A fractal structure input solitary wave metamaterial nondestructive testing device and its application

Abstract

The invention discloses a solitary wave metamaterial nondestructive testing device with fractal structure input and its application, the device comprises a fractal curved cavity track, a vertical cavity track, a group of scattered particles, impact particles and signal collection particles; the fractal curved cavity track is composed of a plurality of sub-curved cavity tracks and a plurality of mother curved cavity tracks, the bottoms of the plurality of mother curved cavity tracks are commonly connected with the top of the vertical cavity track, the top of each mother curved cavity track is connected with the bottoms of the plurality of sub-curved cavity tracks; two openings are arranged oppositely on the track walls of the lower part of the vertical cavity track, each sub-curved cavity track and each mother curved cavity track; the curved cavity track and the vertical cavity track are both filled with a group of scattered particles, the bottom of the vertical cavity track is provided with signal collection particles, the signal collection particles are provided with piezoelectric sheets, the piezoelectric sheets are connected with an external circuit through a wire and an opening, and the top opening of each sub-curved cavity track is used for the free entry of impact particles.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial elastic wave metamaterials, and in particular to a nondestructive testing device for solitary wave metamaterials with fractal structure input. Background Art

[0002] In recent years, phononic crystals have attracted widespread interest from scholars in many fields. They are artificial periodic structures with periodic material constants. Particle phononic crystals and elastic wave metamaterials are the most studied forms. The elastic particles in contact with each other in particle phononic crystals satisfy the Hertz contact law, and their nonlinearity mainly comes from the contact deformation between adjacent particles. The nonlinear wave propagation of particle phononic crystals shows rich wave characteristics and broad application prospects. Among them, highly nonlinear solitary waves can be formed in one-dimensional particle chains composed of the same particles, which can maintain stable propagation at a long distance, and the reflection and transmission of the wave are related to the properties of the contacting materials. It is these special propagation characteristics that make the one-dimensional particle chain a good carrier of highly nonlinear solitary waves. With the development of nondestructive testing technology and the improvement of nondestructive testing instruments, people have higher requirements for nondestructive testing technology, which makes the one-dimensional particle chain solitary wave nondestructive testing method widely concerned. Based on the advantages of small size and high portability of solitary wave flaw detection in particle chains, such solitary wave metamaterials can be used in many engineering applications, including vibration absorbers, impurity detectors, acoustic diodes and nondestructive testing. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a fractal structure input solitary wave metamaterial nondestructive testing device. The present invention can excite nonlinear solitary wave signals at multiple positions by adopting a fractal multi-curved cavity track propagation structure, thereby realizing multiple nondestructive testing of the same material under test. The effect of nondestructive testing of the same material under test by multiple nonlinear solitary wave signals is achieved by converging the same vertical track characteristics through multiple curved cavity tracks, achieving the purpose of multiple nonlinear solitary wave signal detection, improving the efficiency and accuracy of nondestructive testing of the material under test, and at the same time having important significance for the study of nonlinear solitary wave propagation characteristics.

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] A fractal structure input solitary wave metamaterial nondestructive testing device, comprising a fractal curved cavity track, a vertical cavity track, a group of scattered particles, impact particles, and signal collection particles; the fractal curved cavity track and the vertical cavity track are both circular tubular structures composed of white resin; the fractal curved cavity track is composed of a plurality of sub-curved cavity tracks and a plurality of mother curved cavity tracks, the bottoms of the plurality of mother curved cavity tracks are commonly connected to the top of the vertical cavity track, and the top of each mother curved cavity track is connected to the bottoms of a plurality of sub-curved cavity tracks The sub-curved cavity track, the main curved cavity track and the vertical cavity track are connected to each other; two openings are arranged opposite to each other on the track walls of the lower part of the vertical cavity track, each sub-curved cavity track and each main curved cavity track; the curved cavity track and the vertical cavity track are filled with a group of scattered particles, the bottom of the vertical cavity track is provided with signal collection particles, and the signal collection particles are provided with a piezoelectric sheet, which is connected to the external circuit through a wire and an opening, and the top opening of each sub-curved cavity track is used for the free entry of impact particles.

[0006] Furthermore, the elastic modulus of the fractal curved cavity track and the vertical cavity track is E = 2.65 GPa, the Poisson's ratio ν is 0.41, and the density ρ is 0.5 kg / m 3 .

