Electromagnetic Hopkinson bar system with stroke protection device and protection method

Abstract

The present invention provides an electromagnetic Hopkinson bar system with a stroke protection device and a protection method. The electromagnetic Hopkinson bar system with a stroke protection device includes a waveguide rod system, a loading frame system, an electromagnetic loading frame, an electromagnetic launch gun, a U-shaped base and a stroke protection device; the protection method is: the stroke protection device realizes the stroke protection of the waveguide rod by limiting the waveguide rod boss structure, and buffers the energy of axial movement through the springs at the four corners of the stroke protection plate, and the springs at the four corners of the protection plate respectively have corresponding adjustment nuts, and the adjustment nuts are adjusted according to experimental conditions. During the test process, the waveguide rod produces a large displacement under the action of impact force, and the protection device can play a role in protecting the waveguide rod.

Description

Technical Field

[0001] The present invention relates to the field of high-end equipment manufacturing and application, and in particular to the field of rock material dynamics experimental technology. Background Art

[0002] Rock masses or engineering structures may be subjected to multi-axial and multi-directional synchronous impact loads during the construction and operation periods, which can easily cause dynamic disasters, resulting in casualties and property losses. Patents with publication numbers US20210325287A1 and US11703433B2 disclose a dynamic true triaxial electromagnetic Hopkinson bar system and test method, which can be used to conduct experimental research on rock or concrete specimens under multi-axial and multi-directional synchronous impacts. In the process of conducting multi-axial and multi-directional synchronous impact tests, the non-interference and collision between adjacent waveguide rods is an important prerequisite for the validity of the test data. At the same time, the small displacement of the waveguide rod under large load impact is a guarantee of the integrity of the equipment and the safety of the experimental operators. The existing test devices and test methods do not have devices and methods that can limit the axial displacement of the waveguide rod during the impact process, resulting in that when the dynamic true three-axis electromagnetic Hopkinson rod system disclosed in publication numbers US20210325287A1 and US11703433B2 is tested, the waveguide rod will still move forward under the inertial force of the impact load after the sample is destroyed under the impact of a large load. Note: In this article, the direction along the waveguide rod toward the sample is forward. When the multi-axis and multi-directional waveguide rods are loaded with samples at the same time, the inertial force can easily cause adjacent waveguide rods to collide with each other and cause damage, and there is a risk of rushing out of the motion track. Therefore, it is urgent to invent a device that can limit the large axial displacement of the waveguide rod under a large load impact.

[0003] Difficulties: ① The waveguide rod has the inertia to move forward under impact load; ② The allowable moving distance range of the waveguide rod in the test is small; ③ The waveguide rod has lateral displacement under impact load. Note: The lateral direction refers to the direction perpendicular to the axial direction of the waveguide rod.

[0004] In the improved device based on the split Hopkinson system, under the impact load, the waveguide rod has the inertia to move in the impact direction. After the sample is broken, the waveguide rod will continue to move forward, which can easily cause adjacent waveguide rods to collide with each other in the true triaxial state, and even run out of the original motion track. However, there are currently no publicly reported related devices and experimental methods that can achieve the purpose of limiting the displacement of the waveguide rod in the impact direction. Summary of the invention

[0005] In order to solve the problems in the prior art, the present invention provides an electromagnetic Hopkinson bar system with a stroke protection device, including a waveguide rod system, a loading frame system, an electromagnetic loading frame, an electromagnetic launch gun, a U-shaped base and a stroke protection device;

[0006] The waveguide rod system includes six mutually perpendicular waveguide rods, which are coaxially aligned and adjacent to each other. The cross section of the waveguide rod is square. The waveguide rod has a circular boss structure at a distance from the electromagnetic stress pulse loading end. The loading frame system supports the electromagnetic loading frame, the electromagnetic launching gun, the U-shaped base and the waveguide rod system. The electromagnetic loading frame fixes the electromagnetic launching gun and performs axial movement. The electromagnetic launching gun applies electromagnetic stress pulses to the waveguide rod. The U-shaped base supports the electromagnetic launching gun.

[0007] The stroke protection device includes a stroke protection support platform, a stroke protection plate and a notch tenon. The stroke protection support platform is located between two vertical columns of the loading frame system. The stroke protection support platform includes a slider, a buffer adjustment device and a reference positioning structure. In the three-axis six-direction, there are four sets of stroke protection support platforms in each direction, and there are multiple notches tenons. The notches tenons are fixed to the loading frame system. The front and rear of the stroke protection support platform are in contact with the notch tenons respectively.

