Programmable control curved surface type damping and noise reduction piezoelectric superstructure

Abstract

A programmable control curved surface type damping and noise reduction piezoelectric superstructure comprises a curved surface base, piezoelectric fiber composite patches as piezoelectric transducers and programmable digital shunt circuits, wherein the piezoelectric fiber composite patches are symmetrically and uniformly distributed on the curved surface base, the programmable digital shunt circuits are located on the curved surface base and connected with each piezoelectric fiber composite patch to form a unit, and the units are independent of each other; the transfer function realized in the online programming adjustment controller can change the equivalent impedance of the shunt circuit, further change the band gap characteristics of the damping and noise reduction piezoelectric superstructure, and realize the vibration and noise control of the curved surface structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of superstructure, and specifically relates to a programmable control curved surface type damping and noise reduction piezoelectric superstructure. BACKGROUND

[0002] The superstructure is one of the latest technologies for realizing vibration control, and the band gap characteristics can be designed to isolate the propagation of elastic waves / sound waves. The band gap can be divided into two types of Bragg scattering band gap and local resonance band gap, wherein the Bragg scattering band gap is wideband, but it is difficult to control low-frequency waves due to the limitation of the structure size. The local resonance band gap has subwavelength control characteristics and can realize low-frequency damping. However, the existing technology is mainly used for planar structures such as beams and plates, and is not suitable for curved surface structures. Moreover, it is difficult to change after processing, and cannot be adjusted according to the complex working conditions and environment in practice, so the flexibility is poor and the application is limited. SUMMARY

[0003] The present application provides a programmable control curved surface type damping and noise reduction piezoelectric superstructure to solve the problem that the vibration and noise of the existing curved surface structure are difficult to control. The band gap programmability and high-order band gap of the curved surface structure are realized, and the vibration and noise control of the curved surface structure is promoted.

[0004] The present application is realized by the following technical scheme:

[0005] The present application relates to a programmable control curved surface type damping and noise reduction piezoelectric superstructure, comprising: a curved surface substrate, a piezoelectric fiber composite patch serving as a piezoelectric transducer, and a programmable digital shunt circuit. The piezoelectric fiber composite patch is symmetrically and uniformly distributed on the curved surface substrate, the programmable digital shunt circuit is located on the curved surface substrate and connected with each piezoelectric fiber composite patch to form a unit, and each unit is independent of each other. The structure and parameters of the programmable digital shunt circuit are adjusted to change the transfer function of the shunt circuit, and then the band gap characteristics of the damping and noise reduction piezoelectric superstructure are changed to realize the vibration and noise control of the curved surface structure.

[0006] Each unit is independent of each other, that is, the equivalent impedance realized by each digital shunt circuit in the programmable digital shunt circuit can be the same or different, and there is no relationship between each other.

[0007] Adjusting the structure and parameters of the programmable digital shunt circuit means changing the transfer function realized in the microcontroller in the programmable digital shunt circuit, so that the digital shunt circuit in the programmable digital shunt circuit realizes different impedances.

[0008] The transfer function of the shunt circuit refers to the relationship between the output and the input of the microcontroller, and the relationship between the transfer function and the circuit impedance can be derived according to the circuit structure.

[0009] The band gap characteristic refers to: by changing the transfer function in the control, further changing the equivalent impedance of the shunt circuit, adjusting the resonant frequency and order of the shunt circuit, and further affecting the position and order of the band gap.

[0010] The specific steps of the programmable are: converting the transfer function F(s) into the form of a difference equation and realizing it in the single-chip microcomputer, specifically: using the Tustin method to convert the transfer function F(s) from the s domain to the z domain Wherein: P and Q are the orders of the numerator and denominator. In the discrete time domain, the corresponding difference equation is x[n] and y[n] represent the input and output signals at the nth time.

