Electromagnetic shock testing device capable of adjusting shock waveform

Abstract

The application discloses an impact test device based on electromagnetic loading. The device comprises a power supply system, an impact gun, a sensor data acquisition system and a clamp and bracket system. The impact gun converts the electric energy of the power supply system into electromagnetic force impact force to act on the to-be-impacted test piece fixed on the clamp and bracket system in the form of impact load. Before the test starts, the impact gun is in zero-distance contact with the to-be-impacted test piece, and the impact load is horizontally loaded in parallel to the ground. During the test, the sensor data acquisition system records the data of the impact force and deformation displacement of the test piece changing with time. After the test ends, the reaction force between the impact gun and the to-be-impacted test piece is consumed in the form of friction and temperature rise through the buffer system of the impact gun, so that the secondary impact on the to-be-impacted test piece is avoided. The energy storage capacitor and the charging voltage in the power supply system are variable. The application can solve the problems of complicated operation and single impact wave form of the current impact test equipment.

Description

Technical Field

[0001] This invention relates to the field of mechanical impact testing, such as drop hammer and pendulum test, or electromagnetic impact testing, and particularly to an electromagnetic impact testing device with adjustable impact waveform. Background Technology

[0002] During the service life of products and equipment, they inevitably face impact loads, such as car collisions, bird strikes, and explosive impacts. To evaluate the performance of materials, products, or equipment under impact loads, it is necessary to reproduce and simulate the expected impact environment. Currently, most impact testing equipment utilizes free-fall mass, pendulums, pneumatic pistons, or catapults to impact another response structure to generate a transient response environment, such as the widely used drop hammer test machine. However, such methods suffer from problems such as cumbersome testing procedures and limited impact waveform representation.

[0003] Taking a drop hammer testing machine as an example, the impact energy during the test is controlled by the mass of the drop hammer and the release height (E=mgh). If a larger impact energy is obtained, the release height often needs to be increased, which increases the size of the testing machine and makes it impossible to obtain a specific and precise impact energy (due to drop hammer mass error and height setting error). If the test piece is impacted at different positions, the test piece needs to be moved and re-clamped, making it difficult to accurately match the expected impact point with the drop hammer landing point. This greatly reduces the consistency of the test, especially for repeated impacts. The hammer needs to be re-hung after each test, which reduces the test efficiency and poses certain dangers during manual operation. After the impact, if no additional restraint device is designed, the drop hammer will bounce back and impact the test piece again or several times. Therefore, the test process is cumbersome and the test accuracy is poor.

[0004] Secondly, the impact waveforms produced by such impact testing platforms are often classic half-sine waveforms, and they tend to focus only on the pulse peak, without controlling the pulse width response, etc. However, the impact waveforms vary greatly under actual working conditions, and such classic impact waveforms are rarely encountered. Therefore, such impact platforms often lead to over-impact phenomena. In order to obtain different impact peak values ​​and pulse widths, pendulum testing machines often need to change different buffers and swing angles, which also brings the problem of cumbersome operation. Summary of the Invention

[0005] The purpose of this invention is to provide an electromagnetic shock testing device with adjustable shock waveform, which can solve the problems of cumbersome operation and monotonous shock waveform of current shock testing equipment.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] An adjustable electromagnetic shock testing device includes a power supply system, an impact gun, a sensor data acquisition system, and a clamp and bracket system. The impact gun converts the electrical energy of the power supply system into electromagnetic impact force, which is applied as an impact load to the specimen fixed on the clamp and bracket system. Before the test begins, the impact gun is in zero-distance contact with the specimen, and the impact load is applied horizontally parallel to the ground. During the test, the sensor data acquisition system records the impact force and deformation displacement of the specimen over time. After the test, the reaction force between the impact gun and the specimen is consumed by the buffer system of the impact gun in the form of friction and temperature rise, avoiding secondary impact on the specimen. The energy storage capacitor and charging voltage in the power supply system are variable.

[0008] Optionally, the formula for calculating the single-impact energy E of the electrical energy is as follows:

[0009]

[0010] In the formula, C and U represent the energy storage capacitor and charging voltage in the power system, respectively, and η is the electromagnetic energy conversion efficiency. After the components, geometry and materials of the power system and the loading gun are determined, η is a constant. By changing the energy storage capacitor C and the charging voltage U, different single impact energies E can be obtained.

[0011] The formula for calculating the force F of a single electromagnetic impact is as follows:

[0012]

[0013] In the formula, K is the system constant of the RLC resonant circuit of the power supply system, which is a constant once the components of the power supply system are determined, and ω is the damped resonant angular frequency of the power supply system. The phase difference of the current is t, and time is t.