[0008] The reference positioning structure includes a square groove, a slide groove, a support block, a front concave mortise and a rear concave mortise; the main structure of the reference positioning structure is a rectangular parallelepiped, a rectangular parallelepiped notch is set at the front end of the rectangular parallelepiped, which is a front concave mortise, a rectangular parallelepiped notch is set at the rear end of the rectangular parallelepiped, which is a rear concave mortise, a slide groove is set near the front end in the middle of the rectangular parallelepiped, a square groove is set near the rear end in the middle of the rectangular parallelepiped, and the square groove and the slide groove are connected; the slider is put into the square groove of the reference positioning structure, and the slider is pushed into the slide groove in the direction of the front concave mortise; the buffer adjustment device is set in the square groove of the reference positioning structure;

[0009] The buffer adjustment device includes a fixed block, a threaded hole, a stud bolt, an adjustment nut, and a buffer spring, wherein the threaded hole is arranged on the fixed block, and the first end of the stud bolt is fixed to the fixed block through the threaded hole; the adjustment nut is connected to the second end of the stud bolt, and the buffer spring is sleeved on the stud bolt.

[0010] As a further improvement of the present invention, the stroke protection plate includes a plate, a bolt hole and a U-shaped retaining groove. The U-shaped retaining groove is provided in the middle of the bottom of the plate. The width of the U-shaped retaining groove of the stroke protection plate is adapted to the waveguide rod. The bolt holes are provided at the four corners of the plate. The U-shaped retaining groove passes through the waveguide rod, and the stroke protection plate contacts the boss.

[0011] As a further improvement of the present invention, the width of the U-shaped retaining groove of the stroke protection plate is 50.5 mm.

[0012] As a further improvement of the present invention, the slider includes a U-shaped connecting block, a bolt, a front connecting hole, a rear connecting hole and a fastening nut; the front connecting hole and the rear connecting hole are arranged on the U-shaped connecting block; the U-shaped connecting block of the slider is used to embed into the four corners of the stroke protection plate, and the bolt holes are aligned with the front connecting holes and the rear connecting holes of the U-shaped connecting block; the bolts are inserted along the front connecting holes, the bolt holes and the rear connecting holes, and the stroke protection plate and the slider are fixed by fastening the nuts and bolts.

[0013] As a further improvement of the present invention, the mortise and tenon comprises a mortise body, which is a rectangular structure and is provided with a first through hole and a second through hole; there are multiple mortises, and a first hexagon socket bolt and a second hexagon socket bolt are passed through the first through hole and the second through hole on the mortise body, and are screwed into the first fixing hole and the second fixing hole on the loading frame system and fixed.

[0014] A protection method for an electromagnetic Hopkinson bar system with a stroke protection device, using any one of the electromagnetic Hopkinson bar systems with a stroke protection device described above, performs the following steps:

[0015] Here are the steps:

[0016] Step 1: Assemble the dynamic true triaxial electromagnetic Hopkinson bar experimental test system; In the X-direction, assemble the loading frame system, electromagnetic loading frame, U-shaped base, electromagnetic launch gun, waveguide rod and waveguide rod support frame according to the equipment requirements;

[0017] Step 2: Fix the rabbet and tenon to the loading frame system, wherein the rabbet and tenon are multiple;

[0018] Step 3: Place the stroke protection plate; place the U-shaped retaining groove of the stroke protection plate downward, pass the waveguide rod, and the stroke protection plate contacts the boss;

[0019] Step 4: Assemble the buffer adjustment device; change the position of the adjustment nut on the stud bolt to control the compression amount of the buffer spring;

[0020] Assemble four sets of buffer adjustment devices according to step 4;

[0021] Step 5: Assemble the stroke protection support platform; lay the reference positioning structure with the front concave mortise at the front and the rear concave mortise at the rear, insert the slider into the square groove of the reference positioning structure, push the slider into the slide groove in the direction of the front concave mortise, put the buffer adjustment device into the square groove of the reference positioning structure, and assemble four sets of stroke protection support platforms according to the above method;

[0022] Step 6: Assemble the stroke protection device, and slowly slide the front concave mortise and rear concave mortise of the assembled stroke protection support platform along the notch tenon, so that the four corners of the stroke protection plate can be embedded in the slider and fixed;

[0023] Step 7: Adjust the position of the stroke protection plate. The stroke protection device realizes stroke protection of the waveguide rod by limiting the waveguide rod boss structure, and buffers the energy of axial movement through the springs at the four corners of the stroke protection plate. The springs at the four corners of the protection plate have corresponding adjusting nuts, which are adjusted according to the experimental conditions.

[0024] As a further improvement of the present invention, the elastic coefficient of the buffer spring is selected as:

[0025]

[0026] Where: k is the elastic coefficient of the spring, in N / m, F m is the middle value of the impact load required in the experiment, in N; the impact load is borne by four sets of buffer springs. L s is the length of the test specimen, in meters; 2% is the maximum strain at which the specimen fails during the test.

