A device, sample and method for detecting dynamic mechanical properties of materials

Abstract

The present invention discloses a device, a sample and a method for detecting the dynamic mechanical properties of materials, and belongs to the field of dynamic mechanical properties test of materials. The middle part of the sample is an electromagnetic force stretching section, and a transition section, a high-speed stretching section and a clamping section are respectively extended outward from both ends of the electromagnetic force stretching section in sequence. The larger width of the electromagnetic force stretching section is transitioned to the smaller width of the high-speed stretching section through the transition section. The device is based on electromagnetic forming technology and online measurement technology. The electromagnetic forming charge and discharge system controls the charge and discharge of the electromagnetic forming coil. During the detection process, the uniform magnetic field formed by the electromagnetic forming coil applies a uniform electromagnetic force to the electromagnetic force stretching section; a high-speed camera is used to collect the deformation of the high-speed stretching section, and a strain collector collects the strain of the transition section. The dynamic mechanical properties of various materials can be measured in real time and directly, and it has the advantages of wide test range, good test stability, high test accuracy, good repeatability, long equipment life, short test cycle and low cost.

Description

Technical Field

[0001] The present invention belongs to the field of material dynamic mechanical property testing, and relates to a device, a sample and a method for detecting the dynamic mechanical properties of a material. More specifically, it relates to a device and a method for detecting the dynamic mechanical properties of a material under pulse electromagnetic force loading conditions. Background Art

[0002] With the rapid development of the automotive industry, aerospace, high-speed rail transit, military explosives and other fields, the performance and evaluation of the dynamic mechanical properties of various materials and structural parts under conditions such as instantaneous impact loads and collisions, as well as the exploration of forming performance under high-speed and high-energy forming processes have become particularly critical. It is crucial to explore the dynamic mechanical properties of materials in advance for subsequent use. The mechanical properties of materials under conventional deformation are usually measured using quasi-static tensile stress-strain curves. However, during high-rate deformation, the dynamic mechanical behavior of materials is essentially different from that under conventional forming. Therefore, quasi-static tensile cannot be used to measure the dynamic mechanical properties of materials.

[0003] Existing high-speed tensile test equipment mostly uses hydraulic drive, with a speed range of about 5 to 20 m / s, and can only obtain mechanical properties in the low and medium strain rate range of the material. The principle is that the lower end of the sample is fixed with a clamp, and the upper end of the sample is suspended in the air. When the upper end clamp runs to the set speed, it suddenly clamps the sample and breaks the sample. This method has many defects that affect the test accuracy and reliability. For example, the upper end of the sample is suspended in the air and will vibrate violently when subjected to load; the sample is an asymmetric style with one end longer than the other, and the total length is much longer than the static tensile sample. The clamping process is also more complicated and has many influencing factors; when the strength of the sample is high, it is easy to cause damage to the dynamic clamping mechanism.

[0004] The split Hopkinson tension bar technique can measure the mechanical properties of materials at high strain rates. It is based on the one-dimensional elastic stress wave theory. The sample is fixed between the incident rod and the transmission rod with strain gauges attached. The high-speed movement of the incident rod drives the sample to achieve high-speed stretching. Through the pulse signal, the material can be indirectly obtained at 10 2 ~10 4 s -1 Stress-strain curve under strain rate. However, the Hopkinson rod equipment is expensive and the test cost is high; only data after the sample is broken can be obtained, and it is difficult to control a certain fixed deformation; the speed of the incident rod is difficult to control, the test repeatability is poor, and a complete test cycle is long. Therefore, obtaining the dynamic mechanical properties of materials is a major problem faced by scientific research and production. Summary of the invention

[0005] In view of a series of problems in the prior art such as expensive equipment for obtaining dynamic mechanical properties of materials, long test cycle, poor test accuracy and repeatability, the present invention proposes a device, sample and method for detecting dynamic mechanical properties of materials. The device utilizes pulsed electromagnetic force to drive the material to deform at high speed, and directly obtains real-time data of the material during the high-speed deformation process, with high test accuracy and repeatability.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present invention, a device for detecting the dynamic mechanical properties of materials is provided, which is used for detecting the dynamic mechanical properties of materials of a sample, wherein the middle part of the sample is an electromagnetic force stretching section, and a transition section, a high-speed stretching section and a clamping section are respectively and sequentially extended outward from both ends of the electromagnetic force stretching section, and a positioning hole is provided in the clamping section, and the larger width of the electromagnetic force stretching section is transitioned to the smaller width of the high-speed stretching section through the transition section; the detection device comprises:

