Elastic wave invisibility device of ribbed plate mechanical metamaterial with active control function

Abstract

The application discloses an elastic wave stealth device of rib plate mechanical metamaterial with an active control function, which comprises a rib plate, a piezoelectric sheet and an active control circuit; the rib plate is made of uniform ABS material and is composed of a long strip-shaped reinforcing rib and a rectangular base plate; the piezoelectric sheet and the reinforcing rib are arranged on two surfaces of the rectangular base plate respectively; a circular through hole with a radius of 78 mm is formed in the center of the rib plate; the piezoelectric sheet is adhered to one side surface of the rib plate around the through hole; each piezoelectric sheet is connected with the active control circuit to form a mechanical metamaterial capable of being actively controlled; the length and the width of the rectangular base plate are at least 5 times greater than the thickness of the rectangular base plate; the height of the reinforcing rib is less than the thickness of the rectangular base plate; the piezoelectric sheet is a thin sheet with positive and negative poles and in a rectangular shape, is of a PZT-5H type and has an initial elastic modulus of 56 Gpa.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of artificial elastic wave super-materials, and particularly relates to an elastic wave stealth device of a ribbed plate mechanical super-material with an external circuit active adjustment control function. BACKGROUND

[0002] A large number of weight-reducing structures are used in aerospace equipment to reduce the weight of the spacecraft and improve the carrying efficiency, such as the plate shell structure with reinforcing ribs used in a satellite. In the process of ignition and propulsion of a carrier rocket, these plate shell structures are often affected by great vibrations and noises generated from the engine or the friction between the carrier and the air. When these vibration or noise excitations act on the plate shell structure with holes, the dynamic stress concentration will inevitably be generated, thereby causing the destruction of the satellite structure.

[0003] Traditional vibration isolation devices are mostly flexible connections for absorbing vibrations, or achieve the purpose by changing the contact mode and removing the connection. The device structure occupies a relatively large space, and with the precision of aerospace equipment and the complexity of the structure of its parts, it is difficult to flexibly change the internal structure of the vibration isolation device and adapt to more and more complex vibration isolation scenes such as breaking through the original frequency range, and it is difficult to effectively reduce the elastic wave scattering amplitude and dynamic stress concentration, thereby making it difficult to play an advantage on precise equipment such as satellites.

[0004] With the gradual deepening of the research on vibration isolation and noise reduction, artificial periodic mechanical super-materials have attracted more and more attention due to their excellent vibration and elastic wave control capabilities. The significance of designing and applying super-materials is to improve the local concentration of vibration or elastic wave energy around the hole through artificial periodic structures, and to change the physical property parameters of the designed elastic wave stealth device of the super-material by introducing an active control circuit, so as to adapt to different wave control scenes and flexibly and effectively realize elastic wave stealth. SUMMARY

[0005] The purpose of the present application is to overcome the deficiencies in the prior art, and to provide an elastic wave stealth device of a ribbed plate mechanical super-material with an active control function. The device realizes the elastic wave active control stealth function of the plate shell structure with reinforcing ribs, and can flexibly adapt to a larger frequency range to realize elastic wave stealth.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] The application discloses an elastic wave stealth device of a ribbed plate mechanical metamaterial with an active control function, which comprises a ribbed plate, a piezoelectric sheet and an active control circuit.

[0008] The length and the width of the rectangular base plate are at least 5 times larger than the thickness of the rectangular base plate, and the height of the reinforcing rib is smaller than the thickness of the rectangular base plate.

[0009] The piezoelectric sheet is a thin sheet with positive and negative poles and in a rectangular shape, and is of a PZT-5H type with an initial elastic modulus of 56 Gpa.

[0010] Further, the reinforcing rib is integrally formed with the rectangular base plate, and the reinforcing rib is uniformly distributed on one side of the ribbed plate to form a grid shape.

[0011] Further, the piezoelectric sheet is distributed in annular layers around the periphery of the through hole, the piezoelectric sheets in each annular layer are uniformly distributed, and the number of annular layers and the number of piezoelectric sheets in each annular layer are adjusted as required.

[0012] Further, the piezoelectric sheet is distributed in 4 annular layers along the radial direction of the through hole, and the number of piezoelectric sheets in each annular layer from the center of the through hole to the outside is 24, 24, 30 and 36 respectively.

[0013] Further, each piezoelectric sheet is perpendicular to the radial direction of the through hole in the length direction.

[0014] Further, the active control circuit comprises a multiplexer, an analog-to-digital converter, a microcontroller, an adjusting button and an OLED display screen; the working process of the active control circuit is as follows: a frequency signal from one piezoelectric sheet is transmitted to the analog-to-digital converter through the multiplexer for signal conversion, is sent to the microcontroller for signal judgment and processing according to a set program, and the fluctuation frequency at the moment is displayed on the OLED display screen; after the adjusting button is pressed, the complex impedance of the active control circuit is changed by the microcontroller, the electrical control signal generated by the microcontroller is applied to other piezoelectric sheets through the analog-to-digital converter and the multiplexer to change the corresponding elastic modulus, and the purpose of active control is achieved.

