A test device for simulating ejection impact load

Abstract

The present invention provides a test device for simulating ejection impact loads, wherein the side columns of the test device are fixedly arranged, a moving guide rail is arranged on the inner wall of each side column in a vertical direction, a variable stiffness spring is arranged under each moving guide rail, an electromagnet is arranged at a certain height between the two side columns, a load block is connected to the electromagnet under the magnetic force of the electromagnet, two ends of the load block are slidably connected to the moving guide rail, an impact force sensor is arranged on the load block, and the lower bottom surface of the impact force sensor is flush with the lower end surfaces of the two ends of the bracket, a model box is arranged below the load block and filled with soil, the surface of the soil in the model box is flush with the upper end surface of the variable stiffness spring, each crank pulley mechanism is arranged on the corresponding side column and is located above the variable stiffness spring, and when the load block impacts the soil for the first time and bounces up, the limiter in the crank pulley mechanism moves to the moving guide rail to prevent the load block from impacting the soil again.

Description

Technical Field

[0001] The invention relates to a testing device, in particular to a testing device for simulating ejection impact load. Background Art

[0002] At present, domestic and foreign scholars have conducted many studies on the response of soil under dynamic loads. Among them, the dynamic response of soil under impact loads mainly focuses on load forms such as drop hammer impact, rolling impact and rockfall impact. The relevant research on soil under catapult impact loads mainly uses numerical simulation and theoretical analysis methods. There is a lack of experimental research and lack of data support in the field of engineering applications.

[0003] Patent publication number CN106872289B discloses a sand and soil impact load test device and test method thereof, which applies an impact load to the soil through the free fall of a hammer. Patent publication number CN102288347B discloses a lander and soil interaction impact model test device, which vertically impacts the soil by controlling the mass and drop height of the impact cylinder. Most existing patents simulate impact loads based on the gravity impact of a falling hammer, which belongs to a triangular impact load condition and is difficult to simulate the trapezoidal load condition of a catapult impact load. Therefore, researchers are in urgent need of a loading device that simulates catapult impact loads to provide a reference for the mechanism analysis and engineering design of the dynamic response of soil. Summary of the Invention

[0004] The purpose of the present invention is to provide a test device for simulating catapult impact load, comprising two side columns, an electromagnet, a load block, an impact force sensor, two variable stiffness springs, two crank pulley mechanisms, and a model box; the side columns are fixedly arranged, a motion guide rail is arranged along the vertical direction on the inner wall of each side column, a variable stiffness spring is arranged below each motion guide rail, the electromagnet is arranged between the two side columns, the load block is connected to the electromagnet under the magnetic force of the electromagnet, the load block includes a bracket and a counterweight block, the bracket is a U-shaped bracket and the two sides of the bracket are connected. The ends are slidably connected to the moving guide rail, the counterweight block is fixed in the U-shaped groove of the bracket, the impact force sensor is arranged on the load block, and the lower bottom surface of the impact force sensor is flush with the lower end surfaces of both ends of the bracket, the model box is arranged below the load block and filled with soil, the surface of the soil in the model box is flush with the upper end surface of the variable stiffness spring, each crank pulley mechanism is arranged on the corresponding side column and is located above the variable stiffness spring, when the load block impacts the soil for the first time and bounces up, the limiter in the crank pulley mechanism moves to the moving guide rail to prevent the load block from impacting the soil again.

[0005] Furthermore, each crank pulley mechanism also includes a crank, a connecting rod, a limiter, a bearing, and a sliding guide rail; the sliding guide rail is horizontally arranged in a groove on the inner wall of the side column, the lower end wall of the groove is flush with the upper end surface of the variable stiffness spring, the sliding guide rail extends to the moving guide rail, the bearing is rotatably connected to the inner wall of the groove and rotates under the drive of external force, one end of the crank is rotatably connected to the bearing, the other end of the crank is rotatably connected to one end of the connecting rod, the other end of the connecting rod is rotatably connected to the limiter, and the limiter is slidably connected to the sliding guide rail.

[0006] Furthermore, each variable stiffness spring includes a spring, an upper base, and a lower base. The lower base is fixed to the lower end of the corresponding motion guide rail, and the upper and lower ends of the spring are respectively fixed to the upper base and the lower base.

[0007] Furthermore, it also includes an infrared sensor and a limiter control unit. When the load block rebounds and rises, the infrared sensor is triggered, the limiter control unit sends a braking signal, and the crank performs a circular motion.

[0008] Furthermore, the load block also includes a loading rod and bolts. The bracket is a U-shaped bracket. The two ends of the bracket are slidingly connected to the moving guide rail. The loading rod is fixedly connected to the counterweight block by bolts. The loading rod includes two parts, the upper part of the loading rod and the counterweight block are both rectangular, and the lower part of the loading rod is a cylinder. The impact force sensor is arranged on the lower part of the loading rod, and the lower bottom surface of the impact force sensor is flush with the lower end surfaces of the two ends of the bracket.

