A slamming test clamping device and test method suitable for various sandwich structures

Abstract

This invention discloses a slam test clamping device suitable for various sandwich structures, including a slam test chamber, clamping pads, a sandwich structure, and a data acquisition system. The clamping pads include an upper pad, a middle pad, and a lower pad. The sandwich structure includes an upper panel, a lower panel, and a core layer. The middle pad has the same thickness as the core layer and is located between the upper and lower panels, with the middle pad positioned on the outer periphery of the core layer and securing it to its inner side. The upper pad is fixedly connected to the bottom plate by a first fastener, and the upper panel, middle pad, lower panel, and lower pad are sequentially fixedly connected to the upper pad by second fasteners. The data acquisition system includes a pressure sensor and a strain gauge. The pressure sensor is positioned close to the upper surface of the lower panel of the sandwich structure, and the strain gauge is positioned close to the upper surface of the upper panel of the sandwich structure. This invention can perform slam tests on various lightweight and high-strength sandwich structures, effectively improving the efficiency and accuracy of the slam test.

Description

Technical Field

[0001] This invention relates to the field of sandwich structure impact testing technology, and more particularly to the installation and replacement of an impact testing device. Background Technology

[0002] In recent years, ships have been rapidly developing towards higher speeds. When sailing at high speeds in rough seas, they inevitably interact with waves, generating short-duration, high-pressure slamming loads. To meet the requirements of lightweight ship structures and high speeds, and to improve the safety and reliability of hull structures, the slamming problem of lightweight sandwich structures with high specific stiffness, high specific strength, high toughness, and high energy absorption efficiency has become a research hotspot. Experimental research on the slamming of sandwich structures is the most direct and effective method, enabling the investigation of transient deformation modes, hydroelastic effects, and stiffness changes of sandwich structures under slamming loads, further revealing their plastic deformation mechanisms and energy absorption mechanisms.

[0003] Currently, the common problems with clamping devices during impact tests include:

[0004] (1) Currently, common impact test fixtures are mainly for simple structures such as single-layer plates and stiffened plates, but there are no good clamping devices for sandwich structures with diverse cell forms and complex core layer structure combinations.

[0005] (2) If a traditional single-plate clamping device is used to directly drill holes in the sandwich structure, it will damage the internal structure of the core layer, resulting in initial deformation of the core layer, which will lead to inaccurate test results and cannot guarantee that the boundary conditions of the sandwich structure remain constant.

[0006] (3) Since the sandwich structure consists of an upper panel, a lower panel and a middle core layer, after the impact test of the structure, it is necessary to measure the final deformation of the upper and lower panels. When unloading the sandwich structure using the traditional method, the removal of the clamps will cause the sandwich structure to deform and spring back, which will affect the actual structural deformation.

[0007] (4) Traditional simple impact clamping devices require the clamps to be completely removed after each impact test before the next structure can be installed, which greatly reduces the efficiency of continuous impact tests.

[0008] (5) Traditional impact clamping devices cannot guarantee the overall structural water tightness during the impact test. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a slam test clamping device suitable for various sandwich structures, which can perform slam tests on various lightweight and high-strength sandwich structures, effectively improving the efficiency and accuracy of slam tests; at the same time, a method for performing slam tests using the device is also proposed.

[0010] The technical solution adopted in this invention is:

[0011] A slam test clamping device suitable for various sandwich structures includes an slam test chamber, clamping pads, a sandwich structure, and a data acquisition system. The slam test chamber includes an slam box and a bottom plate. The clamping pads include an upper pad, a middle pad, and a lower pad. The sandwich structure includes an upper panel, a lower panel, and a core layer. The middle pad has the same thickness as the core layer, is located between the upper and lower panels, and is positioned on the outer periphery of the core layer, securing it to its inner side. The upper surface of the upper panel is in close contact with the lower surface of the upper pad, and the lower surface of the lower panel is in close contact with the upper surface of the lower pad. The upper pad is fixedly connected to the bottom plate by a first fastener. The upper panel, middle pad, lower panel, and lower pad are sequentially fixedly connected to the upper pad by a second fastener. The bottom plate, upper pad, and lower pad are all provided with an opening in the middle, serving as the impact test area of ​​the sandwich structure. The data acquisition system includes a pressure sensor and a strain gauge. The pressure sensor is set close to the upper part of the lower panel of the sandwich structure to collect the pressure signal of the lower panel during the impact. The strain gauge is set close to the upper part of the upper panel of the sandwich structure to collect the strain signal of the upper panel during the impact.

