A dynamic compression rod impact fatigue testing device
By designing a dynamic pressure bar impact fatigue testing device, a single loading of the specimen is achieved using momentum traps and limiting components, solving the problem of multiple loading in existing devices and improving the accuracy and efficiency of impact fatigue testing.
Patent Information
- Application Number
- CN202411581884.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2025-11-18
- Estimated Expiration
- 2044-11-07
AI Technical Summary
Existing impact fatigue testing equipment cannot ensure a single loading of the specimen, resulting in the specimen being subjected to multiple loadings during the loading process. This affects the accuracy of stress and strain curves, and multiple loadings mask the true fatigue failure mode of the specimen.
A dynamic pressure bar impact fatigue testing device is adopted, including a worktable, a launching component, a pressure bar component, and a momentum trap. By adjusting the gap and limiting component of the momentum trap, the stress wave is ensured to be loaded in a single time. The momentum trap absorbs the reflected tensile wave to achieve a single compression loading of the specimen.
This method enabled single-stage compression loading of the specimen, established an accurate relationship between dynamic impact load and fatigue failure mode, and improved the accuracy and efficiency of the experiment.
Smart Images
Figure CN119375067B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of dynamic impact fatigue testing equipment technology, and more specifically, to a dynamic pressure bar impact fatigue testing device. Background Technology
[0002] Impact fatigue refers to the process by which a material, after being subjected to repeated impact loads, eventually fractures due to the gradual changes in its internal microstructure and the accumulation of damage. This type of fatigue fracture differs from fracture caused by a single high-energy impact; it focuses more on the impact of multiple low-energy impacts on the long-term performance of the material. Impact fatigue is of great significance in many engineering fields, especially in industries with extremely high material performance requirements, such as aerospace, automotive manufacturing, and machinery manufacturing. In these industries, many critical components (such as aircraft engine blades, automotive suspension systems, and valve stems of internal combustion engines) may be affected by impact fatigue during long-term use. Hopkinson bars, for example, can be used to test materials, providing important reference data for the design and optimization of engineering structures. Hopkinson bars can apply high strain rate stresses in a very short time, thus meeting the requirements for studying the mechanical properties of materials under impact loads. Hopkinson bars have advantages such as accurate and reliable data and a wide range of applications. The dynamic stress and strain of a sample can be applied and measured by utilizing the propagation of stress waves in the bar. A Hopkinson pressure bar typically includes an incident bar, a transmission bar, an impact device, and a data acquisition system. An impact bar or projectile strikes the incident bar using a pneumatic, hydraulic, or electromagnetic acceleration device, generating a stress wave within the incident bar. The stress wave propagates along the incident bar; when it reaches the contact surface between the incident bar and the sample, part of the stress wave is reflected, while the rest passes through the sample to the transmission bar. Strain gauges mounted on the incident and transmission bars record the strain signals of the stress wave. By analyzing these signals, the stress, strain, and strain rate of the sample under high strain rate conditions can be calculated.
[0003] Current impact fatigue testing equipment for materials suffers from several problems, primarily due to the inability to achieve single-pass loading during the loading process. Specifically, each dynamic loading event results in multiple reflections of the stress wave along the rod, creating alternating compression and tension waves. Because the specimen remains attached to the rod, it is subjected to multiple compression waves, the magnitude and number of which are uncontrollable. This leads to discrepancies between the load conditions observed in each impact fatigue test and the stress-strain curves, and the multiple loading events can mask the true fatigue failure mode, hindering the establishment of an accurate relationship between dynamic impact load, the number of impacts, and the fatigue failure mode. Summary of the Invention
[0004] To address the problem that impact fatigue testing devices cannot ensure single-shot loading of the specimen, this invention provides a dynamic bar impact fatigue testing device, comprising:
[0005] Workbench;
[0006] A first launching assembly, comprising a first driving unit, a first barrel, and a first impact rod; the first driving unit and the first barrel are detachably connected to the worktable; the first impact rod is slidably connected to the first barrel.
[0007] A pressure rod assembly includes a first pressure rod and a second pressure rod. The first pressure rod is slidably connected to the worktable; the sliding direction of the first pressure rod is parallel to its own length direction; the first pressure rod is coaxially arranged with a first impact rod; the second pressure rod is slidably connected to the worktable; the sliding direction of the second pressure rod is parallel to its own length direction; a clamping space exists between the first pressure rod and the second pressure rod; the first pressure rod is located between the first barrel and the second pressure rod; the first pressure rod and the second pressure rod are coaxially arranged.
[0008] A first momentum trap, comprising a first collision unit and a first mass block; the first collision unit is detachably connected to the first pressure rod; the first mass block is detachably connected to the worktable; the first mass block is located on the side of the first collision unit opposite to the first launching assembly; a first gap exists between the first mass block and the first collision unit; the first gap is calculated using the following formula:
[0009]
[0010] Wherein, d1 is the first gap; ε i1 To eliminate the first momentum trap, the strain of the first pressure rod is measured when the first impact rod strikes the first pressure rod at a preset velocity; c 01 T is the wave velocity of the stress wave in the first compression member; 01 The loading pulse width of the stress wave in the first pressure bar is denoted as .