[0007] Furthermore, the bulk particle group is composed of a number of Q235 stainless steel particle balls with a diameter of 19 mm, and the material and size of the impact particles are the same as those of the particle balls in the bulk particle group.

[0008] Furthermore, the signal collection particles are composed of a disc-shaped piezoelectric piece and two hemispherical particles. The disc-shaped piezoelectric piece is made of DM-5H, with a diameter of 19 mm and a thickness of 0.3 mm. The two hemispherical particles are both Q235 stainless steel with a diameter of 18.7 mm. Polyimide films are pasted on the mating surfaces of the two hemispherical particles, and the piezoelectric pieces are pasted between the polyimide films.

[0009] Furthermore, the outer diameter of the fractal curved cavity track and the vertical cavity track is 21 mm, and the inner diameter is 19 mm.

[0010] Furthermore, the opening diameter is smaller than the outer diameter of each particle ball in the dispersed particle group.

[0011] Furthermore, there are three main curved cavity tracks and nine sub-curved cavity tracks in the fractal curved cavity track.

[0012] The present invention also provides an application of a fractal structure input solitary wave metamaterial nondestructive testing device, which is used to excite nonlinear solitary wave signals at several positions to achieve several nondestructive tests on the same material to be tested.

[0013] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0014] 1. The device of the present invention realizes the effect of non-destructive testing of the same material to be tested by using multiple nonlinear solitary wave signals by converging the same vertical track characteristics through several curved cavity tracks, thereby achieving the purpose of multi-nonlinear solitary wave signal detection and improving the efficiency and accuracy of non-destructive testing of the material to be tested.

[0015] 2. Since there are multiple propagation tracks in the device of the present invention, under the stimulation of multiple nonlinear solitary wave signals, the device can achieve the effect of multiple signal detection of the same material to be tested. Compared with the previous elastic wave metamaterial device, it has the advantage of multi-signal detection and can be used in situations where non-destructive testing of the same material to be tested is required multiple times.

[0016] 3. Different from the conventional nonlinear solitary wave signal detection device, the present invention utilizes a multi-track structure, so that multiple detections of the same substance to be detected can be achieved under multiple excited nonlinear solitary wave signals.

[0017] 4. Since the present invention has a large number of input signal tracks, detection can be performed even if one of the input signals fails, thereby enhancing the anti-interference capability of the detection device.

[0018] 5. When multiple signals are stimulated at the same time, the disadvantage of weak signal in the case of single input can be avoided, so that the strength of the detection signal summarized by the device is significantly enhanced, thereby greatly improving the strength of the detection signal, and having more outstanding recognition ability for small and medium defects in the object to be detected.

[0019] 6. The nonlinear solitary wave signal nondestructive testing device of the present invention has a simple structure, flexible size, convenient installation, and can be applied to a variety of environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the structure of a metamaterial device provided by an embodiment of the present invention.

[0021] Figure 2 A schematic diagram of the top structure of a device provided in an embodiment of the present invention.

[0022] Figure 3 A half-section view of one of the channels of a device containing dispersed particles provided in an embodiment of the present invention.

[0023] Figure 4 Schematic diagram of multiple track dispersion of the device provided by the embodiment of the present invention

[0024] Figure 5 A schematic diagram of the structure of a signal acquisition particle provided by an embodiment of the present invention

[0025] Figure 6 A schematic diagram of a homogeneous particle chain composed of a dispersed particle group provided in an embodiment of the present invention.

[0026] Figure 7 The embodiment of the present invention provides a signal response diagram recorded by the signal collection particles at the bottom of the vertical cavity track 1 during the experiment when an impact particle of 0.313 m / s is excited at the top of the sub-bend cavity track 5.

[0027] Figure 8 The embodiment of the present invention provides a signal response diagram recorded by the signal collection particles at the bottom of the vertical cavity track 1 during the experiment when an impact particle of 0.313 m / s is excited at the top of the sub-bend cavity track 6.

[0028] Fig. 9 The embodiment of the present invention provides a signal response diagram recorded by the signal collection particles at the bottom of the vertical cavity track 1 during the experiment when an impact particle of 0.313 m / s is excited at the top of the sub-bend cavity track 7.

[0029] Fig.10 The embodiment of the present invention provides a signal response diagram recorded by the signal collection particles at the bottom of the vertical cavity track 1 during the experiment when an impact particle of 0.313 m / s is excited at the top of the sub-bend cavity track 8.