[0009] Furthermore, the loading rod includes an upper and lower part. The upper part of the loading rod and the counterweight are both rectangular. The lower part of the impact force sensor is a cylinder. The impact force sensor is arranged on the lower part of the loading rod.

[0010] Furthermore, it also includes a winch, which is arranged on a crossbeam, and the crossbeam is erected on the upper ends of the two side columns. One end of the rope of the winch is fixedly connected to the electromagnet.

[0011] Furthermore, the model box includes a model box body, and a drainage cushion layer, a drainage board and a drainage valve are arranged at the bottom of the model box body.

[0012] Compared with the prior art, the present invention has the following advantages: (1) The crank pulley mechanism blocks the moving guide rail to prevent the load block from causing a secondary impact on the soil. The loading process and the limiter control are simple and easy to operate, and multiple ejection impacts on the soil can be achieved; (2) By adjusting the mass and lifting height of the load block, combined with the stiffness control of the variable stiffness spring, the size and action time of the ejection impact load can be controlled. The device provides an experimental approach for studying the dynamic response of the soil under the action of the ejection impact load, saving space and cost; (3) The moving guide rail, the adjustable stiffness spring and the crank pulley mechanism are arranged inside the side column to achieve a compact structure and effectively reduce the occupied space.

[0013] The present invention will be further described below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the main structure of the present invention.

[0015] Figure 2 Schematic diagram of the load block structure of the present invention.

[0016] Figure 3 It is an enlarged schematic diagram of the local structure of the side column of the present invention.

[0017] Figure 4 It is a cross-sectional view of the crank pulley mechanism of the present invention.

[0018] Figure 5 It is a longitudinal sectional view of the model box of the present invention.

[0019] Figure 6 Flow chart of the test method process of the present invention.

[0020] Among them, winch 1, crossbeam 2, electromagnet 3, load block 4, bracket 41, counterweight block 42, loading rod 43, bolt 44, impact force sensor 5, side column 6, motion guide rail 7, variable stiffness spring 8, spring 81, upper base 82, lower base 83, crank pulley mechanism 9, crank 91, connecting rod 92, limiter 93, bearing 94, sliding guide rail 95, infrared sensor 10, limiter control unit 11, model box 12, model box body 121, drainage pad 122, drainage board 123, drainage valve 124. DETAILED DESCRIPTION

[0021] Combine Figure 1A test device for simulating ejection impact loads includes side columns 6, electromagnets 3, load blocks 4, impact force sensors 5, variable stiffness springs 8, crank pulley mechanisms 9, and a model box 12. The side columns 6 are fixed, and a motion guide rail 7 is provided vertically on the inner wall of the side columns 6. A variable stiffness spring 8 is provided below the motion guide rail 7. An electromagnet 3 is provided at a certain height between the two side columns 6. The load block 4 is connected to the electromagnet 3 under the magnetic force of the electromagnet 3. Both ends of the load block 4 are slidably connected to the motion guide rail 7. The impact force sensor 5 is provided on the load block 4, and the lower bottom surface of the impact force sensor 5 is flush with the lower end surfaces of the bracket 41. The model box 12 is placed below the load block 4 and filled with soil. The soil surface in the model box 12 is flush with the upper end surface of the variable stiffness spring 8. The crank pulley mechanism 9 is placed on the corresponding side column 6 and above the variable stiffness spring 8. When the load block 4 first impacts the soil and bounces, the limiter 93 in the crank pulley mechanism 9 moves to the motion guide 7 to prevent the load block 4 from impacting the soil again. The load block 4 is initially magnetically attracted by the electromagnet 3 and is at the target height. After the test begins, the electromagnet 3 releases its magnetic force, causing the load block 4 to freely fall along the motion guide 7. The gravitational potential energy is converted into kinetic energy, and the load block 4 impacts the soil with a certain momentum.

[0022] In order to prevent the load block 4 from bouncing back after the first impact on the soil and causing a secondary or even multiple impacts on the soil, and to achieve a trapezoidal load condition, when the load block 4 bounces back after the first impact on the soil, the crank pulley mechanism 9 is used to intercept the load block 4 and prevent the load block 4 from impacting downward again. A groove is provided on the inner wall of the side column 6 in the horizontal direction for setting the crank pulley mechanism 9. Figure 4 Each crank pulley mechanism 9 includes a crank 91, a connecting rod 92, a stopper 93, a bearing 94, and a sliding guide rail 95. The sliding guide rail 95 is horizontally arranged in the groove of the side column 6 and extends to the moving guide rail 7. The width of the sliding guide rail 95 is greater than that of the moving guide rail 7. One end of the crank 91 is rotatably connected to the groove of the side column 6 via the bearing 94. The crank 91 performs circular motion under external force. The other end of the crank 91 is rotatably connected to one end of the connecting rod 92 via the bearing. The other end of the connecting rod 92 is rotatably connected to the stopper 93. The stopper 93 reciprocates on the sliding guide rail 95, and one of the movement trajectories of the stopper 93 coincides with the moving guide rail 7.