[0007] Positioning press edge, direction converter, base, electromagnetic forming coil, high-speed camera, clamping positioning device, strain collector, system control and data processing integrator, and electromagnetic forming charging and discharging system;

[0008] A groove is provided on the base, and the electromagnetic forming coil is fixed in the groove; two positioning pressing edges are located on both sides of the groove and are arranged opposite to each other, and are used to press the clamping sections at both ends of the sample; two clamping and positioning devices are located at the two positioning pressing edges and are used to clamp and position the clamping sections; two direction converters are located between the two positioning pressing edges and are used to press down the transition section to change the deformation direction of both sides of the transition section;

[0009] The electromagnetic forming charge and discharge system is used to control the charge and discharge of the electromagnetic forming coil. During the detection process, the uniform magnetic field formed by the electromagnetic forming coil exerts a uniform electromagnetic force in the electromagnetic force stretching section;

[0010] The high-speed camera is used to collect the deformation of the high-speed stretching section;

[0011] The strain collector is used to collect the strain of the transition section;

[0012] The system control and data processing integrator is used to control the operation of the high-speed camera, strain collector, and electromagnetic forming charging and discharging system, and to receive and process the data collected by the high-speed camera and strain collector.

[0013] Furthermore, the electromagnetic forming coil is a runway structure, which is wound or cut by a high-conductivity and high-strength copper alloy such as copper-niobium alloy; the cross-section of the wire is rectangular; the outside of the wire is wrapped with high-strength composite fibers to achieve interlayer reinforcement; the electromagnetic forming coil is encapsulated with insulating material to achieve secondary reinforcement of the coil structure; the electromagnetic forming coil after secondary reinforcement is fixed in a groove of the base to achieve tertiary reinforcement of the coil structure.

[0014] Furthermore, the clamping and positioning device has a wedge-shaped structure, including an upper wedge-shaped clamp block, a lower wedge-shaped clamp block and a positioning guide pin; the clamping surfaces of the upper and lower wedge-shaped clamp blocks are provided with clamping teeth, and the upper and lower wedge-shaped clamp blocks are provided with positioning grooves; the positioning guide pin is used to insert into the positioning groove to achieve precise alignment and positioning of the sample and the upper and lower wedge-shaped clamp blocks.

[0015] Furthermore, the direction converter uses an insulating material with high rigidity; the bottom surfaces at both ends of the direction converter are rectangular for tight positioning; the bottom surface of the middle area of ​​the direction converter is an arc with a smooth surface for pressure-free contact with the sample; when testing samples of different thicknesses, gaskets are added or removed at both ends of the direction converter to adjust the contact state between the direction converter and the sample.

[0016] Furthermore, the high-speed camera and the trigger end of the strain collector are connected to the electromagnetic forming charge and discharge system to capture and collect dynamic mechanical performance data of the sample during high-speed deformation in real time online.

[0017] Furthermore, it includes a plurality of workstations for installing samples, and uses a plurality of sets of high-speed cameras and strain collectors to test a plurality of samples.

[0018] In order to achieve the above-mentioned purpose, according to another aspect of the present invention, a sample for testing the dynamic mechanical properties of a material is provided, wherein the middle portion of the sample is an electromagnetic force stretching section, and a transition section, a high-speed stretching section and a clamping section are respectively extended outward from both ends of the electromagnetic force stretching section, and the clamping section is provided with a positioning hole, and the larger width of the electromagnetic force stretching section is transitioned to the smaller width of the high-speed stretching section through the transition section.

[0019] Furthermore, the thickness of the sample is 0.1 to 10 mm; if the conductivity of the sample material meets the test requirements, it is directly used in the test; if the conductivity does not meet the test requirements, a driving sheet made of a high conductivity material is added under the sample.

[0020] Furthermore, the high-speed stretching section is in the shape of parallel straight lines, a notch or an arc; or, the high-speed stretching section is provided with speckles.

