Underwater explosion impact equivalent loading test device and method

Abstract

The invention discloses an underwater explosion impact equivalent loading test device and method, and belongs to the technical field of dynamic impact test mechanics, the underwater explosion impact equivalent loading test device comprises a light gas gun system, a combined water shock tube system and a measurement control system, the light gas gun system is a shock wave load loading system of a water shock tube, and the combined water shock tube system is connected with the measurement control system. Comprising a piston, a working table support, a steel pipe, a pressure sensor, a connecting flange, a connecting assembly, a transparent pipe, a double-thread screw assembly, a front panel, a test sample, a rear panel, a working table fixing support and a working table top, and a measurement control system comprises a light gas gun pressurization and emission controller, a high-speed acquisition instrument, a first high-speed camera and a second high-speed camera. The underwater explosion impact equivalent loading test device and the underwater explosion impact equivalent loading test method are compact in structure, convenient to use and suitable for researching underwater dynamic impact protection performance and fluid-solid coupling mechanism of materials or structures in laboratories.

Description

Technical Field

[0001] The present invention relates to the technical field of dynamic impact test mechanics, and particularly relates to an underwater explosion shock equivalent loading test device and method. Background Art

[0002] The non-explosive cylindrical water shock tube is a key device for carrying out research on the explosion shock protection of underwater equipment in a laboratory environment. At present, the maximum shock wave peak value of the steel pipe type water shock tube can reach 100 MPa. Due to the performance limitations of transparent non-metallic materials, the peak value of the transparent shock tube is usually below 10 MPa. The marked parameter of the loading time history, that is, the time decay coefficient, is below 0.3 ms. The material compression amount is also below 15 mm. This is quite different from the actual underwater explosion shock load and response. Usually, two independent systems are required for the research of these two types of devices, occupying too much laboratory space. In addition, the existing transparent shock tubes have a relatively small diameter and are less adaptable to typical material / structure samples of the coating layer.

[0003] In order to better study the underwater shock protection mechanism of protective materials and guide the design of protective materials, it is urgent to design and improve the transparent one-dimensional water shock tube to increase the loading peak value, loading time history, and material compression amount, and to conveniently carry out transparent and non-transparent shock tube tests as needed. Summary of the Invention

[0004] The purpose of the present invention is to provide an underwater explosion shock equivalent loading test device and method to increase the system stiffness, improve the loading peak value, loading time history, and material compression amount, and be able to conduct underwater shock tests with cavitation observation for transparent tubes, and also be able to conduct underwater shock tests with greater loads for steel pipes alone.

[0005] To achieve the above purpose, the present invention provides an underwater explosion shock equivalent loading test device, including a light gas gun system, a combined water shock tube system, and a measurement and control system:

[0006] The light gas gun system is a shock wave load loading system for the water shock tube, and is used to generate a high-speed flyer to simulate the shock wave generated by an underwater explosion;

[0007] The combined water shock tube system is coaxially arranged with the light gas gun system, and includes a workbench surface. A workbench support and a workbench fixed support are arranged on the workbench surface. A steel pipe is fixed on the workbench support. A piston is arranged inside the steel pipe. A pressure sensor is arranged outside the steel pipe. One end of the outside of the steel pipe is connected to a double-headed screw component through a connecting flange. The other end of the double-headed screw component is connected to the workbench fixed support. One end of the steel pipe is connected to a transparent pipe through a connecting component. The other end of the transparent pipe is provided with a front panel and a rear panel. A test specimen is clamped between the front panel and the rear panel. Sealing rings are arranged on both the front panel and the rear panel. The transparent pipe, the rear panel and the workbench fixed support are connected;

[0008] The measurement and control system includes a light gas gun pressurization and launch controller, a high-speed data acquisition instrument, a high-speed camera I and a high-speed camera II. The shock wave pressure data measured by the high-speed data acquisition instrument, the velocity data measured by the high-speed camera I and the data of the cavitation in water and the dynamic compression process of materials observed by the high-speed camera II are all transmitted to the main control computer for processing and analysis.

[0009] Preferably, the light gas gun system drives a flyer with a certain mass of m1 and a diameter of d to generate a certain velocity v f to impact the piston. The flyer and the piston jointly impact the water area in the steel pipe to realize shock wave loading;

[0010] The diameter of the piston is D, which is equal to the inner diameter of the steel pipe, the mass is m2, a small boss is arranged at the front end, two sealing rings are arranged circumferentially, the total length is designed to be 50 mm, and the piston is provided with a gas release valve.