[0027] As a further improvement of the present invention, the adjustment distance of the adjusting nut is the distance that the adjusting nut is screwed on the stud bolt, that is, the distance between the adjusting nut and the stud bolt, which is calculated according to the following formula:

[0028] Knowing the elastic coefficient of the spring, the adjustment distance of the X-axis and Y-axis adjustment nuts is:

[0029]

[0030] Where: L is the adjustment distance of the adjusting nut, in m; k is the elastic coefficient of the spring, in N / m; F is the maximum value of the impact load required in the experiment, in N; the impact load is borne by four sets of buffer springs. L s is the length of the test specimen, in meters; 2% is the maximum strain at which the specimen fails during the test.

[0031] As a further improvement of the present invention, the adjustment distance of the adjustment nut in the Z-axis direction is:

[0032]

[0033] Where: L is the adjustment distance of the adjustment nut, in m; L s is the length of the test specimen, in meters; 2% is the maximum strain of a general specimen that is damaged during the test. F is the maximum value of the impact load required in the experiment, in N; the impact load is borne by four sets of buffer springs. k is the elastic coefficient of the spring, in N / m; G is the weight of the waveguide rod, in N.

[0034] As a further improvement of the present invention, the adjustment distance of the adjustment nut in the downward direction of the Z axis is:

[0035]

[0036] Where:L is the adjustment distance of the adjustment nut, in m; L s is the length of the test specimen, in meters; 2% is the maximum strain of a general specimen that is damaged during the test. F is the maximum value of the impact load required in the experiment, in N; the impact load is borne by four sets of buffer springs. k is the elastic coefficient of the spring, in N / m; G is the deadweight of the waveguide rod, in N. L ≤0, indicating that the maximum compression of the spring by the impact load satisfies the maximum travel of the waveguide rod. At this time, there is no need to tighten the adjusting nut. L When >0, it means that the distance to turn the adjusting nut is L After that, the maximum allowable stroke of the waveguide rod can be met.

[0037] The beneficial effects of the present invention are:

[0038] The present invention specifically relates to a protective device based on a dynamic true triaxial electromagnetic Hopkinson bar test system. During the test, the waveguide rod generates a large displacement under the impact force, and the protective device can play a role in protecting the waveguide rod.

[0039] Innovations: ① The displacement of the waveguide rod is controlled by limiting the boss structure of the waveguide rod. Here, the displacement of the waveguide rod is both axial and lateral. The main purpose is the axial displacement, but the structure can also limit the lateral displacement; ② The allowable axial movement distance of the waveguide rod is adjusted by adjusting the nut; ③ The appropriate spring can be selected through the calculation formula, and the moving distance of the adjusting nut can be calculated; ④ Springs (such as four springs) are used to buffer the inertia force of the waveguide rod.

[0040] 1. Limit the axial displacement and lateral runout of the waveguide rod to ensure compliance with test procedures and requirements.

[0041] 2. The axial movement distance of the waveguide rod is controllable and adjustable to meet the test requirements of various materials (rocks of different lithologies, ceramics, plastics, metals, etc.).

[0042] 3. The impact load is borne by four buffer springs to improve the impact resistance of the stroke protection device.

[0043] 4. Improve the accuracy and repeatability of test data.

[0044] 5. Effectively eliminate the influence of the waveguide rod sagging due to its own weight on the Z-axis.

[0045] 6. Prevent waveguide rods from colliding with each other due to large axial displacement, protect the integrity of the equipment, ensure the safety of operation, and reduce the loss of test equipment and economic losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is the overall three-dimensional characteristic diagram of the dynamic true three-axis electromagnetic Hopkinson bar system of the present invention;

[0047] Figure 2 It is a front view of the waveguide rod stroke protection device of the dynamic true three-axis electromagnetic Hopkinson rod system of the present invention (taking the X-axis as an example);

[0048] Figure 3 It is a three-dimensional diagram of the waveguide rod stroke protection device of the dynamic true three-axis electromagnetic Hopkinson rod system of the present invention (taking the X-axis as an example);

[0049] Figure 4 is a three-dimensional diagram of the stroke protection device of the present invention;

[0050] Figure 5 is an exploded view of a portion of the structure of the stroke protection device of the present invention;

[0051] Figure 6 is a schematic diagram of a stroke protection plate 1 of the present invention;

[0052] Figure 7 It is a schematic diagram of the stroke protection support platform of the present invention;

[0053] Figure 8 is a schematic diagram of a reference positioning structure 4 of a stroke protection device of the present invention;

[0054] Fig. 9 It is a schematic diagram of a slider 2 of the present invention;

[0055] Fig.10 is an exploded view of the slider 2 of the present invention;

[0056] Fig.11 is a schematic diagram of the buffer adjustment device 3 of the present invention;

[0057] Fig.12 is an exploded view of the buffer adjustment device 3 of the present invention;

[0058] Fig.13 It is a schematic diagram of the connection and fixing method of the notch mortise and tenon 5 and the loading frame system 12 of the present invention;

[0059] Fig.14 It is a three-dimensional characteristic diagram of the cubic specimen of the present invention;

[0060] Fig.15 It is a diagram illustrating the three-dimensional features and dimensions of the waveguide rod of the present invention.

