CN115979850A - Pendulum-Electromagnetic Collaborative Acceleration Shock Pressing In-situ Test Device - Google Patents

Abstract

The invention relates to a pendulum bob-electromagnetic cooperative accelerated impact pressing in-situ testing device, and belongs to the field of material micromechanics performance testing. The device mainly comprises a pendulum bob action unit, an electromagnetic coil acceleration unit, an in-situ test unit and the like. The direct current motor drives the pendulum bob to lift to a specific high position and the pendulum bob is adsorbed by the electromagnet, so that the consistency of the initial speed and the impact energy in the impact process of the pendulum bob is realized; on the basis of obtaining the kinetic energy converted from the gravitational potential energy of the pendulum bob, the impact pressure head obtains higher speed and impact force through secondary acceleration of the electromagnetic coil, and the pendulum bob-electromagnetic cooperative short-range transient high-speed impact test is realized; an acoustic emission sensor is arranged behind the clamping table of the tested piece and used for monitoring transient elastic waves and crack dynamic expansion behaviors of the tested material in the impact process, and a load and displacement detection unit is used for collecting impact load and indentation displacement of the tested piece respectively. The electromagnetic ejection technology is applied to the impact pressing test, the structure is compact, the size is small, and the impact pressing speed is high.

Description

Pendulum-Electromagnetic Collaborative Acceleration Shock Pressing In-situ Test Device

technical field

The invention relates to the field of testing the microscopic mechanical properties of materials, in particular to a pendulum-type electromagnetic acceleration impact indentation in-situ testing device integrating electromagnetic acceleration and "optical-infrared-acoustic emission" in-situ testing. The secondary acceleration of the electromagnetic coil can impact the material at a short distance and high speed, reduce the volume of the device, and provide new ideas for revealing the mechanical properties and damage mechanism of the material under high strain rate.

Background technique

In the industrial field, impact tests are usually used to study the impact resistance of products under impact loads to provide guarantees for the safety and reliability of materials. In the field of impact, the pendulum impact device is a commonly used equipment in the impact test. Its working principle is: let the pendulum with a certain weight generate kinetic energy through the action of gravity at a specific height, and drop it freely to the lowest level. When the point hits the surface of the test piece, its physical properties are evaluated from the failure results of the test piece. However, the traditional impact test often requires frequent replacement of the hammer head to achieve different impact loads, which undoubtedly reduces the test efficiency and is extremely inconvenient for the test operation. Therefore, it is particularly important to use the principle of electromagnetic ejection to adjust the impact pressure head at different speeds.

Nano-indentation testing technology is mainly used to measure the hardness and elastic modulus of materials at the micro-nano scale. It controls the load to change continuously through a computer program, and measures the indentation depth in real time. Due to the ultra-low load applied, it can reach nanometer level of pressure depth. However, most of the existing nanoindentation tests are static tests, which are suitable for measuring the mechanical properties of ultra-thin materials such as thin films and coatings, such as load-displacement curves, elastic modulus, hardness, fracture toughness, strain hardening effect, viscoelasticity, etc. or creep behavior etc. However, due to the characteristics of its static test, it cannot explain a series of dynamic characteristics such as the structural phase transition of the material under the impact load, the dynamic crack expansion and the impact damage failure mechanism. As far as impact indentation test instruments are concerned, most of them are indentation tests realized by a single loading method, such as the micro-sized impact indenter based on piezoelectric drive developed by Swiss Alemnis Company, with a maximum impact speed of 50mm/s and a maximum The impact strain is 10 ⁵ /s, and the press-in test is carried out by precision driving realized by the inverse piezoelectric effect, which provides new ideas for solving the problems of contact zero point error and unloading curve fitting in dynamic testing of materials. The impact indentation test module based on electromagnetic drive developed by British MicroMaterials company uses the electromagnetic pendulum drive mode for the indenter to carry out fatigue indentation test and impact indentation test through alternating magnetic field. This product mainly focuses on the fatigue performance test of materials, and supplements the mechanical properties of materials from another perspective.

