Hopkinson rod test deformation control device and its use method

Abstract

The invention discloses a device for controlling deformation of a Hopkinson tension rod experiment and a method for using the device, which belongs to the technical field of material mechanical property testing. The device comprises a Hopkinson transmission rod and an incident rod, a first clamp and a second clamp, a sample with a gauge length portion in the middle, and a differential sleeve and an adjustment sleeve on the outside; the two ends of the first clamp are respectively connected to the Hopkinson transmission rod and the differential sleeve, and the second clamp is connected to the Hopkinson incident rod; during operation, the test sample is mounted between the first clamp and the second clamp and connected to the Hopkinson transmission rod and the Hopkinson incident rod, a large baffle and a small baffle for limiting the sample are respectively mounted on the differential sleeve and the adjustment sleeve, and different strains are achieved by rotating the adjustment sleeve to change the distance between the small baffle and the right shoulder of the sample; when the right shoulder of the stretched sample is in close contact with the small baffle, the gauge length portion stops deforming, the right connecting section of the sample can disperse residual energy, constant strain is achieved, and accurate control of different strains during the tensile test is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of material mechanical property testing, and in particular relates to a Hopkinson pull rod test deformation control device and a use method thereof. Background Art

[0002] The dynamic mechanical behavior and plastic deformation mechanisms of crystalline materials under high-strain-rate loading conditions are fundamental scientific issues of shared interest across multiple disciplines, including mechanics, physics, materials science, and mechanics. Related research has significant applications in aerospace equipment development, lightweight automotive design, and military protection. The deformation of crystalline materials under high-speed loading is a complex dynamic process influenced by both material softening and deformation strengthening due to adiabatic temperature rise. Consequently, uncovering the dynamic mechanical deformation mechanisms of crystalline materials presents numerous technical challenges.

[0003] At present, the Hopkinson bar test is a common testing technique used to obtain the mechanical response of crystalline materials under high strain rates. In order to deeply reveal the microstructural evolution characteristics and deformation mechanism of crystalline materials during the entire dynamic loading process, it is necessary to obtain test samples under different strain amounts for further microstructural characterization. Under dynamic loading conditions, the Hopkinson incident bar will have a large impact inertia. After the sample reaches the predetermined deformation amount, the incident bar still has a large residual energy, which causes the sample to further deform. At present, the adjustment of different strains in the Hopkinson bar test can be achieved by prefabricating the height of the stop ring. However, the existing Hopkinson bar test equipment cannot achieve precise control of different strains and unload excessive residual energy under high-speed loading conditions during the Hopkinson bar test. Therefore, the development of an experimental equipment to achieve precise control of different strains during the high-speed tensile process of the sample is a practical problem that needs to be urgently solved in the Hopkinson bar test. Summary of the Invention

[0004] The purpose of the present invention is to provide a device for controlling the deformation of a Hopkinson rod test and a method for using the same, in order to solve the technical problem in the prior art that the Hopkinson rod test equipment cannot accurately control different strains and has excessive residual energy under unloading and high-speed loading conditions.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A device for controlling deformation of a Hopkinson tension rod experiment comprises a Hopkinson transmission rod, a Hopkinson incident rod, and a first clamp and a second clamp for clamping a test sample. The sample is a stepped plate-like structure with a gauge portion in the middle. A strain adjustment mechanism is provided on the outside of the sample for limiting the two ends of the gauge portion and unloading excess energy. The two ends of the first clamp are respectively connected to the Hopkinson transmission rod and the strain adjustment mechanism, and the second clamp is connected to the Hopkinson incident rod.

[0007] Preferably, the specimen is composed of a left connecting portion, a left shoulder, a gauge portion, a right shoulder, a right connecting section and a right connecting portion from left to right. The widths of the left shoulder and the right shoulder are both greater than the width of the gauge portion. The left connecting portion is connected to the left shoulder, and the right shoulder is connected to the right connecting portion through a narrow and long right connecting section. The left connecting portion is connected to clamp one, and the right connecting portion is connected to clamp two. The right side end faces of the left shoulder and the right shoulder can respectively fit tightly against the large baffle and the small baffle in the strain adjustment mechanism.