[0011] Preferably, the distribution expression of the shock wave propagating in the water area is:

[0012]

[0013] The achievable shock wave peak value is P0 = ρ w c w v0, and the shock wave time decay coefficient is θ = m / (ρ w c w );

[0014] Among them, x is the water area coordinate, with the interface between the piston and the water area as the origin, and the direction away from the piston as the positive direction. t is the time, with the piston impacting the water area as the starting point of timing. ρ w is the density of water, c w is the sound speed of water, m = 4(m1 + m2) / (πD 2 ) is the equivalent mass after the flyer and the piston impact and merge, and v0 = m1v f / (m1 + m2) is the equivalent velocity after the flyer plate and the piston merge upon impact.

[0015] Preferably, the inner diameters of the steel pipe and the transparent pipe are equal. The non-impact end of the steel pipe is externally threaded for threaded connection with the connecting flange. Multiple symmetric through holes are provided in the flange plate of the connecting flange for connection with the double-headed screw assembly.

[0016] Preferably, the pressure sensors are piezoelectric overpressure measurement sensors, and multiple are arranged along the axial direction of the steel pipe at a certain distance.

[0017] Preferably, the connection assembly includes a double-headed pipe connector, a steel pipe end sealing gasket, and a transparent pipe end sealing gasket. The double-headed pipe connector is threadedly connected to the steel pipe and the transparent pipe respectively. The steel pipe end sealing gasket is provided between the steel pipe and the double-headed pipe connector, and the transparent pipe end sealing gasket is provided between the transparent pipe and the double-headed pipe connector.

[0018] Preferably, the double-headed screw assembly includes a fastening bolt and a double-headed screw. One end of the double-headed screw is connected to the connecting flange through the fastening bolt, and the other end of the double-headed screw is connected to the workbench fixed bracket.

[0019] Preferably, the test specimen is a sample of the material to be tested processed into a cylindrical shape with a diameter slightly smaller than the inner diameter of the transparent pipe.

[0020] Preferably, both the front panel and the rear panel are lightweight metal pistons, and the rear panel is provided with air holes.

[0021] An underwater explosion shock equivalent loading test method includes the following steps:

[0022] S1. Place the test specimen between the front panel and the rear panel, fill the steel pipe and the transparent pipe with water and seal them.

[0023] S2. Install the pressure sensors and arrange the measurement and control system.

[0024] S3. Start the light gas gun system to launch the flyer plate to impact the piston to simulate underwater explosion shock through the light gas gun pressurization and launch controller of the measurement and control system.

[0025] S4. Measure the flyer plate velocity through the high-speed camera one of the measurement and control system, observe and record the cavitation evolution in water and the dynamic compression process of the test sample through the high-speed camera two, and record the multi-channel shock wave pressure through the high-speed measuring instrument.

[0026] Therefore, by adopting the above-mentioned underwater explosion shock equivalent loading test device and method, the present invention has the following beneficial effects:

[0027] (1) The present invention ingeniously connects a steel equal-diameter water shock tube and a transparent equal-diameter water shock tube into a whole through a set of designed connection components. Combined with a pre-designed piston, it can achieve a larger shock wave loading peak, duration, and material compression during cavitation observation;

[0028] (2) The device of the present invention is convenient to disassemble and replace. It can not only conduct underwater impact tests with cavitation observation in the transparent tube but also conduct underwater impact tests with a larger load on the steel pipe alone;

[0029] (3) The device of the present invention has a compact structure and is convenient to use, and is suitable for studying the underwater dynamic impact protection performance and fluid-structure coupling mechanism of materials or structures in the laboratory.

[0030] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. Description of the Drawings

[0031] Figure 1 is the overall structure diagram of an underwater explosion shock equivalent loading test device and method of the present invention;

[0032] Figure 2 is the structural schematic diagram of a combined water shock tube system of an underwater explosion shock equivalent loading test device and method of the present invention;

[0033] Figure 3 is the enlarged detail diagram at A of an underwater explosion shock equivalent loading test device and method of the present invention;

[0034] Figure 4 is the typical test phenomenon diagram of cavitation evolution in water and dynamic compression of materials observed by the present invention;

[0035] Figure 5 is the diagram of the achieved shock wave loading measured and recorded by an underwater explosion shock equivalent loading test device and method of the present invention;

[0036] Reference numerals: 1, light gas gun barrel; 2, flyer; 3, piston; 4, workbench support; 5, steel pipe; 6, pressure sensor; 7, connecting flange; 8, connection component; 8-1, double-headed pipe connector; 8-2, steel pipe end sealing gasket; 8-3, transparent pipe end sealing gasket; 9, transparent pipe; 10, double-headed screw component; 10-1, fastening bolt; 10-2, double-headed screw; 11, sealing ring; 12, front panel; 13, test specimen; 14, rear panel; 15, workbench fixing bracket; 16, workbench top surface. Detailed Embodiment