Existing analysis methods only deduce the cause through the damage results of the specimen, and cannot know the specific process quantity. Therefore, a testing device that can monitor the change process of various physical quantities of the specimen during the test in multiple dimensions is urgently needed. Through the coupling of "optical-infrared-acoustic emission" multiple physical fields, the in-situ test of various parameters of the material during the impact process is carried out to reveal the dynamic characteristics of the material at different strain rates.

The micro-nano impact intrusion tester is a necessary instrument to obtain the impact dynamic performance parameters such as material dynamic hardness and impact toughness. It is also an important tool for the discovery of new physical properties, new phenomena, and new laws. trend. However, limited by a single driving technology, existing instruments cannot achieve high-speed impact testing, and it is difficult to obtain the dynamic mechanical response of materials and micro-area damage at the same time. The research on the impact damage failure mechanism of key materials is greatly limited.

Contents of the invention

The object of the present invention is to provide a pendulum-type electromagnetic accelerated impact indentation in-situ test device, which can solve the above-mentioned problems in the prior art. The invention combines the impact test with the electromagnetic ejection, uses the electromagnet to drive the pendulum to hit the punch, converts the potential energy into the kinetic energy of the punch, and then uses the electromagnetic coil to perform secondary acceleration to perform the impact indentation test on the material. The invention can realize operations such as changing the type of the punch, adjusting the preset height, changing the size of the coil, and the like. The device mainly realizes the adjustment of the impact speed of the punch by controlling the preset height of the pendulum and the magnitude of the electromagnetic coil current. At the same time, high-speed cameras, infrared thermal imagers, acoustic emission probes and other equipment are integrated, and an in-situ test method of "optical-infrared-acoustic emission" multi-field coupling is constructed, which provides a method for revealing the properties of materials.

Above-mentioned purpose of the present invention is achieved through the following technical solutions:

A pendulum-electromagnetic cooperative acceleration impact in-situ test device is characterized in that it is mainly composed of a pendulum indentation action unit, an electromagnetic coil acceleration unit, a specimen clamping unit, and an in-situ test unit. in. The impact indenter 10 in the pendulum indentation action unit is placed in the impact track 13 sleeved in the electromagnetic coil acceleration unit, and the impact track 13 is sleeved in the support table 12 with a ring structure in the electromagnetic coil acceleration unit, The acoustic emission sensor 2 in the in-situ testing unit is embedded and installed behind the specimen holding platform 3 in the specimen holding unit.

The pendulum indentation action unit is composed of a marble vibration isolation table 5, a pendulum 6, an electromagnet 7, an electromagnet fixing frame 8, a vibration isolation table 9, and an impact pressure head 10. The swing angle of the pendulum ranges from 0° to 180°. The initial drop height can be adjusted according to the impact energy and impact velocity, and the gravity potential energy of the pendulum is converted into impact kinetic energy to provide the initial impact velocity for the secondary electromagnetic ejection.

The electromagnetic coil acceleration unit is composed of an electromagnetic coil 11 , a supporting platform 12 , and an impact rail 13 . The electromagnetic coil 11 is sleeved on the impact rail 13, and the coils of different specifications can be modularly replaced according to the impact pressing speed requirements to achieve the adjustment of the impact speed.

The specimen holding unit is composed of a specimen holding table 3 and a test piece 14 . The test piece clamping table 3 adopts the design of a circular clamping surface, and a cylindrical acoustic emission sensor 2 is embedded in the through hole. The infrared thermal imager 1 and the high-speed camera 4 in the in-situ testing unit monitor the in-situ interaction between the impact indenter 10 and the test piece 14 during the impact indentation process.

The in-situ testing unit is composed of an infrared thermal imager 1 , a high-speed camera 4 and an acoustic emission sensor 2 . The infrared thermal imager 1 and the high-speed camera 4 are respectively arranged on both sides of the tested object, and the tested object 14 is pasted on the surface of the front end probe of the acoustic emission sensor 2 .

