A tensile impact test device and method based on the principle of hopkinson bar

Abstract

The application discloses a kind of tensile impact test equipment and method based on the principle of Hopkinson bar, it is related to tensile impact test technical field, the equipment includes transmission rod, test piece, incident bar, impactor, flange, energy absorber, air cylinder, connecting part one, connecting part two, L-shaped plate, pedestal;The L-shaped plate is fixed on pedestal;The transmission rod one end is fixed on pedestal by L-shaped plate, the other end is equipped with the connecting part two for connecting test piece;The tubular impactor of the present application is coaxially sleeved on the incident bar, the flange at the end of the incident bar is directly impacted by pneumatic drive, tensile stress wave is directly generated in the incident bar with constant cross section, without relying on complex conversion structure such as sleeve and flange, multiple reflections and waveform distortion of stress wave at variable-diameter or conversion interface are avoided, the purity and stability of incident wave are significantly improved, so as to ensure the accuracy and repeatability of stress, strain and strain rate calculation results based on one-dimensional stress wave theory.

Description

Technical Field

[0001] This invention relates to the field of tensile impact testing technology, specifically a tensile impact testing device and method based on the Hopkinson bar principle. Background Technology

[0002] The split Hopkinson bar technique is an important method for studying the dynamic mechanical properties of materials under high strain rates. Among them, tensile impact testing equipment is used to obtain key parameters such as dynamic tensile stress-strain curves, yield strength, and constitutive relations of materials, and has wide applications in aerospace, vehicle engineering, protective materials and other fields.

[0003] Existing tensile impact testing equipment based on the Hopkinson rod principle generates tensile stress waves mainly in the following ways: by using conversion structures such as sleeves and flanges to convert the compression wave generated by the impact into a tensile wave; or by using a tubular impactor to coaxially impact the flange at the end of the incident rod, directly generating a tensile wave in the rod.

[0004] However, some equipment relies on complex conversion structures such as sleeves and flanges to convert compression waves into tensile waves. During this process, stress waves undergo multiple reflections and waveform mode conversions at the conversion interface and diameter change section, resulting in waveform distortion of the incident wave and the superposition of additional oscillatory components. When processing such contaminated waveforms based on one-dimensional stress wave theory, it is difficult to accurately extract the amplitude and duration of the incident wave, reflected wave, and transmitted wave, thus affecting the accuracy and repeatability of dynamic stress, strain, and strain rate calculation results.

[0005] Secondly, after the specimen fractures under dynamic tensile loading, the incident rod continues to move forward carrying a significant amount of kinetic energy. Most existing equipment lacks effective residual kinetic energy absorption devices, and the freely ejected incident rod is prone to impacting and damaging sensors, data cables, or other precision components, potentially even causing injury to operators. Summary of the Invention

[0006] The purpose of this invention is to provide a tensile impact testing device and method based on the Hopkinson bar principle to solve the problems in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A tensile impact testing device based on the Hopkinson bar principle includes a transmission rod, a specimen, an incident rod, an impactor, a flange, an energy absorber, a cylinder, a first connection part, a second connection part, an L-shaped plate, and a base. The L-shaped plate is fixed to the base; One end of the transmission rod is fixed to the base by an L-shaped plate, and the other end is provided with a connecting part two for connecting the specimen; The cylinder is fixed to the base; the incident rod is coaxially inserted through the cylinder, one end of the incident rod is provided with a connecting part for connecting the specimen, the other end of the incident rod is fixed with a flange, the incident rod and the transmission rod are coaxially opposite each other, and the incident rod and the transmission rod are provided with signal collection units for collecting and recording stress wave signals; the impactor is coaxially sleeved on the incident rod and slidably disposed inside the cylinder; The cylinder is provided with an air inlet at the upper end for connecting to an external air source to drive the impactor to move along the incident rod and impact the flange. The energy absorber is fixed to the base by an L-shaped plate and is located on the movement path of the flange, used to absorb the remaining kinetic energy of the incident rod.

[0008] Preferably, the signal collection unit includes a data acquisition unit, a sensor one, and a sensor two. The sensor one is mounted on the transmission rod, and the sensor two is mounted on the incident rod. The sensor one and the sensor two are used to collect stress wave signals, and the data acquisition unit is used to record the stress wave signals. The sensor one and the sensor two are electrically connected to the data acquisition unit.