[0008] Preferably, the strain adjustment mechanism includes a differential sleeve and an adjustment sleeve that are threadedly connected, the left end of the differential sleeve is threadedly connected to the right end of the clamp one, a large baffle is provided in the middle of the differential sleeve, and a small baffle is provided in the middle of the adjustment sleeve. The middle parts of the large baffle and the small baffle are both used for long holes that match the thickness and width of the sample, and the middle parts of the long holes of the large baffle and the small baffle are both provided with circular through holes, and the diameter of the through holes is larger than the width of the gauge part and the narrow long strip connecting section of the sample, and smaller than the width of the left shoulder and the right shoulder.

[0009] Preferably, the left connecting part is connected to the left shoulder through a left connecting section, and the left connecting section and the right connecting section at both ends of the specimen are both trapezoidal structures, and the side of the left connecting section and the right connecting section connected to the left shoulder and the right shoulder respectively is a narrow side, and the side connected to the left connecting part and the right connecting part is a wide side.

[0010] Preferably, the left connecting part and the right connecting part have the same structure, both of which are rectangular plate structures. The left connecting part and the right connecting part are provided with a plurality of positioning holes that cooperate with the positioning pins along their length directions. The left connecting part and the right connecting part are respectively connected to the clamp one and the clamp two through the positioning pins, and the positioning pins on the clamp two are arranged on the outside of the adjustment sleeve.

[0011] Preferably, the top and bottom of clamp one and clamp two are both flat, the side of clamp one is a cylindrical surface that matches the inner hole of the differential sleeve, and the side of clamp two is a cylindrical surface that matches the inner hole of the adjustment sleeve; the width of the left connecting part and the right connecting part is not greater than the outer diameter of clamp one and clamp two.

[0012] Preferably, a semicircular notch is provided in the middle of the differential sleeve and the adjustment sleeve, and the width of the notch on the differential sleeve and the adjustment sleeve matches the width of the large baffle and the small baffle respectively; the large baffle and the small baffle are both circular plates, and the outer diameters of the large baffle and the small baffle are not larger than the inner diameters of the differential sleeve and the adjustment sleeve; the large baffle and the small baffle are respectively fixed in the notches of the differential sleeve and the adjustment sleeve.

[0013] Preferably, a circle of scale lines is provided on the edge of one end of the differential sleeve connected to the adjustment sleeve, and an axial reference line is provided on the edge of the adjustment sleeve for corresponding to the scale lines on the differential sleeve.

[0014] The present invention also provides a method for using a Hopkinson rod test deformation control device, comprising the following steps:

[0015] S100: Adjust the coaxial center of the Hopkinson transmission rod and the Hopkinson incident rod, and install the test sample in the above-mentioned Hopkinson tension rod experimental deformation control device;

[0016] S200: Rotate the differential sleeve to place the large baffle on the right side of the left shoulder of the specimen; rotate the adjustment sleeve to place the small baffle on the right side of the right shoulder of the specimen;

[0017] S300: Tensile operation: Apply tension to the Hopkinson incident rod. When the right shoulder of the specimen is close to the small baffle, the specimen with the predetermined strain is obtained.

[0018] S400: After the stretching is completed, dismantle the Hopkinson rod test deformation control device and remove the sample.