[0021] In order to achieve the above object, according to another aspect of the present invention, a method for detecting the dynamic mechanical properties of a material is provided, wherein the device as described above is used to test the sample as described above, and the method comprises the following steps:

[0022] S1, prepare speckles in the high-speed tensile section of the sample, and attach a strain collector to the transition section;

[0023] S2. Install the sample on the base, use the clamping and positioning device to clamp and position the clamping section; then install the positioning edge press and direction converter and tighten them;

[0024] S3, turning on the electromagnetic forming charge-discharge system, the high-speed camera, and the strain collector, and connecting the triggering ends of the high-speed camera and the strain collector to the electromagnetic forming charge-discharge system;

[0025] S4. The charging and discharging parameters of the electromagnetic forming charging and discharging system are set through the system control and data processing integrator. Then the electromagnetic forming charging and discharging system is charged and discharged after charging. The electromagnetic forming coil forms a uniform magnetic field, and the sample begins to deform at a high speed. At the same time, the high-speed camera and strain collector begin to collect real-time speckle images and elastic strain data in real time.

[0026] S5. Process the obtained real-time speckle image and elastic strain data to obtain dynamic mechanical properties data of the sample, including strain, stress, rate sensitivity, rate hardening index and / or forming limit rate related damage factor.

[0027] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0028] (1) This device has a simple structure, a short test cycle, and low test costs. The sample is easy to clamp, and no complicated connection methods such as bolts are required. The direction converter divides the deformation of the sample transition section into bending deformation and linear deformation, ensuring that the high-speed stretching section is always subjected to linear unidirectional tensile force, greatly reducing the bending stress. At the same time, the deformation in the plane improves the accuracy of speckle measurement. The present invention can directly measure the dynamic mechanical properties of various materials in real time, and has the advantages of a wide test range, good test stability, high test accuracy, good repeatability, long equipment life, short test cycle and low cost.

[0029] (2) The present invention can test various thicknesses, conductive or non-conductive materials by simply adding gaskets at both ends of the direction converter and adding a driving plate under the sample, and has high applicability. The high-speed tensile section of the sample can be designed to be parallel, notched, arc, etc. according to requirements to obtain dynamic mechanical properties under various stress and strain states, and the test range is wide.

[0030] (3) The electromagnetic forming coil described in this device is designed as a runway structure, which can obtain a uniform pulsed strong magnetic field and improve the uniformity and stability of the pulsed electromagnetic force loading, so the test accuracy is high. The electromagnetic forming coil is made of high-strength material and has been reinforced three times, so it has a high mechanical structure strength and greatly extends its service life. It can also withstand ultra-high discharge energy and has a wide strain rate test range.

[0031] (4) The sample provided by the present invention has a symmetrical structure and can be used for multi-purpose analysis.

[0032] (5) The larger width of the electromagnetic force stretching section (94) of the sample provided by the present invention is transitioned to the smaller width of the high-speed stretching section (92) through the transition section (93), so that the bending deformation of the electromagnetic force stretching section (94) with a larger width can be transformed into the rapid stretching deformation of the high-speed stretching section (92) with a smaller width, thereby improving the experimental efficiency.

[0033] (6) The device and method use a high-speed camera and a strain collector to directly measure the high-speed deformation area of ​​the sample in real time online. The dynamic mechanical properties data of the material can be obtained through simple processing with high data accuracy. The charging and discharging parameters of the electromagnetic forming charging and discharging system can be accurately controlled according to demand, and the test repeatability is good, which can ensure the accuracy and stability of the test results.

[0034] (7) The clamping device adopts a wedge-shaped structure. When the specimen is subjected to force and deforms toward the middle at high speed, the clamping ends on both sides move slightly toward the middle, so that the upper and lower wedge-shaped clamps are more tightly engaged; the positioning guide column keeps the relative position of the specimen and the clamping device unchanged; the positioning edge made of high-strength steel further prevents the clamping device from moving toward the middle. The above design can effectively prevent the specimen from slipping during high-speed stretching, avoid vibration during the specimen deformation process, and greatly improve the test accuracy.