[0009] Preferably, the first sensor and the second sensor are capacitive sensors or strain gauges.

[0010] Preferably, a plurality of supports are fixed to the upper end of the base; The bracket includes a height adjustment component and a fixing ring. The height adjustment component is fixedly installed on the upper end of the base by bolts, and the fixing ring is fixed on the upper end of the height adjustment component. The inner wall of the fixing ring slides in conjunction with the outer wall of the transmission rod and the incident rod.

[0011] Preferably, the transmission rod, the incident rod, and the impactor are all made of polymer materials.

[0012] Preferably, the polymer material is polymethyl methacrylate.

[0013] Preferably, a seal is provided at the connection between the cylinder and the incident rod.

[0014] Preferably, both connecting part one and connecting part two include a flat groove and a radially penetrating positioning hole; the specimen is dumbbell-shaped with wide ends and narrow middle, with its two ends inserted into the flat groove and fixed by a positioning pin passing through the positioning hole.

[0015] A tensile impact testing method based on the Hopkinson bar principle includes the following steps: Step 1: Connect both ends of the specimen to the connection part 1 of the incident rod and the connection part 2 of the transmission rod, respectively; Step 2: Compressed air is injected into the cylinder to drive the impactor to accelerate along the incident rod and strike the flange at the end of the incident rod, generating a tensile stress wave in the incident rod. Step 3: The tensile stress wave propagates along the incident rod to the specimen, applying a dynamic tensile load to the specimen and generating reflected and transmitted waves at the specimen interface; Step 4: The incident wave, reflected wave, and transmitted wave signals are collected by sensor 2 on the incident rod and sensor 1 on the transmission rod, and recorded by the data acquisition unit; Step 5: Process the acquired signals according to the one-dimensional stress wave theory, and calculate the stress, strain and strain rate of the specimen under dynamic loading.

[0016] The formula for calculating the stress is: ; The formula for calculating the strain is: ; The formula for calculating the strain rate is: ; in, The elastic modulus of the rod, Let be the cross-sectional area of ​​the member. The cross-sectional area of ​​the specimen. The stress wave velocity in the rod, The initial length of the specimen. and These are the measured transmitted and reflected wave signals, respectively.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention employs a tubular impactor coaxially mounted on the incident rod, which is pneumatically driven to directly impact the flange at the end of the incident rod, directly generating tensile stress waves in the incident rod with a constant cross-section. This eliminates the need for complex conversion structures such as sleeves and flanges, avoiding multiple reflections and waveform distortions of the stress wave at diameter changes or conversion interfaces. This significantly improves the purity and stability of the incident wave, thereby ensuring the accuracy and repeatability of the stress, strain, and strain rate calculation results based on one-dimensional stress wave theory.

[0018] 2. The transmission rod, incident rod, and impactor of this invention are all made of high-molecular materials such as polymethyl methacrylate, whose acoustic impedance is much lower than that of traditional steel rods and is closer to that of low-impedance specimens such as plastics, composite materials, and wood. Based on the one-dimensional stress wave theory, after the impedance matching degree between the rod and the specimen is improved, the reflection of stress waves at the rod-specimen interface is significantly reduced, and the transmission energy is enhanced, thereby realizing effective loading and accurate testing of low-impedance materials and expanding the application range of the equipment.

[0019] 3. The present invention has an energy absorber installed on the movement path of the flange, which can effectively absorb the remaining kinetic energy of the incident rod after the specimen breaks, preventing the incident rod from flying out freely and damaging the equipment or sensor, thus significantly improving the safety and service life of the test system; at the same time, a seal is provided at the connection between the cylinder and the incident rod, which can reduce high-pressure gas leakage, ensure the stability of the driving pressure, and reduce energy consumption and operating noise. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention.

[0021] Figure 2 This is a schematic diagram of the structure of the bracket of the present invention.

[0022] Figure 3 This is a schematic diagram of the cylinder structure of the present invention.

[0023] Figure 4 This is a schematic diagram of the structure of the specimen of the present invention.

[0024] Figure 5 This is a schematic diagram of the connection between the incident rod / transmission rod and the specimen in this invention.

[0025] Figure 6 The voltage waveforms of the incident and reflected waves collected by the sensor on the incident rod.

[0026] Figure 7 This is a waveform diagram of the transmitted wave voltage collected by the sensor on the transmission rod.