[0019] Preferably, in step S300, the thread pitch of the differential sleeve and the adjustment sleeve is M, and when the adjustment sleeve rotates relative to the differential sleeve by an angle α, the adjustment distance l between the right shoulder of the specimen and the small baffle is obtained by formula (1):

[0020]

[0021] The gauge length of the specimen is L, and the strain ε of the specimen during the stretching process is obtained by formula (2):

[0022]

[0023] The beneficial effects of the above technical solution are as follows: Compared with the prior art, in the present invention, one end of the test sample is connected to the Hopkinson transmission rod via clamp 1, and the other end is connected to the Hopkinson incidence rod via clamp 2. A large baffle and a small baffle are respectively installed on the differential sleeve and adjustment sleeve mounted on the outside of the sample to limit the sample position. By rotating the adjustment sleeve, the distance between the small baffle and the right shoulder of the sample is changed to achieve different strains. When the right shoulder of the stretched sample is in close contact with the small baffle, the gauge length portion of the sample stops deforming. The cooperation between the small baffle and the right shoulder disperses the remaining tensile force outside the gauge length portion, thereby achieving a constant strain. The present invention can improve the accuracy of the high-speed tensile test of the Hopkinson rod, achieve precise control of different strains, and unload excess residual energy under high-speed loading conditions, ensuring a safe and reliable test process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] Figure 1 This is a schematic structural diagram of a Hopkinson rod test deformation control device provided by an embodiment of the present invention;

[0026] Figure 2 yes Figure 1 The appearance of the assembled deformation control device for the Hopkinson rod test;

[0027] Figure 3 Schematic diagram of the connection between the sample and the first and second clamps in an embodiment of the present invention;

[0028] Figure 4 2. It is a cross-sectional view of the Hopkinson rod test deformation control device before the test in an embodiment of the present invention;

[0029] Figure 5 2. It is a cross-sectional view of the Hopkinson rod test deformation control device after the test in accordance with an embodiment of the present invention;

[0030] Figure 6 2 is a schematic structural diagram of a differential sleeve in an embodiment of the present invention;

[0031] Figure 7 yes Figure 6 A partial enlarged view of point A in the middle;

[0032] Figure 8 Schematic diagram of the cooperation between the differential sleeve and the adjustment sleeve in an embodiment of the present invention;

[0033] Figure 9 yes Figure 8 A top view of

[0034] Figure 10 Schematic diagram of the cooperation between the large baffle and the sample in an embodiment of the present invention;

[0035] Figure 11 Schematic diagram of the coordination between the adjustment sleeve and the small baffle in an embodiment of the present invention;

[0036] In the figure: 1-Hopkinson transmission rod, 2-fixture 1, 3-locating pin, 4-large baffle, 5-differential sleeve, 6-sample, 60-left connecting part, 61-left connecting section, 62-left shoulder, 63-gauge length part, 64-right shoulder, 65-right connecting section, 66-right connecting part, 67-locating hole; 7-small baffle, 8-adjusting sleeve, 9-fixture 2, 10-Hopkinson incidence rod, 11-notch, 12-scale line, 13-reference line, 14-limiting hole, 15-long hole, 16-through hole. DETAILED DESCRIPTION

[0037] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0038] See also Figure 1 、 2 4. The present invention provides a device for controlling deformation in a Hopkinson bar test, comprising a Hopkinson transmission bar 1, a Hopkinson incident bar 10, and clamps 1 and 2 for holding a test specimen 6. The specimen 6 is a stepped plate-like structure with a gauge portion 23 in the middle. A strain adjustment mechanism is provided on the exterior of the specimen 6 to limit the ends of the gauge portion 63 and to unload excess energy. The ends of clamp 1 are connected to the Hopkinson transmission bar 1 and the strain adjustment mechanism, respectively, while clamp 2 is connected to the Hopkinson incident bar 10. Adjusting the specimen strain through the strain adjustment mechanism improves the accuracy of the Hopkinson bar high-speed tensile test and simultaneously unloads excess tensile energy, thereby achieving a constant strain.