[0011] In some embodiments, the second launching assembly includes a second driving unit, a second barrel, and a second impact rod; the second driving unit and the second barrel are detachably connected to the worktable; the second impact rod is slidably connected to the second barrel; and the second impact rod is coaxially arranged with the second pressure rod.
[0012] The second momentum trap includes a second collision unit and a second mass block; the second collision unit is detachably connected to the second pressure rod; the second mass block is detachably connected to the worktable; the second mass block is located on the side of the second collision unit opposite to the second launching assembly; a second gap exists between the second mass block and the second collision unit; the second gap is calculated using the following formula:
[0013]
[0014] Where d2 is the second gap; ε i2 To eliminate the second momentum trap, the strain of the second pressure rod is measured when the second impact rod strikes the second pressure rod at a preset velocity; c 02 T is the wave velocity of the stress wave in the second compression member; 02 The loading pulse width of the stress wave in the second pressure bar is denoted as .
[0015] In some embodiments, a first limiting assembly includes a first limiting rod and a first guide portion; the first limiting rod is located between the first impact rod and the first pressure rod; the first guide portion is detachably connected to the worktable; the first limiting rod and the first guide portion are slidably connected; the sliding direction of the first limiting rod is parallel to its own length direction; the first guide portion limits the sliding distance of the first limiting rod; the first limiting rod and the first impact rod are coaxially arranged.
[0016] The second limiting component includes a second limiting rod and a second guide portion; the second limiting rod is located between the second impact rod and the second pressure rod; the second guide portion is detachably connected to the worktable; the second limiting rod and the second guide portion are slidably connected; the sliding direction of the second limiting rod is parallel to its own length direction; the second guide portion limits the sliding distance of the second limiting rod; the second limiting rod and the second impact rod are coaxially arranged.
[0017] In some embodiments, the first launching assembly further includes a first reset unit, the first reset unit including a first suction pump and a first pressure sensor; the first suction pump is connected to the first barrel; the suction port of the first suction pump is located between the first driving unit and the first impact rod; the first pressure sensor is detachably connected to the first barrel; the first pressure sensor is located at the end of the first barrel facing the first driving unit;
[0018] The second launching assembly further includes a second reset unit, which includes a second air pump and a second pressure sensor; the second air pump is connected to the second barrel; the air pump port is located between the second drive unit and the second impact rod; the second pressure sensor is detachably connected to the second barrel; the second pressure sensor is located at the end of the second barrel facing the second drive unit.
[0019] In some embodiments, the pressure bar assembly further includes a bar positioning control unit; the bar positioning control unit includes a magnetic suction part and a sliding part; the sliding part is detachably connected to the worktable; the magnetic suction part is detachably connected to the sliding part; the sliding part drives the magnetic suction part to move; the moving direction of the magnetic suction part is parallel to the moving direction of the first impact bar.
[0020] In some embodiments, the first momentum trap further includes a first magnetic adsorption part; the first magnetic adsorption part is detachably connected to the first mass block; when the magnetic adsorption part and the first magnetic adsorption part are close together, there is an adsorption force between them;
[0021] The second momentum trap also includes a second magnetic adsorption part; the second magnetic adsorption part is detachably connected to the second mass block; when the magnetic adsorption part and the second magnetic adsorption part are close to each other, there is an adsorption force between them.
[0022] In some embodiments, the pressure bar assembly further includes an auxiliary sleeve; the auxiliary sleeve has a first clamping cavity, a clearance cavity, and a second clamping cavity; one end of the first pressure bar passes through the first clamping cavity; one end of the second pressure bar passes through the second clamping cavity; when the sample is subjected to a loading test; the sample is located in the clearance cavity; the inner wall of the clearance cavity has a gap with the sample; the inner wall of the first clamping cavity is capable of contraction and expansion; the inner wall of the second clamping cavity is capable of contraction and expansion.
[0023] In some embodiments, the auxiliary sleeve includes a rigid outer cylinder, a rigid inner cylinder, a first elastic sleeve, and a second elastic sleeve; the rigid inner cylinder is coaxially inserted inside the rigid outer cylinder; one end of the first elastic sleeve is fixedly connected to the rigid outer cylinder, and the other end of the first elastic sleeve is fixedly connected to the rigid inner cylinder; one end of the second elastic sleeve is fixedly connected to the rigid outer cylinder, and the other end of the second elastic sleeve is fixedly connected to the rigid inner cylinder; the rigid outer cylinder, the rigid inner cylinder, the first elastic sleeve, and the second elastic sleeve cooperate to form an annular cylindrical inflation cavity; the internal cavity of the first elastic sleeve is the first clamping cavity; the internal cavity of the second elastic sleeve is the second clamping cavity.
[0024] In some embodiments, the auxiliary sleeve further includes a first force sensor and a second force sensor; the first force sensor is located in the first clamping cavity; the first force sensor is detachably connected to the inner wall of the first clamping cavity; the second force sensor is located in the second clamping cavity; the second force sensor is detachably connected to the inner wall of the second clamping cavity.
[0025] In some embodiments, the dynamic pressure bar impact fatigue testing device includes a data acquisition component; the data acquisition component includes a first strain gauge, a second strain gauge, a first bridge box, a second bridge box, a strain amplifier, and an oscilloscope; the first strain gauge is detachably connected to the first pressure bar; the second strain gauge is detachably connected to the second pressure bar; the first strain gauge and the second strain gauge are symmetrically arranged about the midpoint between the first pressure bar and the second pressure bar; the first bridge box is electrically connected to the first strain gauge and the strain amplifier respectively; the second bridge box is electrically connected to the second strain gauge and the strain amplifier respectively; the oscilloscope is electrically connected to the strain amplifier.