[0012] In the above scheme, the data acquisition system also includes a dynamic acquisition instrument and a computer disposed outside the impact chamber. The pressure sensor and strain gauge are respectively connected to the dynamic acquisition instrument via transmission wires, and the dynamic acquisition instrument is connected to the computer. The top of the impact chamber is provided with a through hole for the transmission wires to pass through.

[0013] In the above scheme, multiple pressure sensors are set at different positions above the lower plate, and multiple strain gauges are set at different positions above the upper plate.

[0014] In the above solution, the middle layer pad includes two U-shaped plates arranged opposite each other. The two U-shaped plates are set close to the core layer to avoid initial deformation of the core layer during installation.

[0015] The above solution also includes a waterproof pad, which is installed below the lower pad and the edge of the waterproof pad extends upward to wrap the entire sandwich structure and the upper pad; the waterproof pad has an opening in the middle as the impact test area of ​​the sandwich structure.

[0016] In the above scheme, the rectangular area where the waterproof pad contacts the impact box and the lower pad is coated with waterproof adhesive.

[0017] In the above scheme, the first fastener adopts a countersunk bolt structure, which includes a countersunk bolt and a nut. During the installation of the upper pad, the countersunk bolt passes through the upper pad and the bottom plate in sequence and is tightened and fixed by the nut, ensuring that the lower surface of the upper pad remains flat after the head of the countersunk bolt is installed.

[0018] In the above scheme, the second fastener adopts a round head screw structure, which includes a round head screw and a washer. During the installation of the sandwich structure, the round head screw passes through the washer, the lower pad, the lower panel, the middle pad, the upper panel, and the upper pad in sequence, and is tightened and fixed by the thread.

[0019] Accordingly, the present invention also proposes a slam test method applicable to various sandwich structures, employing the aforementioned slam test clamping device applicable to various sandwich structures, comprising the following steps:

[0020] S1. Fabrication of the sandwich structure and its assembly with the clamping pads: When fabricating the sandwich structure, the middle pad is installed between the upper and lower panels. The middle pad securely clamps the core layer, ensuring that the core layer does not undergo initial deformation. A pressure sensor is placed above the lower panel, and a strain gauge is placed above the upper panel, with transmission wires leading out. After the sandwich structure is fabricated, the lower pad, lower panel, middle pad, upper panel, and upper pad are connected in sequence using a second fastener, forming an integral structure composed of the clamping pads and the sandwich structure, and creating the boundary conditions for the sandwich structure to be fixed around its perimeter.

[0021] S2. Overall Installation and Impact Test of the Clamping Device: After completing the installation of the overall structure consisting of the clamping pad and the sandwich structure, simply install the overall structure onto the impact chamber. Secure the upper pad to the bottom plate using the first fastener, thus completing the overall installation of the clamping device. Then, connect the transmission wires of the pressure sensor and strain gauge to the dynamic acquisition instrument, and connect the dynamic acquisition instrument to the computer. Finally, raise the entire clamping device to a set height above the water surface and release it at rest to simulate the impact effect on the bottom of a real ship. After completing one impact test of the sandwich structure, simply remove the first fastener to remove the overall structure consisting of the clamping pad and the sandwich structure. Since the support conditions around the sandwich structure remain unchanged, it will not affect the deformation rebound effect generated during unloading, ensuring the authenticity of the test deformation results.

