CN114527196A

CN114527196A - Fractal structure input solitary wave metamaterial nondestructive testing device and application

Info

Publication number: CN114527196A
Application number: CN202210147787.9A
Authority: CN
Inventors: 王毅泽; 陆琦
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2022-02-17
Filing date: 2022-02-17
Publication date: 2022-05-24

Abstract

The invention discloses a fractal structure input solitary wave metamaterial nondestructive testing device and application thereof, wherein the device comprises a fractal bending cavity track, a vertical cavity track, discrete particle groups, impact particles and signal acquisition particles; the fractal bending cavity track consists of a plurality of sub bending cavity tracks and a plurality of mother bending cavity tracks, the bottoms of the plurality of mother bending cavity tracks are communicated with the top of the vertical cavity track, and the top of each mother bending cavity track is communicated with the bottoms of the plurality of sub bending cavity tracks; two openings are oppositely formed in the lower portion of the vertical cavity track, the track wall of each secondary bent cavity track and the track wall of each primary bent cavity track; all pack in crooked cavity track and the vertical cavity track and have scattered solid particle group, the orbital bottom of vertical cavity is equipped with the signal acquisition granule, is equipped with the piezoelectric patches in the signal acquisition granule, and the piezoelectric patches passes through wire and trompil and external circuit connection, and the orbital top trompil of every sub-crooked cavity is used for assaulting the granule and freely gets into.

Description

Fractal structure input solitary wave metamaterial nondestructive testing device and application

Technical Field

The invention relates to the technical field of artificial elastic wave metamaterial, in particular to a fractal structure input solitary wave metamaterial nondestructive testing device.

Background

In recent years, phononic crystals have attracted a great deal of interest to researchers in many fields, and are artificial periodic structures in which material constants are periodically changed, and granular phononic crystals and elastic wave metamaterials are currently being studied as one of the more forms. The elastic particles in contact with each other in the particle phononic crystal satisfy the Hertz's law of contact, and the nonlinearity thereof also mainly comes from contact deformation between adjacent particles. The nonlinear wave propagation of the particle phononic crystal shows abundant fluctuation characteristics and shows wide application prospects. The one-dimensional particle chain composed of the same particles can form highly nonlinear solitary waves, can keep stable propagation at a long distance, and the phenomena of reflection, transmission and the like of the waves are related to the properties of contacted substances. It is these special propagation characteristics that make the one-dimensional particle chain a good carrier for highly nonlinear solitary waves. With the development of nondestructive testing technology and the improvement of nondestructive testing instruments, people have higher requirements on nondestructive testing technology and the like, so that the one-dimensional particle chain solitary wave nondestructive testing method is widely concerned. Based on the advantages of small size, high portability and the like of isolated wave flaw detection in a particle chain, the isolated wave metamaterial can be used in many engineering applications, including the fields of vibration absorbers, impurity detectors, acoustic diodes, nondestructive testing and the like.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a fractal structure input solitary wave metamaterial nondestructive testing device. The invention can excite nonlinear solitary wave signals at multiple positions by adopting a structural form of fractal multi-bending cavity track propagation, thereby realizing multiple nondestructive detection of the same measured substance. The effect of carrying out nondestructive testing on the same tested substance by a plurality of nonlinear solitary wave signals is realized by converging the characteristics of the same vertical track through a plurality of curved cavity tracks, the purpose of detecting the nonlinear solitary wave signals is achieved, the efficiency and the accuracy of nondestructive testing on the tested substance are improved, and the method has important significance for researching the propagation characteristics of the nonlinear solitary wave.

The purpose of the invention is realized by the following technical scheme:

a fractal structure input solitary wave metamaterial nondestructive testing device comprises a fractal bending cavity track, a vertical cavity track, a discrete particle group, impact particles and signal acquisition particles; the fractal bending cavity track and the vertical cavity track are both of circular tube-shaped structures consisting of white resin; the fractal bending cavity track consists of a plurality of sub bending cavity tracks and a plurality of mother bending cavity tracks, the bottoms of the plurality of mother bending cavity tracks are communicated with the top of the vertical cavity track, and the top of each mother bending cavity track is communicated with the bottoms of the plurality of sub bending cavity tracks; the interiors of the secondary bent cavity track, the primary bent cavity track and the vertical cavity track are communicated with each other; two openings are oppositely formed in the lower portion of the vertical cavity track, the track wall of each secondary bent cavity track and the track wall of each primary bent cavity track; bulk particle groups are filled in the bending cavity track and the vertical cavity track, signal acquisition particles are arranged at the bottom of the vertical cavity track, piezoelectric patches are arranged in the signal acquisition particles and are connected with an external circuit through leads and openings, and the openings at the top of each sub-bending cavity track are used for allowing impact particles to freely enter.