[0014] The formula for calculating the duration of a single electromagnetic shock force F or the pulse width T of the shock load is as follows:

[0015]

[0016] In the formula, L is the equivalent inductance of the power supply system, R is the equivalent resistance of the power supply system, and L and R are constants after the power supply system is built.

[0017] Optionally, the required impact energy or loading waveform is obtained by changing the charging voltage of the energy storage capacitor to achieve impact under different impact conditions.

[0018] Optionally, the impact gun includes a punch, a quartz pressure sensor, an adapter, a stress wave shaper, a driven coil, an active coil, a buffer system, and a top handle. The punch has a milled flat surface on its side for easy disassembly and replacement. The quartz pressure sensor is used to collect the impact force experienced by the specimen during the test. The punch and the adapter are connected to the stress wave shaper via an external thread in the axial direction. Before the test, the driven coil is pressed against the active coil by a compression spring, and a pulse current generated by the power supply system flows into the active coil. The electromagnetic repulsion force generated between the impact gun and the driven coil drives the driven coil, the stress wave shaper, the adapter, the quartz pressure sensor, and the punch to move along the spindle, forming an electromagnetic impact force. The buffer system includes several compression springs and hydraulic dampers. The kinetic energy generated by the reaction force between the impact gun and the test specimen is dissipated by the compression springs and hydraulic dampers. During this process, the punch is always connected to the impact gun as a whole to avoid the punch rebounding and hitting the test specimen a second or even multiple times, which would interfere with the test results.

[0019] Optionally, the punch is a 16mm hemispherical shape, which can be replaced with different diameters or shapes as needed.

[0020] Optionally, the electromagnetic impact force generated between the pulse current generated by the power supply system and the driven coil after flowing into the active coil propagates in the stress wave shaper in the form of an elastic wave. Through the change of the geometric cross-sectional area of ​​the stress wave shaper, the elastic wave will be continuously reflected and transmitted, which manifests as the amplification of the electromagnetic impact force F(t) and the change of its waveform. The formula for calculating the amplification factor N is as follows:

[0021]

[0022] In the formula, σ s and σ L The stress values ​​at the small and large ends of the stress wave shaper are respectively determined. By changing the geometry of the stress wave shaper, the impact waveform F(t) is corrected, making the impact load closer to the actual working condition.

[0023] Optionally, the fixture and bracket system includes a guide rail, a clamping cylinder, a servo motor, a lead screw, a support fixture, and a holding fixture. The impact gun is fixed on the guide rail and moves vertically along the guide rail. After moving to a predetermined position, the clamping cylinder balances the weight of the impact gun, maintaining the impact gun in the designated position. The horizontal movement of the impact gun is achieved by the servo motor and the lead screw driving the guide rail to move. The specimen to be impacted is fixed between the crossbeam of the fixture and bracket system by the support fixture and the holding fixture. Moving the impact gun can realize impact tests on specimens of different sizes at different impact positions.

[0024] Optionally, the dimensions of the support fixture, the clamping fixture, and the distance between the fixture and the crossbeam of the bracket system are adjusted according to the geometry of the specimen to be impacted.

[0025] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0026] This invention proposes an electromagnetic impact testing device with adjustable impact waveform. It changes the traditional vertical loading to horizontal loading and achieves convenient impact at any position by fixing the specimen and moving the impact gun. This invention relies on electromagnetic loading to achieve zero-distance contact between the punch and the specimen, significantly reducing the size and height of the testing equipment and avoiding secondary or even multiple impacts on the specimen. By changing the values ​​of the energy storage capacitor and charging voltage in the power supply system, and in conjunction with a stress wave shaper, this invention can obtain an impact waveform close to that of actual working conditions. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the electromagnetic impact force waveform (Ft curve);

[0029] Figure 2 This is a schematic diagram of waveforms with consistent pulse width or peak value obtained by adjusting the energy storage capacitor and the charging voltage.

[0030] Figure 3 This is a cross-sectional view of an impact gun;

[0031] Figure 4 This is an axial view of the impact gun;

[0032] Figure 5 This is a partial assembly diagram of the impact gun;

[0033] Figure 6 This is a schematic diagram showing the connection between the punch, quartz pressure sensor, and adapter;

[0034] Figure 7 These are schematic diagrams of different impact waveforms after being shaped by a stress wave shaper.