[0022] S3. Measurement of pressure and strain signals of the dynamic acquisition system: The dynamic acquisition instrument collects signals from the pressure sensor and strain gauge, and the data measured by the dynamic acquisition instrument is processed and displayed by a computer;

[0023] S4. The overall structure, consisting of multiple sets of clamping pads and sandwich structures, undergoes the slamming test in sequence according to steps S1-S3.

[0024] In the above method, in step S2, after the overall installation of the clamping device is completed, the waterproof pad is installed under the lower pad and wraps the entire sandwich structure and the upper pad. At the same time, waterproof adhesive is applied to the area where the waterproof pad contacts the impact box and the lower pad to ensure the wrapping and watertightness of the entire waterproof pad.

[0025] The beneficial effects of this invention are:

[0026] 1. The clamping device in this invention is suitable for impact testing of any sandwich structure: the thickness of the middle layer pad in the clamping device can change with the change of the core layer height, so the clamping device can perform impact testing on sandwich structures with different core layer structures.

[0027] 2. The clamping device in this invention can simulate the fixed boundary conditions of the sandwich structure and ensure that no initial deformation occurs when installing the sandwich structure: the middle layer pad is set on the outer periphery of the core layer and is close to the core layer and clamps the core layer to its inner side, avoiding the initial compression deformation of the core layer caused during the installation process; at the same time, the upper layer pad, upper panel, middle layer pad, lower panel and lower layer pad are connected by the second fastener, which effectively ensures the fixed boundary of the sandwich structure.

[0028] 3. The clamping device in this invention can perform overall installation and disassembly of the sandwich structure, eliminating the springback deformation effect caused by unloading the clamp: Before starting the impact test, the upper pad is installed under the impact box, and then the entire sandwich structure is fixed on the upper pad by the second fastener; after the impact test is completed, when disassembling the sandwich structure, the first fastener can be removed, and the overall structure composed of the clamping pad and the sandwich structure can be disassembled, avoiding the springback effect of the sandwich structure during the disassembly process, thereby ensuring that the true structural deformation is obtained.

[0029] 4. The clamping device in this invention can be mass-produced, improving the efficiency of impact testing and saving time from multiple impact tests: When manufacturing the sandwich structure, the middle layer pad is placed inside the upper and lower panels, and multiple integral clamping devices are mass-produced and installed using a second fastener and a first fastener. The specific installation process is as follows: the first fastener passes through the upper layer pad but is not installed onto the impact chamber; the second fastener passes through the lower layer pad, lower panel, middle layer pad, upper panel, and upper layer pad, forming an integral clamping device that only needs to be installed onto the impact chamber. Multiple clamping devices are disassembled and replaced as a whole after each impact test, reducing the time wasted on multiple impact tests.

[0030] 5. The clamping device in this invention has a significant sealing effect and good water tightness: the waterproof pad is installed last, covering the entire sandwich structure and the upper pad plate. It has an internal recessed hole that completely fits the protruding area of ​​the round head screw. At the same time, waterproof adhesive is applied to the area where the waterproof pad contacts the impact box and the lower pad plate to ensure that the entire waterproof pad has good wrapping and water tightness. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the overall structure of the impact test clamping device applicable to various sandwich configurations of the present invention;

[0033] Figure 2 yes Figure 1 A schematic diagram of the impact chamber of the impact test clamping device shown;

[0034] Figure 3 yes Figure 1 A schematic diagram of the clamping pad of the impact test clamping device shown;

[0035] Figure 4 yes Figure 1 A schematic diagram of the clamping structure of the impact test clamping device is shown.

[0036] Figure 5 yes Figure 1 A schematic diagram of the first fastener of the impact test clamping device shown;

[0037] Figure 6 yes Figure 1 A schematic diagram of the second fastener of the impact test clamping device shown;

[0038] Figure 7 yes Figure 1 A schematic diagram of the waterproof pad of the impact test clamping device shown;

[0039] Figure 8 yes Figure 1 A schematic diagram of the data acquisition system for the impact test clamping device is shown.

