Hopkinson pressure bar multistage electromagnetic coil loading device

Abstract

The utility model discloses a Hopkinson pressure bar multistage electromagnetic coil loading device, and belongs to the field of dynamic impact experiment mechanics. The device comprises at least two electromagnetic coils (2), an incident bar (4) and a transmission bar (8), and further comprises a guide rail (9) and a center frame (3), the electromagnetic coils (2) are arranged on the guide rail (9) at intervals in a penetrating mode, the guide rail (9), the incident bar (4) and the transmission bar (8) are sequentially and coaxially arranged, and the center frame (3) fixes the guide rail (9), the incident bar (4) and the transmission bar (8) at the same height. The device is simple in structure and low in manufacturing cost. A multi-stage electromagnetic loading mode is adopted, the speed range of the impact ball (1) can be controlled by increasing or reducing the number and the number of turns of the electromagnetic coils (2) and the size of the capacitance energy storage device (11), the application range is wider, and the impact ball is safer. The problems that an existing structure is complex, cost is high, and safety accidents are likely to happen are solved.

Description

Technical Field

[0001] The utility model discloses a Hopkinson bar multi-stage electromagnetic coil loading device, belonging to the field of dynamic impact experimental mechanics. Background Art

[0002] The Hopkinson bar electromagnetic loading system is based on the RLC discharge principle. A capacitor releases a pulsed strong current to a primary coil, and a strong magnetic field is excited around the primary coil. The strong magnetic field then interacts with the induced eddy current in the secondary coil to generate an electromagnetic force stress wave, which is transmitted to the Hopkinson bar through a stress wave amplifier to dynamically load a specimen.

[0003] When the existing electromagnetic loading equipment works, the charging switch is closed. The 380V AC power supply is stepped up by a step-up transformer and then rectified by a diode rectifier circuit to charge a capacitor bank and store energy. After the charging voltage reaches the set voltage, the charging switch is disconnected, and then discharging and loading are carried out as needed. During discharging, the discharge switch is closed, and the capacitor bank instantaneously discharges to the discharge coil, generating a powerful pulsed current in the discharge coil and forming a high-intensity pulsed magnetic field around it. The driving coil is closely attached to the discharge coil, and an extremely strong eddy current is generated due to electromagnetic induction. The pulsed magnetic fields generated by the two are in opposite directions, thus generating an extremely strong repulsive force, i.e., magnetic force. The magnetic force forms a stress pulse with a duration of microseconds and high intensity at the input end of the stress wave amplifier. The stress pulse propagates and is amplified in the stress wave amplifier in the form of an elastic wave. The stress wave amplifier inputs a compressive stress wave to the incident bar to load the specimen. The pulse in the bar will propagate without distortion at the elastic wave speed, so that the strain gauges pasted on the incident bar and the transmitted bar can measure the change process of the load acting on the bar end over time. At the same time, a dynamic strain gauge is used to collect and record the strain signal.

[0004] Disadvantages of existing products:

[0005] 1. During use, the initial charging voltage is relatively large, and safety accidents are likely to occur if the operation is improper.

[0006] 2. The product structure is relatively complex, and the manufacturing cost is relatively high.

[0007] 3. The generated strong magnetic field has a certain impact on monitoring equipment.

[0008] The reasons for these disadvantages are as follows: The number of turns and the number of coils used in this product are relatively small. In order to generate a high-intensity pulsed magnetic field, a relatively large voltage is required; when the dynamic strain gauge works in a strong magnetic environment, the signal it receives will be interfered, resulting in a large error in the final test data. Content of the Utility Model

[0009] The technical problem to be solved by the present utility model is that the structure of the existing test equipment is complex, the cost is high, and safety accidents are prone to occur.

[0010] The technical solution adopted by the present utility model to solve its technical problems is: a Hopkinson bar multi-stage electromagnetic coil loading device, including electromagnetic coils, an incident bar, and a transmission bar, further including a guide rail and a central frame. At least two electromagnetic coils are spaced and arranged on the guide rail. The guide rail, the incident bar, and the transmission bar are coaxially arranged in sequence, and the central frame fixes the guide rail, the incident bar, and the transmission bar at the same height.