[0035] (8) By setting the charge and discharge parameters of the electromagnetic forming charge and discharge system, different discharge energies are obtained, thereby obtaining a strain rate range of 100 to 10 5 s -1 Dynamic mechanical properties data. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the overall structure of the detection device for dynamic mechanical properties of materials according to the present invention;

[0037] Figure 2 The direction converter described in the present invention;

[0038] Figure 3 is a cross-sectional view of the direction converter described in the present invention;

[0039] Figure 4 The electromagnetic forming coil described in the present invention;

[0040] Figure 5 The clamping and positioning device described in the present invention;

[0041] Figure 6 It is a cross-sectional view of the clamping and positioning device described in the present invention;

[0042] Figure 7 The positioning guide column described in the present invention;

[0043] Figure 8 The sample described in the present invention;

[0044] Figure 8 a, 8b, 8c and 8d are schematic diagrams of four structural designs of the high-speed tensile section of the sample described in the present invention;

[0045] Fig. 9 This is the true stress-strain curve of dynamic uniaxial tension obtained by processing in an embodiment of the present invention.

[0046] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0047] 1-positioning edge pressing, 2-direction converter, 3-base, 4-electromagnetic forming coil, 5-countersunk screw, 6-high-speed camera, 7-clamping positioning device, 8-strain collector, 9-sample, 10-system control and data processing integrator, 11-electromagnetic forming charging and discharging system;

[0048] 71-upper wedge-shaped clamping block, 72-lower wedge-shaped clamping block, 73-positioning guide column;

[0049] 91-clamping section, 92-high-speed stretching section, 93-transition section, 94-electromagnetic force stretching section. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0051] The overall structure of a device for detecting dynamic mechanical properties of a material proposed by the present invention is as follows: Figure 1 As shown, the device includes a positioning edge press 1, a direction converter 2, a base 3, an electromagnetic forming coil 4, a countersunk screw 5, a high-speed camera 6, a clamping positioning device 7, a strain collector 8, a sample 9, a system control and data processing integrator 10, and an electromagnetic forming charging and discharging system 11.

[0052] The structure of the direction converter 2 is as follows Figure 2 As shown, insulating materials with high rigidity are used, such as ceramic materials, glass fibers, etc. The bottom surfaces of the two ends of the direction converter are rectangular, which are used for tight positioning; the bottom surface of the middle area is a smooth arc, with a distance of 0 from the workpiece but no pressure (that is, maintaining a pressure-free contact state to reduce interference with the sample stretching process). The cross-sectional view of the direction converter is shown in Figure 3 When testing samples of different thicknesses, spacers can be added at both ends of the direction converter.

[0053] The electromagnetic forming coil 4 is designed as a racetrack structure, such as Figure 4 As shown, a copper alloy with high conductivity and high strength, such as copper-niobium alloy, is wound or cut; the conductor cross section is rectangular; the outer side of the conductor is wound with high-strength composite fibers such as Zylon or carbon fiber to achieve interlayer reinforcement. After the electromagnetic forming coil is processed, it is encapsulated with an insulating material with a certain strength, such as epoxy resin, to achieve secondary reinforcement of the coil structure. The coil after the second reinforcement is placed in the groove of the base 3 made of high-strength steel to achieve the third reinforcement of the coil structure.

[0054] The high-speed camera 6 is located directly above the high-speed stretching section 92 of the sample 9, and the acquisition frequency can reach 500,000 frames / s. The strain collector 8 is attached to the transition section 93 of the sample 9. The trigger ends of the high-speed camera 6 and the strain collector 8 are connected to the electromagnetic forming charge and discharge system 11. When the system discharges, it is triggered at the same time to start real-time signal acquisition, and the displacement and strain state of the high-speed stretching section 92 of the sample during the high-speed deformation process and the strain data of the transition section 93 are captured online in real time. Among them, by processing the speckle images of the high-speed camera 6 at different times, the strain value and cloud map of the sample at any time can be obtained; by processing the strain collector 8, the stress value of the high-speed stretching section 92 can be obtained. The above data acquisition system can directly obtain the dynamic mechanical properties of the material under different conditions.

[0055] The structure of the clamping and positioning device 7 is as follows: Figure 5 As shown, a wedge-shaped structure consisting of an upper wedge-shaped clamp block 71 and a lower wedge-shaped clamp block 72 is adopted, and the cross-sectional view is as shown in FIG. Figure 6 As shown, the material is high-strength steel. The clamping surfaces of the upper and lower wedge-shaped clamps are provided with clamping teeth for clamping the specimen; the upper and lower wedge-shaped clamps are provided with positioning grooves inside; the positioning guide pin 73 is used to insert into the positioning groove inside the wedge-shaped block to achieve accurate centering and positioning of the specimen and the wedge-shaped block, as shown in FIG. Figure 7 shown.