[0040] Figure 9 yes Figure 1 A partial structural cross-sectional view of the impact test clamping device shown;

[0041] Figure 10 yes Figure 9 Enlarged view of point A;

[0042] Figure 11 yes Figure 9 Enlarged view of point B;

[0043] Figure 12 This is a schematic diagram of the installation of the clamping pad and the sandwich structure;

[0044] Figure 13 This is an installation diagram of the overall structure consisting of the clamping pad and the sandwich structure;

[0045] Figure 14 This is a diagram showing the installation of the waterproof gasket.

[0046] In the diagram: 10. Impact box; 11. Impact chamber; 12. Through hole; 13. Bottom plate;

[0047] 20. Clamping pad; 21. Upper pad; 22. Middle pad; 23. Lower pad;

[0048] 30. Sandwich structure; 31. Top panel; 32. Bottom panel; 33. Core layer;

[0049] 41. Countersunk bolt structure; 411. Countersunk bolt; 412. Nut; 42. Round head screw structure; 421. Round head screw; 422. Washer;

[0050] 50. Waterproof gasket; 51. Recessed hole; 52. Waterproof adhesive;

[0051] 60. Data acquisition system; 61. Pressure sensor; 62. Strain gauge; 63. Transmission wire; 64. Dynamic acquisition instrument; 65. Computer. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0053] It should be noted that the illustrations provided in the embodiments of the present invention are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0054] In this invention, it should also be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used only for descriptive and distinguishing purposes and should not be construed as indicating or implying relative importance.

[0055] like Figure 1 As shown, an impact test clamping device suitable for various sandwich structures is provided in an embodiment of the present invention, including an impact chamber 10, a clamping pad 20, a sandwich structure 30, and a data acquisition system 60. Figure 2 As shown, the slamming box 10 is the main slamming device, which can simulate the real situation where the outer side of the ship's structure is in contact with water while the inner side is not during a ship slamming. The slamming box 10 includes a slamming box 11 and a bottom plate 13. Figure 3 As shown, the clamping pad 20 includes an upper pad 21, a middle pad 22, and a lower pad 23. Figure 4 As shown, the sandwich structure 30 includes an upper panel 31, a lower panel 32, and a core layer 33. The middle layer pad 22 has the same thickness as the core layer 33 and is located between the upper panel 31 and the lower panel 32. The middle layer pad 22 is positioned around the core layer 33 and secures it to its inner side, ensuring that the core layer 33 does not undergo initial deformation during installation and guaranteeing the boundary conditions for perimeter support. The upper surface of the upper panel 31 is in close contact with the lower surface of the upper layer pad 21, and the lower surface of the lower panel 32 is in close contact with the upper surface of the lower layer pad 23. The upper layer pad 21 is fixedly connected to the bottom plate 13 by a first fastener. The upper panel 31, middle layer pad 22, lower panel 32, and lower layer pad 23 are sequentially fixedly connected to the upper layer pad 21 by second fasteners. An opening is provided in the middle of the bottom plate 13, the upper layer pad 21, and the lower layer pad 23, serving as an impact test area for the sandwich structure 30. The data acquisition system 60 includes a pressure sensor 61 and a strain gauge 62. The pressure sensor 61 is installed close to the upper part of the lower panel 32 of the sandwich structure 30 and is used to collect the pressure signal of the lower panel 32 during the impact. The strain gauge 62 is installed close to the upper part of the upper panel 31 of the sandwich structure 30 and is used to collect the strain signal of the upper panel 31 during the impact.

[0056] Further optimization includes a dynamic data acquisition system 60 that is located outside the impact chamber 10, comprising a dynamic data acquisition unit 64 and a computer 65. The pressure sensor 61 and strain gauge 62 are connected to the dynamic data acquisition unit 64 via transmission wires 63. The dynamic data acquisition unit 64 is connected to the computer 65. The dynamic data acquisition unit 64 collects signals from the pressure sensor 61 and strain gauge 62, while the computer 65 processes the data measured by the dynamic data acquisition unit 64. A through-hole 12 is provided at the top of the impact chamber 11, serving as a connection port for the transmission wires 63 between the pressure sensor 61, strain gauge 62, and dynamic data acquisition unit 64. It should be noted that the through-hole 12 at the top of the impact chamber 10 must be sealed with adhesive when releasing the chamber to prevent water from entering the chamber during the impact process, which could affect the accuracy of the impact test results.

