Cantilever piezoelectric energy harvesting device based on negative poisson's ratio

Abstract

The present application relates to a kind of cantilever beam piezoelectric energy harvesting devices based on negative poisson's ratio, device includes matching mass, piezoelectric harvesting unit and negative poisson's ratio cantilever beam, negative poisson's ratio cantilever beam includes free end and layered negative poisson's ratio beam body with fixed end, fixed end and free end are located at the both ends of negative poisson's ratio beam body respectively, piezoelectric harvesting unit is arranged on negative poisson's ratio beam body, matching mass is arranged on free end, fixed end is fixedly arranged on existing structure;Negative poisson's ratio beam body is subjected to external vibration excitation and makes negative poisson's ratio beam body occur bending deformation, and piezoelectric harvesting unit generates corresponding polarized charge after collection arrangement and output.Poisson's ratio beam body and fixed end are all composed of multilayer structure, and layered independent deformation, each layer can be in-plane independent expansion and contraction, reduce the strain loss caused by interlayer constraint, so that piezoelectric material is fully stressed;While avoiding the problem of stress concentration, reduce the risk of overall fracture of structure.

Description

Technical Field

[0001] This invention relates to the field of cantilever beam piezoelectric energy harvesting technology, and in particular to a cantilever beam piezoelectric energy harvesting device based on negative Poisson's ratio. Background Technology

[0002] Low-frequency vibration signals exist in various aspects of daily life and production, such as railways, road traffic, and building bridges. The widely present vibration energy can be harvested and stored through appropriate electromechanical conversion methods. Piezoelectric vibration energy harvesting technology has attracted attention due to its unique high energy density and output power at a small scale. However, piezoelectric energy harvesters face problems such as difficulty in matching the resonant frequency to the operating frequency, resulting in low energy conversion efficiency. Developing high-performance piezoelectric ceramic materials and improving the structure of piezoelectric energy harvesters are considered effective means to improve energy conversion efficiency. For example, the cantilever structure with an end mass has been proven to significantly reduce the resonant frequency.

[0003] A single cantilever beam structure has a limited effect on reducing the overall resonant frequency. The effective power generation area is often concentrated near the fixed end, resulting in low overall material utilization. At the same time, there is a problem of stress concentration at the tip, which leads to low collection efficiency of the device and increases the risk of structural fracture.

[0004] The invention patent with publication number CN120301248A discloses a piezoelectric energy harvesting device based on a negative Poisson's ratio structure. A negative Poisson's ratio structural hole is formed on the surface of the beam, and an epoxy resin layer is bonded to the top of the hole, conformally bonded to the hole. A piezoelectric element is bonded to the top of the epoxy resin layer. A mass block is fixed to the front end of the beam, and a fixed base is located at the root. Distributing the negative Poisson's ratio structural holes on the beam surface allows the piezoelectric element to extend or contract synchronously in both length and width directions, significantly reducing and canceling the generation of opposite charges on the electrode surface of the piezoelectric element. The negative Poisson's ratio structural beam is a trapezoidal beam with a linearly increasing cross-sectional area from the front end to the root, preventing stress concentration at the root of the cantilever beam and distributing stress throughout the piezoelectric element, resulting in more uniform stress distribution and extending the lifespan of the energy harvester. However, the patent uses a single-layer beam and a single-layer fixing base, which still has the problem of stress concentration, resulting in low collection efficiency of the device and increasing the risk of structural fracture.

[0005] Therefore, how to improve the traditional cantilever energy harvesting structure, optimize the stress distribution area, and further reduce the resonant frequency are urgent problems to be solved. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art and provide a cantilever beam piezoelectric energy harvesting device based on negative Poisson's ratio.

[0007] The objective of this invention can be achieved through the following technical solutions: According to one aspect of the present invention, a piezoelectric energy harvesting device for a cantilever beam based on negative Poisson's ratio is provided. The device is installed on an existing structure for converting, harvesting, and storing vibration energy. The device includes a matching mass block, a piezoelectric harvesting unit, and a negative Poisson's ratio cantilever beam. The negative Poisson's ratio cantilever beam includes a free end and a layered negative Poisson's ratio beam body and a fixed end. The fixed end and the free end are respectively located at both ends of the negative Poisson's ratio beam body. The piezoelectric harvesting unit is installed on the negative Poisson's ratio beam body. The matching mass block is installed on the free end. The fixed end is fixedly installed on the existing structure. The negative Poisson's ratio beam is subjected to external vibration excitation, causing it to bend and deform. The piezoelectric acquisition unit generates corresponding polarization charges, collects and processes them, and outputs them.

[0008] As a preferred technical solution, the negative Poisson's ratio beam body includes a negative Poisson's ratio surface layer, a negative Poisson's ratio intermediate layer, and a negative Poisson's ratio bottom layer arranged in sequence. The fixed end includes an upper flange, a middle waist plate, and a lower flange arranged in sequence in an I-shape. The two ends of the negative Poisson's ratio surface layer are respectively connected to the free end and the upper flange. The two ends of the negative Poisson's ratio intermediate layer are respectively connected to the free end and the middle waist plate. The two ends of the negative Poisson's ratio bottom layer are respectively connected to the free end and the lower flange.