The impact indenter 10 is composed of a transmission pressure rod and a miniature indenter. The micro indenter is rigidly connected with the transmission pressure rod through the external thread at its tail end, and the shape of the micro indenter can be changed to spherical, conical, triangular pyramid, or quadrangular pyramid. shape and cube corner to meet the impact test requirements of the test piece 14 with different impact toughness and dynamic hardness, combined with the thickness of the test piece 14, the length of the impact indenter 10 and the shape adjustment of the micro-indenter, different indenters can be realized. Impact indentation test under strain rate. At the same time, both the pendulum 6 and the impact indenter 10 transmission rods are made of high-entropy alloy materials with excellent impact resistance and fatigue resistance, and the cross-sectional area ratio and thickness/length of the pendulum 6 and the impact indenter 10 The ratios are all fixed values, and the same impact inertia ratio under different loads can be achieved.

The geometric axis of the electromagnetic coil 11 is consistent with the direction of motion of the impact indenter 10, that is, the impact velocity direction, and the electromagnet 7 is fixed on the electromagnet holder 8 by bolt connection, and drives the pendulum to accelerate for the first time; the electromagnetic coil 11 Drive the impact indenter 10 to accelerate for the second time through the principle of electromagnetic ejection acceleration. The pendulum-electromagnetic collaborative acceleration impact transforms the gravitational potential energy of the pendulum 6 and the electromagnetic energy of the electromagnetic coil 11 into the kinetic energy of the impact indenter 10. The coil 11 is accelerated twice to obtain a higher impact velocity and impact force, thereby realizing a pendulum-electromagnetic coordinated transient high-speed impact indentation test within a short range. By adjusting the transient current value applied by the energy storage device to the electromagnetic coil 11 , the controllable adjustment of the velocity of the impact indenter 10 in the secondary electromagnetic ejection mode can be realized.

The beneficial effect of the invention lies in that the structural design is novel, the overall size is small, and the impact test of the material is realized. In the design of the impact indentation action unit, the initial impact velocity of the pendulum is further improved by using the electromagnet; the electromagnetic ejection is applied to the device, due to its non-contact acceleration characteristics, the friction resistance is reduced and the sensitivity is improved. A good dynamic impact effect can be achieved. Compared with the traditional pendulum impact testing machine, the invention provides a new idea for the pendulum impact indentation testing machine.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention, and constitute a part of the application. The schematic examples and descriptions of the present invention are used to explain the present invention, and do not constitute improper limitations to the present invention.

Fig. 1 is the axonometric view of the three-dimensional structure of the present invention;

Fig. 2 is the front schematic view of the three-dimensional structure of the present invention;

Fig. 3 is a schematic side view of a three-dimensional structure of the present invention;

Fig. 4 is the structural diagram of electromagnetic spring coil of the present invention;

Fig. 5 is a structural diagram of the pendulum indentation action unit of the present invention;

Figure 6(a) is a schematic diagram of the adsorption state of the pendulum indentation action unit of the present invention;

Fig. 6(b) is a schematic diagram of the impact state of the pendulum indentation action unit of the present invention.

In the figure: 1. Infrared thermal imager; 2. Acoustic emission sensor; 3. Specimen clamping table; 4. High-speed camera; 5. Marble isolation table; 6. Pendulum; 7. Electromagnet; 8. Electromagnet Fixing frame; 9. Isolation table; 10. Impact pressure head; 11. Electromagnetic coil; 12. Track support platform; 13. Impact track; 14. Test piece.

Detailed ways

The detailed content of the present invention and its specific implementation will be further described below in conjunction with the accompanying drawings.