[0057] Further optimization involves setting multiple pressure sensors 61 at different positions above the lower plate 32 and multiple strain gauges 62 at different positions above the upper plate 31 to collect pressure and strain signals generated by the impact of the sandwich structure 30 at different measuring points.

[0058] Further optimization involves the middle layer pad 22 comprising two U-shaped plates arranged opposite each other, which are set tightly against the core layer 33 to prevent initial deformation of the core layer 33 caused by tightening bolts during installation.

[0059] Further optimization is possible; the upper panel 31 and lower panel 32 can be made of steel, aluminum, composite materials, etc.; the core layer 33 can be made of steel, aluminum, foam, balsa wood, composite materials, etc.; the core layer 33 has various structural forms, such as honeycomb, corrugated, and dot matrix. The clamping pad 20 is preferably made of lightweight aluminum alloy so that the entire clamping device is lightweight and easy to install as a whole during installation; the thickness of the middle pad 22 varies with the height of the core layer 33, ensuring the structural diversity of the core layer 33.

[0060] Further optimization includes a waterproof pad 50, which is installed below the lower pad 23, with its edges extending upwards to enclose the entire sandwich structure 30 and the upper pad 21. The waterproof pad 50 has an opening in the middle, serving as the impact test area for the sandwich structure 30. The rectangular area of ​​the waterproof pad 50 in contact with the impact chamber 10 and the lower pad 23 is coated with waterproof adhesive 52 to ensure good encapsulation and watertightness of the entire waterproof pad 50.

[0061] Further optimization involves using a countersunk bolt structure 41 as the first fastener for securing the upper pad 21 and the impact chamber 10. For example... Figure 5As shown, the countersunk bolt structure 41 includes a countersunk bolt 411 and a nut 412. During the installation of the upper pad 21, the countersunk bolt 411 passes through the upper pad 21 and the bottom plate 13 in sequence, and is tightened and fixed by the nut 412. This ensures that the lower surface of the upper pad 21 remains flat after the head of the countersunk bolt 411 is installed, so that the sandwich structure 30 can fit tightly.

[0062] Further optimization involves using a round-head screw structure 42 as the second fastener. This fastener is used to fix the entire sandwich structure 30, the middle layer pad 22, and the lower layer pad 23 onto the upper layer pad 21, ensuring the boundary conditions for the fixed support around the sandwich structure 30. Figure 6 As shown, the round-head screw structure 42 includes a round-head screw 421 and a washer 422. During the installation of the sandwich structure 30, the round-head screw 421 passes sequentially through the washer 422, the lower pad 23, the lower panel 32, the middle pad 22, the upper panel 31, and the upper pad 21, and is tightened and fixed by the threads. Correspondingly, the waterproof gasket 50 has a recessed hole 51 inside, which completely fits the protruding area of ​​the round-head screw 421.

[0063] Accordingly, the present invention also proposes a slam test method applicable to various sandwich structures 30, employing the aforementioned slam test clamping device applicable to various sandwich structures 30, comprising the following steps:

[0064] S1. Fabrication of the sandwich structure 30 and its assembly with the clamping pad 20: During the fabrication of the sandwich structure 30, the middle pad 22 is installed between the upper panel 31 and the lower panel 32. The middle pad 22 securely clamps the core layer 33, ensuring that the core layer 33 does not undergo initial deformation. A pressure sensor 61 is arranged above the lower panel 32, and a strain gauge 62 is arranged above the upper panel 31, and the strain gauges are led out through the transmission wire 63. After the sandwich structure 30 is fabricated, the lower pad 23, lower panel 32, middle pad 22, upper panel 31, and upper pad 21 are connected in sequence using the second fastener, forming an integral structure composed of the clamping pad 20 and the sandwich structure 30, and establishing the boundary conditions for the sandwich structure 30 to be fixed around its perimeter.

