terms used herein are consistent with the corresponding directions or orientations in the accompanying drawings. It should be noted that the accompanying drawings are intended to explain the present invention, and equivalent solutions obtained by those skilled in the art through rotation, substitution, or other means based on them are all within the scope of the present invention.

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and preferred embodiments.

[0022] Example 1: See Figure 1As shown, the pressure measuring structure of the present invention includes a base 2, a diaphragm support cover 3, and a conical fixing ring 4. The base 2 has an installation cylinder with a depth greater than the maximum deformation depth of the diaphragm 1 to be tested, ensuring it does not affect the deformation of the diaphragm 1. The diaphragm support cover 3 is a cover structure with circumferential sidewalls, and its top surface has a diaphragm mounting groove. The shape and size of this groove are determined according to the diaphragm to be tested; for example, a circular structure can be selected, with a depth of approximately 0.2mm-0.5mm and a diameter greater than or equal to twice the diameter of the pressure-bearing area of ​​the diaphragm to be tested (or the diameter of the impact through hole), ensuring the diaphragm to be tested is firmly fixed. An impact through hole is opened at the center of the diaphragm mounting groove, the size of which is taken as the diameter of the pressure-bearing area of ​​the diaphragm to be tested, approximately 10mm-30mm. The conical fixing ring is a hollow conical structure, and the top part of the cylindrical structure is cut into a frustum structure. Along the axial direction, the top ring inside the hollow structure is an upper fixing ring, and the bottom ring is a lower fixing ring. The components are assembled as follows: the diaphragm support cover 3 is mounted on the mounting cylinder, and the diaphragm support cover is threadedly connected to the base mounting cylinder. At the same time, the diaphragm support cover 3 does not extend beyond the base 2 in all directions. Meanwhile, an impact cavity is formed inside the mounting cylinder, and the cross-sectional area of ​​the impact through hole is smaller than the cross-sectional area of ​​the impact cavity. The conical fixing ring 4 is fitted outside the diaphragm support cover 3, wherein the upper fixing ring is threadedly fixed to the diaphragm support cover 3. At the same time, the height of the conical fixing ring 4 is the same as the height of the diaphragm support cover 3. That is, after assembly, the top surface of the diaphragm support cover with the diaphragm is at the same height as the top of the conical fixing ring or is located on the same plane.

[0023] In the preferred embodiment, the lower part of the base is a cylinder with a certain degree of roughness on its bottom surface, which facilitates fixing it to the wall surface being tested with adhesive.

[0024] In some designs, the conical retaining ring can be adjusted between 10° and 40°. Figure 1 The cone angle θ in the embodiment shown is specifically 10°.

[0025] To ensure the overall structure is securely installed on the wall and will not deform under the action of shock waves, the base, mounting base, and sloping cover are all made of low-density, high-strength materials, such as aluminum alloy, magnesium alloy, or titanium-aluminum alloy.

[0026] When measuring using the above-mentioned device, the peak value of the shock wave pressure is first established. P 0 and the maximum deformation depth of the diaphragm under test w max Relationship model: P 0= f ( w maxCurrently, it can be done in two ways: (1) Shock tube dynamic calibration: arrange the plastic pressure measuring diaphragm and the standard pressure sensor in the same position, apply different shock wave loads using the shock tube, and establish a relationship model through the pressure measured by the standard pressure sensor and the diaphragm deformation; (2) Explosion test calibration: carry out an explosion test, set up the plastic pressure measuring device and the standard pressure sensor at the same distance from the explosion center, and establish a relationship model through the pressure measured by the standard pressure sensor and the diaphragm deformation.

[0027] Next, use glue to attach the diaphragm to be tested to the diaphragm mounting slot on the top of the mounting base, and then attach the bottom surface of the base to the wall surface to be tested. Wait for the glue to fully cure, and then fix the diaphragm support cover to the base with threads. Finally, fix the conical fixing ring to the diaphragm support cover with threads to complete the test preparation.