Furthermore, the modulus of elasticity of the fractal bending cavity track and the vertical cavity track is 2.65GPa, the Poisson ratio v is 0.41, and the density rho is 0.5kg/m³。

Furthermore, the discrete particle group consists of a plurality of Q235 stainless steel particle balls with the diameter of 19mm, and the material and the size of the impact particles are the same as those of the particle balls in the discrete particle group.

Furthermore, the signal acquisition particles consist of a disc-shaped piezoelectric piece and two hemispherical particles, the disc-shaped piezoelectric piece is DM-5H, the diameter is 19mm, the thickness is 0.3mm, and the two hemispherical particles are both made of Q235 stainless steel with the diameter of 18.7 mm; polyimide films are pasted on the butt joint surfaces of the two hemispherical particles, and the piezoelectric sheets are pasted between the polyimide films.

Further, the outer diameter of the fractal bending cavity track and the outer diameter of the fractal bending cavity track are 21mm, and the inner diameter of the fractal bending cavity track is 19 mm.

Further, the diameter of the opening is smaller than the outer diameter of each particle ball in the discrete particle group.

Furthermore, the fractal bending cavity tracks comprise three main bending cavity tracks and nine sub bending cavity tracks.

The invention also provides application of the solitary wave metamaterial nondestructive testing device with fractal structure input, which is used for exciting nonlinear solitary wave signals at a plurality of positions to realize nondestructive testing of the same tested substance for a plurality of times.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

1. the device realizes the effect of carrying out nondestructive testing on the same tested substance by a plurality of nonlinear solitary wave signals by converging the characteristics of the same vertical track through a plurality of curved cavity tracks, achieves the aim of detecting the nonlinear solitary wave signals, and improves the efficiency and the accuracy of the nondestructive testing on the tested substance.

2. Because the device has a plurality of propagation tracks, the device can realize the effect of detecting the same substance to be detected by a plurality of signals under the excitation of a plurality of nonlinear solitary wave signals. Compared with the traditional elastic wave metamaterial device, the device has the advantage of multi-signal detection, and can be used for the situation that the same substance to be detected needs to be subjected to nondestructive detection for multiple times.

3. Different from the traditional nonlinear solitary wave signal detection device, the invention utilizes a multi-track structure, thus realizing the multiple detection of the same detected substance under the condition of a plurality of excited nonlinear solitary wave signals.

4. Because the number of the input signal tracks is large, if one input signal fails, the detection can be carried out, so that the anti-interference capability of the detection device is enhanced.

5. When a plurality of signals are excited simultaneously, the defect of weak signals under the condition of single input can be avoided, the detection signal intensity summarized by the device is obviously enhanced, the detection signal intensity can be greatly improved, and the device has outstanding identification capability on small and medium-sized defects of objects to be detected.

6. The nonlinear solitary wave signal nondestructive testing device has the advantages of simple structural form, flexible size and convenience in installation, and is suitable for various environments.

Drawings

Fig. 1 is a schematic structural diagram of a metamaterial device according to an embodiment of the present invention.

Fig. 2 is a schematic top view of the apparatus according to the embodiment of the present invention.

Fig. 3 is a half sectional view of one channel of the apparatus containing discrete particles according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of a device with multiple tracks dispersed according to an embodiment of the present invention

FIG. 5 is a schematic structural diagram of a signal acquisition particle according to an embodiment of the present invention

Fig. 6 is a schematic view of a homogeneous particle chain composed of a group of discrete particles according to an embodiment of the present invention.

FIG. 7 is a signal response graph of a signal acquisition particle record at the bottom of the vertical cavity track 1 during an experiment when a 0.313m/s impact particle is excited at the top end of the sub-curved cavity track 5 according to an embodiment of the present invention.

FIG. 8 is a signal response graph of a signal acquisition particle record at the bottom of the vertical cavity track 1 during an experiment when a 0.313m/s impact particle is excited at the top end of the sub-curved cavity track 6 according to an embodiment of the present invention.

FIG. 9 is a signal response graph of a signal acquisition particle record at the bottom of the vertical cavity track 1 during an experiment when a 0.313m/s impact particle is excited at the top end of the sub-curved cavity track 7 according to an embodiment of the present invention.