[0009] As a preferred technical solution, the negative Poisson's ratio surface layer, the negative Poisson's ratio intermediate layer, and the negative Poisson's ratio bottom layer are all composed of multiple columns of negative Poisson's ratio arrays arranged alternately.

[0010] As a preferred technical solution, the negative Poisson's ratio array includes negative Poisson's ratio units composed of left and right components, which are arranged sequentially end to end, with the ends of the left and right components aligned and connected.

[0011] As a preferred technical solution, the longitudinal sections of both the left and right components are M-shaped.

[0012] As a preferred technical solution, the end of the left or right member is located at the waist of the left or right member in the adjacent negative Poisson's ratio array.

[0013] As a preferred technical solution, the width of the negative Poisson's ratio bottom layer is adjusted by rectangular or tapered cutting.

[0014] As a preferred technical solution, the width of the middle waist plate is smaller than that of the upper wing plate or the lower wing plate, and the upper wing plate and the lower wing plate have the same width.

[0015] As a preferred technical solution, the width of the negative Poisson's ratio intermediate layer is smaller than the width of the negative Poisson's ratio surface layer or the negative Poisson's ratio bottom layer, and the width of the negative Poisson's ratio surface layer is larger than the width of the negative Poisson's ratio bottom layer.

[0016] As a preferred technical solution, the piezoelectric acquisition unit includes epoxy resin, piezoelectric ceramic sheets and copper sheets. The copper sheets are bonded to the negative Poisson's ratio beam with epoxy resin, and the piezoelectric ceramic sheets are symmetrically bonded to the copper sheets with epoxy resin. The piezoelectric ceramic sheets are electrically connected to each other.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The negative Poisson's ratio beam and the fixed end of the present invention are both composed of multi-layer structures, with each layer deforming independently. Each layer can expand and contract independently in the plane, reducing strain loss caused by interlayer constraints and allowing the piezoelectric material to be fully stressed. At the same time, it avoids the problem of stress concentration and reduces the risk of overall structural fracture.

[0018] 2. The cantilever beam of the present invention is designed with an I-shaped structural profile, which reduces the moment of inertia of the cross section, optimizes the bending deformation capacity, increases the stress level on the upper surface of the structure, and presents a lower resonant frequency and higher energy conversion efficiency; it realizes the redistribution of stress on the upper surface of the piezoelectric cantilever beam, avoids stress concentration at the fixed end, alleviates the phenomenon that the effective power generation area is concentrated near the fixed end, improves the overall utilization rate of piezoelectric materials, and extends the cycle life of the structure.

[0019] 3. The multi-column negative Poisson's ratio array of the present invention is arranged in an alternating manner to homogenize the stress distribution, avoid material fatigue or damage caused by local stress concentration in a single column array, and extend the service life; improve the overall stiffness and stability, and ensure that the beam maintains the expected negative Poisson's ratio deformation under large deformation conditions.

[0020] 4. The end of the component of the present invention is located at the waist of the adjacent array component, forming a stable topology with cross constraints. Geometric interlocking is generated between adjacent columns to prevent the columns from sliding relative to each other in the lateral direction, so that the whole array moves in concert when bending and deforming; the negative Poisson's ratio deformation path is controlled so that the strain is concentrated in the region where the piezoelectric material is located, thereby improving the energy conversion efficiency.

[0021] 5. This invention employs an M-type negative Poisson's ratio unit, which eliminates the bidirectional strain cancellation problem of piezoelectric patches on the surface of traditional piezoelectric cantilever beams, achieves synchronous positive gain of piezoelectric strain, and further improves the energy conversion level. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a front view of the negative Poisson's ratio cantilever beam of the present invention; Figure 3 This is a side view of the negative Poisson's ratio cantilever beam of the present invention; Figure 4 This is a top view of the negative Poisson's ratio cantilever beam of the present invention; Figure 5This is a three-dimensional structural schematic diagram of the negative Poisson's ratio cantilever beam of the present invention; Figure 6 This is a schematic diagram of the layered structure of the negative Poisson's ratio cantilever beam of the present invention; Figure 7 This is a schematic diagram of the structure of the negative Poisson's ratio surface layer, the negative Poisson's ratio intermediate layer, and the negative Poisson's ratio bottom layer of the present invention; Figure 8 This is a schematic diagram illustrating the rectangular and tapered cutting processes of the present invention; Figure 9 This is a schematic diagram of the negative Poisson's ratio unit structure of the present invention; 1. Fixed end; 2. Negative Poisson's ratio beam; 3. Piezoelectric ceramic sheet; 4. Copper sheet; 5. Matching mass block; 6. Upper flange; 7. Intermediate waist plate; 8. Lower flange. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0024] Example 1 like Figure 1 As shown, a piezoelectric energy harvesting device for a cantilever beam based on negative Poisson's ratio is provided. The device is installed on an existing structure to convert, harvest, and store vibration energy. The device includes a matching mass block 5, a piezoelectric harvesting unit, and a negative Poisson's ratio cantilever beam 2. The negative Poisson's ratio cantilever beam 2 includes a free end and a layered negative Poisson's ratio beam body and a fixed end 1. The fixed end 1 and the free end are located at the two ends of the negative Poisson's ratio beam body, respectively. The piezoelectric harvesting unit is installed on the negative Poisson's ratio beam body, the matching mass block 5 is installed on the free end, and the fixed end 1 is fixedly installed on the existing structure. The negative Poisson's ratio beam is subjected to external vibration excitation, causing it to bend and deform. The piezoelectric acquisition unit generates corresponding polarization charges, collects and processes them, and outputs them.