[0035] Figure 8 This is a schematic diagram of the clamp and bracket system;

[0036] Figure 9 This is a schematic diagram of the impact process of the impact gun in conjunction with the clamp and bracket system;

[0037] Icon labels:

[0038] 1 Impact gun, 2 Punch, 2-1 Plane, 3 Quartz pressure sensor, 3-1 External thread, 4 Adapter, 5 Stress wave shaper, 6 Driven coil, 7 Driven coil, 7-1 Mandrel, 8 Buffer system, 8-1 Hydraulic damper, 8-2 Spring, 9 Top handle, 10 Clamp and bracket system, 10-1 Guide rail, 10-2 Clamping cylinder, 10-3 Servo motor, 10-4 Lead screw, 12 Specimen to be impacted, 13 Support clamp, 14 Clamping clamp, 15 Horizontal frame. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The purpose of this invention is to provide an electromagnetic shock testing device with adjustable shock waveform, which can solve the problems of cumbersome operation and monotonous shock waveform of current shock testing equipment.

[0041] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] An adjustable electromagnetic shock testing device includes a power supply system, an impact gun, a sensor data acquisition system, and a clamp and bracket system. The impact gun converts the electrical energy of the power supply system into electromagnetic impact force, which is applied as an impact load to the specimen fixed on the clamp and bracket system. Before the test, the impact gun is in zero-distance contact with the specimen, and the impact load is applied horizontally parallel to the ground. During the test, the sensor data acquisition system records the impact force and deformation displacement of the specimen over time. After the test, the reaction force between the impact gun and the specimen is consumed by the buffer system of the impact gun in the form of friction and temperature rise, avoiding secondary impact on the specimen. The energy storage capacitor and charging voltage in the power supply system are variable.

[0043] The formula for calculating the single-impact energy E of the electrical energy is as follows:

[0044]

[0045] In the formula, C and U represent the energy storage capacitor and charging voltage in the power system, respectively, and η is the electromagnetic energy conversion efficiency. After the components, geometry and materials of the power system and the loading gun are determined, η is a constant. By changing the energy storage capacitor C and the charging voltage U, different single impact energies E can be obtained.

[0046] The formula for calculating the force F of a single electromagnetic impact is as follows:

[0047]

[0048] In the formula, K is the system constant of the RLC resonant circuit of the power supply system, which is a constant once the components of the power supply system are determined, and ω is the damped resonant angular frequency of the power supply system. The phase difference of the current is t, and time is t.

[0049] Classic half-sine impulse waveform as follows Figure 1 As shown, the duration of a single electromagnetic impact force F or the pulse width T of the impact load can be calculated using the formula:

[0050]

[0051] In the formula, L is the equivalent inductance of the power supply system, R is the equivalent resistance of the power supply system, and L and R are constants after the power supply system is built.

[0052] From the above calculation formulas for single impact energy E, single electromagnetic impact force F, and impact load pulse width T, it can be seen that when the power system components, loading gun geometry, and materials are determined, the required impact energy or loading waveform can be obtained by changing the energy storage capacitor C and charging voltage U, thus achieving different impact conditions (low-energy, high-energy impacts, low-speed, high-speed impacts, or impact responses under different strain rates). In one embodiment of the present invention, combined with the appendix... Figure 2 It can be seen that by changing the energy storage capacitor C and the charging voltage U, electromagnetic impact force waveforms with the same pulse width but different amplitudes or different pulse widths but the same amplitude can be obtained, which can better meet the impact load conditions under different working conditions. At the same time, in the comparative test of single variable control, the interference of other variables is effectively eliminated.

[0053] Figure 3 This is a cross-sectional view of an impact gun. Figure 4 This is an axial view of the impact gun. Figure 5 This is a partial assembly diagram of the impact gun. Figure 6 This is a diagram showing the connection between the punch, quartz pressure sensor, and adapter. Figure 7 These are schematic diagrams of different impact waveforms after being shaped by a stress wave shaper. Figure 3-7 It can be seen that the impact gun consists of a punch (2), a quartz pressure sensor (3), an adapter (4), a stress wave shaper (5), a driven coil (6), an active coil (7), a buffer system (8), and a top handle (9). The punch is generally a 16mm hemispherical shape, but it can be replaced with different diameters or shapes (hemispherical, conical, pointed, etc.) as needed. The side of the punch is milled with a flat surface (2-1) for easy disassembly and replacement. The deformation displacement of the specimen (12) to be impacted during the impact can be obtained by measuring the impact-reset stroke of the punch (2) through a displacement sensor. The quartz pressure sensor (3) is used to collect the impact force borne by the specimen during the test. The punch (2) and the adapter (4) are connected to the stress wave shaper (5) of the main body of the impact gun (1) through the external thread (3-1) in the axial direction. Before the test, the driven coil is... The coil (6) is attached to the active coil (7) through a compression spring. The pulse current generated by the power system flows into the active coil (7) and generates an electromagnetic repulsion between it and the driven coil (6). The electromagnetic repulsion drives the driven coil (6), stress wave shaper (5), adapter (4), quartz pressure sensor (3) and punch (2) to move along the spindle (7-1) to form an electromagnetic impact force. The buffer system (8) of the impact gun (1) consists of several springs (8-2) and hydraulic dampers (8-1). The kinetic energy generated by the reaction force between the impact gun (1) and the specimen (12) is dissipated through the compression springs (8-2) and hydraulic dampers (8-1). During this process, the punch (2) is always connected to the impact gun (1) as a whole to avoid the punch (2) from rebounding and hitting the specimen (12) a second or even multiple times, interfering with the test results.