FIG. 10 is a signal response graph of a signal acquisition particle record at the bottom of the vertical cavity track 1 during an experiment when a 0.313m/s impact particle is excited at the top end of the sub-curved cavity track 8 according to an embodiment of the present invention.

FIG. 11 is a signal response graph of a signal acquisition particle record at the bottom of the vertical cavity track 1 during an experiment when a 0.313m/s impact particle is excited at the top end of the sub-curved cavity track 9 according to an embodiment of the present invention.

FIG. 12 is a signal response graph of a signal acquisition particle record at the bottom of the vertical cavity track 1 during an experiment when a 0.313m/s impact particle is excited at the top end of the sub-curved cavity track 10 according to an embodiment of the present invention.

FIG. 13 is a signal response graph of a signal acquisition particle record at the bottom of the vertical cavity track 1 during an experiment when a 0.313m/s impact particle is excited at the top end of the sub-curved cavity track 11 according to an embodiment of the present invention.

FIG. 14 is a signal response graph of a signal acquisition particle record at the bottom of the vertical cavity track 1 during an experiment when a 0.313m/s impact particle is excited at the top end of the sub-curved cavity track 12 according to an embodiment of the present invention.

FIG. 15 is a signal response graph of a signal acquisition particle record at the bottom of the vertical cavity track 1 during an experiment when a 0.313m/s impact particle is excited at the top end of the sub-curved cavity track 13 according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

As shown in fig. 1 to 5, an embodiment of the present invention provides a fractal structure input solitary wave metamaterial nondestructive testing apparatus, including a fractal bending cavity track, a vertical cavity track 1, a discrete particle group, an impact particle, and a signal acquisition particle; the fractal bending cavity track and the vertical cavity track are both of circular tube-shaped structures consisting of white resin; in the embodiment, the fractal curved cavity track consists of nine sub

curved cavity tracks

5, 6, 7, 8, 9, 10, 11, 12 and 13 and three mother curved

cavity tracks

2, 3 and 4, wherein the bottoms of the mother curved

cavity tracks

2, 3 and 4 are communicated with the top of the vertical cavity track 1, and the top of the mother curved cavity track 2 is communicated with the bottoms of the sub

curved cavity tracks

10, 12 and 13; the top of the mother bending cavity track 3 is communicated with the bottoms of the son

bending cavity tracks

7, 9 and 11; the top of the female curved cavity track 4 is communicated with the bottoms of the male curved

cavity tracks

5, 6 and 8; each sub-bending cavity track and each mother bending cavity track are communicated with the inside of the vertical cavity track 1; two narrow and long openings are oppositely formed in the lower part of the vertical cavity track 1, the track wall of each sub-bent cavity track and the track wall of each main bent cavity track; bulk particle groups are filled in the bending cavity track and the vertical cavity track, signal acquisition particles are arranged at the bottom of the vertical cavity track, piezoelectric patches are arranged in the signal acquisition particles and are connected with an external circuit through wires and open holes, and the open hole at the top of each sub-bending cavity track is used for allowing impact particles to freely enter.

The embodiment of the invention provides a fractal structure input solitary wave metamaterial nondestructive testing device, and nonlinear solitary wave signals can be stably propagated in homogeneous small spherical particles, so that the effect of performing nondestructive testing on the same tested substance by a plurality of nonlinear solitary wave signals is realized. The through track structure provided by the invention enables the elastic wave metamaterial to achieve the effect of multi-track propagation of a plurality of excitation signals.

The scheme adopted by the solitary wave metamaterial nondestructive testing device input by the fractal structure in the embodiment of the invention is as follows: impact small ball particles with the height of 5mm are respectively released above the top ends of the

sub-bending cavity rails

5, 6, 7, 8, 9, 10, 11, 12 and 13 of the nondestructive testing device, instantaneous impact excitation is applied, and signal acquisition particles at the bottom of the vertical cavity rail 1 receive detection excitation signals. The response signal of the same receiving end under the impact of the small excitation ball at the same impact speed excited by multiple positions is tested, the aim of carrying out multiple times of nondestructive testing on the same tested substance is fulfilled, and the efficiency and the accuracy of the nondestructive testing on the tested substance are improved.

In this embodiment, the bottom of the vertical cavity track 1 is not closed, when an object to be detected is detected, the signal acquisition particles are in surface contact with the object to be detected, and the impact particle balls are released at the top end of the sub-bending cavity track, so that the signal acquisition particles at the bottom of the vertical cavity track detect nonlinear solitary wave signals.