[0037] The following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0038] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] Embodiment

[0040] As Figures 1 - 3 shown, the present invention provides an underwater explosion shock equivalent loading test device, including a light gas gun system, a combined water shock tube system, and a measurement and control system:

[0041] The light gas gun system is a shock wave load loading system for the water shock tube, used to generate a high-speed flyer 2 to simulate the shock wave generated by underwater explosion. Its specific composition and principle can refer to the existing technical solutions.

[0042] The combined water shock tube system is coaxially arranged with the light gas gun system, including a workbench tabletop 16. A workbench support 4 and a workbench fixed support 15 are arranged on the workbench tabletop 16. A steel pipe 5 is fixed on the workbench support 4. A piston 3 is arranged inside the steel pipe 5. A pressure sensor 6 is arranged outside the steel pipe 5. One end of the outside of the steel pipe 5 is connected to a double-headed screw component 10 through a connecting flange 7. The other end of the double-headed screw component 10 is connected to the workbench fixed support 15. One end of the steel pipe 5 is connected to a transparent tube 9 through a connecting component 8. The other end of the transparent tube 9 is provided with a front panel 12 and a rear panel 14. A test specimen 13 is clamped between the front panel 12 and the rear panel 14. Sealing rings 11 are arranged on both the front panel 12 and the rear panel 14. The transparent tube 9 and the rear panel 14 are connected to the workbench fixed support 15;

[0043] The light gas gun system drives a flyer 2 with a certain mass m1 and diameter d by high-pressure gas to generate a certain speed v f to impact the piston 3. The flyer 2 and the piston 3 jointly impact the water area inside the steel pipe 5 to achieve shock wave loading;

[0044] The piston 3 is made of stainless steel, with a diameter of D, equal to the inner diameter of the steel pipe 5, a mass of m2, a small boss is provided at the front end for easy removal after impact, two sealing rings 11 are arranged circumferentially to ensure sliding watertightness, and the total length is designed to be 50 mm to ensure sufficient compression of the test sample. The piston 3 is provided with a gas release valve to discharge the air remaining in the steel pipe 5 during impact.

[0045] The shock wave is jointly determined by the flyer 2 and the piston 3, and the distribution expression during propagation in the water area is:

[0046]

[0047] The achievable peak shock wave is P0 = ρ w c w v0, and the shock wave time decay coefficient is θ = m / (ρ w c w );

[0048] where x is the water area coordinate, with the interface between the piston 3 and the water area as the origin, and the direction away from the piston 3 as the positive direction, t is the time, starting from when the piston 3 impacts the water area, ρ w is the density of water, which is 1000 kg / m 3 , c w is the sound speed of water, which is 1500 m / s, m = 4(m1 + m2) / (πD 2 ) is the equivalent mass after the flyer plate 2 and the piston 3 impact and combine, v0 = m1v f / (m1 + m2) is the equivalent velocity after the flyer plate 2 and the piston 3 impact and combine.

[0049] The workbench support 4 is a metal component that fixes and supports the impact end of the steel pipe 5. The workbench fixed support 15 is the fixed boundary of the test sample. The workbench surface 16 is the foundation of the combined water shock wave tube system, featuring large mass, fixed, and horizontal characteristics, ensuring the axial alignment of the water shock wave tube and the light gas gun barrel 1.

[0050] The inner diameters of the steel pipe 5 and the transparent pipe 9 are equal. The steel pipe 5 is a water shock wave tube made of stainless steel, with an inner diameter of 50 mm, a wall thickness of 5 mm, and a length of 1 m. The non-impact end of the steel pipe 5 is tapped with external threads for threaded connection with the connecting flange 7; the flange of the connecting flange 7 is provided with 4 symmetric through holes for connection with the double-headed screw component 10, and the connecting flange 7 is a stainless steel flange component.

[0051] The pressure sensor 6 is a piezoelectric overpressure measurement sensor. A plurality of them are arranged along the axial direction of the steel pipe 5 at a certain distance. Three of them are arranged at a distance of 300 mm, and the measuring range is selected to be above 60 MPa to measure the loading pressure situation.