[0028] The shock wave is directed vertically toward the diaphragm under test. After the shock wave is completed, the maximum deformation depth of the diaphragm on the mounting base is measured using a depth gauge. w max After completing data reading, the peak shock wave pressure in the measuring area is calculated, specifically the maximum deformation depth. w max The peak shock wave pressure was calculated by substituting the values ​​into the calibrated plastic pressure measurement model. P 0.

[0029] Example 2: The aforementioned plastic pressure measuring structure and testing method were used to measure the shock wave pressure on a rigid cement floor. The test condition was an aerial static explosion test with a detonation height of 1.5m and a charge of 8kg TNT. The distances of the measuring points from the detonation center were 3m, 4m, and 5m, respectively. To simulate wall-side testing, steel plates were laid on the ground at the test points to simulate a rigid cement floor.

[0030] Measuring the peak value of wall shock wave pressure using the aforementioned plastic pressure measuring device includes the following steps: Step 1: Calibration of the plasticity testing device A diaphragm made of 1060 pure aluminum with a thickness of 0.2 mm and a load-bearing area of ​​20 mm² was calibrated to establish the peak value of the shock wave pressure. P 0 and the maximum deformation depth of the diaphragm w max Relationship model: P 0 = 0.04716 + 0.02237 w max +0.07505* w 2 max The pressure measurement range is (0.1~1.5) MPa, and the maximum deformation depth of the diaphragm is less than 8 mm.

[0031] The pressure at the test point was estimated based on the Sartovsky formula, with an estimated value between 0.3 and 0.6 MPa. An aluminum diaphragm made of 1060 pure aluminum, 0.2 mm thick, and with a load-bearing area of ​​20 mm², was selected for testing. The selected diaphragm bearing cap had a wall thickness of 3 mm, a top mounting groove depth of 0.24 mm, a mounting groove diameter of 50 mm, an impact through-hole diameter of 20 mm, and an inner depth of 8 mm in the mounting cylinder. The overall height of the selected base was 11.5 mm. Because the tested steel plate had a flat surface and a large area, a 10° slope cap was chosen, with an overall height of 14.5 mm. All components were made of aluminum alloy.

[0032] Step Two: Device Fixing and Measurement First, use glue to attach the diaphragm to the top mounting groove of the diaphragm support cover. Then, attach the bottom surface of the base to the steel plates at distances of 3m, 4m, and 5m from the rupture center, respectively. Wait for the glue to fully cure before fixing the remaining components.

[0033] After the test, first remove the inclined cover, then remove the mounting base, and measure the maximum deformation depth of the diaphragm on the mounting base using a depth gauge. w max Complete data reading.

[0034] The maximum deformation depths read were 3.13mm, 2.21mm, and 1.40mm, respectively.

[0035] Then the maximum deformation depth w max The peak shock wave pressure was calculated by substituting the values ​​into the calibrated plastic pressure measurement model. P The values ​​are 0.852 MPa, 0.463 MPa, and 0.226 MPa, respectively.

[0036] Comparative example: The difference between this comparative example and the embodiment is that the pressure measuring device does not have a conical fixing ring 4.

[0037] To verify the feasibility of the plastic pressure measuring device and testing method described in this invention, electrical pressure sensors and identical plastic pressure measuring devices without inclined covers were respectively installed at the same location from the center of the explosion in the experiment described in the embodiment (except for the absence of inclined covers, the dimensions, materials, and usage were the same). The measured pressure values ​​are shown in the table below.

[0038] Table 1 Comparison Results

[0039] As can be seen from the comparison results shown in the table above, compared with the plastic pressure measuring device without a slanted cover, the plastic pressure measuring device and testing method described in this invention can effectively measure the shock wave pressure, and the measured pressure is closer to the actual measured pressure value.