In the embodiment of the invention, the fractal bending cavity track and the vertical cavity track are both of circular tube-shaped structures consisting of white resin, the elastic modulus E is 2.65GPa, the Poisson ratio v is 0.41, and the density rho is 0.5kg/m³FIG. 2 is a schematic top view of the device of this embodiment, each of the sub-curved cavity track, the main curved cavity track andthe vertical track cavity has an outer diameter of 21mm and an inner diameter of 19 mm.

Fig. 3 is a half sectional view of one channel of the apparatus containing discrete particles according to an embodiment of the present invention. Q235 stainless steel particles with the diameter of 19mm are filled in the device; the plurality of stainless steel particles comprise a discrete particle population.

Fig. 4 is a schematic diagram illustrating a state in which a plurality of tracks are dispersed in an apparatus according to an embodiment of the present invention. Two narrow and long openings along the length direction of the rail are symmetrically formed in the pipe wall of each section of the bent cavity rail and the pipe wall of each section of the vertical cavity rail, the width of each opening is 10mm, and therefore a wire can be conveniently led out and a particle ball can be conveniently adjusted.

Referring to fig. 5, the signal acquisition particles are composed of a circular piezoelectric plate and two hemispherical particles. The piezoelectric plate is 19mm in diameter and 3mm in thickness, is embedded between two hemispheres, and is isolated from hemispherical grains by a polyimide film. The diameter of the hemisphere particles is 18.7mm, and the material is Q235 stainless steel. The hemispherical particles, the polyimide film and the piezoelectric sheet are all connected with each other in a pasting mode, and a groove is formed in the butt joint surface of one of the hemispherical particles in each signal acquisition particle and used for accommodating a lead.

Fig. 6 is a schematic view of a homogeneous particle chain composed of discrete particle groups under static pre-pressure provided by an embodiment of the invention, and the homogeneous particle chain is a typical one-dimensional homogeneous spherical particle chain composed of the same solid particle globules. The granular balls are made of Q235 stainless steel balls. The deformation process of the contact area between two adjacent particle spheres meets the Hertz contact law:

F＝kδ^3/2

in the formula, F represents dynamic contact force, k represents contact rigidity between particles, and delta represents displacement difference of the sphere centers of two adjacent particles.

The contact rigidity k is related to the elastic modulus and the geometric parameters of the particles, and the expression is as follows:

wherein E represents the elastic modulus of the particle, upsilon represents the Poisson's ratio of the moving particle, and R represents the radius of the particle.

In the absence of an external impact load, the equation of motion for the nth pellet can be described as:

wherein m represents the mass of the pellet; u. of_nRepresenting the displacement of the nth pellet relative to the initial position.

The working principle of the solitary wave metamaterial nondestructive testing device with fractal structure input in the embodiment is as follows:

the discrete particle model is a commonly used numerical model of particle dynamics, and is widely applied to research on mechanical behavior of particle materials. During kinetic analysis, the particles can be simplified into mass points, and meanwhile, the particles are connected through nonlinear springs. And analyzing the fluctuation behavior of the particle material by calculating a motion equation of the particle-particle interaction. When impact particles impact a particle chain to introduce energy, an incident nonlinear solitary wave propagating at a stable speed can be formed, and a nonlinear solitary wave signal recorded by the signal acquisition particles is used as a piezoelectric sheet deformation force at the center.

Fig. 7 is a diagram of transient excitation signals of signal acquisition particle detection at the bottom of a vertical cavity track 1, wherein impact particle pellets with the height of 5mm are released at the top end of a sub-bending cavity track 5 of the device, transient impact excitation is applied to a particle chain to generate a nonlinear soliton signal, and the nonlinear soliton signal propagated in a system is detected at the vertical cavity track 1, wherein the time of reaching the signal acquisition particles is about 0.97 ms. In the above model, when the impact particle is the same as the particle material size in the particle chain, the impact particle impacts the particle chain to introduce an incident nonlinear isolated wave, and the propagation velocity v of the incident nonlinear isolated wave can be expressed as:

v＝(16/25)^1/5(2R)(0.682Vk²/m²)^1/5

≈1.694R(Vk²/m²)^1/5

where V represents the incident velocity of the nonlinear solitary wave and V represents the impact velocity of the impacting particle.

Fig. 8 to 15 are response diagrams of nonlinear soliton wave signals propagated in the system for detecting signal collection particles at the bottom of the vertical cavity rail 1 when impact particle pellets with the height of 5mm are released at the top ends of the sub-curved cavity rails 6 to 13 of the device respectively. The impact particle ball applies instantaneous impact excitation to the particle chain to generate a nonlinear solitary wave signal, and under the same impact speed, the time of reaching each point is about 0.97ms when the nonlinear solitary wave signal propagates in the vertical cavity track 1 detection system.