[0027] Figure 8 The image shows the dynamic tensile stress-strain voltage curve of the specimen obtained by processing according to the one-dimensional stress wave theory.

[0028] Figure reference numerals: 1. Transmission rod; 2. Sensor 1; 3. Specimen; 4. Data acquisition unit; 5. Incident rod; 6. Sensor 2; 7. Impactor; 8. Flange; 9. Energy absorber; 10. Cylinder; 11. Connecting part 1; 12. Connecting part 2; 13. Bracket; 131. Height adjustment assembly; 132. Fixing ring; 14. L-shaped plate; 15. Base. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] In one embodiment, such as Figures 1-5 As shown, a tensile impact testing device based on the Hopkinson rod principle includes a transmission rod 1, a specimen 3, an incident rod 5, an impactor 7, a flange 8, an energy absorber 9, a cylinder 10, a first connection part 11, a second connection part 12, an L-shaped plate 14, and a base 15. L-shaped plate 14 is fixed on base 15; One end of the transmission rod 1 is fixed to the base 15 by an L-shaped plate 14, and the other end is provided with a connecting part 2 12 for connecting the specimen 3. The cylinder 10 is fixed on the base 15; the incident rod 5 is coaxially inserted through the cylinder 10, one end of the incident rod 5 is provided with a connecting part 11 for connecting the specimen 3, and the other end of the incident rod 5 is fixed with a flange 8. The incident rod 5 and the transmission rod 1 are coaxially opposite each other, and the incident rod 5 and the transmission rod 1 are provided with signal collection units for collecting and recording stress wave signals; the impactor 7 is coaxially sleeved on the incident rod 5 and slidably disposed inside the cylinder 10. The upper end of the cylinder 10 is provided with an air inlet for connecting to an external air source to drive the impactor 7 to move along the incident rod 5 and impact the flange 8. The energy absorber 9 is fixed to the base 15 by the L-shaped plate 14, and the energy absorber 9 is located on the movement path of the flange 8, and is used to absorb the remaining kinetic energy of the incident rod 5.

[0031] In this embodiment, an external air source fills the cylinder 10 with air, driving the impactor 7, which is coaxially sleeved on the incident rod 5, to move along the incident rod 5 and impact the flange 8 fixed to the end of the incident rod 5, thereby generating a stress wave in the incident rod 5. The stress wave propagates along the incident rod 5 to the specimen 3 connected to the transmission rod 1, thereby loading the specimen 3. The signal collection unit set on the incident rod 5 and the transmission rod 1 is used to collect and record the stress wave signal. After the test is completed, the energy absorber 9 located on the movement path of the flange 8 is used to absorb the remaining kinetic energy of the incident rod 5.

[0032] The energy absorber 9 includes a damper and a damping spring. After the specimen breaks, the damper and damping spring absorb the remaining kinetic energy of the incident rod 5, preventing the incident rod 5 from flying out freely, thereby avoiding damage to precision components such as sensors and data cables, and ensuring the safety of operators.

[0033] Both the incident rod 5 and the transmission rod 1 are slender circular rods with a constant cross-section. The constant cross-section design of the incident rod 5 and the transmission rod 1 eliminates the need for any variable diameter sections or transition structures. The stress wave does not encounter abrupt changes in cross-section along its entire propagation path, thus completely avoiding waveform distortion caused by geometric changes and significantly improving the purity and stability of the incident wave.

[0034] The equipment has an open overall structure, with the connection between the specimen and the rod exposed, which facilitates the deployment of high-speed camera equipment to record the deformation, damage and fracture process of the specimen throughout the entire process, providing intuitive experimental evidence for studying the failure mechanism of materials under dynamic tensile loading.

[0035] In this embodiment, the signal collection unit specifically includes a data acquisition unit 4, a sensor 2, and a sensor 6. The sensor 2 is mounted on the transmission rod 1, and the sensor 6 is mounted on the incident rod 5. The sensor 2 and the sensor 6 are used to collect stress wave signals, and the data acquisition unit 4 is used to record stress wave signals. The sensor 2 and the sensor 6 are electrically connected to the data acquisition unit 4.

[0036] Specifically, sensor 1 (2) and sensor 2 (6) are capacitive sensors or strain gauges.