[0039] In the specific embodiment of the present invention, Figure 1 、 4 As shown, the specimen 6 comprises, from left to right, a left connecting portion 60, a left shoulder 62, a gauge portion 63, a right shoulder 64, a right connecting section 65, and a right connecting portion 65. The widths of the left shoulder 62 and the right shoulder 64 are both greater than the width of the gauge portion 63. The left connecting portion 60 is connected to the left shoulder 62, and the right shoulder 64 is connected to the right connecting portion 65 via a narrow and long right connecting section 65. The left connecting portion 60 is connected to the clamp 1 2, and the right connecting portion 65 is connected to the clamp 2 9. The right end faces of the left shoulder 62 and the right shoulder 64 can respectively cling to the large baffle 4 and the small baffle 7 in the strain adjustment mechanism. A specimen adopting this structure can stop further deformation after reaching prestrain by virtue of the cooperation between the small baffle 7 and the right shoulder 64. The excess energy applied by the Hopkinson incident rod 10 is absorbed by the right connecting section 65, and the specimen is broken and unloaded (as shown in FIG. 1 ). Figure 5 as shown), without affecting the deformation amount within the gauge portion 63.

[0040] As a preferred structure, Figure 1 、 3As shown in Figures 4 and 5, the left connecting portion 60 is connected to the left shoulder 62 via a narrow, long left connecting section 61. The left connecting section 61 and the right connecting section 65 at both ends of the specimen 6 are both trapezoidal in structure. The narrow side of the left connecting section 61 and the right connecting section 65, respectively, connected to the left shoulder 62 and the right shoulder 64, is the narrow side, and the wide side of the side connected to the left connecting portion 60 and the right connecting portion 66 is the wide side. The left connecting portion 60 and the right connecting portion 66 have the same structure, both being rectangular plate-like structures. Multiple positioning holes 67 are provided along the length of the left connecting portion 60 and the right connecting portion 66 for cooperating with the positioning pins 3. The left connecting portion 60 and the right connecting portion 66 are respectively connected to the clamp 1 2 and the clamp 2 9 via the positioning pins 3. The positioning pins 3 on the clamp 2 9 are disposed on the outside of the adjustment sleeve 8. In this embodiment, two positioning holes 67 are provided at both ends of the specimen, and the two ends are connected to the clamp 1 2 and the clamp 2 9 via two positioning pins 3. At the same time, the left connecting section 61 and the right connecting section 65 adopt the same structure, and the left connecting part 60 and the right connecting part 66 can also adopt the same structure. The sleeve can be differentiated and the length of the sleeve can be adjusted according to actual needs, so that both ends of the sample have universality and are convenient for batch production.

[0041] In order to facilitate the installation of the locating pin 3, the top and bottom of the clamp 1 2 and the clamp 2 9 are processed into flat surfaces. The side of the clamp 1 2 is a cylindrical surface that matches the inner hole of the differential sleeve 5, and the side of the clamp 2 9 is a cylindrical surface that matches the inner hole of the adjustment sleeve 8; the width of the left connecting part 60 and the right connecting part 65 is not greater than the outer diameter of the clamp 1 2 and the clamp 2 9.

[0042] During the specific production, the specific dimensions of each part of the sample 6 are as follows:

[0043] The test sample 6 is a plate-like structure: the total length of the sample is 76.5 mm, the thickness of the sample is 1 mm, the size of the middle gauge portion 63 is 8 mm × 3 mm, the width of the left shoulder 62 is 6.5 mm, the width of the right shoulder 64 is 14 mm, the left connecting section 61 is a trapezoidal structure with an upper base of 4 mm, a lower base of 5 mm, and a height of 5.7, and the right connecting section 61 is a trapezoidal structure with an upper base of 4 mm, a lower base of 5 mm, and a height of 6.2; the left connecting portion 60 and the right connecting portion 65 at the left and right ends are respectively provided with two positioning holes with a diameter of 3 mm, the diameter of the Hopkinson transmission rod 1 and the Hopkinson incidence rod 10 are 20 mm, and the two rods are respectively processed with internal threads M10 × 10, which are threadedly connected to the clamp 1 2 and the clamp 2 9 respectively.