[0023] In order to extend and control the duration of the ejection impact load, a variable stiffness spring 8 is provided in the side column 6. There are two variable stiffness springs 8, one for each of the left and right side columns 6. Figure 3Each variable stiffness spring 8 includes a spring 81, an upper base 82 and a lower base 83. The lower base 83 is fixed to the lower end of the motion guide rail 7, and the upper and lower ends of the spring 81 are fixed to the upper base 82 and the lower base 83 respectively. In the process of being compressed by the impact of the bracket 41, the spring 81 stores elastic potential energy by deformation, which can regulate the duration of the ejection impact load; when the energy of the load block 4 is completely converted into the potential energy of the soil and the elastic potential energy of the spring 81, the loading section ends, and the elastic potential energy stored in the spring 81 begins to be converted into the kinetic energy and gravitational potential energy of the load block 4, rebounding the load block 4 and stopping at the limiter 93, completing the unloading process of the ejection impact load. The impact force sensor 5 is installed at the lower edge of the loading rod 43 to measure the load impact value of the soil during the impact test, thereby obtaining the ejection impact load time curve of the soil.

[0024] The model test device simulating ejection impact loads also includes an infrared sensor 10 and a stopper control unit 11, which work in conjunction with the crank pulley mechanism 9 to block the load block 4. Specifically, when the load block 4 rebounds and rises, it triggers the infrared sensor 10, and the stopper control unit 11 sends a braking signal. The crank 91 begins to move in a circular motion, transmitting torque through the bearing 94. The connecting rod 92 pulls the stopper 93 forward in the sliding guide 95, blocking the moving guide 7. When the load block 4 rebounds and descends, it stops at the stopper 93, avoiding secondary impact on the soil and completing the braking.

[0025] Combine Figure 2 The load block 4 includes a bracket 41, a counterweight 42, a loading rod 43 and a bolt 44. The bracket 41 is a U-shaped bracket, and both ends of the bracket 41 are slidably connected to the motion guide rail 7. The counterweight 42 and the loading rod 43 are fixed in the U-shaped groove of the bracket 41 by bolts 44. The two sides of the bracket 41 are embedded in the motion guide rails 7 of the two side columns 6 to limit the spatial movement direction of the bracket 41 and ensure that the load block 4 performs free fall motion. The impact force sensor 5 is arranged on the loading rod 43, and the lower bottom surface of the impact force sensor 5 is flush with the lower end surfaces of the two ends of the bracket 41. Specifically, the loading rod 43 includes an upper and lower part. The shape of the upper part of the loading rod 43 and the shape of the counterweight 42 are both rectangular parallelepipeds, and the lower part of the loading rod 43 is a cylinder. The impact force sensor 5 is arranged on the lower part of the loading rod 43. Changing the number of counterweights 42 can change the impulse of the load block 4.

[0026] Combine Figure 1 The test device for simulating ejection impact loads also includes a hoist 1, which is installed on a crossbeam 2, which is installed at the upper ends of two side columns 6. The hoist 1 is connected to the electromagnet 3 via a rope, and the electromagnet 3 and the load block 4 are lifted to the target height.

[0027] like Figure 5As shown, a drainage pad 122 and a drainage board 123 are installed at the bottom of the model box 121. Before the test begins, the soil moisture content can be changed by adjusting the drainage valve 124 at the bottom of the model box 12. Earth pressure sensors and pore water pressure sensors can be embedded in the soil to detect changes in effective stress within the soil and its liquefaction characteristics. A plexiglass observation window is installed on one side of the model box 12, allowing the overall dynamic deformation of the soil to be monitored and analyzed using high-speed imaging analysis technology. This allows data collection on the forces and deformations of the soil during the entire ejection impact test.

[0028] Combine Figure 6 A test method using the above-mentioned simulated ejection impact load test device has the following specific process:

[0029] Step S100: Connect and debug the test control circuit, brake circuit, and measurement circuit to ensure that all components are working properly and the data circuit operates in accordance with regulations;

[0030] Step S200: Fill the model box 12 with the soil to be tested in layers, controlling parameters such as density and moisture content. Simultaneously, an earth pressure sensor and an excess pore pressure sensor are embedded in the soil. A high-speed camera is installed on one side of the model box 12 where the organic glass observation window is located, at a height consistent with the soil height.