[0026] To address the problem that impact fatigue testing devices cannot ensure a single loading of the specimen, this invention has the following advantages:
[0027] The formula for adjusting the gap of the first momentum trap in this invention is based on the difference in material properties of the wave impedance between the first momentum trap and the first pressure rod. Therefore, a portion of the reflected tensile wave is absorbed by the first momentum trap, while the other portion is reflected within the first momentum trap. Furthermore, the first momentum trap primarily alters the wave's propagation direction, not its properties, so the reflected wave remains a tensile wave. In other words, due to the combined effects of the obstruction from the first collision unit and the first mass block, the requirements of the boundary conditions, and the conservation of energy and momentum, during the reflection of the tensile wave, some or all of its energy and momentum can be reflected back, thus forming a reflected wave with the same properties as the tensile wave. This allows for a single loading of the specimen with a compressive wave in impact fatigue testing, which is beneficial for establishing an accurate relationship between dynamic impact load, the number of dynamic impacts, and the fatigue failure mode. Attached Figure Description
[0028] Figure 1 A schematic diagram of the structure of a dynamic pressure bar impact fatigue testing device according to one embodiment is shown;
[0029] Figure 2 A schematic diagram of the structure of a dynamic pressure bar impact fatigue testing device according to another embodiment is shown;
[0030] Figure 3 A schematic diagram of the structure of a dynamic pressure bar impact fatigue testing device according to another embodiment is shown;
[0031] Figure 4 A schematic diagram of the structure of a first limiting component and a second limiting component according to one embodiment is shown;
[0032] Figure 5 A schematic diagram of the structure of a rod positioning control unit according to one embodiment is shown;
[0033] Figure 6 A top view of an embodiment of an auxiliary sleeve is shown;
[0034] Figure 7 It shows Figure 6 A cross-sectional view of the auxiliary sleeve along AA;
[0035] Figure 8 A schematic diagram of the structure of a data acquisition component according to one embodiment is shown.
[0036] Reference numerals: Workbench 10; First launching assembly 20; First drive unit 21; First barrel 22; First impact rod 23; First reset unit 24; First vacuum pump 241; First pressure sensor 242; Pressure rod assembly 30; First pressure rod 31; Second pressure rod 32; Rod position control unit 33; Magnetic suction part 331; Sliding part 332; First momentum trap 40; First collision unit 41; First mass block 42; Second launching assembly 50; Second drive unit 51; Second barrel 52; Second impact rod 53; Second reset unit 54; Second vacuum pump 541; Second pressure sensor 54 2; Second momentum trap 60; Second collision unit 61; Second mass block 62; First limiting component 70; First limiting rod 71; First guide part 72; Second limiting component 80; Second limiting rod 81; Second guide part 82; Data acquisition component 90; First strain gauge 91; Second strain gauge 92; First bridge box 93; Second bridge box 94; Strain amplifier 95; Oscilloscope 96; Auxiliary sleeve 100; First clamping cavity 110; Second clamping cavity 120; Clearance cavity 130; Rigid outer cylinder 140; Rigid inner cylinder 150; First elastic sleeve 160; Second elastic sleeve 170; Sample 180. Detailed Implementation
[0037] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the present disclosure, and are not intended to imply any limitation on the scope of the disclosure.
[0038] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment". The term "another embodiment" is to be interpreted as "at least one other embodiment". The terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments and are not intended to limit the indicated devices, elements, or components to having a specific orientation or being constructed and operated in a specific orientation. Furthermore, some of the above terms may be used to indicate other meanings besides orientations or positional relationships; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application according to the specific circumstances. In addition, the terms "installed", "set up", "equipped with", "connected", and "linked" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, elements, or components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. Furthermore, the terms "first," "second," etc., are mainly used to distinguish different devices, elements, or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.
[0039] Impact fatigue testing provides crucial reference data for the design and optimization of engineering structures. Currently, the Hopkinson bar is commonly used for impact fatigue testing. While the Hopkinson bar allows for repeated dynamic loading tests on compressed specimens, when a bullet impacts the bar, the stress wave propagates through alternating tensile and compressive waves. Because the specimen and bar are not separated, the resulting stress wave is reflected multiple times upon impact, creating alternating tensile and compressive waves. This results in the specimen being subjected to multiple compression loads, the magnitude and number of which are uncontrollable. In other words, it's impossible to ensure a single compression load on the specimen. Consequently, the loading conditions of each impact fatigue test specimen do not match the stress and strain curves. Furthermore, multiple loadings can mask the true fatigue failure mode of the specimen, hindering the establishment of an accurate relationship between dynamic impact load, the number of dynamic impacts, and the fatigue failure mode. To achieve a single impact load, the incident bar could be eliminated, and the bullet could directly impact the specimen. However, this presents challenges such as difficulty in verifying stress balance and inaccurate bar repositioning. Therefore, to solve the above problems, the present invention provides a dynamic pressure bar impact fatigue testing device, such as... Figure 1 As shown, a dynamic pressure bar impact fatigue testing device may include a worktable 10, a first launching component 20, a pressure bar component 30, and a first momentum trap 40.