[0044] In addition, the total length of the clamp 2 is 32 mm, the left end is provided with an external thread M10 that cooperates with the Hopkinson transmission rod 1, and the right end is provided with an external thread M22 that cooperates with the differential sleeve 5. A limiting hole 14 that cooperates with the tested sample 6 is provided on the horizontal surface of the clamping end. The horizontal height of the clamping end is 18 mm, and a card slot with a depth of 18 mm and a thickness of 1 mm is provided. The left connecting part 60 of the sample can be inserted into the card slot so that the positioning hole 66 of the left connecting part 60 of the sample corresponds to the limiting hole 14 on the clamp 2. The positioning pin 3 is inserted to connect and fix the sample 6 to the clamp 2.

[0045] The total length of the clamp 2 9 is 32 mm. The right end is provided with an external thread M10 that cooperates with the Hopkinson incident rod 10. The horizontal surface of the clamping end is provided with a limiting hole 14 that cooperates with the test sample 6. The horizontal height of the clamping end is 18 mm. It is also provided with a card slot with a depth of 18 mm and a thickness of 1 mm. The positioning hole 66 of the right connecting part 65 of the sample corresponds to the limiting hole 14 on the clamp 2 9. The positioning pin 3 is inserted to connect and fix the sample 6 to the clamp 2 9.

[0046] In a specific embodiment of the present invention, Figure 1 、 4 As shown in Figures 6, 8-11, the strain adjustment mechanism includes a differential sleeve 5 and an adjustment sleeve 8 connected by threads. The left end of the differential sleeve 5 is threadedly connected to the right end of the clamp 2. A large baffle 4 is provided in the middle of the differential sleeve 5, and a small baffle 7 is provided in the middle of the adjustment sleeve 8. The middle portions of the large baffle 4 and the small baffle 7 are each provided with an elongated hole 15 that matches the thickness and width of the specimen 6. The elongated holes 15 of the large baffle 4 and the small baffle 7 are each provided with a circular through-hole 16 in the middle. The diameter of the through-hole 16 is greater than the width of the gauge portion 63 and the narrow left connecting section 61 and right connecting section 65 of the specimen 6, and smaller than the width of the left shoulder 62 and right shoulder 64. A circle of scale lines 12 is provided on the edge of the end of the differential sleeve 5 connected to the adjustment sleeve 8, and an axial reference line 13 is provided on the edge of the adjustment sleeve 8 to correspond to the scale lines 12 on the differential sleeve 5. By rotating the adjustment sleeve to align its reference line with the scale line on the differential sleeve, the distance between the small baffle and the specimen gauge can be accurately adjusted. The deformation of the specimen can be accurately adjusted through the relationship between the pitch and the thread rotation angle at the fitting point between the differential sleeve and the adjustment sleeve, thereby improving the accuracy of the Hopkinson rod high-speed tensile test.

[0047] As a preferred structure, Figure 1 、 2As shown in Figures 6, 8, 10 and 11, a semicircular notch 11 is provided in the middle of the differential sleeve 5 and the adjusting sleeve 8, and the width of the notch 11 on the differential sleeve 5 and the adjusting sleeve 8 matches the width of the large baffle 4 and the small baffle 7 respectively; the large baffle 4 and the small baffle 7 are both circular plates, and the outer diameters of the large baffle 4 and the small baffle 7 are not larger than the inner diameters of the differential sleeve 5 and the adjusting sleeve 8; the large baffle 4 and the small baffle 7 are fixed in the notches of the differential sleeve 5 and the adjusting sleeve 8 respectively.