[0030] Fig.11 The embodiment of the present invention provides a signal response diagram recorded by the signal collection particles at the bottom of the vertical cavity track 1 during the experiment when an impact particle of 0.313 m / s is excited at the top of the sub-bend cavity track 9.

[0031] Fig.12 The embodiment of the present invention provides a signal response diagram recorded by the signal collection particles at the bottom of the vertical cavity track 1 during the experiment when an impact particle of 0.313 m / s is excited at the top of the sub-bend cavity track 10.

[0032] Fig.13 The embodiment of the present invention provides a signal response diagram recorded by the signal collection particles at the bottom of the vertical cavity track 1 during the experiment when an impact particle of 0.313 m / s is excited at the top of the sub-bend cavity track 11.

[0033] Fig.14 The embodiment of the present invention provides a signal response diagram recorded by the signal collection particles at the bottom of the vertical cavity track 1 during the experiment when an impact particle of 0.313 m / s is excited at the top of the sub-bend cavity track 12.

[0034] Fig.15The embodiment of the present invention provides a signal response diagram recorded by the signal collection particles at the bottom of the vertical cavity track 1 during the experiment when an impact particle of 0.313 m / s is excited at the top of the sub-bend cavity track 13. DETAILED DESCRIPTION

[0035] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0036] like Figures 1 to 5 As shown, an embodiment of the present invention provides a solitary wave metamaterial nondestructive testing device with fractal structure input, including a fractal curved cavity track, a vertical cavity track 1, a group of scattered particles, impact particles, and signal collection particles; the fractal curved cavity track and the vertical cavity track are both circular tubular structures composed of white resin; in this embodiment, the fractal curved cavity track is composed of nine sub-curved cavity tracks 5, 6, 7, 8, 9, 10, 11, 12, 13 and three mother curved cavity tracks 2, 3, 4, the bottoms of the mother curved cavity tracks 2, 3, 4 are connected to the top of the vertical cavity track 1, the top of the mother curved cavity track 2 is connected to the bottoms of the sub-curved cavity tracks 10, 12, 13; the mother curved cavity track 3 The top is connected with the bottom of the sub-curved cavity track 7, 9, 11; the top of the mother curved cavity track 4 is connected with the bottom of the sub-curved cavity track 5, 6, 8; each sub-curved cavity track and each mother curved cavity track are interconnected with the interior of the vertical cavity track 1; the lower part of the vertical cavity track 1, each sub-curved cavity track and each mother curved cavity track are provided with two narrow and long openings on the track wall; the curved cavity track and the vertical cavity track are filled with a group of scattered particles, the bottom of the vertical cavity track is provided with signal collection particles, and the signal collection particles are provided with a piezoelectric sheet, which is connected to the external circuit through wires and openings, and the top opening of each sub-curved cavity track is used for the free entry of impact particles.

[0037] The embodiment of the present invention proposes a fractal structure input solitary wave metamaterial nondestructive testing device. Since the nonlinear solitary wave signal can stably propagate in the homogeneous spherical particles, the effect of nondestructive testing of the same material under test by multiple nonlinear solitary wave signals can be achieved. The present invention provides a through track structure to enable the elastic wave metamaterial to achieve the effect of multi-track propagation of multiple excitation signals.

[0038] The scheme adopted by the fractal structure input solitary wave metamaterial nondestructive testing device of the embodiment of the present invention is: release impact ball particles with a height of 5 mm above the top of the sub-bend cavity tracks 5, 6, 7, 8, 9, 10, 11, 12, and 13 of the nondestructive testing device respectively, apply instantaneous impact excitation, and receive the detection excitation signal at the signal collection particles at the bottom of the vertical cavity track 1. Test the response signal of the same receiving end under the impact of the excitation ball with the same impact speed excited at multiple positions, so as to achieve the purpose of performing multiple nondestructive tests on the same material to be tested, thereby improving the efficiency and accuracy of nondestructive testing of the material to be tested.

[0039] In this embodiment, the bottom of the vertical cavity track 1 is not closed. When detecting the object to be detected, the signal collection particles are brought into contact with the surface of the object to be detected. By releasing the impact particle balls at the top of the sub-curved cavity track, the signal collection particles at the bottom of the vertical cavity track detect nonlinear solitary wave signals.