[0040] In this embodiment, as Figure 1 As shown, the worktable 10 can be made of metal, which can ensure the stability of the first launching assembly 20, the pressure rod assembly 30 and the first momentum trap 40.
[0041] like Figure 1 As shown, the first launching assembly 20 may include a first driving unit 21, a first barrel 22, and a first impact rod 23. The first driving unit 21 and the first barrel 22 are detachably connected to the worktable 10. The first impact rod 23 may be a cylinder made of steel or aluminum, or it may be spindle-shaped or multi-step. The cross-sectional diameter of the first impact rod 23 may be the same as the inner diameter of the first barrel 22. The first impact rod 23 may be slidably connected to the first barrel 22. The first driving unit 21 may drive the first impact rod 23 to be launched along the axis of the first barrel 22, thereby performing an impact loading test on the sample 180 and obtaining accurate experimental results.
[0042] like Figure 1As shown, the pressure bar assembly 30 may include a first pressure bar 31 and a second pressure bar 32. The first pressure bar 31 serves as the incident rod, and the second pressure bar 32 serves as the transmission rod. The first pressure bar 31 can be slidably connected to the worktable 10. The sliding direction of the first pressure bar 31 can be parallel to its own length direction, such as the horizontal direction. The first pressure bar 31 can be coaxially arranged with the first impact rod 23. The second pressure bar 32 can be slidably connected to the worktable 10. The sliding direction of the second pressure bar 32 can be parallel to its own length direction, such as the horizontal direction. There can be a clamping space between the first pressure bar 31 and the second pressure bar 32. The sample 180 can be placed in the clamping space. The first pressure bar 31 can be located between the first barrel 22 and the second pressure bar 32. The first pressure bar 31 can be coaxially arranged with the second pressure bar 32. The first driving unit 21 can drive the first impact rod 23 to impact the first pressure bar 31 to form a stress wave. The stress wave is transmitted along the first pressure bar 31 to the sample 180, and a single impact loading test of the compression wave is performed on the sample 180. In other words, when the first impact rod 23 strikes the contact surface between the first pressure rod 31 and the sample 180, a portion of the stress wave is reflected. This reflected stress wave forms alternating tensile and compressive waves. The reflected tensile wave is absorbed by the first momentum trap, resulting in a single impact loading test of the compressive wave on the sample 180. The remaining stress wave propagates through the sample 180 to the second pressure rod 32. The first and second pressure rods 31 and 32 clamp and fix the sample 180, thus buffering the generated stress and achieving a more balanced stress, thereby reducing the loading force. Therefore, sudden changes are less likely to occur when adjusting the loading force, making it easier to control the magnitude of the impact force applied by the first launching component 20 each time to match the actual situation. This, in turn, reduces the cost of the impact fatigue testing equipment and improves experimental efficiency.
[0043] like Figure 1 As shown, the first momentum trap 40 may include a first collision unit 41 and a first mass block 42. The first collision unit 41 may be detachably connected to the first pressure rod 31. The first mass block 42 may be detachably connected to the worktable 10. The first mass block 42 may be located on the side of the first collision unit 41 opposite to the first launching assembly 20. A first gap exists between the first mass block 42 and the first collision unit 41. The first gap is calculated using the following formula:
[0044]
[0045] Where d1 is the first gap. ε i1 The strain of the first pressure rod 31 is measured when the first impact rod 23 strikes the first pressure rod 31 at a preset speed to cancel the first momentum trap 40. 01 T represents the wave velocity of the stress wave in the first compression member 31. 01This represents the loading pulse width of the stress wave in the first pressure bar 31. The formula for adjusting the gap of the first momentum trap 40 is based on the difference in material properties between the wave impedance of the first momentum trap 40 and the first pressure bar 31. Therefore, the tensile wave reflected from the contact surface between the first pressure bar 31 and the specimen 180 is partially absorbed by the first momentum trap 40, while the other part is reflected within the first momentum trap 40. Since the effect of the first momentum trap 40 on the stress wave is to change the propagation direction rather than the wave properties, the reflected wave is still a tensile wave. That is, the propagation speed of the tensile wave in the medium depends on factors such as the elastic properties and density of the medium. Therefore, the measured wave velocity can reflect the material properties, and thus the gap of the momentum trap can be adjusted to ensure that the reflected stress wave is a tensile wave. This ensures that the displacement of the first momentum trap 40 is zero and the stress is continuous, realizing a single loading of the specimen 180 by the compression wave in the first pressure bar 31, which is beneficial for establishing an accurate relationship between dynamic impact load, dynamic impact number, and fatigue failure mode.
[0046] In this embodiment, as Figure 2 As shown, a dynamic pressure bar impact fatigue testing device may include a second launching component 50 and a second momentum trap 60.
[0047] like Figure 2 As shown, the second launching assembly 50 may include a second driving unit 51, a second barrel 52, and a second impact rod 53. The second driving unit 51 and the second barrel 52 are detachably connected to the worktable 10, respectively. The second impact rod 53 is slidably connected to the second barrel 52. The second impact rod 53 is coaxially arranged with the second pressure rod 32. The second driving unit 51 can drive the second impact rod 53 to fire along the axial direction of the second barrel 52, impacting the second pressure rod 32 to form a stress wave, thereby testing the sample 180 and obtaining accurate experimental results.