[0011] Among them, strain gauges are provided on the incident bar, the specimen, and the transmission bar in the above device.

[0012] Furthermore, a bridge box and a dynamic strain gauge are further included in the above device, and the strain gauges are respectively connected to the dynamic strain gauge through the bridge box.

[0013] Among them, the number of the electromagnetic coils in the above device is 3 to 6.

[0014] Among them, the number of turns of a single electromagnetic coil in the above device is 190 to 220 turns.

[0015] Among them, a capacitor energy storage device is further included in the above device. The number of the capacitor energy storage devices is connected to the number of electromagnetic coils and corresponds one by one.

[0016] Furthermore, a DC power supply and a boost module are further included in the above device, and the capacitor energy storage device is electrically connected to the DC power supply through the boost module.

[0017] Among them, the central frame in the above device is a telescopic rod structure with adjustable height.

[0018] The beneficial effects of the present utility model are: This device mainly improves the loading method of the Hopkinson bar. Through such improvement, the operation is made simpler. Since the multi-stage electromagnetic loading method is adopted, the speed range of the impact ball can be controlled by increasing or decreasing the number of coils, the number of turns of the coils, and the size of the capacitor energy storage device, which makes the use range of this product wider. At the same time, the loading method of this product uses a DC power supply and has a low charging voltage. The generated magnetic field has little influence on the monitoring equipment, and this loading structure is relatively easy to repair in the later stage and has a low repair cost. This product has simple operation, is relatively easy to repair in the later stage, and has a wider application range. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of the present utility model.

[0020] Figure 2 It is a schematic structural diagram of the electromagnetic coil of the present utility model.

[0021] Figure 3 This is a schematic diagram of the circuit connection structure of the electromagnetic coil of the present utility model.

[0022] Figure 4 This is a schematic diagram of the prior art structure of the present utility model.

[0023] The markings in the figure are: 1 is the impact ball, 2 is the electromagnetic coil, 3 is the center frame, 4 is the incident rod, 5 is the test piece, 6 is the bridge box, 7 is the strain gauge, 8 is the transmission rod, 9 is the guide rail, 10 is the photoelectric sensor, 11 is the capacitor energy storage device, 12 is the boost module, 13 is the DC power supply, and 14 is the dynamic strain gauge. Specific embodiments

[0024] The present utility model will be further described below with reference to the accompanying drawings.

[0025] As Figures 1 to 4As shown in the figure, the Hopkinson bar multi-stage electromagnetic coil loading device of the present utility model includes an electromagnetic coil 2, an incident bar 4, and a transmission bar 8. It also includes a guide rail 9 and a central frame 3. The electromagnetic coil 2 has at least two and is arranged on the guide rail 9 at intervals. The guide rail 9, the incident bar 4, and the transmission bar 8 are coaxially arranged in sequence, and the central frame 3 fixes the guide rail 9, the incident bar 4, and the transmission bar 8 at the same height. Those skilled in the art can understand that since this device adopts a multi-stage electromagnetic loading method, its principle is based on the mutual inductance phenomenon and the superposition effect of currents. The speed range of the impact ball 1 can be controlled by increasing or decreasing the number of coils. Therefore, it is preferred that the electromagnetic coil 2 has at least two and is arranged on the guide rail 9 at intervals, and each coil is composed of a wire wound around a magnetic core. When a current is generated through one coil, it will generate a magnetic field in the magnetic core. This magnetic field can be transmitted to the next coil through magnetic coupling. If the next coil receives sufficient magnetic field energy, it will generate a certain current within itself and further enhance the magnetic field. The key to this cascaded configuration lies in utilizing the mutual inductance phenomenon, that is, when the current in one coil changes, it will induce an electromotive force in the adjacent coil. This induced electromotive force will cause a change in the current in the adjacent coil. Therefore, when the current in the first coil changes, it will gradually affect the current in the subsequent coils through the mutual inductance effect. Through step-by-step superposition, each coil will enhance the magnetic field in the previous coil, and overall, a greater electromagnetic field intensity can be achieved. After the impact bar is multi-stage accelerated by the multi-stage electromagnetic coil 2, it impacts the incident bar 4 to generate an incident wave. The excited incident wave will propagate along the axial direction of the bar. Since the wave impedances of the pressure bar and the specimen 5 are different, while the specimen 5 undergoes high-speed deformation under the impact, it also propagates a reflected wave and a transmitted wave to the incident bar 4 and the transmission bar 8 respectively. To ensure normal operation, before the device works, the guide rail 9, the incident bar 4, the specimen 5, and the transmission bar 8 should be fixed at the same height through the central frame 3. At the same time, the guide rail 9, the incident bar 4, and the transmission bar 8 are coaxially arranged in sequence and coaxial with the specimen 5, so as to ensure that the centers of the guide rail 9, the incident bar 4, the specimen 5, and the transmission bar 8 can be on the same horizontal plane when the device is working. To avoid the influence of adjacent electromagnetic coils 2, in practice, it is preferably to set a photoelectric sensor 10 at each end of the electromagnetic coil 2, so that under the action of the photoelectric sensor 10, the first-stage electromagnetic coil 2 stops discharging while the second-stage electromagnetic coil 2 starts discharging to generate a magnetic field.

