Plate crack propagation device based on electromagnetic driving

Abstract

The utility model discloses a plate crack propagation device based on electromagnetic drive, and relates to the technical field of test devices. Comprising an upper clamping block, a lower clamping block, a supporting seat, a plate test piece, a permanent magnet and an electromagnet, the lower clamping block is connected with the supporting seat through a screw, the upper clamping block is connected with the lower clamping block through a screw, the middle parts of the upper clamping block and the lower clamping block are provided with long-strip-shaped convex blocks, the end surfaces of the long-strip-shaped convex blocks are planes, the long-strip-shaped convex blocks of the upper clamping block are pressed on the top end plane of a plate test piece, the convex blocks of the lower clamping block are propped against the bottom end plane of the plate test piece, and the permanent magnet is arranged on the plate test piece; the permanent magnet comprises an upper permanent magnet and a lower permanent magnet, the upper permanent magnet and the lower permanent magnet are consistent in structural shape and size, and the upper permanent magnet and the lower permanent magnet are connected through a bolt; the electromagnets comprise the upper electromagnet and the lower electromagnet, the upper electromagnet and the upper permanent magnet are oppositely arranged, and the lower electromagnet and the lower permanent magnet are oppositely arranged. According to the utility model, row-to-row non-contact excitation can be carried out on the plate test piece, the excitation precision is high, the electromagnet cannot be burnt out, and the device can be used for a long time.

Description

Technical Field

[0001] The utility model relates to the technical field of test devices, in particular to a plate crack propagation device based on electromagnetic drive. Background Technique

[0002] The blade is a key component affecting the safety and efficiency of the turbine, and occupies an important position in improving the comprehensive performance of the turbine. Under high speed, high load and complex working conditions, the blade is prone to fatigue cracks. Under the action of cyclic stress, the fatigue cracks will continuously expand and lead to fracture. The sudden fracture of the blade not only affects the stable operation of production, but may also induce disaster accidents, causing casualties and economic losses. According to data statistics, more than 70% of engineering failure accidents are caused by fatigue failure, and often have suddenness and disaster. Thus, it can be seen that fatigue cracks seriously threaten the safety and reliability of the beam structure.

[0003] In order to ensure the safety of the blade structure, it is usually necessary to monitor the life of the blade structure. Life monitoring is another important content of structural health monitoring. This method is to monitor through the load / environment spectrum, conduct damage tolerance analysis, and determine the crack initiation and crack propagation time. Among them, the crack propagation time analysis mainly determines the life of the structure from the detectable crack size to the critical crack size under the service load, and provides a basis for determining the structure maintenance cycle. From this perspective, in order to ensure the safety of the key beam structure, it is necessary to conduct damage tolerance analysis, determine the crack propagation life, and provide a basis for formulating the maintenance cycle.

[0004] In order to study the extended life of the blade structure, scholars conduct crack propagation tests through plate structures. The scholars connect the shaker and the plate through a push rod, and the plate is fixed on the base. In this case, the crack propagation test is carried out. Since the conventional shaker cannot operate continuously, after two hours of operation, the experiment needs to be interrupted for a period of time. After the shaker cools down, the crack propagation test is carried out again. Under long-term operation conditions, the shaker is very easy to burn out. In addition, since the push rod and the specimen are usually connected by threads, which is a rigid connection, the push rod is very easy to deform, resulting in a decrease in accuracy and damage, making it very difficult to carry out the plate crack propagation test. Therefore, how to develop a plate crack propagation device that can be used for a long time is an urgent problem that needs to be solved by researchers. Content of the Utility Model