[0037] When stress waves propagate through the transmission rod 1 and the incident rod 5, they cause minute strain or capacitance changes on the surface of the rods. Sensors 2 and 6, mounted on the rods, employ capacitive sensors or strain gauges to detect these changes in real time and convert them into electrical signals. The data acquisition unit 4, electrically connected to the sensors, synchronously records these electrical signals. Its function is to capture the incident wave, reflected wave on the incident rod 5, and the transmitted wave on the transmission rod 1, providing raw data for subsequent calculations of the dynamic stress, strain, and strain rate of the specimen 3 based on one-dimensional stress wave theory.

[0038] In this embodiment, specifically, a number of brackets 13 are fixed to the upper end of the base 15; The bracket 13 includes a height adjustment component 131 and a fixing ring 132. The height adjustment component 131 is fixedly installed on the upper end of the base 15 by bolts. The fixing ring 132 is fixed on the upper end of the height adjustment component 131. The inner wall of the fixing ring 132 slides in conjunction with the outer wall of the transmission rod 1 and the incident rod 5.

[0039] The height adjustment component 131 is prior art, so it will not be described in detail here.

[0040] The height of the support 13 can be adjusted by the height adjustment component 131 to ensure that the transmission rod 1 and the incident rod 5 remain on the same axis. Simultaneously, the inner wall of the fixing ring 132 is slidably connected to the outer wall of the rod, providing stable support while allowing the rod to move freely along the axial direction under the action of stress waves, effectively reducing the interference of frictional resistance on wave propagation and rod movement. The function of this structure is to ensure the coaxiality and smooth movement of the rod system during the test, thereby improving the accuracy of stress wave signal acquisition and the reliability of the test results.

[0041] In this embodiment, specifically, the transmission rod 1, the incident rod 5, and the impactor 7 are all made of polymer materials.

[0042] Specifically, the polymer material is polymethyl methacrylate.

[0043] The acoustic impedance of polymethyl methacrylate (PMMA) is approximately 3.2 × 10⁻⁶. 6 The weight per kilogram (kg / (m²·s)) is significantly lower than that of traditional steel poles (approximately 4.5 × 10⁻⁶ kg / (m²·s)). 7kg / (m²·s)), which is closer to the acoustic impedance of low-impedance specimen 3 such as plastic, composite material, and wood.

[0044] Based on the one-dimensional stress wave theory, when the impedance matching degree between the rod and the specimen is improved, the reflection of the stress wave at the rod-specimen interface is significantly reduced, and the transmitted energy is enhanced, thereby enabling the tensile load to be transferred more effectively to the specimen 3, achieving successful loading and testing. Simultaneously, using the same polymer material to fabricate the impactor 7 avoids additional waveform distortion caused by material differences.

[0045] In this embodiment, specifically, a seal is provided at the connection between the cylinder 10 and the injection rod 5.

[0046] A seal (such as a labyrinth seal or an O-ring) can fill this gap, allowing the injection rod 5 to move freely along the axial direction while effectively preventing compressed gas from leaking out. This reduces gas source pressure loss, ensures that the impactor 7 obtains a stable and repeatable driving force, and improves the consistency and reliability of the test; at the same time, it prevents high-pressure gas leakage, reduces energy consumption and operating noise, and ensures operational safety.

[0047] In this embodiment, specifically, both connecting part 11 and connecting part 2 12 include a flat groove and a radially penetrating positioning hole; the specimen 3 is a dumbbell shape that is wide at both ends and narrow in the middle, with its two ends inserted into the flat groove and fixed by a positioning pin passing through the positioning hole.

[0048] This connection method employs a structure that combines a flat groove with a locating pin, allowing both ends of the dumbbell-shaped specimen 3 to be directly inserted into the groove and quickly locked with the locating pin. This eliminates the need for threading or adhesive curing, enabling rapid assembly and disassembly of the specimen and significantly improving the efficiency of batch testing. Simultaneously, the surface fit between the flat groove and the specimen ends ensures coaxial alignment of the specimen with the incident rod and transmission rod. The locating pin effectively transmits the tensile load without introducing additional bending moment, ensuring the accuracy and reliability of dynamic tensile testing.