[0040] In the embodiment of the present invention, the fractal curved cavity track and the vertical cavity track are both circular tubular structures composed of white resin, with an elastic modulus of E=2.65 GPa, a Poisson's ratio ν of 0.41, and a density ρ of 0.5 kg / m 3 , Figure 2 Schematic diagram of the top view of the structure of the device of this embodiment. The outer diameter of each sub-bending cavity track, the main bending cavity track and the vertical track cavity is 21 mm, and the inner diameter is 19 mm.

[0041] Figure 3 A half-section view of one channel of a device containing dispersed particles provided in an embodiment of the present invention. The device contains Q235 stainless steel particles with a diameter of 19 mm; a large number of stainless steel particles form a dispersed particle group.

[0042] Figure 4 Schematic diagram of the dispersed state of multiple tracks in the device provided by the embodiment of the present invention. Two narrow and long openings are symmetrically opened on the tube wall of each curved cavity track and the vertical cavity track along the length direction of the track, and the width of the opening is 10mm, which is convenient for leading out the wire and adjusting the particle ball.

[0043] See Figure 5 The signal collection particle consists of a circular piezoelectric sheet and two hemispherical particles. The piezoelectric sheet has a diameter of 19 mm and a thickness of 3 mm. It is embedded between the two hemispheres and isolated from the hemispherical particles by a polyimide film. The hemispherical particle has a diameter of 18.7 mm and is made of Q235 stainless steel. The hemispherical particles, polyimide film and piezoelectric sheet are all connected to each other by pasting. A groove is provided on the docking surface of one of the hemispherical particles in each signal collection particle to accommodate the wire.

[0044] Figure 6The schematic diagram of a homogeneous particle chain composed of a group of bulk particles under static preload provided in the embodiment of the present invention is a typical one-dimensional homogeneous spherical particle chain composed of identical solid particle balls. The particle balls are made of Q235 stainless steel balls. The deformation process of the contact area between two adjacent particle balls satisfies the Hertz contact law:

[0045] F=kδ 3 / 2

[0046] In the formula, F represents the dynamic contact force, k represents the contact stiffness between particles, and δ represents the displacement difference between the centers of two adjacent particles.

[0047] Among them, the contact stiffness k is related to the elastic modulus and geometric parameters of the particles, and its expression is:

[0048]

[0049] Where E represents the elastic modulus of the particle, υ represents the Poisson's ratio of the moving particle, and R represents the radius of the particle.

[0050] When there is no external impact load, the motion equation of the nth spherical particle can be described as:

[0051]

[0052] In the formula, m represents the mass of the pellet; u n Represents the displacement of the nth ball particle relative to the initial position.

[0053] The working principle of the fractal structure input solitary wave metamaterial nondestructive testing device involved in the above embodiment is as follows:

[0054] The discrete particle model is a commonly used numerical model for particle dynamics and is widely used in the study of the mechanical behavior of granular materials. In dynamic analysis, particles can be simplified to mass points, and nonlinear springs are used to connect particles. The wave behavior of granular materials is analyzed by calculating the equations of motion for the interaction between particles. When the impact particle hits the particle chain and introduces energy, an incident nonlinear solitary wave propagating at a stable speed can be formed. The nonlinear solitary wave signal recorded by the signal acquisition particle is generated by the deformation force of the piezoelectric plate at the center.

[0055] Figure 7This is a transient excitation signal diagram of the signal collection particle detection at the bottom of the vertical cavity track 1. A small impact particle ball with a height of 5 mm is released at the top of the sub-bend cavity track 5 of the device, and a transient impact excitation is applied to the particle chain to generate a nonlinear solitary wave signal. The nonlinear solitary wave signal propagating in the system is detected at the vertical cavity track 1. At this time, the time to reach the signal collection particle is about 0.97ms. In the above model, when the impact particle is the same size as the particle material in the particle chain, the impact particle hits the particle chain to introduce an incident nonlinear solitary wave. The propagation speed v of the incident nonlinear solitary wave can be expressed as:

[0056] v=(16 / 25) 1 / 5 (2R)(0.682Vk 2 / m 2 ) 1 / 5

[0057] ≈1.694R(Vk 2 / m 2 ) 1 / 5

[0058] Where v represents the incident velocity of the nonlinear solitary wave, and V represents the impact velocity of the impacting particle.