Referring to Fig. 1 to Fig. 4, the pendulum-electromagnetic cooperative acceleration impact in-situ test device of the present invention mainly consists of a pendulum indentation action unit, an electromagnetic coil acceleration unit, a specimen clamping unit, and an in-situ test unit and other parts. The impact indenter in the pendulum indentation action unit is placed in the impact track sleeved in the electromagnetic coil acceleration unit, and the impact track is sleeved and installed in the supporting platform with a ring structure in the electromagnetic coil acceleration unit. The in-situ test unit The acoustic emission sensor in is embedded and installed behind the specimen holding table in the specimen holding unit. The electromagnetic coil acceleration unit is composed of an electromagnetic coil, a support platform, and an impact track. The electromagnetic coil is sleeved on the impact track, and the coils of different specifications can be modularly replaced according to the impact pressing speed requirements to achieve the adjustment of the impact speed. The specimen holding unit is composed of a specimen holding table and a tested piece. The specimen clamping table adopts the design of circular clamping surface, and the cylindrical acoustic emission sensor is embedded in the through hole. In-situ monitoring of the interaction behavior between the impact indenter and the test piece during the impact indentation process by the infrared thermal imager and the high-speed camera. The in-situ testing unit is composed of an infrared thermal imager, a high-speed camera and an acoustic emission sensor. Infrared thermal imagers and high-speed cameras are respectively arranged on both sides of the test piece, and the test piece is pasted on the surface of the front end probe of the acoustic emission sensor.

Referring to Figure 5, Figure 6(a) and Figure 6(b), the pendulum indentation action unit consists of a marble vibration isolation table, a pendulum, an electromagnet, an electromagnet fixing frame, a vibration isolation table, and an impact indenter constitute. The swing angle of the pendulum ranges from 0° to 180°. The initial drop height can be adjusted according to the impact energy and impact velocity, and the gravity potential energy of the pendulum is converted into impact kinetic energy to provide the initial impact velocity for the secondary electromagnetic ejection. Select the appropriate pendulum according to the impact velocity required for the experimental design and research. Pendulums of different masses hit the impact indenter, and the impact indenter is given different initial velocities through the momentum theorem; it can also be determined by changing the current of the electromagnetic coil. Control the speed of the second acceleration of the punch. The impact head is placed in the impact track, so that the impact head can move along a straight line; the electromagnetic coil is sleeved on the impact track, because of its non-contact acceleration characteristics, the friction during the movement of the impact head is reduced, so that The experimental error is smaller. Also because of the special acceleration characteristics of the electromagnetic coil, the design of the impact track is more tolerant to adapt to different types of impact indenters, such as ball heads, cone heads, etc.

When the pendulum-electromagnetic coordinated acceleration impact pressing in-situ test device of the present invention is in use, its working process is specifically as follows:

First, select the appropriate impact indenter and pendulum matching it according to the test design requirements, install the test piece on the circular clamping surface, adjust the position of the impact indenter and the pendulum, and make the pendulum adsorb on the electromagnet , so that the impact head is placed in the impact track and one-third of the body is exposed for the pendulum to strike. Adjust the high-speed camera and infrared thermal imager to focus on the impacted surface of the test piece; turn on the acoustic emission sensor to keep its signal in a stable state. After the pre-work preparation is completed, the electromagnet is triggered to make the pendulum fall, and the electromagnetic coils accelerate together when the pendulum hits the impact pressure head. After the impact test is completed, recover the impact indenter and the test piece and turn off the high-speed camera, infrared thermal imager and acoustic emission sensor, and fully discharge the electromagnetic coil.

The above descriptions are only preferred examples of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (3)

1. A pendulum bob-electromagnetic cooperative accelerated impact indentation in-situ testing device is characterized by mainly comprising a pendulum bob indentation action unit, an electromagnetic coil acceleration unit, a test piece clamping unit, an in-situ testing unit and the like; the device comprises a pendulum bob indentation action unit, an electromagnetic coil acceleration unit, an acoustic emission sensor (2) and a pendulum bob indentation action unit, wherein an impact pressure head (10) in the pendulum bob indentation action unit is arranged in an impact track (13) sleeved in the electromagnetic coil acceleration unit, the impact track (13) is sleeved in a support table (12) with an annular structure in the electromagnetic coil acceleration unit, and the acoustic emission sensor (2) in an in-situ test unit is embedded behind a test piece clamping table (3) in the test piece clamping unit;