[0049] A tensile impact testing method based on the Hopkinson bar principle includes the following steps: Step 1: Connect both ends of the specimen 3 to the connecting part 11 of the incident rod 5 and the connecting part 2 12 of the transmission rod 1, respectively; Step 2: Compressed air is injected into cylinder 10 to drive impactor 7 to accelerate along incident rod 5 and strike flange 8 at the end of incident rod 5, generating tensile stress wave in incident rod 5. Step 3: The tensile stress wave propagates along the incident rod 5 to the specimen 3, applying a dynamic tensile load to the specimen 3, and generating reflected and transmitted waves at the interface of the specimen 3. Step 4: The incident wave, reflected wave and transmitted wave signals are collected by the sensor 6 set on the incident rod 5 and the sensor 2 set on the transmission rod 1, and recorded by the data acquisition unit 4. Step 5: Process the acquired signals according to the one-dimensional stress wave theory, and calculate the stress, strain and strain rate of specimen 3 under dynamic loading.

[0050] Specifically, the formula for calculating the stress is: ; The formula for calculating the strain is: ; The formula for calculating the strain rate is: ; in, The elastic modulus of the rod, Let be the cross-sectional area of ​​the member. The cross-sectional area of ​​the specimen. The stress wave velocity in the rod, The initial length of the specimen. and These are the measured transmitted and reflected wave signals, respectively.

[0051] The impactor 7 strikes the flange 8 at the end of the incident rod 5 at high speed. Due to the sudden tensile force exerted by the flange 8 on the end of the incident rod 5, a tensile stress wave is directly generated in the incident rod 5 and propagates to the specimen 3.

[0052] When the tensile wave propagates to the interface of specimen 3, it generates a reflected wave (returning to incident rod 5) and a transmitted wave (entering transmission rod 1) due to the difference in material impedance. The amplitude of the reflected wave is directly related to the dynamic mechanical properties of the specimen, while the transmitted wave reflects the stress transmission characteristics inside specimen 3.

[0053] from Figure 6 Data table extracted

[0054] The table shows that the incident wave reaches a peak value of 750mV at 13.0ms, and the waveform rise is steep (only 0.4ms from 12.6 to 13.0ms), indicating that the pneumatic drive system responds quickly.

[0055] The reflected wave exhibits a negative peak value of -600mV at 13.6ms, which is consistent with the polarity reversal characteristic of the wave when reflected at the interface of the specimen in the one-dimensional stress wave theory.

[0056] The waveform decayed to the baseline in just 1.3ms (13.6-14.9ms), verifying the energy absorber's effective absorption of the remaining kinetic energy of the incident rod.

[0057] from Figure 7 Data table extracted

[0058] The table shows that the transmitted wave reaches a peak value of 65mV at 13.5ms and the waveform width is only 0.4ms, indicating that the stress wave propagation efficiency of the specimen is high under dynamic loading.

[0059] Compared with the incident wave peak of 750mV, the transmitted wave amplitude is significantly reduced, which is consistent with the wave impedance characteristics of low-impedance specimens (such as polymers).

[0060] from Figure 8 Data table extracted

[0061] The table shows that the incident wave reaches 800mV in 0.09ms, the reflected wave reaches -800mV in 0.18ms, and the time difference between the two waves is 0.09ms, which corresponds to the stress wave propagation time in the thickness direction of the specimen.

[0062] During the waveform decay phase (0.24-0.30ms), the incident wave and the reflected wave synchronously approach 0, verifying the wave superposition decay law in the one-dimensional stress wave theory.

[0063] Technical verification conclusion: Improved waveform purity: The incident wave exhibits no distortion due to multiple reflections, and the peak voltage remains stable, verifying the innovative design advantages of the bushing-less conversion structure.

[0064] Impedance matching optimization: The ratio of transmitted wave amplitude to incident wave (65 / 750≈8.7%) meets the expected acoustic impedance matching between polymer rods and low-impedance specimens.

[0065] Dynamic testing reliability: The three-wave (incident, reflection, transmission) time series are clear, supporting the accurate calculation of the dynamic stress-strain curve of the specimen through one-dimensional stress wave theory.

[0066] Any aspects of this invention not described in detail are well-known to those skilled in the art.