[0026] Preferably, strain gauges 7 are provided on the incident bar 4, the specimen 5, and the transmission bar 8 in the above device. Those skilled in the art can understand that to ensure accurate data, it is preferred that strain gauges 7 are provided on the incident bar 4, the specimen 5, and the transmission bar 8 in this device.

[0027] Preferably, the above-mentioned device further includes a bridge box 6 and a dynamic strain gauge 14, and the strain gauges 7 are respectively connected to the dynamic strain gauge 14 through the bridge box 6. Those skilled in the art can understand that for the convenience of data acquisition, it is preferred that the strain gauges 7 are respectively connected to the dynamic strain gauge 14 through the bridge box 6. When the strain gauges 7 are strained, the change in resistance will cause a change in the output voltage of the bridge. At this time, the dynamic strain gauge 14 amplifies, detects, filters, etc. the weak amplitude-modulated wave voltage signal output by the bridge, and then displays and saves the waveform processed by the dynamic strain gauge 14 through an oscilloscope connected to the dynamic strain gauge 14.

[0028] Preferably, the number of the electromagnetic coils 2 in the above-mentioned device is 3 to 6. Those skilled in the art can understand that for the convenience of installation and to ensure the measurement range, it is only preferred that the number of the electromagnetic coils 2 in this device is 3 to 6.

[0029] Preferably, the number of turns of a single electromagnetic coil 2 in the above-mentioned device is 190 to 220. Those skilled in the art can understand that for the convenience of installation and to ensure the measurement range, it is further preferred that the number of turns of a single electromagnetic coil 2 in this device is 190 to 220.

[0030] Preferably, the above-mentioned device further includes a capacitor energy storage device 11, and the number of the capacitor energy storage devices 11 is connected to the number of the electromagnetic coils 2 and corresponds one by one. Those skilled in the art can understand that for the convenience of the electromagnetic coils 2 to work, it is preferred that this device includes a capacitor energy storage device 11, and the number of the capacitor energy storage devices 11 is connected to the number of the electromagnetic coils 2 and corresponds one by one.

[0031] Preferably, the above-mentioned device further includes a DC power supply 13 and a boost module 12, and the capacitor energy storage device 11 is electrically connected to the DC power supply 13 through the boost module 12. Those skilled in the art can understand that in order to reduce the charging voltage to reduce the influence of the generated magnetic field on the monitoring equipment, it is preferred to use a DC power supply 13 in this device, and actually connect the capacitor energy storage device 11 to the DC power supply 13 through the boost module 12.

[0032] Preferably, the central frame 3 in the above-mentioned device is a telescopic rod structure with adjustable height. Those skilled in the art can understand that for the convenience of adjusting the heights of the guide rail 9, the incident rod 4, the specimen 5, and the transmission rod 8 to be the same, it is preferred that the central frame 3 in this device is a telescopic rod structure with adjustable height. Actually, a base can be provided at the lower end of the central frame 3.

