Testing device for simulating ejection impact load

Abstract

The invention provides a test device for simulating ejection impact load, which is characterized in that side columns of the test device are fixedly arranged, a movement guide rail is arranged on the inner wall of each side column along the vertical direction, a variable stiffness spring is arranged below each movement guide rail, and an electromagnet is arranged at a certain height between the two side columns. The load block is connected with the electromagnet under the magnetic force effect of the electromagnet, the two ends of the load block are slidably connected with the movement guide rails, the impact force sensor is arranged on the load block, the lower bottom face of the impact force sensor is flush with the lower end faces of the two ends of the support, and the model box is arranged below the load block and filled with soil. The surface of a soil body in the model box is flush with the upper end face of the variable-rigidity spring, each crank pulley mechanism is arranged on the corresponding side column and located above the variable-rigidity spring, and after the load block impacts the soil body for the first time and bounces, limiters in the crank pulley mechanisms move to the movement guide rails to prevent the load block from impacting the soil body again.

Description

Technical Field

[0001] The present invention relates to a test device, in particular to a test device for simulating ejection shock loads. Background Art

[0002] At present, domestic and foreign scholars have carried out many studies on the response of soil under dynamic loads. Among them, the research on the dynamic response of soil under impact loads mainly focuses on load forms such as drop hammer ramming, rolling impact, and rockfall impact. The relevant research on soil under ejection shock loads mainly adopts numerical simulation and theoretical analysis methods, lacking experimental research and data support in the field of engineering applications.

[0003] The patent with the publication number CN106872289B discloses a test device and test method for impact loads on sandy soil, which applies impact loads to the soil by the free fall of a hammer. The patent with the publication number CN102288347B discloses an impact model test device for the interaction between a lander and soil, which vertically impacts the soil by controlling the mass and falling height of an impact cylinder. Existing patents mostly simulate impact loads based on the gravitational impact of a drop hammer, belonging to the triangular impact load condition, and it is difficult to simulate the trapezoidal load condition of ejection shock loads. Therefore, researchers urgently need a loading device for simulating ejection shock loads to provide reference for the mechanism analysis of soil dynamic response and engineering design. Summary of the Invention

[0004] The object of the present invention is to provide a test device for simulating ejection shock loads, including two side columns, an electromagnet, a load block, an impact force sensor, two variable stiffness springs, two crank and pulley mechanisms, and a model box; the side columns are fixedly arranged, and on the inner wall of each side column, a movement guide rail is arranged vertically. Below each movement guide rail, a variable stiffness spring is arranged. 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 both ends of the bracket are slidably connected to the movement 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 inside. The soil surface in the model box is flush with the upper end surface of the variable stiffness spring. Each crank and pulley mechanism is arranged on the corresponding side column and above the variable stiffness spring. When the load block rebounds after the first impact on the soil, the limiter in the crank and pulley mechanism moves to the movement guide rail to block the load block from impacting the soil again.

[0005] Furthermore, each crank pulley mechanism further includes a crank, a connecting rod, a stopper, 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 an 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 stopper, and the stopper 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 moving 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 further includes an infrared transmission sensor and a stopper control unit. During the rebound and upward movement of the load block, the infrared sensor is triggered, and the stopper control unit issues a braking signal, and the crank makes a circular motion.

[0008] Furthermore, the load block further includes a loading rod and a bolt. The bracket is a U-shaped bracket, the two ends of the bracket are slidably connected to the moving guide rail, the loading rod is fixedly connected to the counterweight through the bolt, the loading rod includes upper and lower parts, the shapes of the upper part of the loading rod and the counterweight are both cuboids, 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 upper and lower parts, the shapes of the upper part of the loading rod and the counterweight are both cuboids, the lower part of the impact force sensor is a cylinder, and the impact force sensor is arranged on the lower part of the loading rod.

[0010] Furthermore, it further includes a winch, the winch is arranged on the cross beam, the cross beam is erected at the upper ends of the two side columns, and 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, drainage plates and drainage valves 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 moving guide rail is blocked by the crank pulley mechanism to avoid secondary impact on the soil body by the load block. The loading process and the stopper control are simple and easy to operate, and multiple ejection impacts on the soil body can be realized; (2) By adjusting the mass and lifting height of the load block and combining with the stiffness control of the variable stiffness spring, the magnitude and action time of the ejection impact load can be controlled. This device provides an experimental approach for the study of the dynamic response of the soil body under the ejection impact load, saving the site and cost; (3) The moving guide rail, adjustable stiffness spring and crank pulley mechanism are arranged inside the side column to realize the compact structure and effectively reduce the occupied space.