[0015] Further, after the active control circuit adjusts the elastic modulus of the piezoelectric sheet, the bending wave stealth frequency interval of the rib plate mechanical metamaterial elastic wave stealth device is 4250Hz-4310Hz.

[0016] Compared with the prior art, the technical scheme of the present application has the following beneficial effects:

[0017] 1. The device can effectively adjust the elastic wave propagation in the rib plate, suppress the scattering amplitude and dynamic stress concentration around the hole of the rib plate, and widen the frequency interval of the elastic wave stealth through active control.

[0018] 2. Based on the design of artificial periodic elastic wave metamaterial, the piezoelectric material is attached to the hole of the rib plate, without using flexible connection, changing contact, and removing connection, etc. Compared with the traditional vibration isolation and noise reduction structure, it is more stable, lighter and has a longer service life.

[0019] 3. The device uses a combination of piezoelectric sheets and active control circuits to regulate the elastic wave of the rib plate. The components are easy to obtain and process, and some parts are standard parts that can be purchased. Compared with general electronic control structures, it has the advantages of low cost, easy adjustment and high reliability.

[0020] 4. The device has the advantages of simple structure, small space occupation, no need to disassemble and damage the existing piezoelectric sheet arrangement structure when dealing with high-frequency fluctuation stealth, wide control frequency range, flexible adaptation to different elastic wave stealth working conditions, high intelligence, and low energy consumption.

[0021] 5. The piezoelectric sheets are evenly distributed along the hole of the rib plate in 4 circles, with 24, 24, 30 and 36 pieces in each circle, respectively. The number of circles and the number of pieces in each circle can be appropriately increased or decreased according to other calculations and control needs. The above setting can make the stealth device applicable to different size target stealth situations, and can be used for specific frequency elastic wave and vibration after the active control circuit works, to realize vibration protection of precision equipment. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The overall structure diagram of the elastic wave stealth device provided by the embodiment of the present application.

[0023] Figure 2 The local split structure diagram of the elastic wave stealth device provided by the embodiment of the present application.

[0024] Figure 3 The variable elastic modulus circuit principle diagram provided by the embodiment of the present application.

[0025] Figure 4 The working process schematic diagram of the active control circuit provided for the embodiment of the present application is shown.

[0026] Figure 5 The finite element simulation effect diagram when the active control is not started for the embodiment of the present application is shown.

[0027] Figure 6 The finite element simulation effect diagram when the active control is started for the embodiment of the present application is shown.

[0028] Figure 7 The acceleration value sampling comparison diagram of 13 points when the active control is not started / stared for the embodiment of the present application is shown.

[0029] The reference signs: 1-rib plate, 11-rectangular base plate, 12-stiffening rib, 2-piezoelectric sheet, 3-active control circuit DETAILED DESCRIPTION

[0030] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application, and cannot be interpreted as a limitation on the present application.

[0031] The position and width of the elastic wave band gap in the mechanical metamaterial can be artificially controlled by changing the geometric and material parameters of the artificial periodic structure. The elastic wave stealth device of the rib plate mechanical metamaterial with active control function is proposed in the embodiment of the present application. For the hole target on the plate shell structure with stiffening ribs, the artificial metamaterial is designed based on piezoelectric material, and the elastic modulus of the piezoelectric material is changed through the active control circuit to realize the active control of the different frequency to avoid the local concentration of the elastic wave energy and the propagation characteristics of the elastic wave, so that the designed metamaterial structure has a wider elastic wave stealth interval, so as to reduce the scattering amplitude and dynamic stress concentration around the hole, thereby avoiding the damage to the protected device.