[0048] like Figure 2 As shown, the second momentum trap 60 may include a second collision unit 61 and a second mass block 62. The second collision unit 61 may be detachably connected to the second pressure rod 32. The second mass block 62 may be detachably connected to the worktable 10. The second mass block 62 is located on the side of the second collision unit 61 opposite to the second launching assembly 50. A second gap exists between the second mass block 62 and the second collision unit 61. The second gap is calculated using the following formula:
[0049]
[0050] Where d2 is the second gap. ε i2 The strain of the second pressure rod 32 is measured when the second impact rod 53 strikes the second pressure rod 32 at a preset speed to cancel the second momentum trap 60. 02T represents the wave velocity of the stress wave in the second pressure bar 32. 02 This represents the loading pulse width of the stress wave in the second pressure bar 32. A portion of the tensile wave reflected back from inside the second pressure bar 32 is absorbed by the second momentum trap 60, while the remaining portion is reflected within the second momentum trap 60. Since the second momentum trap 60 primarily alters the wave's propagation direction rather than its properties, the reflected wave remains tensile. This allows for a single impact loading test of the compression wave on the specimen 180. After performing an impact fatigue test on the specimen 180 in one direction using the first pressure bar 31 as the incident bar and the second pressure bar 32 as the transmission bar, a reverse impact loading test can be performed on the specimen 180 using the second pressure bar 32 as the incident bar and the first pressure bar 31 as the transmission bar. This allows for bidirectional alternating impact fatigue testing. By obtaining parameters of the specimen 180's resistance to multiple impact loading fatigue tests, the experimental efficiency of dynamic impact fatigue testing on the specimen 180 can be improved while ensuring that the compression wave in the impact fatigue test is a single loading.
[0051] In this embodiment, as Figure 4 As shown, a dynamic pressure bar impact fatigue testing device may include a first limiting component 70 and a second limiting component 80.
[0052] like Figure 4 As shown, the first limiting component 70 may include a first limiting rod 71 and a first guide portion 72. The first limiting rod 71 may be located between the first impact rod 23 and the first pressure rod 31. The first guide portion 72 may be detachably connected to the worktable 10. The first limiting rod 71 may be slidably connected to the first guide portion 72. The sliding direction of the first limiting rod 71 may be parallel to its own length direction, such as the horizontal direction. The first guide portion 72 may limit the sliding distance of the first limiting rod 71. The first limiting rod 71 may be coaxially arranged with the first impact rod 23. The first limiting rod 71 may have a small displacement space. The first limiting rod 71 is slidably connected to the worktable 10, which can prevent the worktable 10 from affecting the transmission of stress waves. Moreover, the first limiting rod 71 is a variable cross-section cylinder. Increasing the contact cross-section between the first limiting rod 71 and the first guide portion 72 can prevent the first pressure rod 31 from moving too much, thus avoiding affecting the test results.
[0053] like Figure 4As shown, the second limiting assembly 80 may include a second limiting rod 81 and a second guide portion 82. The second limiting rod 81 may be located between the second impact rod 53 and the second pressure rod 32. The second guide portion 82 may be detachably connected to the worktable 10. The second limiting rod 81 may be slidably connected to the second guide portion 82. The sliding direction of the second limiting rod 81 may be parallel to its own length direction, such as the horizontal direction. The second guide portion 82 may limit the sliding distance of the second limiting rod 81. The second limiting rod 81 may be coaxially arranged with the second impact rod 53. The second limiting rod 81 may have a small displacement space. The second limiting rod 81 is slidably connected to the worktable 10, which can avoid the worktable 10 from affecting the transmission of stress waves. Moreover, the second limiting rod 81 is a variable cross-section cylinder. Increasing the contact cross-section between the second limiting rod 81 and the second guide portion 82 can prevent the second pressure rod 32 from moving too much, thus avoiding affecting the test results.
[0054] In this embodiment, as Figure 3 As shown, the first launching assembly 20 may further include a first reset unit 24, which may include a first vacuum pump 241 and a first pressure sensor 242. The first vacuum pump 241 may be connected to the first barrel 22. The vacuum port of the first vacuum pump 241 may be located between the first drive unit 21 and the first impact rod 23. The first pressure sensor 242 may be detachably connected to the first barrel 22. The first pressure sensor 242 may be located at the end of the barrel facing the first drive unit 21. The first vacuum pump 241 can extract the gas from the first barrel 22, thereby allowing the first impact rod 23 to return to the side of the first barrel 22 closer to the first drive unit 21 after the impact fatigue test, that is, to reset the first impact rod 23.
[0055] like Figure 2 , Figure 3 As shown, the second launching assembly 50 may further include a second reset unit 54, which may include a second vacuum pump 541 and a second pressure sensor 542. The second vacuum pump 541 may be connected to the second barrel 52. The vacuum port of the second vacuum pump 541 may be located between the second drive unit 51 and the second impact rod 53. The second pressure sensor 542 may be detachably connected to the second barrel 52. The second pressure sensor 542 may be located at the end of the barrel facing the second drive unit 51. The second vacuum pump 541 can extract the gas from the second barrel 52, thereby allowing the second impact rod 53 to return to the side of the second barrel 52 closer to the second drive unit 51 after the impact fatigue test, that is, to reset the second impact rod 53.