[0013] The present invention will be further described below in conjunction with the accompanying drawings of the specification. Description of the Drawings

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

[0015] Figure 2 It is a 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 sectional view of the crank and 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 It is a process flow chart of the test method of the present invention.

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

[0021] In conjunction with Figure 1, A test device for simulating catapult impact loads, comprising side columns 6, an electromagnet 3, a load block 4, an impact force sensor 5, a variable stiffness spring 8, a crank and pulley mechanism 9, and a model box 12. Among them, the side columns 6 are fixedly arranged. Movement guide rails 7 are arranged vertically on the inner walls of the side columns 6. A variable stiffness spring 8 is arranged below the movement guide rails 7. The electromagnet 3 is arranged 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 movement guide rails 7. The impact force sensor 5 is arranged on the load block 4, and the lower bottom surface of the impact force sensor 5 is flush with the lower end surfaces of both ends of the support 41. The model box 12 is arranged below the load block 4 and filled with soil inside. The surface of the soil in the model box 12 is flush with the upper end surface of the variable stiffness spring 8. The crank and pulley mechanism 9 is arranged on the corresponding side column 6 and above the variable stiffness spring 8. When the load block 4 rebounds after the first impact on the soil, the stopper 93 in the crank and pulley mechanism 9 moves to the movement guide rail 7 to block the load block 4 from impacting the soil again. Initially, the load block 4 is adsorbed by the electromagnet 3 through magnetic force and is located at the target height. After the test starts, the electromagnet 3 releases the magnetic force, and the load block 4 makes a free fall motion along the movement guide rail 7. The gravitational potential energy is converted into kinetic energy, and the soil is impacted with a certain impulse.

[0022] To prevent the load block 4 from rebounding after the first impact on the soil and causing secondary or even multiple impacts on the soil, and to achieve a trapezoidal load condition, when the load block 4 rebounds after the first impact on the soil, the load block 4 is intercepted through the crank and pulley mechanism 9 to prevent the load block 4 from impacting downward again. Grooves are provided horizontally on the inner walls of the side columns 6 for arranging the crank and pulley mechanism 9. Combined with Figure 4 , Each crank and 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. The sliding guide rail 95 extends to the movement guide rail 7. The width of the sliding guide rail 95 is greater than that of the movement guide rail 7. One end of the crank 91 is rotatably connected to the groove of the side column 6 through the bearing 94. The crank 91 makes a circular motion under an external force. The other end of the crank 91 is rotatably connected to one end of the connecting rod 92 through 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. One of the movement trajectories of the stopper 93 coincides with the movement guide rail 7.

[0023] To extend and control the duration of the catapult impact load, variable stiffness springs 8 are arranged inside the side columns 6. A total of two variable stiffness springs 8 are arranged, one for each of the left and right side columns 6. Combined with Figure 3, each 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 moving guide rail 7, and the upper and lower ends of the spring 81 are respectively fixed to the upper base 82 and the lower base 83. During the process of the spring 81 being compressed by the impact of the bracket 41, elastic potential energy is stored through deformation, and the duration of the ejection impact load can be regulated. When all the energy of the load block 4 is converted into the potential energy of the soil body 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 staying at the stopper 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 impact value of the load received by the soil body during the impact test, thereby obtaining the time history curve of the ejection impact load received by the soil body.

[0024] The model test device for simulating the ejection impact load further includes an infrared sensor 10 and a stopper control unit 11, which cooperate with the crank pulley mechanism 9 to jointly complete the blocking of the load block 4. Specifically, during the upward rebound of the load block 4, the infrared sensor 10 will be triggered, the stopper control unit 11 issues a braking signal, the crank 91 starts to perform circular motion, transmits torque through the bearing 94, and the connecting rod 92 pulls the stopper 93 to move forward in the sliding guide rail 95, blocking the moving guide rail 7. When the load block 4 rebounds and descends, it will stop at the stopper 93 to avoid secondary impact on the soil body and complete the braking.

[0025] Combined with 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 moving guide rail 7. The counterweight 42 and the loading rod 43 are fixed in the U-shaped groove of the bracket 41 through the bolt 44. Both sides of the bracket 41 are embedded in the moving guide rails 7 of the two side columns 6 to limit the spatial movement direction of the bracket 41, ensuring that the load block 4 performs free fall motion. The impact force sensor 5 is arranged on the loading rod �, and the lower bottom surface of the impact force sensor 5 is flush with the lower end surfaces of both ends of the bracket 41. Specifically, the loading rod 43 includes upper and lower parts. The upper part of the loading rod 43 and the counterweight 42 are both in the shape of a cuboid, 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] Combined with Figure 1 , the test device for simulating the ejection impact load further includes a winch 1. The winch 1 is arranged on the cross beam 2, and the cross beam 2 is erected on the upper ends of the two side columns 6. The winch 1 is connected to the electromagnet 3 through a rope to lift the electromagnet 3 and the load block 4 as a whole to the target height.