[0056] Sample 9 is a sample to be tested for dynamic mechanical properties. Figure 8 As shown. The sample can be made of a variety of materials, such as aluminum alloy, copper alloy, steel, titanium alloy, polymer composite material, etc., and the thickness can be 0.1 to 10 mm. When the conductivity is good, it is directly used for the test. When the conductivity is poor, a driving plate made of a conductive material such as copper, aluminum pure metal or alloy is placed under the sample. The sample is designed to be a clamping section 91, a high-speed stretching section 92, a transition section 93, and an electromagnetic force stretching section 94. The structural design of the high-speed stretching section is shown in the figure below. Figure 8As shown in Figs. 8a, 8b, 8c and 8d, it can be used to study the dynamic uniaxial tensile stress-strain relationship, biaxial tensile stress-strain relationship, plane strain stress-strain relationship, dynamic strain damage tolerance, dynamic forming limit, dynamic damage threshold, etc. The clamping section 91 is provided with a positioning hole for precise positioning and fixing with the positioning guide pin 73, which effectively limits the displacement of the non-deformed end of the specimen during high-speed deformation and improves the test accuracy.

[0057] The electromagnetic forming charging and discharging system 11 is composed of electrical components such as power supply, capacitor bank, charging / discharging switch, current limiting resistor, inductor, etc. The charging capacitor is 50-860μF, the discharging voltage is 0-50kV, and the total energy can reach 1MkJ. According to the material and structural characteristics of the sample 9, the corresponding discharge parameters are selected through the system control and data processing integrator 10 to make the sample reach different strain rates. The achievable strain rate range is 100-10 5 s -1 .

[0058] The above-mentioned device and method for detecting the dynamic mechanical properties of a material realizes the acquisition of the dynamic mechanical properties of the material through the following steps:

[0059] S1. Processing and manufacturing a sample 9, preparing speckles in the high-speed stretching section 92 of the sample 9, and attaching a strain collector 8 to the transition section 93.

[0060] S2. Install the sample 9 on the base 3, insert the positioning guide column 73 into the positioning hole of the clamping section 94 and the positioning groove of the lower wedge-shaped clamp block 72, and then align the positioning groove of the upper wedge-shaped clamp block 71 with the positioning guide column 73 and install them; finally install the positioning edge clamp 1 and tighten it with the countersunk tightening screw 5. Then install the direction converter 2 and tighten the two ends of the direction converter with the countersunk tightening screws 5.

[0061] S3. Turn on the electromagnetic forming charge and discharge system 11, the high-speed camera 6, and the strain collector 8, and connect the trigger ends of the high-speed camera 6 and the strain collector 8 to the electromagnetic forming charge and discharge system 11, and check and adjust various equipment parameters through the system control and data processing integrator 10.

[0062] S4. Set the charging and discharging parameters of the electromagnetic forming charging and discharging system 11 through the system control and data processing integrator 10. After the safety check is completed, click on charging. After charging is completed, click on discharging, and the sample begins to deform at a high speed. At the same time, the high-speed camera 6 and the strain collector 8 begin real-time collection.

[0063] The dynamic deformation process of the specimen is:

[0064] The electromagnetic force stretching section 94 is deformed at a high speed under the uniform electromagnetic force generated by the electromagnetic forming coil 4 . Since the clamping section 91 is constrained, the electromagnetic force stretching section 94 is bent and deformed in a direction away from the coil.

[0065] The transition section 93 is subjected to the tensile force of the electromagnetic tensile section 94 and moves toward the middle. Under the restriction of the direction converter 2, a bending deformation occurs near the middle side of the sample, while a linear deformation occurs near the high-speed tensile section 92 of the sample.

[0066] The high-speed stretching section 92 is subjected to the unidirectional stretching force of the transition section 93 and undergoes plastic deformation. As the deformation process proceeds, the high-speed stretching section 92 continues to undergo plastic deformation until a certain deformation amount is reached and the deformation stops or the section breaks.

[0067] S5. Process the obtained real-time speckle image and elastic strain data to obtain dynamic mechanical performance data of the sample, such as strain and stress.