the pendulum impression action unit consists of a marble shock insulation platform (5), a pendulum (6), an electromagnet (7), an electromagnet fixing frame (8), a shock insulation platform (9) and an impact pressure head (10); the pendulum angle range of the pendulum bob is 0-180 degrees, the initial falling height of the pendulum bob can be adjusted according to the impact energy and the impact speed, and the gravitational potential energy of the pendulum bob is converted into impact kinetic energy to provide the initial impact speed for secondary electromagnetic ejection;

the electromagnetic coil accelerating unit is composed of an electromagnetic coil (11), a support table (12) and an impact track (13); the electromagnetic coil (11) is sleeved on the impact track (13), and coils with different specifications can be modularly replaced according to the impact pressing speed requirement so as to realize the adjustment of the impact speed;

the test piece clamping unit consists of a test piece clamping table (3) and a tested piece (14); the test piece clamping table (3) is designed to be a circular clamping surface, a cylindrical acoustic emission sensor (2) is embedded into a through hole of the test piece clamping table, a certain distance is kept between a vertical plane of the test piece clamping table (3) and the end surface of the impact track (13), and an infrared thermal imager (1) and a high-speed camera (4) in an in-situ testing unit can conveniently monitor the interaction behavior between an impact pressure head (10) and a tested piece (14) in the impact pressing-in process in situ;

the in-situ test unit consists of an infrared thermal imager (1), a high-speed camera (4) and an acoustic emission sensor (2); the infrared thermal imaging instrument (1) and the high-speed camera (4) are respectively arranged at two sides of the tested piece, and the surface of the front probe of the acoustic emission sensor (2) is stuck with the tested piece (14).

2. The pendulum bob-electromagnetic cooperative accelerated impact indentation in-situ test device as claimed in claim 1, wherein the impact indenter (10) is composed of a transmission compression rod and a micro indenter, the micro indenter is rigidly connected with the transmission compression rod through an external thread at the tail end of the micro indenter, and the shape of the micro indenter can be changed into a spherical shape, a conical shape, a triangular pyramid shape, a quadrangular pyramid shape and a cubic angle shape, so as to meet the impact test requirements of the tested piece (14) with different impact toughness and dynamic hardness, and the impact indentation test under different strain rates can be realized by combining the thickness of the tested piece (14), the length of the impact indenter (10) and the shape adjustment of the micro indenter; meanwhile, the pendulum bob (6) and the transmission compression bar of the impact pressure head (10) are both made of high-entropy alloy materials with excellent impact resistance and fatigue resistance, and the cross-sectional area ratio and the thickness/length ratio of the pendulum bob (6) and the impact pressure head (10) are both constant values, so that the same impact inertia ratio under different loads can be realized.

3. The pendulum bob-electromagnetic cooperative acceleration impact indentation in-situ test device according to claim 1, characterized in that the geometric axis of the electromagnetic coil (11) is consistent with the motion direction of the impact pressure head (10), i.e. the impact speed direction, the electromagnet (7) is fixed on the electromagnet fixing frame (8) through a bolt connection, and drives the pendulum bob to accelerate for the first time; the electromagnetic coil (11) drives the impact pressure head (10) to accelerate for the second time through an electromagnetic ejection type acceleration principle; the pendulum bob-electromagnetism cooperative accelerated impact is converted into kinetic energy of an impact pressure head (10) through the gravitational potential energy of the pendulum bob (6) and the electromagnetic energy of the electromagnetic coil (11) in the cooperative direction, and the impact pressure head (10) obtains higher impact speed and impact force through the secondary acceleration of the electromagnetic coil (11) on the basis of obtaining the kinetic energy converted from the gravitational potential energy of the pendulum bob, so that the pendulum bob-electromagnetism cooperative transient high-speed impact press-in test in a short distance is realized; the controllable regulation of the speed of the impact ram (10) in the secondary electromagnetic ejection mode can be realized by regulating the transient current value applied to the electromagnetic coil (11) by the energy storage device.

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