[0027] As Figure 5As shown in the figure, a drainage cushion 122 and drainage plates 123 are provided at the bottom of the model box body 121. Before the test starts, the water content of the soil can be changed by adjusting the drainage valve 124 provided at the bottom of the model box 12. Earth pressure sensors and pore water pressure sensors can be buried in the soil to obtain the change of the effective stress inside the soil and the liquefaction characteristics of the soil. An acrylic observation window is provided on one side of the model box 12, and the overall dynamic deformation of the soil can be monitored and analyzed by high-speed imaging analysis technology. Thus, the data collection of the force and deformation of the soil during the entire ejection impact test process is realized.

[0028] Combined with Figure 6 , a test method using the above-mentioned simulation ejection impact load test device is as follows: Step S100: Connect and debug the test control circuit, braking circuit, and measurement circuit to ensure that all components work properly and the data circuit operates normally; Step S200: Fill the soil to be tested in layers in the model box 12, and the control indicators include density, water content, etc. At the same time, earth pressure sensors and excess pore pressure sensors are buried inside the soil, and a high-speed camera is installed on the side of the model box 12 where the acrylic observation window is provided, and the installation height is the same as the height of the soil; Step S300: Make the load block 4 reach the specified counterweight by changing the mass of the counterweight block 42. The impact force sensor 5 is installed at the lower edge of the loading rod 43, and the winch 1 - electromagnet 3 cooperate to lift the load block to the specified height; Step S400: Release the electromagnetic force of the electromagnet 3. 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 stays at the stopper 93, and a single ejection impact is completed; Step S500: After the ejection impact is completed, save the mechanical data of the sensors and the imaging data of the soil deformation; Step S600: If the soil does not show damage or liquefaction, after the soil stabilizes, following the principle of increasing load step by step, gradually increase the mass of the load block 4, and repeat the above steps to continuously eject and impact the soil.

Claims

1. An experimental device for simulating catapult impact load, characterized in that, It includes two side columns (6), an electromagnet (3), a load block (4), an impact force sensor (5), two variable stiffness springs (8), two crank and pulley mechanisms (9), and a model box (12); among them The side columns (6) are fixedly arranged, On the inner wall of each side column (6), a motion guide rail (7) is arranged vertically, Below each motion guide rail (7), a variable stiffness spring (8) is arranged, The electromagnet (3) is arranged in the middle of 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 lower 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 and pulley mechanism (9) is arranged on the corresponding side column (6) and above the variable stiffness spring (8), When the load block (4) rebounds and impacts the soil for the first time and bounces up, the limiter (93) in the crank and pulley mechanism (9) moves to the motion guide rail (7) to block the load block (4) from impacting the soil again.

2. The test device according to claim 1, wherein, Each crank and pulley mechanism (9) further includes a crank (91), a connecting rod (92), a limiter (93), a bearing (94), and a sliding guide rail (95); among them The sliding guide rail (95) is arranged horizontally in the groove on the inner wall of the side column (6), The lower end wall surface of the groove is flush with the upper end surface of the variable stiffness spring (8), The sliding guide rail (95) extends to the motion guide rail (7), The bearing (94) is rotatably connected to the inner wall of the groove and rotates under the drive of an 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 limiter (93) is slidably connected to the sliding guide rail (95).

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

4. The test device according to claim 2, characterized in that It further includes an infrared sensor (10) and a limiter control unit (11). During the process of the load block (4) rebounding and rising, the infrared sensor (10) is triggered, and the limiter control unit (11) issues a braking signal, and the crank (91) makes a circular motion.

5. The test device according to claim 1, characterized in that, The load block (4) further includes a loading rod (43) and a bolt (44), The loading rod (43) is fixedly connected to the counterweight (42) through the bolt (44), The loading rod (43) includes upper and lower parts. The upper part of the loading rod (43) and the counterweight (42) are both in the shape of a cuboid, 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), and The lower bottom surface of the impact force sensor (5) is flush with the lower end surfaces of both ends of the bracket (41).

6. The test device according to claim 1, characterized in that, It further includes a winch (1), the winch (1) is arranged on the cross beam (2), the cross beam (2) is erected on the upper ends of two side columns (6), and one end of the rope of the winch (1) is fixedly connected to the electromagnet (3).

7. The test device according to claim 1, wherein The model box (12) includes a model box body (121), and a drainage cushion layer (122), drainage plates (123) and drainage valves (124) are arranged at the bottom of the model box body (121).

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