[0068] The data processing method for the high-speed camera 6 is:

[0069] 1) Assuming that the total deformation time of the sample is t, the number of photos of the high-speed stretching section collected by the high-speed camera within t time is i, and each deformation time t i The corresponding photo number is p ti , p ti Contains the plane coordinate information of each speckle point;

[0070] 2)t i The plane coordinates of each speckle on the high-speed stretching section of the sample at time t i-1 The change at time t i The engineering strain at the time is denoted as ε ei , ε ei =(p ti –p ti-1 ) / p ti .

[0071] 3) True strain ε of the specimen in high-speed tensile section i =ln(1+ε ei ). Furthermore, since the coordinates of each speckle are two-dimensional, the strain data are also two-dimensional.

[0072] The data processing method of the strain collector 8 is:

[0073] 1) Assuming that the total deformation time of the sample is t, the strain data collected by the strain collector in the transition section within t time is i, and each deformation time t i The corresponding strain data is ε ti ;

[0074] 2)ti The load F at the transition section of the specimen at the moment i =S t *ε ti *E,s t is the cross-sectional area of ​​the transition section, E is the elastic modulus of the sample material;

[0075] 3) According to the mechanical formula, the load on the transition section is equal to the load on the high-speed stretching section. So the high-speed stretching section t i The engineering stress at the moment is σ ei =F i / S0, S0 is the original cross-sectional area of ​​the high-speed stretching section;

[0076] 4)t i The real stress σ in the high-speed stretching section at time i =σ ei (1+ε i ).

[0077] For example, when the charging capacitance of a 2mm thick high-strength aluminum alloy material is 213μF and the discharge voltage is 4kV, 5kV and 6kV respectively, the strain rate is 2436s -1 , 3000s -1 and 5043s -1 The real stress-strain curve of dynamic uniaxial tension obtained by the above data processing method is as follows: Fig. 9 shown.

[0078] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for detecting the dynamic mechanical properties of a material, used for detecting the dynamic mechanical properties of a sample (9), wherein the middle portion of the sample (9) is an electromagnetic force stretching section (94), and a transition section (93), a high-speed stretching section (92) and a clamping section (91) are respectively and sequentially extended outward from both ends of the electromagnetic force stretching section (94), wherein the clamping section (91) is provided with a positioning hole, and the larger width of the electromagnetic force stretching section (94) is transitioned to the smaller width of the high-speed stretching section (92) through the transition section (93); It is characterized in that The device for detecting the dynamic mechanical properties of materials comprises: A positioning edge press (1), a direction converter (2), a base (3), an electromagnetic forming coil (4), a high-speed camera (6), a clamping and positioning device (7), a strain collector (8), a system control and data processing integrator (10), and an electromagnetic forming charging and discharging system (11); A groove is provided on the base (3), and an electromagnetic forming coil (4) is fixed in the groove; two positioning pressing edges (1) are located on both sides of the groove and are arranged opposite to each other, and are used to press and fix the clamping sections (91) at both ends of the sample (9); two clamping and positioning devices (7) are located at the two positioning pressing edges (1) and are used to clamp and position the clamping sections (91); two direction converters (2) are located between the two positioning pressing edges (1) and are used to press down the transition section (93) to change the deformation direction of both sides of the transition section (93); The electromagnetic forming charge and discharge system (11) is used to control the charge and discharge of the electromagnetic forming coil (4). During the detection process, the uniform magnetic field formed by the electromagnetic forming coil (4) applies a uniform electromagnetic force to the electromagnetic force stretching section (94); The high-speed camera (6) is used to collect the deformation of the high-speed stretching section (92); The strain collector (8) is used to collect the strain of the transition section (93); The system control and data processing integrator (10) is used to control the operation of the high-speed camera (6), the strain collector (8), and the electromagnetic forming charging and discharging system (11), and to receive and process the data collected by the high-speed camera (6) and the strain collector (8).

2. A device for detecting dynamic mechanical properties of a material according to claim 1, Features: The electromagnetic forming coil (4) is a runway structure, and is made of a copper alloy with high conductivity and high strength, such as a copper-niobium alloy, by winding or cutting; the cross-section of the conductor is rectangular; the outer side of the conductor is wound with high-strength composite fibers to achieve interlayer reinforcement; the electromagnetic forming coil (4) is encapsulated with an insulating material to achieve secondary reinforcement of the coil structure; the electromagnetic forming coil (4) after secondary reinforcement is fixed in a groove of the base (3) to achieve tertiary reinforcement of the coil structure.