[0065] S2. Overall Installation and Impact Test of the Clamping Device: After completing the installation of the overall structure consisting of the clamping pad 20 and the sandwich structure 30, simply install the overall structure onto the impact chamber 10. Secure the upper pad 21 to the bottom plate 13 using the first fastener, thus completing the overall installation of the clamping device. Then, connect the transmission wires 63 of the pressure sensor 61 and strain gauge 62 to the dynamic acquisition instrument 64, and connect the dynamic acquisition instrument 64 to the computer 65. Finally, raise the entire clamping device to a set height above the water surface and release it statically to simulate the impact effect on the bottom of a real ship. After completing one impact test of the sandwich structure 30, simply remove the first fastener to remove the overall structure consisting of the clamping pad 20 and the sandwich structure 30. Since the surrounding support conditions of the sandwich structure 30 remain unchanged, it will not affect the deformation and springback effect generated during unloading, ensuring the authenticity of the test deformation results.

[0066] S3. Measurement of pressure and strain signals of the dynamic acquisition system: The dynamic acquisition instrument 64 collects the signals from the pressure sensor 61 and the strain gauge 62, and the computer 65 processes and displays the data measured by the dynamic acquisition instrument 64.

[0067] S4. The overall structure consisting of multiple sets of clamping pads 20 and sandwich structure 30 shall undergo the slam test in sequence according to steps S1-S3.

[0068] Further optimization is achieved in step S2. After the overall installation of the clamping device is completed, the waterproof pad 50 is installed under the lower pad 23 and wraps around the entire sandwich structure 30 and the upper pad 21. At the same time, waterproof adhesive 52 is applied to the area where the waterproof pad 50 contacts the impact chamber 10 and the lower pad 23 to ensure the wrapping and watertightness of the entire waterproof pad 50. This achieves waterproofing of the sandwich structure 30 during the impact test and improves the accuracy of the test data.

[0069] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0070] The order of the steps in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0071] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A slamming test clamping device suitable for various sandwich structures, characterized in that, The device includes an impact chamber, clamping pads, a sandwich structure, and a data acquisition system. The impact chamber comprises an impact box and a bottom plate. The clamping pads include an upper pad, a middle pad, and a lower pad. The sandwich structure includes an upper panel, a lower panel, and a core layer. The middle pad has the same thickness as the core layer and is located between the upper and lower panels. The middle pad is positioned around the core layer and secures it to its inner side. The upper surface of the upper panel is in close contact with the lower surface of the upper pad, and the lower surface of the lower panel is in close contact with the upper surface of the lower pad. The upper pad is secured by a first fastener. The bottom plate, middle pad, bottom plate, and lower pad are fixedly connected to the bottom plate. The top plate, middle pad, bottom plate, and lower pad are sequentially fixedly connected to the top pad via a second fastener. Each of the bottom plate, top pad, and lower pad has an opening in the middle, serving as the impact test area for the sandwich structure. The data acquisition system includes a pressure sensor and a strain gauge. The pressure sensor is positioned close to the top of the bottom plate of the sandwich structure to collect the pressure signal of the bottom plate during the impact test. The strain gauge is positioned close to the top of the top plate of the sandwich structure to collect the strain signal of the top plate during the impact test.

2. The impact test clamping device applicable to various sandwich structures according to claim 1, characterized in that, The data acquisition system also includes a dynamic acquisition instrument and a computer disposed outside the impact chamber. The pressure sensor and strain gauge are respectively connected to the dynamic acquisition instrument via transmission wires, and the dynamic acquisition instrument is connected to the computer. The top of the impact chamber is provided with a through hole for the transmission wires to pass through.