[0061] The names of the components in the figure are as follows:

[0062] Stroke protection plate 1, slider 2, buffer adjustment device 3, reference positioning structure 4, notch mortise 5, waveguide rod support frame 6, waveguide rod 7, boss 8, electromagnetic launch gun 9, U-shaped base 10, electromagnetic loading frame 11, loading frame system 12, cubic specimen 13;

[0063] Plate 101, bolt hole 102, U-shaped retaining groove 103;

[0064] U-shaped connecting block 201, bolt 202, front connecting hole 203, rear connecting hole 204, fastening nut 205;

[0065] Fixed block 301, threaded hole 302, stud bolt 303, adjusting nut 304, buffer spring 305;

[0066] Square groove 401, slide groove 402, support block 403, front concave mortise 404, rear concave mortise 405;

[0067] A first hexagon socket bolt 501, a second hexagon socket bolt 502, a first through hole 503, a second through hole 504, and a tenon 505;

[0068] Loading frame 1201 , first fixing hole 1202 , second fixing hole 1203 . DETAILED DESCRIPTION

[0069] The present invention will be further described below in conjunction with the accompanying drawings. The following dimensions are for illustration only and are not intended to be limiting.

[0070] Specific implementation method 1: The electromagnetic Hopkinson bar system with a stroke protection device has the following structure: it is mainly composed of a waveguide rod system, a loading frame system, an electromagnetic loading frame, an electromagnetic launching gun, a U-shaped base, and a stroke protection device.

[0071] The waveguide rod system includes six mutually perpendicular waveguide rods, which are coaxially aligned and adjacent to each other. The cross section of the waveguide rod is square, and the waveguide rod has a circular boss structure at a distance (such as 100 mm) from the electromagnetic stress pulse loading end. The loading frame system is made of high-strength rigid material (such as silicon-manganese steel) and is used to support the electromagnetic loading frame, the electromagnetic launch gun and the U-shaped base 10, the waveguide rod system, and to maintain the stability of the equipment structure under impact. The electromagnetic loading frame is made of high-strength rigid material (such as silicon-manganese steel) and is used for the fixation and axial movement of the electromagnetic launch gun. The electromagnetic launch gun is used to apply electromagnetic stress pulses to the waveguide rod. The U-shaped base is used to support the electromagnetic launch gun. The stroke protection device realizes the stroke protection of the waveguide rod by limiting the waveguide rod boss structure, and buffers the energy of the axial movement through the springs at the four corners of the stroke protection plate 1. The springs at the four corners of the protection plate have corresponding adjustment nuts, which can be adjusted according to the experimental conditions (impact load, allowable movement distance of the waveguide rod).

[0072] like Fig.15 At present, the experimental waveguide rod is generally: a square with a cross section of 50 mm and a length of 2800 mm. The boss 8 is 100 mm away from the stress wave application end face, the boss 8 has a diameter of 90 mm and a length of 70 mm.

[0073] like Fig.14 The size of the cubic specimen is 51×51×51mm, and each side is chamfered with 0.5mm.

[0074] like Figure 1 As shown, the stroke protection support platform ( Figure 7 As shown) is located between two vertical columns of the loading frame system 12.

[0075] like Figure 3 , Figure 4 and Figure 6 The stroke protection plate 1 includes a plate 101, a bolt hole 102 and a U-shaped retaining groove 103. The U-shaped retaining groove 103 is provided in the middle of the bottom of the plate 101. The width of the U-shaped retaining groove 103 of the stroke protection plate 1 is 50.5 mm. The bolt holes 102 are provided at the four corners of the plate 101. The U-shaped retaining groove passes through the waveguide rod 7, and the stroke protection plate 1 contacts the boss 8. Figure 3 For a clearer observation, the stroke protection plate 1 is not in contact with the boss 8, but they should be in contact during actual installation.

[0076] like Fig.13 The notch tenon 5 includes a tenon body 505 , which is a rectangular parallelepiped structure. A first through hole 503 and a second through hole 504 are provided on the tenon body 505 .

[0077] There are multiple notches 5. The first hexagon socket bolt 501 and the second hexagon socket bolt 502 are passed through the first through hole 503 and the second through hole 504 on the tenon body 505, screwed into the first fixing hole 1202 and the second fixing hole 1203 on the loading frame system 12 and fixed.