[0067] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A tensile impact testing device based on the Hopkinson bar principle, characterized in that, Includes a transmission rod (1), a specimen (3), an incident rod (5), an impactor (7), a flange (8), an energy absorber (9), a cylinder (10), a first connection part (11), a second connection part (12), an L-shaped plate (14), and a base (15); The L-shaped plate (14) is fixed on the base (15); One end of the transmission rod (1) is fixed to the base (15) by an L-shaped plate (14), and the other end is provided with a connecting part (12) for connecting the specimen (3). The cylinder (10) is fixed on the base (15); the incident rod (5) is coaxially inserted through the cylinder (10), one end of the incident rod (5) is provided with a connecting part (11) for connecting the specimen (3), the other end of the incident rod (5) is fixed with a flange (8), the incident rod (5) and the transmission rod (1) are coaxially opposite each other, and the incident rod (5) and the transmission rod (1) are provided with signal collection units for collecting and recording stress wave signals; the impactor (7) is coaxially sleeved on the incident rod (5) and slidably disposed inside the cylinder (10); The cylinder (10) is provided with an air inlet at the upper end for connecting to an external air source to drive the impactor (7) to move along the incident rod (5) and impact the flange (8). The energy absorber (9) is fixed to the base (15) by an L-shaped plate (14), and the energy absorber (9) is located on the movement path of the flange (8) to absorb the remaining kinetic energy of the incident rod (5).

2. The tensile impact testing device based on the Hopkinson bar principle according to claim 1, characterized in that, The signal collection unit includes a data acquisition unit (4), a sensor one (2), and a sensor two (6). The sensor one (2) is mounted on the transmission rod (1), and the sensor two (6) is mounted on the incident rod (5). The sensor one (2) and the sensor two (6) are used to collect stress wave signals. The data acquisition unit (4) is used to record the stress wave signals. The sensor one (2) and the sensor two (6) are electrically connected to the data acquisition unit (4).

3. The tensile impact testing equipment based on the Hopkinson bar principle according to claim 1, characterized in that, The sensor one (2) and sensor two (6) are capacitive sensors or strain gauges.

4. The tensile impact testing device based on the Hopkinson bar principle according to claim 1, characterized in that, Several supports (13) are fixed to the upper end of the base (15); The bracket (13) includes a height adjustment component (131) and a fixing ring (132). The height adjustment component (131) is fixedly installed on the upper end of the base (15) by bolts. The fixing ring (132) is fixed on the upper end of the height adjustment component (131). The inner wall of the fixing ring (132) slides in cooperation with the outer wall of the transmission rod (1) and the incident rod (5).

5. The tensile impact testing device based on the Hopkinson bar principle according to claim 1, characterized in that, The transmission rod (1), the incident rod (5), and the impactor (7) are all made of polymer materials.

6. The tensile impact testing device based on the Hopkinson bar principle according to claim 5, characterized in that, The polymer material is polymethyl methacrylate.

7. The tensile impact testing device based on the Hopkinson bar principle according to claim 1, characterized in that, A seal is provided at the connection between the cylinder (10) and the incident rod (5).

8. The tensile impact testing device based on the Hopkinson bar principle according to claim 1, characterized in that, Both the first connecting part (11) and the second connecting part (12) include a flat groove and a radially penetrating positioning hole; the specimen (3) is a dumbbell shape with wide ends and narrow middle, with its two ends inserted into the flat groove and fixed by a positioning pin passing through the positioning hole.

9. A tensile impact testing method based on the Hopkinson bar principle, characterized in that, Includes the following steps: Step 1: Connect the two ends of the specimen (3) to the first (11) connection part of the incident rod (5) and the second (12) connection part of the transmission rod (1), respectively. Step 2: Compressed air is injected into the cylinder (10) to drive the impactor (7) to accelerate along the incident rod (5) and strike the flange (8) at the end of the incident rod (5), generating a tensile stress wave in the incident rod (5); Step 3: The tensile stress wave propagates along the incident rod (5) to the specimen (3), applying a dynamic tensile load to the specimen (3) and generating reflected and transmitted waves at the interface of the specimen (3); Step 4: The incident wave, reflected wave and transmitted wave signals are collected by the sensor 2 (6) set on the incident rod (5) and the sensor 1 (2) set on the transmission rod (1), and recorded by the data acquisition unit (4); Step 5: Process the collected signals according to the one-dimensional stress wave theory, and calculate the stress, strain and strain rate of the specimen (3) under dynamic loading.

10. A tensile impact testing method based on the Hopkinson bar principle according to claim 9, characterized in that, The formula for calculating the stress is: ; The formula for calculating the strain is: ; The formula for calculating the strain rate is: ; in, The elastic modulus of the rod, Let be the cross-sectional area of ​​the member. The cross-sectional area of ​​the specimen. The stress wave velocity in the rod, The initial length of the specimen. and These are the measured transmitted and reflected wave signals, respectively.

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