[0011] Technical effects

[0012] The application can realize the adjustable band gap behavior without changing the mechanical structure and electrical elements, thereby adjusting the vibration and noise reduction characteristics of the structure, and is suitable for programmable piezoelectric superstructure of curved surface structure. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the application;

[0014] Figure 2 It is a schematic diagram of a digital circuit;

[0015] Figure 3 It is an axonometric view of the mechanical structure of the ring-shaped piezoelectric superstructure;

[0016] Figure 4 It is a top view of the mechanical structure of the ring-shaped piezoelectric superstructure;

[0017] Figure 5 It is an axonometric view of the mechanical structure of the shell-shaped piezoelectric superstructure;

[0018] Figure 6 It is a top view of the mechanical structure of the shell-shaped piezoelectric superstructure;

[0019] Figure 7 It is a vibration transmission curve schematic diagram of the embodiment;

[0020] Figure 8 It is a sound radiation curve schematic diagram of the embodiment;

[0021] In the figure: 1 curved surface base, 2 piezoelectric fiber composite patch, 3 digital circuit. DETAILED DESCRIPTION

[0022] As Figures 1-6As shown, a programmable control curved surface type damping and noise reduction piezoelectric superstructure involved in the embodiment comprises: a curved surface substrate 1, piezoelectric fiber composite patches 2 as piezoelectric transducers and programmable digital shunt circuits 3, wherein: the piezoelectric fiber composite patches 2 are uniformly distributed on the curved surface substrate 1 in a central symmetry, the curved surface substrate 1 is grounded, each piezoelectric fiber composite patch 2 is connected with a programmable digital shunt circuit 3 to form a unit, and the units are independent of each other; by adjusting the structure and parameters of the programmable digital shunt circuit 3, the transfer function of the shunt circuit is changed, and then the band gap characteristics of the curved surface piezoelectric superstructure are changed, so as to realize the vibration and noise control of the curved surface structure.

[0023] The curved surface substrate 1 is Figure 3 or Figure 4 The annular structure as shown or the shell-shaped structure, the curved surface substrate 1 is made of aluminum, copper and other metal thin walls. Figure 5 or Figure 6 The curved surface substrate 1 is made of aluminum, copper and other metal thin walls.

[0024] In the embodiment, the curved surface substrate 1 is an annular structure, the thickness is 2mm, the radius is 110mm, and the width is 18mm.

[0025] The piezoelectric fiber composite patch 2 is a square sheet structure of flexible material.

[0026] In the embodiment, the width of the piezoelectric fiber composite patch 2 is 14mm, the length is 28mm, the thickness is 0.3mm, the number is 16, and the average capacitance is 34.8nF.

[0027] As shown Figure 2 The programmable digital shunt circuit 3 comprises: three operational amplifiers, a digital-to-analog converter, an analog-to-digital converter and a microcontroller, wherein: the first and second operational amplifiers and the analog-to-digital converter convert the voltage information of the piezoelectric fiber composite patch from an analog signal to a digital signal and transmit it to the microcontroller, the microcontroller outputs the voltage information of the digital signal after processing, and then the digital-to-analog converter converts the voltage information from a digital signal to an analog signal and outputs it to the circuit through the third operational amplifier.

[0028] The voltage of the input and output ends of the microcontroller satisfies U co =F(s)·U ci , wherein: F(s) is the s-domain representation of the transfer function realized in the controller.

[0029] The admittance of the programmable digital shunt circuit 3 and the transfer function in the controller satisfy:

[0030]

[0031] The impedance of the programmable digital shunt circuit 3 is Impedance Z s (s) determines the dynamic characteristics of the piezoelectric superstructure, so various shunt circuits can be realized by designing the transfer function F(s), that is, programmability is realized.

[0032] In this embodiment, the digital-to-analog converter, analog-to-digital converter and microcontroller in the digital shunt circuit 3 are provided by an STM32F407 single-chip microcomputer; the resistance parameters in the circuit are R1 = 2.2KΩ, R2 = 22KΩ and Rc = 22KΩ. The 16 piezoelectric fiber composite patches are independently controlled by 16 digital circuits.

[0033] Through specific actual experiments, in the anechoic chamber environment, running the above device, as shown in Figure 7 , the vibration transmission curve of this embodiment. Taking a two-order resonant shunt circuit as an example, as shown in the figure, in the absence of a shunt circuit, peak values appear near 620Hz and 1010Hz, indicating that elastic waves near these two frequencies are almost not inhibited. Therefore, a local resonance band gap is designed near the two natural frequencies to suppress vibrations in two modes. As can be seen from the dashed line in Figure 7 , under the action of the designed two-order resonant shunt circuit, two resonant modes near 620Hz and 1010Hz are suppressed. Similarly, through programming, adjustable frequency band gaps and higher-order band gaps can be realized, which well verifies the programmability and high-order band gap property of the curved surface piezoelectric superstructure, and has excellent vibration reduction performance.