[0048] During specific production, the specific dimensions of the differential sleeve 5 and the adjustment sleeve 8 are as follows:

[0049] Differential sleeve 5 has an outer diameter of 34mm and a length of 45mm. The inner diameters of its left and right ends are 22mm and 26mm, respectively, and its lengths are 10mm and 35mm. The left end features an M22×7 internal thread that mates with fixture 1-2, while the right end features an M26×11 internal thread that mates with adjustment sleeve 8. The outer surface of differential sleeve 5 is provided with a notch 11, 17mm deep and 1.5mm wide, for mounting large baffle 4. A circular scale line 12 is engraved around the mating end of differential sleeve 5 and adjustment sleeve 8. The spacing between adjacent long scale lines is set as a unit pitch, with each unit pitch divided into five equal parts. Every two unit pitches are marked with a degree.

[0050] The outer diameter of the adjusting sleeve 8 is 26mm, the length is 23.5mm, the inner through hole diameter is 22mm, and the left end is provided with an external thread M26 that cooperates with the differential sleeve. The outer surface of the adjusting sleeve 8 is provided with a notch 11 with a depth of 13mm and a width of 1.5mm for mounting the small baffle 7; and a 23.5mm long reference line 13 is axially engraved on the left end of the adjusting sleeve.

[0051] At the same time, the sizes of the large baffle 4 and the small baffle 7 are designed as follows:

[0052] The large baffle 4 has a diameter of 26mm and a thickness of 1.5mm. A portion is cut away to form a strip hole 15 with a through hole 16 in the center. The through hole 16 has a diameter of 5.2mm, a length of 19mm, and a width of 1.5mm. The small baffle 7 has a diameter of 22mm and a thickness of 1.5mm. Similarly, a portion is cut away to form a strip hole with a through hole in the center. The through hole has a diameter of 5.2mm, a length of 19mm, and a width of 1.5mm. During assembly, the specimen is passed through the strip hole and rotated so that the plane of the specimen is perpendicular to the length of the strip hole. The gauge portion is placed in the through hole of the large baffle and the right connecting section is placed in the through hole of the small baffle, thus achieving length limitation of the specimen by the large and small baffles.

[0053] The present invention also provides a method for using a Hopkinson rod test deformation control device, comprising the following steps:

[0054] S100: Adjust the positions of the Hopkinson transmission rod 1 and the Hopkinson incident rod 10 so that they are coaxial and have a relative distance to facilitate the installation of other components. Install the test sample 6 in the above-mentioned Hopkinson tension rod test deformation control device. The specific steps are as follows:

[0055] Step 1: Connect the clamp 2 to the Hopkinson transmission rod 1 through threads, and make the slot surface of the clamping end of the clamp 2 parallel to the workbench. Install the left connecting part 60 of the test sample 6 into the slot of the clamp 2 and fix it with the positioning pin 3.

[0056] Step 2: Pre-weld the large baffle 4 to the notch 11 of the differential sleeve 5, weld the small baffle 7 to the notch 11 of the adjustment sleeve 8, and thread the left end of the differential sleeve 5 to the clamp 1 2 (the clamp 1 can also be connected after the sample 6 is installed in the differential sleeve 5 and the adjustment sleeve 8); insert the test sample 6 into the differential sleeve 5, and rotate the differential sleeve 5 so that the large baffle 4 is tightly against the left shoulder 62 of the test sample 6; insert the right end of the sample 6 into the adjustment sleeve 8, thread the right end of the differential sleeve 5 to the left end of the adjustment sleeve 8, and rotate the adjustment sleeve 8 so that the small baffle 7 is tightly against the right shoulder 64 of the test sample 6, as shown in FIG. Figure 10 Note: Before welding, adjust the position of the large baffle 4 and the small baffle 7 to ensure that the long hole 15 does not overlap with the test sample after installation, otherwise it will not play a fixing role when the tensile force is applied during the test.

[0057] Step 3: The second clamp 9 is connected to the Hopkinson incident rod 10 through threads, and the second clamp 9 is connected and fixed to the test sample 6 through the positioning pin 3. Figure 2 As shown, the installation of the Hopkinson rod experimental deformation control device is completed.