[0052] The connection component 8 includes a double-headed pipe connector 8-1, a steel pipe end sealing gasket 8-2, and a transparent pipe end sealing gasket 8-3. The double-headed pipe connector 8-1 is a double-headed pipe connector made of Teflon, which is respectively threadedly connected with the steel pipe 5 and the transparent pipe 9. A steel pipe end sealing gasket 8-2 is arranged between the steel pipe 5 and the double-headed pipe connector 8-1, and a transparent pipe end sealing gasket 8-3 is arranged between the transparent pipe 9 and the double-headed pipe connector 8-1. The sealing gasket is a polytetrafluoroethylene sealing gasket.

[0053] The transparent pipe 9 is a non-metallic pipe made of polycarbonate, with the same inner diameter as the steel pipe 5, and the wall thickness can be increased, which is 10 mm, and the length is 1 m.

[0054] The double-headed screw assembly 10 includes a fastening bolt 10-1 and a double-headed screw 10-2. One end of the double-headed screw 10-2 is connected to the connecting flange 7 through the fastening bolt 10-1, and the other end of the double-headed screw 10-2 is connected to the workbench fixing bracket 15, which is used to increase the connection strength between the steel pipe 5 and the transparent pipe 9 and improve the system stiffness.

[0055] The test specimen 13 is a sample of the material to be tested processed into a cylindrical shape with a diameter slightly smaller than the inner diameter of the transparent pipe 9.

[0056] Both the front panel 12 and the rear panel 14 are lightweight metal pistons 3. In this embodiment, both the front panel 12 and the rear panel 14 are aluminum pistons 3. The front panel 12 is provided with a sealing ring 11 to ensure sliding watertightness, realizing a plane-uniform shock wave loading of the test sample. The rear panel 14 is provided with air holes for eliminating the influence of air compression work.

[0057] The measurement and control system includes a light gas gun pressurization and launch controller, a high-speed data acquisition instrument for measuring the shock wave pressure, a first high-speed camera for measuring the speed, and a second high-speed camera for observing the cavitation in water and the dynamic compression process of the material. The shock wave pressure measured by the high-speed data acquisition instrument comes from the pressure sensor 6. The shock wave pressure data measured by the high-speed data acquisition instrument, the speed data measured by the first high-speed camera, and the data of the cavitation in water and the dynamic compression process of the material observed by the second high-speed camera are all transmitted to the main control computer for processing and analysis.

[0058] An underwater explosion shock equivalent loading test method includes the following steps:

[0059] S1. Place the test specimen 13 between the front panel 12 and the rear panel 14, and inject water into the steel pipe 5 and the transparent pipe 9 and seal them;

[0060] S2. Install the pressure sensor 6 and arrange the measurement and control system;

[0061] S3. Start the light gas gun system to launch the flyer 2 to impact the piston 3 through the light gas gun pressurization and launch controller of the measurement and control system to simulate the underwater explosion shock;

[0062] S4. Measure the speed of the flyer 2 through the first high-speed camera of the measurement and control system, and observe and record the cavitation evolution in water and the dynamic compression process of the test sample through the second high-speed camera, as Figure 4 shown. It is observed from the compression image recorded by the second high-speed camera that the compression amount is greater than 40 mm. Record the multi-channel shock wave pressure through the high-speed measuring instrument, as Figure 5 shown. The measured and fitted peak pressure reaches 13.5 MPa > 10 MPa, and the time decay coefficient is 0.49 ms > 0.3 ms.

[0063] Therefore, the present invention adopts the above-mentioned underwater explosion shock equivalent loading test device and method, and ingeniously connects a steel equal-diameter water shock tube and a transparent equal-diameter water shock tube into a whole through a set of designed connection components. Combined with the pre-designed piston 3, it can achieve a greater shock wave loading peak, time history and material compression amount during cavitation observation; at the same time, it is convenient to disassemble and replace, and can not only conduct underwater shock tests with cavitation observation on the transparent tube 9, but also conduct underwater shock tests with a greater load on the steel tube 5 alone; the device has a compact structure and is convenient to use, and is suitable for studying the underwater dynamic shock protection performance and fluid-structure coupling mechanism of materials or structures in the laboratory.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An underwater explosion shock equivalent loading test device, characterized in that It includes a light gas gun system, a combined water shock tube system, and a measurement and control system: The light gas gun system is a shock wave load loading system for the water shock tube, used to generate a high-speed flying plate to simulate the shock wave generated by an underwater explosion; The combined water shock tube system is coaxially arranged with the light gas gun system and includes a workbench tabletop. On the workbench tabletop, there are a workbench support and a workbench fixed support. A steel pipe is fixed on the workbench support. A piston is arranged inside the steel pipe, and a pressure sensor is arranged outside the steel pipe. One end of the outside of the steel pipe is connected to a double-headed screw component through a connecting flange, and the other end of the double-headed screw component is connected to the workbench fixed support. One end of the steel pipe is connected to a transparent tube through a connecting component. The other end of the transparent tube is provided with a front panel and a rear panel. A test specimen is clamped between the front panel and the rear panel. Sealing rings are arranged on both the front panel and the rear panel. The transparent tube, the rear panel, and the workbench fixed support are connected; The measurement and control system includes a light gas gun pressurization and firing controller, a high-speed data acquisition instrument, a high-speed camera one, and a high-speed camera two. The shock wave pressure data measured by the high-speed data acquisition instrument, the velocity data measured by the high-speed camera one, and the data of the underwater cavitation and material dynamic compression process observed by the high-speed camera two are all transmitted to the main control computer for processing and analysis.