3. The impact test clamping device applicable to various sandwich structures according to claim 1, characterized in that, Multiple pressure sensors are installed at different positions above the lower plate, and multiple strain gauges are installed at different positions above the upper plate.

4. The impact test clamping device applicable to various sandwich structures according to claim 1, characterized in that, The middle layer pad includes two U-shaped plates arranged opposite each other, which are closely attached to the core layer to avoid initial deformation of the core layer during installation.

5. The impact test clamping device applicable to various sandwich structures according to claim 1, characterized in that, It also includes a waterproof pad, which is installed below the lower pad and the edge of the waterproof pad extends upward to cover the entire sandwich structure and the upper pad; the waterproof pad has an opening in the middle as a slam test area for the sandwich structure.

6. The impact test clamping device applicable to various sandwich structures according to claim 5, characterized in that, The rectangular area where the waterproof pad contacts the impact chamber and the lower pad is coated with waterproof adhesive.

7. The impact test clamping device applicable to various sandwich structures according to claim 1, characterized in that, The first fastener adopts a countersunk bolt structure, which includes a countersunk bolt and a nut. During the installation of the upper pad, the countersunk bolt passes through the upper pad and the bottom plate in sequence and is tightened and fixed by the nut, ensuring that the lower surface of the upper pad remains flat after the head of the countersunk bolt is installed.

8. The impact test clamping device applicable to various sandwich structures according to claim 1, characterized in that, The second fastener adopts a round head screw structure, which includes a round head screw and a washer. During the installation of the sandwich structure, the round head screw passes through the washer, the lower pad, the lower panel, the middle pad, the upper panel, and the upper pad in sequence, and is tightened and fixed by the thread.

9. A slamming test method applicable to various sandwich structures, characterized in that, The impact test clamping device according to any one of claims 1-8, applicable to various sandwich structures, includes the following steps: S1. Fabrication of the sandwich structure and its assembly with the clamping pads: When fabricating the sandwich structure, the middle pad is installed between the upper and lower panels. The middle pad securely clamps the core layer, ensuring that the core layer does not undergo initial deformation. A pressure sensor is placed above the lower panel, and a strain gauge is placed above the upper panel, with transmission wires leading out. After the sandwich structure is fabricated, the lower pad, lower panel, middle pad, upper panel, and upper pad are connected in sequence using a second fastener, forming an integral structure composed of the clamping pads and the sandwich structure, and creating the boundary conditions for the sandwich structure to be fixed around its perimeter. S2. Overall Installation and Impact Test of the Clamping Device: After completing the installation of the overall structure consisting of the clamping pad and the sandwich structure, simply install the overall structure onto the impact chamber. Secure the upper pad to the bottom plate using the first fastener, thus completing the overall installation of the clamping device. Then, connect the transmission wires of the pressure sensor and strain gauge to the dynamic acquisition instrument, and connect the dynamic acquisition instrument to the computer. Finally, raise the entire clamping device to a set height above the water surface and release it at rest to simulate the impact effect on the bottom of a real ship. After completing one impact test of the sandwich structure, simply remove the first fastener to remove the overall structure consisting of the clamping pad and the sandwich structure. Since the support conditions around the sandwich structure remain unchanged, it will not affect the deformation rebound effect generated during unloading, ensuring the authenticity of the test deformation results. S3. Measurement of pressure and strain signals of the dynamic acquisition system: The dynamic acquisition instrument collects signals from the pressure sensor and strain gauge, and the data measured by the dynamic acquisition instrument is processed and displayed by a computer; S4. The overall structure, consisting of multiple sets of clamping pads and sandwich structures, undergoes the slamming test in sequence according to steps S1-S3.

10. The impact test method applicable to various sandwich structures according to claim 9, characterized in that, In step S2, after the overall installation of the clamping device is completed, the waterproof pad is installed under the lower pad and wraps around the entire sandwich structure and the upper pad. At the same time, waterproof adhesive is applied to the area where the waterproof pad contacts the impact box and the lower pad to ensure the wrapping and watertightness of the entire waterproof pad.

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