[0058] S200: Rotate the adjusting sleeve 8 to place the small baffle 7 on the right side of the right shoulder 64 of the sample 6;

[0059] S300: Tensile operation: A tensile force is applied to the Hopkinson incident rod 10. When the right shoulder 64 of the specimen 6 is in close contact with the small baffle 7, the gauge portion 63 is no longer subjected to the force, so that the excess energy is absorbed by the portion of the specimen outside the gauge portion (the right trapezoidal connecting section), thereby obtaining a specimen with a predetermined strain.

[0060] (1) The thread pitch of the differential sleeve 5 and the adjustment sleeve 8 is M. Given that the strain and the thread pitch are constant, the degree of rotation α of the adjustment sleeve 8 relative to the differential sleeve 5 is calculated according to formula (1), and then the adjustment sleeve is rotated counterclockwise. Here, the adjustment distance l between the right shoulder 64 of the specimen 6 and the small baffle 7 is calculated.

[0061]

[0062] The scale lines and reference lines on the differential sleeve 5 and the adjustment sleeve 8 ensure the accuracy of the data and reduce the experimental error.

[0063] (2) After determining the position of the adjustment sleeve 8, the Hopkinson incident rod 10 applies a tensile force. When the right shoulder 64 of the test sample 6 is stretched to a position close to the small baffle 7, the gauge portion 63 will no longer be subjected to force. At this time, the small baffle will disperse the force to the part outside the gauge portion 63 until the outer side of the gauge portion is broken, preventing the rebound force from destroying the test sample and playing a force-relieving role.

[0064] Wherein, the length of the gauge portion 63 of the sample 6 is L, and the strain ε of the sample 6 during the stretching process is obtained by formula (2):

[0065]

[0066] S400: After the stretching is completed, the Hopkinson rod test deformation control device is disassembled and sample 6 is removed.

[0067] In summary, the present invention has the advantages of simple and compact structure and convenient and quick operation, specifically the following points:

[0068] (1) The test sample is wrapped in the differential sleeve and the adjustment sleeve. Its structure can prevent the sample fragments from causing harm to the operator, play a protective role, and improve the safety of the test.

[0069] (2) The outside of the differential sleeve and the adjustment sleeve are engraved with scale lines and reference lines, which can accurately adjust the strain and can perform small strain experiments.

[0070] (3) The rational design of the stepped specimen structure allows the excess energy to be absorbed by the specimen part outside the gauge length without affecting the deformation of the specimen at the gauge length part, thus achieving the unloading effect.

[0071] (4) The clamps 1 and 2 are directly slotted at the ends of the specimen and fixed with positioning pins. This allows for fast installation and a stable force on the specimen, improving test efficiency.

[0072] In the above description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed above.

Claims

1. A device for controlling deformation of a Hopkinson rod test, characterized by: The apparatus comprises a Hopkinson transmission rod, a Hopkinson incident rod, and two clamps for holding the sample under test. The sample is a stepped plate-like structure with a gauge portion in the middle. A strain adjustment mechanism is provided on the outside of the sample to limit the ends of the gauge portion and unload excess energy. The two ends of the clamp are respectively connected to the Hopkinson transmission rod and the strain adjustment mechanism, and the clamp is connected to the Hopkinson incident rod. The specimen comprises, from left to right, a left connecting portion, a left shoulder, a gauge portion, a right shoulder, a right connecting section, and a right connecting portion. The widths of the left shoulder and the right shoulder are both greater than the width of the gauge portion. The left connecting portion is connected to the left shoulder, and the right shoulder is connected to the right connecting portion via a narrow right connecting section. The left connecting portion is connected to the first clamp, and the right connecting portion is connected to the second clamp. The right end surfaces of the left shoulder and the right shoulder can respectively cling to the large baffle and the small baffle in the strain adjustment mechanism. The strain adjustment mechanism includes a differential sleeve and an adjusting sleeve connected by threads, the left end of the differential sleeve is threadedly connected to the right end of the clamp one, a large baffle is provided in the middle of the differential sleeve, and a small baffle is provided in the middle of the adjusting sleeve, the middle parts of the large baffle and the small baffle are both used for long strip holes matching the thickness and width of the sample, the middle parts of the long strip holes of the large baffle and the small baffle are both provided with circular through holes, and the diameter of the through holes is larger than the width of the gauge part and the narrow long strip connecting section of the sample, and smaller than the width of the left shoulder and the right shoulder; the middle parts of the differential sleeve and the adjusting sleeve are both provided with semicircular notches, the widths of the notches on the differential sleeve and the adjusting sleeve respectively match the widths of the large baffle and the small baffle; the large baffle and the small baffle are both circular plates, and the outer diameters of the large baffle and the small baffle are not larger than the inner diameters of the differential sleeve and the adjusting sleeve; the large baffle and the small baffle are respectively fixed in the notches of the differential sleeve and the adjusting sleeve.