Claims

1. A plastic pressure measuring device for measuring shock wave pressure on a rigid wall, characterized in that, The device includes a base, a diaphragm support cover, and a conical fixing ring; The base is provided with an installation cylinder; the top surface of the diaphragm support cover is provided with a diaphragm installation groove and an impact through hole, the cross-sectional area of ​​the impact through hole is smaller than the bottom area of ​​the diaphragm installation groove and the impact through hole is located at the center of the diaphragm installation groove; the main body of the conical fixing ring is a cone structure, and the cone structure is hollow. At the same time, the top part of the cone structure is cut off. Along the axial direction of the cone structure, the top of the hollow structure is the upper fixing ring and the bottom of the hollow structure is the lower fixing ring. The diaphragm support cover is assembled on the mounting cylinder, and the diaphragm support cover is threadedly connected to the base mounting cylinder. At the same time, the diaphragm support cover does not extend radially beyond the base. An impact cavity is formed inside the mounting cylinder, and the cross-sectional area of ​​the impact through hole is smaller than the cross-sectional area of ​​the impact cavity. The conical fixing ring is fitted onto the outside of the diaphragm support cover, wherein the upper fixing ring is fixedly connected to the diaphragm support cover by threads, and the axial height of the conical fixing ring is the same as the height of the diaphragm support cover.

2. The plastic pressure measuring device for measuring shock wave pressure on a rigid wall according to claim 1, characterized in that, The shape and size of the diaphragm mounting groove are determined according to the diaphragm to be tested, which is a circular structure with a thickness of 0.2mm-0.5mm.

3. The plastic pressure measuring device for measuring shock wave pressure on a rigid wall according to claim 1, characterized in that, The diameter of the diaphragm mounting groove is at least twice the diameter of the impact through hole to ensure sufficient adhesive bonding force and prevent relative displacement of the bonded part of the diaphragm during deformation.

4. The plastic pressure measuring device for measuring shock wave pressure on a rigid wall according to claim 1, characterized in that, The base has a rough bottom surface, which makes it easy to fix to the wall surface being tested with glue.

5. The plastic pressure measuring device for measuring shock wave pressure on a rigid wall according to claim 1, characterized in that, The diameter of the impact through-hole is consistent with the diameter of the pressure-loaded area of ​​the diaphragm under test.

6. The plastic pressure measuring device for measuring shock wave pressure on a rigid wall according to claim 1, characterized in that, The diameter of the impact through hole is 10mm~30mm.

7. The plastic pressure measuring device for measuring shock wave pressure on a rigid wall according to claim 1, characterized in that, The cone angle of the conical fixing ring is 5°~30°.

8. The plastic pressure measuring device for measuring shock wave pressure on a rigid wall according to claim 1, characterized in that, The base, diaphragm support cover, and conical fixing ring are all made of aluminum alloy, magnesium alloy, or titanium-aluminum alloy.

9. A method for measuring shock wave pressure, characterized in that, The method is used to measure the impact pressure on a rigid wall surface, and the method includes: Diaphragms with different pressure-loaded region diameters were selected for testing. Shock tube dynamic calibration or explosion tests were used to calibrate the diaphragms with different pressure-loaded region diameters, establishing the peak shock wave pressure for diaphragms of different diameters. P 0 and the maximum deformation depth of the diaphragm w max Relationship model; The diaphragm to be tested is fixed in the diaphragm mounting groove of the device of claim 1, and then the device of claim 1 is fixed to the rigid wall surface by the bottom surface of the base and the lower fixing ring of the conical fixing ring. The shock wave acts on the diaphragm to be tested in a direction perpendicular to the diaphragm to be tested. After the impact, the maximum deformation depth of the diaphragm under test is measured. w max , to the maximum deformation depth w max Substitution P 0- w max The peak pressure of the shock wave was calculated from the relational model.

10. The shock wave pressure measurement method according to claim 9, characterized in that, The method is used to measure the impact pressure on a vertical rigid wall perpendicular to the ground.

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