2. The underwater explosion shock equivalent loading test device according to claim 1, characterized in that: The light gas gun system drives a flyer plate with a certain mass m1 and diameter d through high-pressure gas to generate a certain velocity v f to impact the piston, and the flyer plate and the piston jointly impact the water area in the steel pipe to achieve shock wave loading; The diameter of the piston is D, which is equal to the inner diameter of the steel pipe, the mass is m2, there is a small boss at the front end, two sealing rings are arranged circumferentially, the total length is designed to be 50 mm, and the piston is provided with a gas release valve.

3. An underwater explosion shock equivalent loading test device according to claim 2, characterized in that, The distribution expression of the shock wave propagating in the water area is: The achievable peak shock wave is P0 = ρ w c w v0, and the shock wave time decay coefficient is θ = m / (ρ w c w ); Among them, x is the water area coordinate, with the interface between the piston and the water area as the origin, and the direction away from the piston as the positive direction. t is the time, starting from the moment when the piston impacts the water area. ρ w is the density of water, c w is the sound speed of water, m = 4(m1 + m2) / (πD 2 ) is the equivalent mass after the flyer and the piston impact and combine, and v0 = m1v f / (m1 + m2) is the equivalent velocity after the flyer and the piston impact and combine.

4. An underwater explosion shock equivalent loading test device according to claim 1, characterized in that: The inner diameters of the steel pipe and the transparent tube are equal. The non-impact end of the steel pipe is externally threaded for threaded connection with the connecting flange. Multiple symmetric through holes are opened on the flange plate of the connecting flange for connection with the double-headed screw component.

5. An underwater explosion shock equivalent loading test device according to claim 1, characterized in that: The pressure sensor is a piezoelectric overpressure measurement sensor, and multiple are arranged at a certain distance along the axial direction of the steel pipe.

6. An underwater explosion shock equivalent loading test device according to claim 1, characterized in that: The connecting component includes a double-headed pipe connector, a steel pipe end sealing gasket, and a transparent tube end sealing gasket. The double-headed pipe connector is respectively threadedly connected to the steel pipe and the transparent tube. The steel pipe end sealing gasket is arranged between the steel pipe and the double-headed pipe connector, and the transparent tube end sealing gasket is arranged between the transparent tube and the double-headed pipe connector.

7. An underwater explosion shock equivalent loading test device according to claim 1, characterized in that: The double-headed screw component includes a fastening bolt and a double-headed screw. One end of the double-headed screw is connected to the connecting flange through the fastening bolt, and the other end of the double-headed screw is connected to the workbench fixed support.

8. An underwater explosion shock equivalent loading test device according to claim 1, characterized in that: The test specimen is a sample of the material to be measured processed into a cylindrical shape with a diameter slightly smaller than the inner diameter of the transparent tube.

9. An underwater explosion shock equivalent loading test device according to claim 1, characterized in that: Both the front panel and the rear panel are lightweight metal pistons, and the rear panel is provided with air holes.

10. An underwater explosion shock equivalent loading test method, characterized in that, Applied to an underwater explosion shock equivalent loading test device according to any one of claims 1-9, it includes the following steps: S1. Place the test specimen between the front panel and the rear panel, inject water into the steel pipe and the transparent tube and seal them; S2. Install the pressure sensor and arrange the measurement and control system; S3. Start the light gas gun system to launch the flyer to impact the piston to simulate underwater explosion shock by pressurizing the light gas gun with the measurement control system; S4. Measure the flyer velocity with the high-speed camera 1 in the measurement control system, observe and record the cavitation evolution in water and the dynamic compression process of the test sample with the high-speed camera 2, and record the multi-channel shock wave pressure with the high-speed measuring instrument.

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