2. The Hopkinson rod test deformation control device according to claim 1, characterized in that: The left connecting part is connected to the left shoulder through a left connecting section. The left connecting section and the right connecting section at both ends of the specimen are both trapezoidal structures. The side where the left connecting section and the right connecting section are connected to the left shoulder and the right shoulder respectively is a narrow side, and the side where they are connected to the left connecting part and the right connecting part is a wide side.

3. The Hopkinson rod test deformation control device according to claim 1, characterized in that: The left connecting part and the right connecting part have the same structure, both of which are rectangular plate structures. The left connecting part and the right connecting part are provided with multiple positioning holes that cooperate with positioning pins along their length directions. The left connecting part and the right connecting part are respectively connected to clamp one and clamp two through positioning pins, and the positioning pins on clamp two are arranged on the outside of the adjustment sleeve.

4. The Hopkinson rod test deformation control device according to claim 1, characterized in that: The top and bottom of clamp one and clamp two are both flat, the side of clamp one is a cylindrical surface that matches the inner hole of the differential sleeve, and the side of clamp two is a cylindrical surface that matches the inner hole of the adjustment sleeve; the width of the left connecting part and the right connecting part is not greater than the outer diameter of clamp one and clamp two.

5. The Hopkinson rod test deformation control device according to claim 1, characterized in that: A circle of scale lines is provided on the edge of one end of the differential sleeve connected to the adjustment sleeve, and an axial reference line is provided on the edge of the adjustment sleeve for corresponding to the scale lines on the differential sleeve.

6. A method for using a Hopkinson rod test deformation control device, characterized in that: The following steps are involved: S100: Adjusting the coaxial center of the Hopkinson transmission rod and the Hopkinson incident rod, and installing the test sample in the Hopkinson tension rod test deformation control device according to any one of claims 1 to 5; S200: Rotate the differential sleeve to place the large baffle on the right side of the left shoulder of the specimen; rotate the adjustment sleeve to place the small baffle on the right side of the right shoulder of the specimen; S300: Tensile operation: Apply tension to the Hopkinson incident rod. When the right shoulder of the specimen is close to the small baffle, the specimen with the predetermined strain is obtained. S400: After the stretching is completed, dismantle the Hopkinson rod test deformation control device and remove the sample.

7. The method for using the Hopkinson rod test deformation control device according to claim 6, characterized in that: In step S300, the thread pitch of the differential sleeve and the adjustment sleeve is M, and when the adjustment sleeve rotates relative to the differential sleeve by an angle α, the adjustment distance l between the right shoulder of the specimen and the small baffle is obtained by formula (1): The length of the gauge portion of the specimen is L, and the strain ε of the specimen during the stretching process is obtained by formula (2): （1） The gauge length of the specimen is L, and the strain ε of the specimen during the stretching process is obtained by formula (2): （2）。

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