[0054] The pulse current generated by the power supply system flows into the active coil (7) and generates an electromagnetic shock force between it and the driven coil (6) in the form of an elastic wave in the stress wave shaper (5). Through the change of the geometric cross-sectional area of ​​the stress wave shaper (5), the elastic wave will be continuously reflected and transmitted, which will eventually manifest as the amplification of the electromagnetic shock force F(t) and the change of its waveform. The amplification factor N can be calculated by the formula:

[0055]

[0056] In the formula, σ s and σ L The values ​​represent the stress magnitudes at the small and large ends of the stress wave shaper (5), respectively. By changing the geometry of the stress wave shaper (5), the impact waveform F(t) can be further modified, making the impact load closer to the actual working condition. Figure 7 Several electromagnetic shock waveforms corresponding to the actual impact load waveforms after shaping are given.

[0057] Figure 8 This is a schematic diagram of the clamp and bracket system. Figure 9 This is a schematic diagram of the impact process of the impact gun in conjunction with the clamp and bracket system. Figure 8-9 It can be seen that the impact gun (1) is fixed on the guide rail (10-1) of the clamp and bracket system (10). The impact gun (1) can move vertically along the guide rail (10-1). After moving to the predetermined position, the weight of the impact gun (1) is balanced by the clamping cylinder (10-2) to maintain the impact gun (1) in the designated position. The horizontal movement of the impact gun (1) is driven by the servo motor (10-3) and the lead screw (10-4) at the top of the clamp and bracket system (10-1) to drive the guide rail (10-1). 1) The impact test specimen (12) is fixed between the clamp and the cross frame (15) of the bracket system (10) by the support clamp (13) and the clamping clamp (14). The impact gun (1) can be moved to realize the impact test of different impact positions of the impact test specimen (12) of different sizes. The size of the support clamp (13) and the clamping clamp (14) and the distance between the clamp and the cross frame (15) of the bracket system can be adjusted by the geometric size of the impact test specimen (12).

[0058] Compared with the prior art, the present invention has the following advantages:

[0059] 1. Simple operation and good repeatability. With the device and method of this invention, after the specimen to be impacted is fixed in the clamp and bracket system, the impact gun can be moved freely in the horizontal and vertical directions, enabling impact at any position. For multiple impact tests, the repeatability is excellent. In contrast, traditional drop hammer testing machines have a fixed impact point, requiring adjustment of the specimen position. Furthermore, by adjusting the dimensions of the support clamp, the holding clamp, and the distance between the clamp and the crossbeam of the bracket system, a wider range of geometric dimensions of the specimen to be impacted can be accommodated.

[0060] 2. Avoids secondary impacts, ensuring high safety. Electromagnetic loading technology is currently mature and widely used in assembly connections, electromagnetic launching, electromagnetic forming, and material testing, with reliable technical safety. This invention relies on electromagnetic loading technology to achieve zero-distance contact between the punch and the specimen before the impact test. During the impact test, the punch is always connected to the impact gun via a mandrel. The kinetic energy generated by the reaction force between the impact gun and the specimen is dissipated by a compression spring and a hydraulic damper, avoiding secondary or even multiple rebounds of the punch that could interfere with the test results.

[0061] 3. Adjustable waveform, wide range of applications, and high experimental realism. This invention can change the peak value and pulse width of the loading waveform by changing the energy storage capacitor in the power supply system and setting the charging power supply, thereby improving the selectivity of impact velocity and energy. At the same time, by adjusting the geometric dimensions of the stress wave shaper, different loading waveforms can be obtained, thus realizing the simulation of the predetermined waveform and better conforming to actual working conditions.