[0056] The control time for either the first air pump 241 to pump air until the first impact rod 23 resets, or the second air pump 541 to pump air until the second impact rod 53 resets, is as follows:
[0057]
[0058] Among them, V G V represents the gas volume in the space between the first impact rod 23 and the first drive unit 21, or between the second impact rod 53 and the second drive unit 51; R P is the pumping rate of the first pumping pump 241 or the second pumping pump 541. a The pressure of the air before evacuation inside the first barrel 22 or the second barrel 52 is typically atmospheric pressure, or 1013 Mbar; P e The required air pressure to reset the first impact rod 23 or the second impact rod 53 inside the first barrel 22 or the second barrel 52 is generally set to 400 Mbar; k is a correction factor, usually set to 1.3. This allows for more precise setting of the pumping time of the first pumping pump 241 and the second pumping pump 541, thereby controlling the reset of the first impact rod 23 or the second impact rod 53 and effectively avoiding energy waste from prolonged pumping.
[0059] In this embodiment, as Figure 3 , Figure 5 As shown, the pressure rod assembly 30 may further include a rod positioning control unit 33, and two rod positioning control units 33 may be provided. The rod positioning control unit 33 may include a magnetic attraction part 331 and a sliding part 332. The sliding part 332 may be detachably connected to the worktable 10. The magnetic attraction part 331 may be detachably connected to the sliding part 332. The sliding part 332 can drive the magnetic attraction part 331 to move. The moving direction of the magnetic attraction part 331 may be parallel to the moving direction of the first impact rod 23. The end of the magnetic attraction part 331 facing away from the sliding part 332 is an electromagnetic semi-circular structure. The diameter of the magnetic attraction part 331 is the same as the cross-sectional diameter of the first pressure rod 31 and the second pressure rod 32. The semi-circular structure can generate a strong magnet, allowing the first pressure rod 31 or the second pressure rod 32 to be attracted and slid along the sliding part 332 through the magnetic attraction part 331, adjusting the contact between the end face of the first pressure rod 31 and the first limiting rod 71. Alternatively, the second pressure rod 32 can be adjusted to contact the end face of the second limiting rod 81. This facilitates the control of the first pressure rod 31 and the second pressure rod 32 to reset, thereby facilitating the propagation of stress waves during the next dynamic impact loading.
[0060] In this embodiment, as Figure 3 As shown, the first momentum trap 40 may further include a first magnetic adsorption part. The first magnetic adsorption part may be detachably connected to the first mass block 42. When the magnetic adsorption part 331 is close to the first magnetic adsorption part, there is an adsorption force between them. This facilitates the adjustment of the gap of the first momentum trap using the rod position control unit 33, ensuring that a single impact loading is applied to the sample 180.
[0061] The second momentum trap 60 may further include a second magnetic adsorption part. The second magnetic adsorption part can be detachably connected to the second mass block 62. When the magnetic adsorption part 331 and the second magnetic adsorption part are close together, there is an adsorption force between them. This facilitates the adjustment of the gap of the second momentum trap using the rod position control unit 33, ensuring that a single impact loading is applied to the sample 180.
[0062] In this embodiment, Figure 6 , Figure 7 As shown, the pressure bar assembly 30 may further include an auxiliary sleeve 100. The auxiliary sleeve 100 is an openable variable cross-section cylindrical structure. The auxiliary sleeve 100 may have a first clamping cavity 110, a clearance cavity 130, and a second clamping cavity 120. One end of the first pressure bar 31 may pass through the first clamping cavity 110. One end of the second pressure bar 32 may pass through the second clamping cavity 120. When loading the specimen 180, the specimen 180 may be located in the clearance cavity 130. There may be a gap between the inner wall of the clearance cavity 130 and the specimen 180. The inner wall of the first clamping cavity 110 can contract and expand. The inner wall of the second clamping cavity 120 can contract and expand. The inner diameter of the clearance cavity 130 in the portion aligned with the specimen 180 is larger than the cross-sectional diameter of the specimen 180, thereby avoiding restriction of the lateral expansion of the specimen 180 during impact loading. When the first clamping cavity 110 and the second clamping cavity 120 are in a contracted state, the first pressure rod 31 and the second pressure rod 32 move synchronously, thus making it less likely to cause unloaded damage to the sample 180.
[0063] In this embodiment, as Figure 7As shown, the auxiliary sleeve 100 may include a rigid outer cylinder 140, a rigid inner cylinder 150, a first elastic sleeve 160, and a second elastic sleeve 170. The rigid inner cylinder 150 may be coaxially inserted inside the rigid outer cylinder 140. One end of the first elastic sleeve 160 may be fixedly connected to the rigid outer cylinder 140, and the other end of the first elastic sleeve 160 may be fixedly connected to the rigid inner cylinder 150. One end of the second elastic sleeve 170 may be fixedly connected to the rigid outer cylinder 140, and the other end of the second elastic sleeve 170 may be fixedly connected to the rigid inner cylinder 150. The rigid outer cylinder 140, the rigid inner cylinder 150, the first elastic sleeve 160, and the second elastic sleeve 170 cooperate to form an annular cylindrical inflation chamber. The internal cavity of the first elastic sleeve 160 may be a first clamping cavity 110. The internal cavity of the second elastic sleeve 170 may be a second clamping cavity 120. The first elastic sleeve 160 and the second elastic sleeve 170 are made of a flexible material with high frictional resistance. During the adjustment of the pressure bar assembly 30, the contact surfaces of the first elastic sleeve 160 and the first pressure bar 31 tightly grip the bar, and the contact surfaces of the second elastic sleeve 170 and the second pressure bar 32 tightly grip the bar. Therefore, when one of the first pressure bar 31 or the second pressure bar 32 is moved using the bar positioning unit 33, the other pressure bar will also be moved and adjusted to the appropriate position. This avoids the force of the pressure bar assembly 30 moving being directly applied to the specimen 180, thus preventing unloaded damage to the specimen 180.