[0005] Aiming at the deficiencies of the prior art, the utility model provides a plate crack propagation device based on electromagnetic drive.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A plate crack propagation device based on electromagnetic drive, comprising an upper clamp block, a lower clamp block, a support base, a plate specimen, a permanent magnet and an electromagnet; the lower clamp block and the support base are connected by screws, the upper clamp block and the lower clamp block are connected by screws, the middle parts of the upper clamp block and the lower clamp block are provided with long strip-shaped convex blocks, the end faces of the long strip-shaped convex blocks are flat, the long strip-shaped convex block of the upper clamp block presses on the top plane of the plate specimen, the convex block of the lower clamp block abuts against the bottom plane of the plate specimen, and the permanent magnet is installed on the plate specimen; the permanent magnet includes an upper permanent magnet and a lower permanent magnet, the structural shapes and sizes of the upper permanent magnet and the lower permanent magnet are the same, the upper permanent magnet is installed above the plate specimen, the lower permanent magnet is below the plate specimen, and the upper permanent magnet and the permanent magnet are connected by bolts; the electromagnet includes an upper electromagnet and a lower electromagnet, the upper electromagnet is arranged opposite to the upper permanent magnet, and the lower electromagnet is arranged opposite to the lower permanent magnet.

[0008] Further, the upper electromagnet is electrically connected to a first current amplifier, a first voltage controllable oscillator, a first PI controller, and a signal generator in sequence, the signal generator is further electrically connected to a phase shift circuit, and the phase shift circuit is electrically connected to a second PI controller, a second voltage controllable oscillator, a second current amplifier, and the lower electromagnet in sequence.

[0009] Further, the phase angle of the phase shift circuit is π / 2.

[0010] Through the above technical solutions, compared with the prior art, the present utility model provides a plate crack propagation device based on electromagnetic drive, which has the following beneficial effects:

[0011] Since the upper permanent magnet is installed above the plate specimen, the lower permanent magnet is below the plate specimen, and the upper permanent magnet and the permanent magnet are connected by bolts; the electromagnet includes an upper electromagnet and a lower electromagnet, the upper electromagnet is arranged opposite to the upper permanent magnet, and the lower electromagnet is arranged opposite to the lower permanent magnet, non-contact excitation can be performed on the plate specimen. This excitation method has high precision, and the electromagnet will not burn out and can be used for a long time. Description of the Drawings

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0013] Figure 1 It is a schematic structural diagram of a plate crack propagation device of the present utility model;

[0014] Figure 2 It is Figure 1 The top view of the plate specimen in

[0015] Figure 3It is a schematic diagram of the electrical connection driven by an electromagnet. Specific implementation mode

[0016] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0017] In this application, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the presence of additional identical elements in the process, method, article or device including the element.

[0018] See Figures 1-3 As shown, the plate crack propagation device based on electromagnetic drive includes a plate clamping seat 1, a plate specimen 2, a permanent magnet 3 and an electromagnet. The plate clamping seat 1 includes an upper clamping block 11, a lower clamping block 12 and a support seat 13. The lower clamping block 12 and the support seat 13 are fixedly connected by four countersunk head screws 14. The upper clamping block 11 and the lower clamping block 12 are fixedly connected by four countersunk head screws 15. By loosening the four countersunk head screws 15, the upper clamping block 11 and the lower clamping block 12 can be separated. A first long strip-shaped protrusion 111 and a second long strip-shaped protrusion 112 are provided in the middle of the bottom surface of the upper clamping block 11 and the middle of the top surface of the lower clamping block 12, and the end faces of the first long strip-shaped protrusion and the second long strip-shaped protrusion are flat surfaces. The first long strip-shaped protrusion 111 of the upper clamping block 11 presses on the top plane of the plate specimen 2, and the second long strip-shaped protrusion 112 of the lower clamping block 12 abuts against the bottom plane of the plate specimen 2. In this way, through the pre-tightening force of the countersunk head screws 15, the plate specimen 2 is fixed on the plate clamping seat 1.