In summary, compared with the conventional nonlinear solitary wave signal detection device, the device provided by the embodiment of the invention adopts multiple tracks to excite the propagation of nonlinear solitary waves in a particle ball chain, and adopts a structural form of propagation of multiple fractal multiple bending tracks, so that the nonlinear solitary wave signal can be excited at multiple positions, the purposes of performing multiple nondestructive detections on the same substance to be detected and enhancing the solitary wave signal detection are achieved, and the efficiency and the accuracy of the nondestructive detection on the substance to be detected are improved.

The device only tests a certain transient impact excitation, but can realize the detection of nonlinear solitary waves generated by impact particles with different initial speeds by adjusting the impact particle balls.

The whole device is formed by 3D printing white resin. The device has simple structural design, is easy to purchase and assemble, and is very easy to operate after the design is finished.

Those of ordinary skill in the art will understand that: the figures are merely schematic representations of one embodiment, and the blocks or flow diagrams in the figures are not necessarily required to practice the present invention.

The above-described embodiments of the apparatus and system are merely illustrative, and the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. One of ordinary skill in the art can understand and implement without inventive effort.

As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or coupled. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Claims

1. A fractal structure input solitary wave metamaterial nondestructive testing device is characterized by comprising a fractal bending cavity track, a vertical cavity track, discrete particle groups, impact particles and signal acquisition particles; the fractal bending cavity track and the vertical cavity track are both of circular tube-shaped structures consisting of white resin; the fractal bending cavity track consists of a plurality of sub bending cavity tracks and a plurality of mother bending cavity tracks, the bottoms of the plurality of mother bending cavity tracks are communicated with the top of the vertical cavity track, and the top of each mother bending cavity track is communicated with the bottoms of the plurality of sub bending cavity tracks; the interiors of the secondary bent cavity track, the primary bent cavity track and the vertical cavity track are communicated with each other; two openings are oppositely formed in the lower portion of the vertical cavity track, the track wall of each secondary bent cavity track and the track wall of each primary bent cavity track; bulk particle groups are filled in the bending cavity track and the vertical cavity track, signal acquisition particles are arranged at the bottom of the vertical cavity track, piezoelectric patches are arranged in the signal acquisition particles and are connected with an external circuit through leads and openings, and the openings at the top of each sub-bending cavity track are used for allowing impact particles to freely enter.

2. The fractal-structure-input solitary wave metamaterial nondestructive testing device as claimed in claim 1, wherein the fractal bending cavity rail and the vertical cavity rail have elastic modulus of E-2.65 GPa, poisson ratio v of 0.41, and density p of 0.5kg/m³。

3. The solitary wave metamaterial nondestructive testing device as claimed in claim 1, wherein the discrete particle group is composed of a plurality of Q235 stainless steel particle balls with a diameter of 19mm, and the impact particles are the same in material and size as the particle balls in the discrete particle group.

4. The solitary wave metamaterial nondestructive testing device with fractal structure input as claimed in claim 1 wherein the signal collection particles are composed of a disc-shaped piezoelectric plate and two hemispherical particles, the disc-shaped piezoelectric plate is DM-5H, the diameter is 19mm, the thickness is 0.3mm, and the two hemispherical particles are both Q235 stainless steel with the diameter of 18.7 mm; polyimide films are pasted on the butt joint surfaces of the two hemispherical particles, and the piezoelectric sheets are pasted between the polyimide films.

5. The fractal-structure-input soliton wave metamaterial nondestructive testing device as claimed in claim 1 or 2, wherein the fractal bending cavity track and the vertical cavity track have an outer diameter of 21mm and an inner diameter of 19 mm.

6. The fractal-structure-input soliton metamaterial nondestructive testing device as claimed in claim 1, wherein the diameter of the opening is smaller than the outer diameter of each particle sphere in the discrete particle group.

7. The fractal-structure-input solitary wave metamaterial nondestructive testing device as claimed in claim 1, wherein the fractal bending cavity rails comprise three mother bending cavity rails and nine daughter bending cavity rails.

8. The application of the fractal structure input solitary wave metamaterial nondestructive testing device is characterized by being used for exciting nonlinear solitary wave signals at a plurality of positions to realize nondestructive testing on the same tested substance for a plurality of times.