[0078] like Figure 7 The stroke protection support platform includes a slider 2, a buffer adjustment device 3 and a reference positioning structure 4. There are four sets of stroke protection support platforms.

[0079] like Fig. 9 and Fig.10 , Fig. 9 This is the overall structure diagram of slider 2. Fig.10It is an exploded view of the slider 2; the slider 2 includes a U-shaped connecting block 201, a bolt 202, a front connecting hole 203, a rear connecting hole 204 and a fastening nut 205; the front connecting hole 203 and the rear connecting hole 204 are set on the U-shaped connecting block 201; the U-shaped connecting block 201 of the slider 2 is used to embed the four corners of the stroke protection plate 1, and the bolt hole 102 is aligned with the front connecting hole 203 and the rear connecting hole 204 of the U-shaped connecting block 201; the bolt 202 penetrates along the front connecting hole 203, the bolt hole 102 and the rear connecting hole 204, and the stroke protection plate 1 and the slider 2 are fixed by fastening the nut 205 and the bolt 202.

[0080] like Fig.11 and Fig.12 , Fig.11 is the overall structure diagram of the buffer adjustment device 3, Fig.12 : is an exploded view of the buffer adjustment device 3. The buffer adjustment device 3 comprises a fixing block 301, a threaded hole 302, a stud bolt 303, an adjustment nut 304, and a buffer spring 305, wherein the threaded hole 302 is provided on the fixing block 301, and the first end of the stud bolt 303 is fixed to the fixing block 301 through the threaded hole 302; the adjustment nut 304 is connected to the second end of the stud bolt 303, and the buffer spring 305 is sleeved on the stud bolt 303. Changing the position of the adjustment nut 304 on the stud bolt 303 is used to control the compression amount of the buffer spring 305.

[0081] like Figure 8 , is a schematic diagram of the reference positioning structure 4 of the stroke protection device of the present invention; the reference positioning structure 4 includes a square groove 401, a slide groove 402, a support block 403, a front concave mortise 404 and a rear concave mortise 405; the main structure of the reference positioning structure 4 is a rectangular parallelepiped, a rectangular parallelepiped notch is set at the front end of the rectangular parallelepiped, which is the front concave mortise 404, a rectangular parallelepiped notch is set at the rear end of the rectangular parallelepiped, which is the rear concave mortise 405, a slide groove 402 is set near the front end of the middle part of the rectangular parallelepiped, and a square groove 401 is set near the rear end of the middle part of the rectangular parallelepiped, and the square groove 401 and the slide groove 402 are connected.

[0082] The slide block 2 is put into the square groove 401 of the reference positioning structure 4, and the slide block 2 is pushed into the slide groove 402 in the direction of the front concave mortise 404. The buffer adjustment device 3 is arranged in the square groove 401 of the reference positioning structure 4.

[0083] Specific implementation method 2: Dynamic true three-axis electromagnetic Hopkinson rod waveguide rod stroke protection method, the steps are as follows:

[0084] Step 1: Assemble the dynamic true triaxial electromagnetic Hopkinson bar experimental test system ( Figure 1 ). For example, in the X-direction, the loading frame system 12, the electromagnetic loading frame 11, the U-shaped base 10, the electromagnetic launch gun 9, the waveguide rod 7 and the waveguide rod support frame 6 are assembled according to the equipment requirements.

[0085] Step 2: Fix the notch 5 ( Fig.13 ), there are multiple notches 5. The first hexagon socket bolt 501 and the second hexagon socket bolt 502 are passed through the first through hole 503 and the second through hole 504 on the tenon body 505, screwed into the first fixing hole 1202 and the second fixing hole 1203 on the loading frame system 12 and fixed.

[0086] Step 3: Place the stroke guard plate 1. Figure 3 and Figure 4 , place the U-shaped retaining groove of the stroke protection plate 1 downward, pass through the waveguide rod 7, and the stroke protection plate 1 contacts the boss 8. Figure 3 For a clearer observation, the stroke protection plate 1 is not in contact with the boss 8, but they should be in contact during actual installation.

[0087] Step 4: Assemble the buffer adjustment device 3 ( Fig.11 , Fig.12 ). The stud bolt 303 is screwed onto the fixing block 301 along the threaded hole 302, and the stud bolt 303 is fixed to the fixing block 301. Then the adjusting nut 304 is screwed onto the stud bolt 303, and finally the buffer spring 305 is sleeved onto the stud bolt 303 to form a set of buffer adjustment device 3. By changing the position of the adjusting nut 304 on the stud bolt 303, the compression amount of the buffer spring 305 can be controlled.