3. A device for detecting dynamic mechanical properties of a material according to claim 1, Features: The clamping and positioning device (7) has a wedge-shaped structure, comprising an upper wedge-shaped clamping block (71), a lower wedge-shaped clamping block (72) and a positioning guide column (73); the clamping surfaces of the upper and lower wedge-shaped clamping blocks are provided with clamping teeth, and the upper and lower wedge-shaped clamping blocks are provided with positioning grooves; the positioning guide column (73) is used to be inserted into the positioning groove to achieve accurate centering and positioning of the sample and the upper and lower wedge-shaped clamping blocks.

4. A device for detecting dynamic mechanical properties of a material according to claim 1, Features: The direction converter (2) is made of insulating material with high rigidity; the bottom surfaces at both ends of the direction converter (2) are rectangular and used for tight positioning; the bottom surface of the middle area of ​​the direction converter (2) is in the shape of an arc with a smooth surface and is in pressure-free contact with the sample; when testing samples of different thicknesses, gaskets are added or removed at both ends of the direction converter (2) to adjust the contact state between the direction converter (2) and the sample.

5. A device for detecting dynamic mechanical properties of a material according to claim 1, Features: The trigger end of the high-speed camera (6) and the strain collector (8) is connected to the electromagnetic forming charge-discharge system (11) to capture and collect dynamic mechanical performance data of the sample (9) during high-speed deformation in real time online.

6. A device for detecting dynamic mechanical properties of a material according to claim 1, Features: It comprises a plurality of workstations for installing samples (9), and uses a plurality of sets of high-speed cameras and strain collectors to detect the plurality of samples.

7. A test specimen for testing the dynamic mechanical properties of a material. Features: The middle part of the sample is an electromagnetic force stretching section (94), and a transition section (93), a high-speed stretching section (92) and a clamping section (91) are respectively and sequentially extended outward from both ends of the electromagnetic force stretching section (94). The clamping section (91) is provided with a positioning hole. The larger width of the electromagnetic force stretching section (94) is transitioned to the smaller width of the high-speed stretching section (92) through the transition section (93).

8. A sample for testing the dynamic mechanical properties of a material as claimed in claim 7, Features: The thickness of the sample is 0.1 to 10 mm. If the conductivity of the sample material meets the test requirements, it can be directly used in the test. If the conductivity does not meet the test requirements, a driving sheet made of a high conductivity material is added under the sample.

9. A sample for testing the dynamic mechanical properties of a material according to claim 7, Features: The high-speed stretching section (92) is in the shape of parallel straight lines, a notch or an arc; or the high-speed stretching section (92) is provided with speckles.

10. A method for detecting the dynamic mechanical properties of materials. It is characterized in that The device according to any one of claims 1 to 6 is used to test the sample according to any one of claims 7 to 9, comprising the following steps: S1, preparing speckles in the high-speed stretching section (92) of the sample (9), and attaching a strain collector (8) to the transition section (93); S2, mounting the sample (9) on the base (3), using the clamping and positioning device (7) to clamp and position the clamping section (91); then installing the positioning edge press (1) and the direction converter (2) and tightening them; S3, turning on the electromagnetic forming charge-discharge system (11), the high-speed camera (6), and the strain collector (8), and connecting the triggering ends of the high-speed camera (6) and the strain collector (8) to the electromagnetic forming charge-discharge system (11); S4, setting various charging and discharging parameters of the electromagnetic forming charging and discharging system (11) through the system control and data processing integrator (10), and then the electromagnetic forming charging and discharging system is charged, and then discharged after charging is completed, the electromagnetic forming coil (4) forms a uniform magnetic field, and the sample begins to deform at a high speed. At the same time, the high-speed camera (6) and the strain collector (8) begin to collect real-time speckle images and elastic strain data in real time; S5. Process the obtained real-time speckle image and elastic strain data to obtain dynamic mechanical properties data of the sample, including strain, stress, rate sensitivity, rate hardening index and / or forming limit rate related damage factor.

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