[0034] As shown in Figure 8 , the sound radiation curve of this embodiment. The sound pressure at a distance of 300mm from the center of the ring is measured to obtain the frequency response curve. As can be seen from the figure, for sound waves, the piezoelectric superstructure of this embodiment also has corresponding band gap characteristics and good sound absorption performance.

[0035] Compared with the prior art, the device successfully realizes vibration and noise control of the curved surface structure. In the case of keeping the mechanical structure and electrical elements unchanged, by only programming the digital controller online, the equivalent impedance of the shunt circuit can be changed, the local resonance frequency and order can be adjusted, and the tunability of the band gap can be realized, so that vibration and sound absorption in a specific frequency band range can be more conveniently realized, and the vibration and noise reduction characteristics of the piezoelectric superstructure are greatly improved. Based on the principle of local resonance band gap, the flexibility and diversity of the external circuit are fully utilized to realize the programmability of vibration and noise control of the curved surface structure, lay a foundation for the application of the piezoelectric superstructure in the curved surface structure in engineering, and provide a train of thought for dealing with vibration and noise control in changing and unpredictable engineering environments, which has important engineering application value.

[0036] The above specific embodiments can be partially adjusted in different ways by those skilled in the art without departing from the principles and purposes of the present application, the protection scope of the present application is subject to the claims and is not limited by the above specific embodiments, each implementation within the scope is subject to the present application.

Claims

1. A programmable governing curved surface type vibration and noise reduction piezoelectric superstructure, characterized in that, The application relates to a curved surface substrate, piezoelectric fiber composite patches as piezoelectric transducers and programmable digital shunt circuits, wherein: the piezoelectric fiber composite patches are uniformly distributed on the curved surface substrate in a central symmetry mode, the programmable digital shunt circuits are arranged on the curved surface substrate and connected with each piezoelectric fiber composite patch to form a unit, and the units are independent of each other; the equivalent impedance of the shunt circuit is changed by adjusting the transfer function realized in an online programming adjustment controller, the band gap characteristics of a vibration and noise reduction piezoelectric superstructure are changed, and vibration and noise control of the curved surface structure is realized. The curved surface substrate is in a ring structure or a shell structure, and the curved surface substrate is made of a metal thin wall. The programmable specific steps are: converting the transfer function F(s) into a difference equation form and implementing in a single-chip microcomputer, specifically: converting the transfer function F(s) from an s domain to a z domain using a Tustin method , wherein: P and Q are the orders of the numerator and the denominator, in a discrete time domain, the corresponding difference equation is , x[n] and y[n] represent the input and output signals at the n time. The conductance of the programmable digital shunt circuit and the transfer function in the controller satisfy: The impedance of the programmable digital shunt circuit is , and the impedance Z s (s) determines the dynamic characteristics of the piezoelectric superstructure, so various shunt circuits can be realized by designing the transfer function F(s), that is, programmability, specifically: the voltages at the input and output ends of the microcontroller in the programmable digital shunt circuit satisfy , wherein F(s) is the s-domain representation of the transfer function realized in the controller.

2. The programmable governing curved surface piezoelectric superlattice of claim 1, wherein, The piezoelectric fiber composite patch is a square sheet structure made of a flexible material.

3. The programmable governing curved surface piezoelectric superlattice of claim 1, wherein, The programmable digital shunt circuit comprises three operational amplifiers, a digital-to-analog converter, an analog-to-digital converter and a microcontroller, wherein: the first and second operational amplifiers and the analog-to-digital converter convert voltage information of the piezoelectric fiber composite patch from an analog signal into a digital signal and transmit the digital signal to the microcontroller, the microcontroller outputs voltage information of the digital signal after processing, and the voltage information is converted from the digital signal into an analog signal by the digital-to-analog converter and output to the circuit through the third operational amplifier.

4. The programmable governing curved surface piezoelectric superlattice of claim 1, wherein, ​

Images