[0088] Assemble four sets of buffer adjustment devices 3 according to step 4.

[0089] Step 5: Assemble the Stroke Guard Support Platform ( Figure 7 ).like Figure 5 , according to the reference positioning structure 4, the front concave mortise 404 is in front and the rear concave mortise 405 is in the back. Fig. 9 ) from the reference positioning structure 4 ( Figure 8 ) into the square groove 401, and push the slider 2 into the slide groove 402 in the direction of the concave mortise 404. Fig.11 ) is placed into the square groove 401 of the reference positioning structure 4 ( Figure 8 ). Four sets of stroke protection support platforms are assembled according to the above method.

[0090] Step 6: Assemble the Stroke Guard ( Figure 4 Slowly slide the assembled front concave mortise 404 and rear concave mortise 405 of the stroke protection support platform along the notch 5 to make the stroke protection plate 1 ( Figure 6 ) can be embedded in the U-shaped connecting block 201 of the slider 2 ( Fig.10), and align the bolt hole 102 with the front connection hole 203 and the rear connection hole 204 of the U-shaped connection block 201. Then, the bolt 202 is inserted along the front connection hole 203, the bolt hole 102 and the rear connection hole 204, and the fastening nut 205 is screwed onto the bolt 202 and fixed.

[0091] Step 7: Adjust the stroke protection plate 1 to a suitable position. It is known that in rock dynamics tests, the maximum failure strain of the sample is 2%, which refers to the maximum deformation percentage of the sample. For example, if the length of the sample is 50 mm, the effective deformation after the sample is destroyed is 50×2%=1 mm.

[0092] Therefore, according to the estimated value of the impact load required in the test, the elastic coefficient of the required spring is determined by formula calculation, and a suitable spring is selected. The adjusting nut 304 is turned to make the buffer spring 305 contact the slider 2. The adjustment distance of the adjusting nut 304 is calculated according to the impact load size and the formula, and then the adjusting nut 304 is turned to the calculated position. The buffer spring 305 shows a certain degree of compression under the adjustment of the adjusting nut 304, so that the stroke protection plate 1 fits with the boss 8. The impact load acts on the loading end of the waveguide rod 7 to move toward the sample loading end. Then the boss 8 contacts the stroke protection plate 1, and the stroke protection plate 1 is hindered by the buffer spring 305, thereby controlling the displacement of the waveguide rod 7 under the impact.

[0093] The selection of the buffer spring 305 and the adjustment distance of the adjustment nut 304, the adjustment distance here is the distance that the adjustment nut 304 is screwed on the stud bolt 303, that is, the distance between the adjustment nut 304 and the stud bolt 303, can be calculated according to the following formula:

[0094] The elastic coefficient of the buffer spring 305 is selected as follows:

[0095]

[0096] Where: k is the elastic coefficient of the spring, in N / m, F m is the middle value of the impact load required in the experiment, in N; the impact load is borne by four sets of buffer springs. L s is the length of the test specimen, in meters; 2% is the maximum strain at which the specimen fails during the test.

[0097] Knowing the elastic coefficient of the spring, the adjustment distance of the X-axis and Y-axis adjustment nuts is:

[0098]

[0099] Where: L is the adjustment distance of the adjusting nut, in m; kis the elastic coefficient of the spring, in N / m; F is the maximum value of the impact load required in the experiment, in N; the impact load is borne by four sets of buffer springs. L s is the length of the test specimen, in meters; 2% is the maximum strain at which the specimen fails during the test.

[0100] Since the Z-axis waveguide rod is placed vertically, considering its own weight, the adjustment distance of the adjustment nut in the Z-axis upward direction is: (Taking into account the weight of the waveguide rod, the adjustment calculation formula of the Z-axis is added)

[0101]

[0102] Then the adjustment distance of the adjustment nut in the downward direction of the Z axis is:

[0103]

[0104] Where: L is the adjustment distance of the adjustment nut, in m; L s is the length of the test specimen, in meters; 2% is the maximum strain of a general specimen that is damaged during the test. F is the maximum value of the impact load required in the experiment, in N; the impact load is borne by four sets of buffer springs. k is the elastic coefficient of the spring, in N / m; G is the weight of the waveguide rod, in N.

[0105] when L When ≤0, it indicates that the maximum compression of the spring by the impact load satisfies the maximum travel of the waveguide rod, and there is no need to tighten the adjustment nut. L When >0, it means that the distance to turn the adjusting nut is L After that, the maximum allowable stroke of the waveguide rod can be met.