[0059] Figures 8 to 15 The nonlinear solitary wave signal response diagrams propagated in the system of the signal collection particle detection at the bottom of the vertical cavity track 1 when the impact particle ball with a height of 5 mm is released at the top of the sub-bend cavity track 6 to 13 of the device. The impact particle ball applies instantaneous impact excitation to the particle chain to generate a nonlinear solitary wave signal. At the same impact speed, the nonlinear solitary wave signal propagated in the vertical cavity track 1 detection system has a time of about 0.97ms to reach each point.

[0060] In summary, compared with the previous nonlinear solitary wave signal detection device, the device of the embodiment of the present invention adopts multiple tracks to stimulate the propagation of nonlinear solitary waves in the particle ball chain. By adopting a structural form of multiple fractal multi-curved track propagation, nonlinear solitary wave signals can be stimulated at multiple positions, thereby achieving the purpose of multiple nondestructive detection of the same material to be tested and enhancing the detection of solitary wave signals, thereby improving the efficiency and accuracy of nondestructive detection of the material to be tested.

[0061] The device of the present invention only tests a certain transient impact excitation, but by adjusting the impact particle ball, it is possible to realize the detection of nonlinear solitary waves generated by impact particles with different initial velocities.

[0062] The whole device is made of white resin through 3D printing. The structure of the device is simple, easy to purchase and assemble, and very easy to operate after the design is completed.

[0063] Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of an embodiment, and the modules or processes in the accompanying drawings are not necessarily required to implement the present invention.

[0064] The device and system embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without creative work.

[0065] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "one", "said", and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. In addition, the "connection" or "coupling" used herein may include wireless connection or coupling. The term "and / or" used herein includes any unit and all combinations of one or more associated listed items.

Claims

1. A fractal structure input solitary wave metamaterial nondestructive testing device, characterized in that: It includes a fractal curved cavity track, a vertical cavity track, a group of scattered particles, impact particles, and signal collection particles; the fractal curved cavity track and the vertical cavity track are both tubular structures made of white resin; the fractal curved cavity track is composed of a number of sub-curved cavity tracks and a number of mother curved cavity tracks, the bottoms of the several mother curved cavity tracks are commonly connected to the top of the vertical cavity track, and the top of each mother curved cavity track is connected to the bottoms of a number of sub-curved cavity tracks; the interiors of the sub-curved cavity track, the mother curved cavity track and the vertical cavity track are interconnected; two openings are oppositely provided on the track walls of the lower part of the vertical cavity track, each sub-curved cavity track and each mother curved cavity track; the curved cavity track and the vertical cavity track are both filled with a group of scattered particles, the bottom of the vertical cavity track is provided with signal collection particles, and the signal collection particles are provided with a piezoelectric sheet, which is connected to the external circuit through a wire and an opening, and the top opening of each sub-curved cavity track is used for the free entry of impact particles.

2. The solitary wave metamaterial nondestructive testing device with fractal structure input according to claim 1, characterized in that: The elastic modulus of the fractal curved cavity track and the vertical cavity track is E = 2.65 GPa, the Poisson's ratio ν is 0.41, and the density ρ is 0.5 kg / m 3 .

3. The solitary wave metamaterial nondestructive testing device with fractal structure input according to claim 1, characterized in that: The bulk particle group is composed of a number of Q235 stainless steel particle balls with a diameter of 19 mm. The material and size of the impact particles are the same as those of the particle balls in the bulk particle group.

4. The solitary wave metamaterial nondestructive testing device with fractal structure input according to claim 1, characterized in that: The signal collection particles consist of a disc-shaped piezoelectric piece and two hemispherical particles. The disc-shaped piezoelectric piece is made of DM-5H with a diameter of 19 mm and a thickness of 0.3 mm. The two hemispherical particles are both Q235 stainless steel with a diameter of 18.7 mm. Polyimide films are pasted on the butt surfaces of the two hemispherical particles, and the piezoelectric pieces are pasted between the polyimide films.

5. A fractal structure input solitary wave metamaterial nondestructive testing device according to claim 1 or 2, characterized in that: The outer diameter of the fractal curved cavity track and the vertical cavity track is 21 mm and the inner diameter is 19 mm.

6. The solitary wave metamaterial nondestructive testing device with fractal structure input according to claim 1, characterized in that: The opening diameter is smaller than the outer diameter of each particle ball in the dispersed particle group.

7. The solitary wave metamaterial nondestructive testing device with fractal structure input according to claim 1, characterized in that: There are three main curved cavity tracks and nine sub-curved cavity tracks in the fractal curved cavity track.

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