[0064] In this embodiment, as Figure 7 As shown, the auxiliary sleeve 100 may further include a first force sensor and a second force sensor. The first force sensor may be located within the first clamping cavity 110. The first force sensor may be detachably connected to the inner wall of the first clamping cavity 110. The second force sensor may be located within the second clamping cavity 120. The second force sensor may be detachably connected to the inner wall of the second clamping cavity 120. The first force sensor can accurately monitor the magnitude of the loading force on the end of the sample 180 near the first pressure rod 31 during each impact loading and feed it back to the computer. The second force sensor can accurately monitor the magnitude of the loading force on the end of the sample 180 near the second pressure rod 32 during each impact loading and feed it back to the computer. This allows adjustment of the air pressure required for the next impact loading test, enabling impact fatigue testing of the sample 180.
[0065] In this embodiment, as Figure 3 , Figure 8As shown, the dynamic pressure bar impact fatigue testing device may include a data acquisition component 90. The data acquisition component 90 may include a first strain gauge 91, a second strain gauge 92, a first bridge box 93, a second bridge box 94, a strain amplifier 95, and an oscilloscope 96. The first strain gauge 91 is detachably connected to the first pressure bar 31. The second strain gauge 92 is detachably connected to the second pressure bar 32. The first strain gauge 91 and the second strain gauge 92 are symmetrically arranged about the midpoint between the first pressure bar 31 and the second pressure bar 32. The first bridge box 93 can be electrically connected to both the first strain gauge 91 and the strain amplifier 95. The second bridge box 94 can be electrically connected to both the second strain gauge 92 and the strain amplifier 95. The first bridge box 93 and the second bridge box 94 can convert the electrical signals generated by the first strain gauge 91 and the second strain gauge 92 into pulse signals for the characterization of stress and strain data. The strain amplifier 95 can amplify the transmitted weak pulse signals without distortion to facilitate the observation of stress-strain variation patterns. The oscilloscope 96 is electrically connected to the strain amplifier 95. The oscilloscope 96 can be used to display real-time waveforms and record and export test data.
[0066] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes can be made in form and detail without departing from the scope of this disclosure.
Claims
1. A dynamic pressure bar impact fatigue testing device, characterized in that, The dynamic pressure bar impact fatigue testing device includes: Workbench; A first launching assembly, comprising a first driving unit, a first barrel, and a first impact rod; the first driving unit and the first barrel are detachably connected to the worktable; the first impact rod is slidably connected to the first barrel. A pressure bar assembly includes a first pressure bar and a second pressure bar. The first pressure bar is slidably connected to the worktable; the sliding direction of the first pressure bar is parallel to its own length direction; the first pressure bar is coaxially arranged with a first impact bar; the second pressure bar is slidably connected to the worktable; the sliding direction of the second pressure bar is parallel to its own length direction; a clamping space exists between the first pressure bar and the second pressure bar; the first pressure bar is located between the first barrel and the second pressure bar; the first pressure bar and the second pressure bar are coaxially arranged; the pressure bar assembly also includes an auxiliary sleeve; the auxiliary sleeve has a first clamping cavity, a clearance cavity, and a second clamping cavity; one end of the first pressure bar passes through the first clamping cavity; one end of the second pressure bar passes through the second clamping cavity; when a sample is subjected to a loading test; the sample is located in the clearance cavity; the inner wall of the clearance cavity has a gap with the sample; the inner wall of the first clamping cavity can contract and expand; the inner wall of the second clamping cavity can contract and expand. A first momentum trap, comprising a first collision unit and a first mass block; the first collision unit is detachably connected to the first pressure rod; the first mass block is detachably connected to the worktable; the first mass block is located on the side of the first collision unit opposite to the first launching assembly; a first gap exists between the first mass block and the first collision unit; the first gap is calculated using the following formula: Wherein, d1 is the first gap; ε i1 To eliminate the first momentum trap, the strain of the first pressure rod is measured when the first impact rod strikes the first pressure rod at a preset velocity; c 01 T is the wave velocity of the stress wave in the first compression member; 01 The loading pulse width of the stress wave in the first compression bar; The second launching assembly includes a second drive unit, a second barrel, and a second impact rod; the second drive unit and the second barrel are detachably connected to the worktable; the second impact rod is slidably connected to the second barrel; the second impact rod and the second pressure rod are coaxially arranged; the pressure rod assembly is located between the first launching assembly and the second launching assembly.