[0032] The scheme adopted by the elastic wave stealth device of the rib plate mechanical metamaterial with active control function in the embodiment is as follows: Figure 1 and Figure 2As shown, the elastic wave stealth device of the ribbed plate mechanical metamaterial with active control function comprises a ribbed plate 1, a piezoelectric sheet 2 and an active control circuit 3; the ribbed plate 1 is made of ABS material and comprises a long strip-shaped reinforcing rib 12 with a width of 5 mm and a rectangular base plate 11 with a thickness of 8 mm; the piezoelectric sheet 2 and the reinforcing rib 12 are respectively arranged on two surfaces of the rectangular base plate 11; the reinforcing rib 12 is uniformly distributed on the ribbed plate 1 to form a grid shape; the reinforcing rib and the rectangular base plate are integrally processed and formed; the rectangular base plate 11 is a thin plate with a length and a width at least 5 times greater than its thickness, and is used to simulate a larger plane; in this embodiment, the length and the width of the rectangular base plate are 1500 mm and 1200 mm respectively; a circular through hole with a radius of 78 mm is formed in the center of the ribbed plate; the piezoelectric sheet 2 is uniformly adhered to the peripheral surface of the through hole and is connected with the active control circuit 3 to form a periodic structure capable of active control; the piezoelectric sheet 2 adopts a PZT-5H model, which is a thin sheet with positive and negative poles and a rectangular shape, has an initial elastic modulus of 56 GPa and can adjust the elastic modulus by connecting with an external circuit; the piezoelectric sheet 2 is distributed in a ring layer around the periphery of the through hole; in this embodiment, the piezoelectric sheet is uniformly distributed in 4 rings along the radial direction of the circular through hole of the ribbed plate, and the number of each ring layer from near to far is 24, 24, 30 and 36 respectively; to ensure periodicity, each piezoelectric sheet is perpendicular to the radial direction of the hole of the ribbed plate in the length direction, and the interval angle between every two piezoelectric sheets in each ring layer is the same.

[0033] Specifically, the active control circuit 3 comprises a multiplexer, an analog-to-digital converter, a microcontroller, an adjustment button and an OLED display screen; the circuit principle of variable elastic modulus and the active control signal flow are shown in Figure 3 and Figure 4 The working process of the active control circuit is as follows: the frequency signal from a piezoelectric sheet is transmitted to the analog-to-digital converter through the multiplexer for signal conversion; the converted signal is sent to the microcontroller for judgment and processing according to the set program, and the fluctuation frequency at this time is displayed on the OLED display screen; after pressing the adjustment button, the complex impedance of the active control circuit is changed by the microcontroller, and the electrical control signal generated by the microcontroller acts on other piezoelectric sheets through the analog-to-digital converter and the multiplexer to change the elastic modulus, so as to achieve the goal of active control.

[0034] In this embodiment, after the active control circuit adjusts the elastic modulus of the piezoelectric sheet, the bending wave stealth frequency range of the elastic wave stealth device of the ribbed plate mechanical metamaterial is 4250-4310 Hz.

[0035] As shown in Figure 5 and Figure 6As shown, respectively, are finite element simulation effect pictures of the rib plate provided by the embodiment of the present application when the active control is not opened and opened. A normal sinusoidal excitation with a frequency of 4280 Hz is applied to the left end of the rib plate to generate bending waves, and the bending waves are scattered when passing through the circular through hole of the rib plate, and the scattering degree is inhibited by the piezoelectric sheets arranged periodically around the through hole; but when the active control circuit is not connected, the far-field scattering displacement stripes behind the through hole are in an intermittent state; when the active control circuit is opened, the elastic modulus of the piezoelectric sheet is increased accordingly, and the part of the intermittent stripes scattered in the far field of the through hole is connected, and thus the elastic wave stealth effect is improved.

[0036] As shown in the figure, Figure 7 As shown is a comparison chart of acceleration value sampling of 13 uniformly distributed points in the scattering far field when the finite element simulation calculation of the active control not opened / opened is performed, according to the result, when the bending wave frequency is 4280 Hz, the difference between the maximum value and the minimum value on the acceleration value curve after the active control is opened is relatively smaller, indicating that the energy distribution aggregation degree on the rib plate is reduced and the uniformity is improved, and it is proved that the elastic wave stealth effect under the active control circuit is improved.

[0037] The working principle of the elastic wave stealth device with the rib plate mechanical metamaterial with active control function in the above embodiment of the present application includes:

[0038] The artificial periodic form elastic wave metamaterial configuration composed of the bulk piezoelectric sheet has a frequency band gap with a propagation inhibition characteristic for elastic waves of a specific frequency. When the elastic wave propagates in the artificial periodic structure, under the interaction of the internal components, the elastic wave in a certain frequency range cannot propagate, and the corresponding frequency range is called a band gap; and the elastic wave in other frequency ranges can propagate, and the corresponding frequency range is called a passband.

[0039] The device utilizes the band gap characteristic of the artificial periodic structure, and can regulate the propagation of elastic waves and vibrations in a certain frequency range, so as to achieve the purpose of elastic wave stealth.

[0040] The device utilizes the active control system composed of the piezoelectric sheet and the active control circuit, adjusts the circuit parameters to change the internal physical property parameters of such mechanical metamaterials, and the equivalent elastic modulus of the piezoelectric sheet under simple harmonic vibration is

[0041]

[0042] wherein H p represents the thickness value of the piezoelectric sheet; Z represents the complex impedance of the external circuit; C p is the inherent capacitance value of the piezoelectric sheet under constant stress; A s is the area of the piezoelectric sheet, and d 31respectively, the compliance and the strain of the piezoelectric sheet; s = iω is the value of the Laplace variable, wherein ω = 2πf represents the angular frequency.