[0031] Step S300: The load block 4 is brought to a specified weight by changing the mass of the counterweight block 42. The impact force sensor 5 is mounted on the lower edge of the loading rod 43. The winch 1 and the electromagnet 3 work together to lift the load block to a specified height.

[0032] Step S400: The electromagnetic force of the electromagnet 3 is released. During the process of the loading rod 43 ejecting and impacting the soil, the variable stiffness spring 8 and the crank pulley mechanism 9 start to work, so that the ejected load block 4 stops at the stopper 93, and the single ejection impact is completed;

[0033] Step S500: After the ejection impact is completed, the sensor mechanical data and the imaging data of the soil deformation are saved;

[0034] In step S600, if the soil is not damaged or liquefied, after the soil is stable, the mass of the load block 4 is gradually increased according to the load increasing principle, and the above steps are repeated to perform continuous ejection impact on the soil.

Claims

1. A test device for simulating ejection impact load, characterized in that: The invention comprises two side columns (6), an electromagnet (3), a load block (4), an impact force sensor (5), two variable stiffness springs (8), two crank pulley mechanisms (9), an infrared sensor (10), a limiter control unit (11), and a model box (12); each crank pulley mechanism (9) further comprises a crank (91), a connecting rod (92), a limiter (93), a bearing (94), and a sliding guide rail (95); The side column (6) is fixedly arranged. A motion guide rail (7) is provided on the inner wall of each side column (6) in the vertical direction. A variable stiffness spring (8) is provided below each moving guide rail (7). The electromagnet (3) is set between the two side columns (6). The load block (4) is connected to the electromagnet (3) under the magnetic force of the electromagnet (3). The load block (4) includes a bracket (41) and a counterweight (42). The bracket (41) is a U-shaped bracket and both ends of the bracket (41) are slidably connected to the motion guide rail (7). The counterweight (42) is fixed in the U-shaped groove of the bracket (41). The impact force sensor (5) is arranged on the load block (4), and the bottom surface of the impact force sensor (5) is flush with the lower end surfaces of both ends of the bracket (41). The model box (12) is arranged below the load block (4) and filled with soil. The surface of the soil in the model box (12) is flush with the upper end surface of the variable stiffness spring (8). Each crank pulley mechanism (9) is arranged on a corresponding side column (6) and is located above a variable stiffness spring (8). The sliding guide rail (95) is arranged in the groove of the inner wall of the side column (6) along the horizontal direction. The lower end wall of the groove is flush with the upper end surface of the variable stiffness spring (8). The sliding guide rail (95) extends to the moving guide rail (7). The bearing (94) is rotatably connected to the inner wall of the groove and rotates under the driving force of the external force. One end of the crank (91) is rotatably connected to the bearing (94). The other end of the crank (91) is rotatably connected to one end of the connecting rod (92). The other end of the connecting rod (92) is rotatably connected to the limiter (93). The stopper (93) is slidably connected to the sliding guide rail (95). When the load block (4) first impacts the soil and bounces up, during the rebound process, the infrared sensor (10) is triggered, the limiter control unit (11) sends a braking signal, the crank (91) performs a circular motion, and the limiter (93) moves to the motion guide rail (7) to prevent the load block (4) from impacting the soil again.

2. The test device according to claim 1, characterized in that Each variable stiffness spring (8) comprises a spring (81), an upper base (82), and a lower base (83). The lower base (83) is fixed to the lower end of the corresponding motion guide rail (7). The upper and lower ends of the spring (81) are respectively fixed to the upper base (82) and the lower base (83).

3. The test device according to claim 1, characterized in that The load block (4) further comprises a loading rod (43) and a bolt (44). The loading rod (43) is fixedly connected to the counterweight (42) via a bolt (44). The loading rod (43) comprises an upper and lower part. The upper part of the loading rod (43) and the counterweight (42) are both rectangular parallelepipeds. The lower part of the loading rod (43) is a cylinder. The impact force sensor (5) is arranged on the lower part of the loading rod (43). The lower bottom surface of the impact force sensor (5) is flush with the lower end surfaces of both ends of the bracket (41).

4. The test device according to claim 1, characterized in that It also includes a winch (1), which is arranged on a crossbeam (2). The crossbeam (2) is mounted on the upper ends of two side columns (6). One end of the rope of the winch (1) is fixedly connected to the electromagnet (3).

5. The test device according to claim 1, characterized in that The model box (12) comprises a model box body (121), and a drainage cushion layer (122), a drainage board (123) and a drainage valve (124) are arranged at the bottom of the model box body (121).

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