[0106] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. Electromagnetic Hopkinson bar system with stroke protection device, characterized in that: It comprises a waveguide rod system, a loading frame system (12), an electromagnetic loading frame (11), an electromagnetic launching gun (9), a U-shaped base (10) and a stroke protection device; The waveguide rod system comprises six mutually perpendicular waveguide rods, which are coaxially aligned and adjacent to each other and perpendicular to each other. The cross section of the waveguide rod is square, and the waveguide rod has a circular boss structure at a distance from the electromagnetic stress pulse loading end. The loading frame system (12) supports the electromagnetic loading frame (11), the electromagnetic emission gun (9), the U-shaped base (10) and the waveguide rod system. The electromagnetic loading frame (11) fixes the electromagnetic emission gun (9) to perform axial movement. The electromagnetic emission gun (9) applies electromagnetic stress pulses to the waveguide rod. The U-shaped base (10) supports the electromagnetic emission gun. The stroke protection device comprises a stroke protection support platform, a stroke protection plate (1) and a notch tenon (5); the stroke protection support platform is located between two vertical columns of the loading frame system (12); the stroke protection support platform comprises a slider (2), a buffer adjustment device (3) and a reference positioning structure (4); in the three-axis six-direction, there are four sets of stroke protection support platforms in each direction, there are a plurality of notches tenon (5), and the notches tenon (5) is fixed to the loading frame system (12); the front and rear of the stroke protection support platform are in contact with the notch tenon (5) respectively; The reference positioning structure (4) comprises a square groove (401), a slide groove (402), a support block (403), a front concave mortise (404) and a rear concave mortise (405); the main structure of the reference positioning structure (4) is a rectangular parallelepiped, a rectangular parallelepiped notch is provided at the front end of the rectangular parallelepiped, which is the front concave mortise (404), a rectangular parallelepiped notch is provided at the rear end of the rectangular parallelepiped, which is the rear concave mortise (405), a slide groove (402) is provided at the middle part of the rectangular parallelepiped near the front end, a square groove (401) is provided at the middle part of the rectangular parallelepiped near the rear end, and the square groove (401) and the slide groove (402) are connected; a sliding block (2) is placed into the square groove (401) of the reference positioning structure (4), and the sliding block (2) is pushed into the slide groove (402) in the direction of the front concave mortise (404); and a buffer adjustment device (3) is provided in the square groove (401) of the reference positioning structure (4); The buffer adjustment device (3) comprises a fixed block (301), a threaded hole (302), a stud bolt (303), an adjustment nut (304), and a buffer spring (305), wherein the threaded hole (302) is arranged on the fixed block (301), and the first end of the stud bolt (303) is fixed to the fixed block (301) through the threaded hole (302); the adjustment nut (304) is connected to the second end of the stud bolt (303), and the buffer spring (305) is sleeved on the stud bolt (303).

2. The electromagnetic Hopkinson bar system with a stroke protection device according to claim 1, characterized in that: The stroke protection plate (1) comprises a plate (101), a bolt hole (102) and a U-shaped retaining groove (103); the U-shaped retaining groove (103) is provided in the middle of the bottom of the plate (101); the width of the U-shaped retaining groove (103) of the stroke protection plate (1) is adapted to the waveguide rod (7); the bolt holes (102) are provided at four corners of the plate (101); the U-shaped retaining groove (103) passes through the waveguide rod (7); and the stroke protection plate (1) is in contact with the boss (8).

3. The electromagnetic Hopkinson bar system with a stroke protection device according to claim 2, characterized in that: The U-shaped retaining groove (103) of the stroke protection plate (1) has a width of 50.5 mm.

4. The electromagnetic Hopkinson bar system with a stroke protection device according to claim 1, characterized in that: The slider (2) comprises a U-shaped connection block (201), a bolt (202), a front connection hole (203), a rear connection hole (204) and a fastening nut (205); the front connection hole (203) and the rear connection hole (204) are arranged on the U-shaped connection block (201); the U-shaped connection block (201) of the slider (2) is used to embed into the four corners of the stroke protection plate (1), and the bolt hole (102) is aligned with the front connection hole (203) and the rear connection hole (204) of the U-shaped connection block (201); the bolt (202) is inserted along the front connection hole (203), the bolt hole (102) and the rear connection hole (204), and the stroke protection plate (1) and the slider (2) are fixed by the fastening nut (205) and the bolt (202).

5. The electromagnetic Hopkinson bar system with a stroke protection device according to claim 1, characterized in that: The notch tenon (5) comprises a tenon body (505), the tenon body (505) is a rectangular parallelepiped structure, and a first through hole (503) and a second through hole (504) are provided on the tenon body (505); the notch tenon (5) is provided in plurality, and a first hexagon socket bolt (501) and a second hexagon socket bolt (502) are passed through the first through hole (503) and the second through hole (504) on the tenon body (505), and are screwed onto the first fixing hole (1202) and the second fixing hole (1203) on the loading frame system (12) and fixed.