2. The dynamic pressure bar impact fatigue testing device according to claim 1, characterized in that, The dynamic pressure bar impact fatigue testing device also includes: The second momentum trap includes a second collision unit and a second mass block; the second collision unit is detachably connected to the second pressure rod; the second mass block is detachably connected to the worktable; the second mass block is located on the side of the second collision unit opposite to the second launching assembly; a second gap exists between the second mass block and the second collision unit; the second gap is calculated using the following formula: Wherein, d2 is the second gap; ε i2 To eliminate the second momentum trap, the strain of the second pressure rod is measured when the second impact rod strikes the second pressure rod at a preset velocity; c 02 T is the wave velocity of the stress wave in the second compression member; 02 The loading pulse width of the stress wave in the second pressure bar is denoted as .
3. The dynamic pressure bar impact fatigue testing device according to claim 2, characterized in that, The dynamic pressure bar impact fatigue testing device also includes: A first limiting assembly includes a first limiting rod and a first guide portion; the first limiting rod is located between the first impact rod and the first pressure rod; the first guide portion is detachably connected to the worktable; the first limiting rod and the first guide portion are slidably connected; the sliding direction of the first limiting rod is parallel to its own length direction; the first guide portion limits the sliding distance of the first limiting rod; the first limiting rod and the first impact rod are coaxially arranged. The second limiting component includes a second limiting rod and a second guide portion; the second limiting rod is located between the second impact rod and the second pressure rod; the second guide portion is detachably connected to the worktable; the second limiting rod and the second guide portion are slidably connected; the sliding direction of the second limiting rod is parallel to its own length direction; the second guide portion limits the sliding distance of the second limiting rod; the second limiting rod and the second impact rod are coaxially arranged.
4. The dynamic pressure bar impact fatigue testing device according to claim 2, characterized in that, The first launching assembly further includes a first reset unit, which includes a first suction pump and a first pressure sensor; the first suction pump is connected to the first barrel; the suction port of the first suction pump is located between the first driving unit and the first impact rod; the first pressure sensor is detachably connected to the first barrel; the first pressure sensor is located at the end of the first barrel facing the first driving unit; The second launching assembly further includes a second reset unit, which includes a second air pump and a second pressure sensor; the second air pump is connected to the second barrel; the air pump port is located between the second drive unit and the second impact rod; the second pressure sensor is detachably connected to the second barrel; the second pressure sensor is located at the end of the second barrel facing the second drive unit.
5. The dynamic pressure bar impact fatigue testing device according to claim 2, characterized in that, The pressure bar assembly further includes a bar positioning control unit; the bar positioning control unit includes a magnetic suction part and a sliding part; the sliding part is detachably connected to the worktable; the magnetic suction part is detachably connected to the sliding part; the sliding part drives the magnetic suction part to move; the moving direction of the magnetic suction part is parallel to the moving direction of the first impact bar.
6. The dynamic pressure bar impact fatigue testing device according to claim 5, characterized in that, The first momentum trap further includes a first magnetic adsorption part; the first magnetic adsorption part is detachably connected to the first mass block; when the magnetic adsorption part and the first magnetic adsorption part are close together, there is an adsorption force between them; The second momentum trap also includes a second magnetic adsorption part; the second magnetic adsorption part is detachably connected to the second mass block; when the magnetic adsorption part and the second magnetic adsorption part are close to each other, there is an adsorption force between them.
7. The dynamic compression bar impact fatigue testing device according to claim 1, characterized in that, The auxiliary sleeve includes a rigid outer cylinder, a rigid inner cylinder, a first elastic sleeve, and a second elastic sleeve; the rigid inner cylinder is coaxially inserted inside the rigid outer cylinder; one end of the first elastic sleeve is fixedly connected to the rigid outer cylinder, and the other end of the first elastic sleeve is fixedly connected to the rigid inner cylinder; one end of the second elastic sleeve is fixedly connected to the rigid outer cylinder, and the other end of the second elastic sleeve is fixedly connected to the rigid inner cylinder; the rigid outer cylinder, the rigid inner cylinder, the first elastic sleeve, and the second elastic sleeve cooperate to form an annular cylindrical inflation cavity; the internal cavity of the first elastic sleeve is the first clamping cavity; the internal cavity of the second elastic sleeve is the second clamping cavity.
8. The dynamic pressure bar impact fatigue testing device according to claim 1, characterized in that, The auxiliary sleeve further includes a first force sensor and a second force sensor; the first force sensor is located in the first clamping cavity; the first force sensor is detachably connected to the inner wall of the first clamping cavity; the second force sensor is located in the second clamping cavity; the second force sensor is detachably connected to the inner wall of the second clamping cavity.
9. The dynamic pressure bar impact fatigue testing device according to claim 1, characterized in that, The dynamic pressure bar impact fatigue testing device includes a data acquisition component; the data acquisition component includes a first strain gauge, a second strain gauge, a first bridge box, a second bridge box, a strain amplifier, and an oscilloscope. The first strain gauge is detachably connected to the first pressure bar; the second strain gauge is detachably connected to the second pressure bar; the first strain gauge and the second strain gauge are symmetrically arranged about the midpoint between the first pressure bar and the second pressure bar; the first bridge box is electrically connected to the first strain gauge and the strain amplifier respectively; the second bridge box is electrically connected to the second strain gauge and the strain amplifier respectively; the oscilloscope is electrically connected to the strain amplifier.