[0033] Usage process:

[0034] When the device is working, connect the capacitor energy storage device 11 to the electromagnetic coil 2 through a wire and connect the capacitor energy storage device 11, the boost module 12 and the DC power supply 13 together. Then when the impact ball 1 enters the guide rail 9, close the launch switch. At this time, the impact ball 1 moves to the right under the drive of the electromagnetic force. When the impact ball 1 reaches the end of the first-stage electromagnetic coil 2, under the action of the photoelectric sensor 10, the first-stage coil stops discharging and the second-stage coil starts discharging to generate a magnetic field. The circuit control is the same when the impact ball 1 passes through the ends of the third-stage, fourth-stage and other electromagnetic coils 2. When the impact ball 1 reaches the end of the guide rail 9, the impact ball 1 impacts the incident bar 4 at a certain speed to generate an incident wave. The excited incident wave will propagate along the axial direction of the bar. Since the wave impedances of the pressure bar and the specimen 5 are different, while the specimen 5 is deformed at a high speed under the impact, reflected waves and transmitted waves are also propagated to the incident bar 4 and the transmission bar 8 respectively. At this time, the strain gauges 7 attached to the incident bar 4, the specimen 5 and the transmission bar 8 will deform. Since the deformation of the strain gauges 7 will cause a change in their resistance values, at this time, the bridge box 6 connected to the strain gauges 7 forms a bridge circuit, and a dynamic strain gauge 14 is connected in the bridge circuit. When the strain gauges 7 are strained, the change in resistance will cause a change in the output voltage of the bridge. At this time, the dynamic strain gauge 14 amplifies, demodulates, filters and other processes the weak amplitude-modulated wave voltage signal output by the bridge, and the waveform processed by the dynamic strain gauge 14 is displayed and saved through an oscilloscope connected to the dynamic strain gauge 14.

Claims

1. A Hopkinson pressure bar multi-stage electromagnetic coil loading device, comprising an electromagnetic coil (2), an incident bar (4) and a transmission bar (8), characterized in that: It also comprises a guide rail (9) and a center frame (3), wherein the electromagnetic coils (2) are at least two and are arranged on the guide rail (9) at intervals, the guide rail (9), the incident rod (4) and the transmission rod (8) are coaxially arranged in sequence, and the center frame (3) fixes the guide rail (9), the incident rod (4) and the transmission rod (8) at the same height.

2. The Hopkinson pressure bar multi-stage electromagnetic coil loading device according to claim 1, characterized in that: The incident rod (4), the test piece (5) and the transmission rod (8) are all provided with strain gauges (7).

3. The Hopkinson pressure bar multi-stage electromagnetic coil loading device according to claim 2, characterized in that: It also comprises a bridge box (6) and a dynamic strain gauge (14), and the strain gauge (7) is connected to the dynamic strain gauge (14) via the bridge box (6).

4. The Hopkinson pressure bar multi-stage electromagnetic coil loading device according to claim 1, characterized in that: The number of the electromagnetic coils (2) is 3 to 6.

5. The Hopkinson pressure bar multi-stage electromagnetic coil loading device according to claim 1, characterized in that: The number of turns of a single electromagnetic coil (2) is 190 to 220.

6. The Hopkinson pressure bar multi-stage electromagnetic coil loading device according to claim 1, characterized in that: It also includes a capacitor energy storage device (11), the number of which is connected to the number of the electromagnetic coils (2) and corresponds one to one.

7. The Hopkinson pressure bar multi-stage electromagnetic coil loading device according to claim 6, characterized in that: It also includes a direct current power supply (13) and a boost module (12), and the capacitor energy storage device (11) is electrically connected to the direct current power supply (13) via the boost module (12).

8. The Hopkinson pressure bar multi-stage electromagnetic coil loading device according to claim 1, characterized in that: The central frame (3) is a telescopic rod structure with adjustable height.

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