[0019] A permanent magnet 3 is also provided at the free end of the plate specimen 2. The permanent magnet 3 includes an upper permanent magnet 31 and a lower permanent magnet 32. The upper permanent magnet 31 and the lower permanent magnet 32 have the same structural shape and size, and both the upper permanent magnet 31 and the lower permanent magnet 32 are provided with two through holes. The plate specimen 2 is also provided with two through holes, and the two through holes are arranged along the axial direction of the plate specimen 2. The upper permanent magnet 31 is installed above the plate specimen 2, and the lower permanent magnet 32 is installed below the plate specimen 2 corresponding to the position of the upper permanent magnet 31. The upper permanent magnet 31 and the lower permanent magnet 32 are connected by two bolts. The bolts sequentially pass through the through holes of the upper permanent magnet 31, the plate specimen 2, and the lower permanent magnet 32. The electromagnet includes an upper electromagnet 41 and a lower electromagnet 42. The upper electromagnet 41 is arranged opposite to the upper permanent magnet 31, and the lower electromagnet 42 is arranged opposite to the lower permanent magnet 32.

[0020] In the present utility model, the upper electromagnet 41 is electrically connected to a first current amplifier, a first voltage-controlled oscillator, a first PI controller, and a signal generator in sequence. The signal generator is also electrically connected to a phase-shifting circuit, and the phase-shifting circuit is electrically connected to a second PI controller, a second voltage-controlled oscillator, a second current amplifier, and the lower electromagnet 42 in sequence. The phase angle of the phase-shifting circuit is π / 2.

[0021] When the present utility model is used for the plate crack propagation test, first, the cracked plate specimen 2 is prefabricated with an initial crack 21 through a fatigue testing machine or wire cutting. Then, the four upper countersunk head screws 15 on the plate clamping seat 1 are loosened, and the upper clamping block 11 and the lower clamping block 12 are released. After the plate specimen 2 is installed in a predetermined position, the upper countersunk head screws 15 are tightened. Then, the electromagnet is started to work, and the two electromagnets have a phase difference of 90 degrees during operation. That is, the two electromagnets generate a resultant force on the plate specimen. If the function formula of the force generated by the upper electromagnet on the upper permanent magnet is Q0sin(pt / 2), then the function formula of the force generated by the lower electromagnet on the lower permanent magnet is Q0sin(pt - π) / 2. Therefore, the movement trajectory of the plate specimen is a vibration along the vertical direction.

[0022] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the key points of each embodiment are the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative labor.

[0023] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present utility model. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present utility model. Therefore, the present utility model will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electromagnetic drive-based plate crack propagation device, characterized in that: It includes an upper clamping block, a lower clamping block, a support base, a plate specimen, a permanent magnet and an electromagnet; the lower clamping block and the support base are connected by screws, the upper clamping block and the lower clamping block are connected by screws, a long strip-shaped convex block is provided in the middle of the upper clamping block and the lower clamping block, the end face of the long strip-shaped convex block is a plane, the long strip-shaped convex block of the upper clamping block presses on the top plane of the plate specimen, the convex block of the lower clamping block abuts against the bottom plane of the plate specimen, and the permanent magnet is installed on the plate specimen; the permanent magnet includes an upper permanent magnet and a lower permanent magnet, the structural shapes and sizes of the upper permanent magnet and the lower permanent magnet are the same, the upper permanent magnet is installed above the plate specimen, the lower permanent magnet is below the plate specimen, and the upper permanent magnet and the permanent magnet are connected by bolts; the electromagnet includes an upper electromagnet and a lower electromagnet, the upper electromagnet is arranged opposite to the upper permanent magnet, and the lower electromagnet is arranged opposite to the lower permanent magnet.

2. The electromagnetic drive-based plate crack propagation device according to claim 1, wherein: The upper electromagnet is electrically connected to a first current amplifier, a first voltage controllable oscillator, a first PI controller, and a signal generator in sequence, the signal generator is also electrically connected to a phase-shifting circuit, and the phase-shifting circuit is electrically connected to a second PI controller, a second voltage controllable oscillator, a second current amplifier, and the lower electromagnet in sequence.

3. The electromagnetic drive-based plate crack propagation device according to claim 2, characterized in that: The phase angle of the phase-shifting circuit is π / 2.

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