6. A protection method for an electromagnetic Hopkinson bar system with a stroke protection device, characterized in that: The electromagnetic Hopkinson bar system with a stroke protection device according to any one of claims 1 to 5 is used to perform the following steps: Here are the steps: Step 1: Assemble a dynamic true triaxial electromagnetic Hopkinson bar experimental test system; In the X-direction, assemble the loading frame system (12), the electromagnetic loading frame (11), the U-shaped base (10), the electromagnetic launch gun (9), the waveguide rod (7) and the waveguide rod support frame (6) according to the equipment requirements; Step 2: Fix the notch and tenon (5) to the loading frame system (12), wherein the notch and tenon (5) are multiple; Step 3: Place the stroke protection plate (1); place the U-shaped retaining groove of the stroke protection plate (1) downward, pass through the waveguide rod (7), and make the stroke protection plate (1) contact the boss (8); Step 4: Assemble the buffer adjustment device (3); change the position of the adjustment nut (304) on the stud bolt (303) to control the compression amount of the buffer spring (305); Assemble four sets of buffer adjustment devices (3) according to step 4; Step 5: Assemble the stroke protection support platform; The reference positioning structure (4) is laid flat with the front concave mortise (404) in front and the rear concave mortise (405) in the rear, the slider (2) is placed into the square groove (401) of the reference positioning structure (4), the slider (2) is pushed into the slide groove (402) in the direction of the front concave mortise (404), the buffer adjustment device (3) is placed into the square groove (401) of the reference positioning structure (4), and four sets of stroke protection support platforms are assembled; Step 6: Assemble the stroke protection device, and slowly slide the assembled front concave mortise (404) and rear concave mortise (405) of the stroke protection support platform along the notch (5), so that the four corners of the stroke protection plate (1) can be embedded in the slider (2) and fixed; Step 7: Adjust the position of the stroke protection plate (1). The stroke protection device realizes stroke protection of the waveguide rod by limiting the waveguide rod boss structure, and buffers the energy of axial movement through the springs at the four corners of the stroke protection plate (1). The springs at the four corners of the protection plate have corresponding adjustment nuts, which are adjusted according to experimental conditions.

7. The protection method of the electromagnetic Hopkinson bar system with a stroke protection device according to claim 6, characterized in that: Selection of elastic coefficient of buffer spring (305): Where: k is the elastic coefficient of the spring, in N / m, F m is the middle value of the impact load required in the experiment, in N; the impact load is borne by four sets of buffer springs. L s is the length of the test specimen, in meters; 2% is the maximum strain at which the specimen fails during the test.

8. The protection method of the electromagnetic Hopkinson bar system with a stroke protection device according to claim 7, characterized in that: The adjustment distance of the adjusting nut (304) is the distance that the adjusting nut (304) is screwed on the stud bolt (303), that is, the distance between the adjusting nut (304) and the stud bolt (303), and is calculated according to the following formula: Knowing the elastic coefficient of the spring, the adjustment distance of the X-axis and Y-axis adjustment nuts is: Where: L is the adjustment distance of the adjusting nut, in m; k is the elastic coefficient of the spring, in N / m; F is the maximum value of the impact load required in the experiment, in N; the impact load is borne by four sets of buffer springs. L s is the length of the test specimen, in meters; 2% is the maximum strain at which the specimen fails during the test.

9. The protection method of the electromagnetic Hopkinson bar system with a stroke protection device according to claim 7, characterized in that: The adjustment distance of the adjustment nut in the Z-axis direction is: Where: L is the adjustment distance of the adjustment nut, in m; L s is the length of the test specimen, in m; 2% is the maximum strain of a general specimen that is destroyed during the test. F is the maximum value of the impact load required in the experiment, in N; the impact load is borne by four sets of buffer springs. k is the elastic coefficient of the spring, in N / m; G is the weight of the waveguide rod, in N.

10. The protection method of the electromagnetic Hopkinson bar system with a stroke protection device according to claim 7, characterized in that: Then the adjustment distance of the adjustment nut in the downward direction of the Z axis is: Where: L is the adjustment distance of the adjustment nut, in m; L s is the length of the test specimen, in m; 2% is the maximum strain of a general specimen that is destroyed during the test. F is the maximum value of the impact load required in the experiment, in N; the impact load is borne by four sets of buffer springs. k is the elastic coefficient of the spring, in N / m; G is the deadweight of the waveguide rod, in N. L ≤0, indicating that the maximum compression of the spring by the impact load satisfies the maximum travel of the waveguide rod. At this time, there is no need to tighten the adjusting nut. L When >0, it means that the distance to turn the adjusting nut is L After that, the maximum allowable stroke of the waveguide rod can be met.

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