[0043] In summary, compared with the prior art periodic vibration isolation device or the elastic wave metamaterial device, the device of the embodiment of the application has the outstanding feature that the periodic piezoelectric sheet structure and the active control circuit are combined to realize the elastic wave invisibility of the rib plate mechanical metamaterial. The device can be used to realize the elastic wave and vibration invisibility of multiple specific frequencies of the rib plate. Based on the working condition, an elastic wave invisibility device is provided, which is easy to manufacture, simple to operate, flexible to design, occupies less space, and can realize the selection of different wave frequencies.

[0044] The device and system embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., they can be located in one place, or distributed on multiple network units. Part or all of the modules can be selected to achieve the purpose of the embodiment according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0045] Those skilled in the art can understand that, unless specifically stated, the singular forms "a", "an" and "the" used herein also include the plural forms. It should be further understood that the use of the term "including" in the specification of the application means that the features, integers, steps, operations, elements, and / or components described exist, but do 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 say that an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there can be intermediate elements. In addition, "connected" or "coupled" used herein can include wireless connection or coupling. The phrase "and / or" used herein includes any one of the associated listed items and all combinations thereof.

[0046] The present application is not limited to the embodiments described above. The above description of the specific embodiments is intended to describe and illustrate the technical solutions of the present application, and the specific embodiments described above are merely illustrative and not restrictive. Without departing from the purpose of the present application and the scope protected by the claims, those skilled in the art can make many forms of specific changes under the inspiration of the present application, which are all within the scope of protection of the present application.

Claims

1. An elastic wave invisibility device of ribbed panel mechanical metamaterial with active control function, characterized in that, It comprises a ribbed plate, a piezoelectric sheet and an active control circuit; the ribbed plate is made of ABS material, which is composed of long-stripe reinforcing ribs and a rectangular base plate, the piezoelectric sheet and the reinforcing ribs are arranged on the two surfaces of the rectangular base plate respectively; a circular through hole with a radius of 78 mm is formed in the center of the ribbed plate; the piezoelectric sheet is adhered to one side surface of the ribbed plate around the through hole; each piezoelectric sheet is connected with the active control circuit to form a mechanically metamaterial capable of active control. The length and width of the rectangular base plate are at least 5 times the thickness of the rectangular base plate, and the height of the reinforcing rib is less than the thickness of the rectangular base plate. The piezoelectric sheet is a thin sheet with positive and negative poles and a rectangular shape, the model is PZT-5H, and the initial elastic modulus is 56 Gpa.

2. The elastic wave invisibility cloaking device with active control function of ribbed panel mechanical metamaterial according to claim 1, characterized in that, The reinforcing rib is integrally processed with the rectangular base plate, and the reinforcing rib is uniformly distributed on one side of the ribbed plate to form a grid shape.

3. The elastic wave invisibility cloaking device with active control function of ribbed panel mechanical metamaterial according to claim 1, characterized in that, The piezoelectric sheet is distributed in a ring layer around the periphery of the through hole, and the piezoelectric sheet in each ring layer is uniformly distributed, and the number of ring layers and the number of piezoelectric sheets in each ring layer are adjusted as needed.

4. The elastic wave invisibility cloaking device with active control function of ribbed panel mechanical metamaterial according to claim 3, characterized in that, The number of piezoelectric sheets along the radial direction of the through hole is 4, and the number of piezoelectric sheets in each ring layer from the center of the through hole to the outside is 24, 24, 30 and 36 respectively.

5. The elastic wave invisibility cloaking device with active control function of ribbed panel mechanical metamaterial according to claim 1, characterized in that, Each piezoelectric sheet is perpendicular to the radial direction of the through hole in the length direction.

6. The elastic wave invisibility cloaking device with active control function of ribbed panel mechanical metamaterial according to claim 1, characterized in that, The active control circuit comprises a multiplexer, an analog-to-digital converter, a microcontroller, a regulating button and an OLED display screen; the working process of the active control circuit is as follows: the frequency signal from one piezoelectric sheet is transmitted to the analog-to-digital converter for signal conversion through the multiplexer, and is sent to the microcontroller for signal judgment and processing according to the set program, and the fluctuation frequency at this time is displayed on the OLED display screen, after pressing the regulating button, the complex impedance of the active control circuit is changed by the microcontroller, and the electrical control signal generated by the microcontroller acts on other piezoelectric sheets through the analog-to-digital converter and the multiplexer to change the corresponding elastic modulus, so as to achieve the purpose of active control.

7. The elastic wave invisibility cloaking device with active control function of ribbed panel mechanical metamaterial according to claim 1, characterized in that, After the active control circuit adjusts the elastic modulus of the piezoelectric sheet, the bending wave stealth frequency range of the elastic wave stealth device of the ribbed plate mechanically metamaterial is 4250-4310 Hz.

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