[0062] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0063] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An electromagnetic impact testing device with adjustable impact waveform, characterized in that, include: The system comprises a power supply system, an impact gun, a sensor data acquisition system, and a fixture and bracket system. The impact gun converts the electrical energy from the power supply system into electromagnetic impact force, which is applied as an impact load to the specimen fixed on the fixture and bracket system. Before the test begins, the impact gun is in zero-distance contact with the specimen, and the impact load is applied horizontally parallel to the ground. During the test, the sensor data acquisition system records the impact force and deformation displacement of the specimen over time. After the test, the reaction force between the impact gun and the specimen is dissipated through the impact gun's buffer system in the form of friction and temperature rise, preventing secondary impact on the specimen. The power supply system includes a variable energy storage capacitor and a variable charging voltage. The impact gun includes a punch, a quartz pressure sensor, an adapter, a stress wave shaper, a driven coil, an active coil, a buffer system, and a top-holding handle; the buffer system includes several compression springs and a hydraulic damper. The pulse current generated by the power system flows into the active coil and generates an electromagnetic impact force between it and the driven coil. This force propagates in the stress wave shaper in the form of an elastic wave. The change in the geometric cross-sectional area of ​​the stress wave shaper causes the elastic wave to be continuously reflected and transmitted, which manifests as an amplification of the electromagnetic impact force and a change in the waveform. The formula for calculating the single-impact energy E of the electrical energy is as follows: In the formula, C and U represent the energy storage capacitor and charging voltage in the power system, respectively, and η is the electromagnetic energy conversion efficiency. After the components, geometry and materials of the power system and the loading gun are determined, η is a constant. By changing the energy storage capacitor C and the charging voltage U, different single impact energies E can be obtained. The formula for calculating the force F of a single electromagnetic impact is as follows: In the formula, K is the system constant of the RLC oscillation circuit of the power supply system, which is a constant after the components of the power supply system are determined; ω is the decaying resonant angular frequency of the power supply system; φ is the current phase difference; and t is time. The formula for calculating the duration of a single electromagnetic shock force F or the pulse width T of the shock load is as follows: In the formula, L is the equivalent inductance of the power supply system, R is the equivalent resistance of the power supply system, and L and R are constants after the power supply system is built. By changing the energy storage capacitor and the charging voltage, the required impact energy or loading waveform can be obtained, thus achieving different impact conditions.

2. The electromagnetic shock testing device with adjustable shock waveform according to claim 1, characterized in that, The punch has a milled flat surface on its side for easy disassembly and replacement. The quartz pressure sensor is used to collect the impact force borne by the specimen during the test. The punch and the adapter are connected to the stress wave shaper via an external thread in the axial direction. Before the test, the driven coil is in contact with the active coil through a compression spring. The pulse current generated by the power system flows into the active coil and generates an electromagnetic repulsion force between it and the driven coil. The electromagnetic repulsion force pushes the driven coil, the stress wave shaper, the adapter, the quartz pressure sensor, and the punch to move along the mandrel, forming an electromagnetic impact force. The kinetic energy generated by the reaction force between the impact gun and the specimen is dissipated by the compression spring and the hydraulic damper. During this process, the punch is always connected to the impact gun as a whole to avoid the punch rebounding and hitting the specimen a second or even multiple times, which would interfere with the test results.

3. The electromagnetic shock testing device with adjustable shock waveform according to claim 2, characterized in that, The punch is a 16mm hemispherical shape.

4. The electromagnetic shock testing device with adjustable shock waveform according to claim 2, characterized in that, The formula for calculating the amplification factor N of electromagnetic shock force is as follows: In the formula, σ s and σ L The stress values ​​at the small and large ends of the stress wave shaper are respectively determined. By changing the geometry of the stress wave shaper, the impact waveform F(t) is corrected, making the impact load closer to the actual working condition.

5. The electromagnetic shock testing device with adjustable shock waveform according to claim 2, characterized in that, The fixture and bracket system includes a guide rail, a clamping cylinder, a servo motor, a lead screw, a support fixture, and a holding fixture. The impact gun is fixed on the guide rail and moves vertically along the guide rail. After moving to a predetermined position, the clamping cylinder balances the weight of the impact gun, maintaining it in the designated position. The horizontal movement of the impact gun is achieved by the servo motor and the lead screw driving the guide rail to move. The specimen to be impacted is fixed between the crossbeam of the fixture and bracket system by the support fixture and the holding fixture. Moving the impact gun allows for impact tests of specimens of different sizes at different impact positions.

6. The electromagnetic shock testing device with adjustable shock waveform according to claim 5, characterized in that, The dimensions of the support fixture, the clamping fixture, and the distance between the fixture and the crossbeam of the bracket system are adjusted according to the geometry of the specimen to be impacted.

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