[0025] In this embodiment, low-frequency vibration signals exist in various life and production scenarios such as railways, road traffic, and building bridges. The widely existing vibration energy can be collected and stored through a suitable electromechanical conversion method. The system includes a matching mass block 5, a piezoelectric acquisition unit, and a negative Poisson's ratio cantilever beam 2. The negative Poisson's ratio cantilever beam 2 is divided into three parts: a free end, a negative Poisson's ratio beam body, and a fixed end. The negative Poisson's ratio beam body and the fixed end 1 are layered structures, while the free end is a single unit. The free end and the fixed end 1 are respectively installed on existing structures, and both ends of the negative Poisson's ratio beam body are connected and fixed to the free end and the fixed end 1, respectively. The matching mass block 5 is placed on the free end, and the piezoelectric acquisition unit is placed on the negative Poisson's ratio beam body. When the negative Poisson's ratio beam body is subjected to external vibration excitation, causing it to bend and deform, the force is applied to the piezoelectric acquisition unit. The piezoelectric acquisition unit generates corresponding polarization charges, collects and processes them, and outputs the data.

[0026] The negative Poisson's ratio cantilever beam 2 is made of high-performance polylactic acid (PLA) material using 3D printing technology and is cut on the side based on a rectangular outline, so that the negative Poisson's ratio beam body and the fixed end 1 present a layered structure.

[0027] like Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown, the negative Poisson's ratio beam body includes a negative Poisson's ratio surface layer, a negative Poisson's ratio intermediate layer, and a negative Poisson's ratio bottom layer arranged in sequence. The fixed end 1 includes an upper flange 6, a middle waist plate 7, and a lower flange 8 arranged in sequence in an I-shape. The two ends of the negative Poisson's ratio surface layer are respectively connected to the free end and the upper flange 6. The two ends of the negative Poisson's ratio intermediate layer are respectively connected to the free end and the middle waist plate 7. The two ends of the negative Poisson's ratio bottom layer are respectively connected to the free end and the lower flange 8.

[0028] In this embodiment, the negative Poisson's ratio beam is divided into a negative Poisson's ratio surface layer, a negative Poisson's ratio intermediate layer, and a negative Poisson's ratio bottom layer from top to bottom, with the three layers overlapping. The fixed end 1 is also arranged with the upper flange 6, the middle waist plate 7, and the lower flange 8 overlapping from top to bottom. The number of layers in the negative Poisson's ratio beam and the fixed end 1 can be set as needed and the numbers should match each other; this embodiment uses a three-layer structure as an example. One end of the negative Poisson's ratio surface layer, the negative Poisson's ratio intermediate layer, and the negative Poisson's ratio bottom layer is connected and fixed to the free end, and the other end is connected and fixed to the upper flange 6, the middle waist plate 7, and the lower flange 8 in sequence.

[0029] like Figure 6 , Figure 7 As shown, the negative Poisson's ratio surface layer, the negative Poisson's ratio intermediate layer, and the negative Poisson's ratio bottom layer are all composed of multiple columns of negative Poisson's ratio arrays arranged alternately.

[0030] The negative Poisson's ratio array includes negative Poisson's ratio units composed of left and right components, which are arranged sequentially end to end, with the ends of the left and right components aligned and connected.

[0031] Both the left and right components have M-shaped longitudinal sections.

[0032] The end of the left or right member is located at the waist of the left or right member in the adjacent negative Poisson's ratio array.

[0033] In this embodiment, a negative Poisson's ratio unit is composed of a left component and a right component. Multiple negative Poisson's ratio units are arranged in sequence to form a negative Poisson's ratio array. The negative Poisson's ratio surface layer (such as...) Figure 7 a) Negative Poisson's ratio intermediate layer (e.g.) Figure 7 b) and negative Poisson's ratio bottom layer (e.g.) Figure 7 c) All are composed of multiple columns of negative Poisson's ratio arrays arranged in an alternating pattern.

[0034] Both the left and right members have M-shaped longitudinal sections. The ends of the M-shaped left and right members are spliced ​​together to form a negative Poisson's ratio element. The middle recesses of the left and right members of the M-shaped structure face outwards. The middle axis (or line of symmetry) of the left and right members of the M-shaped structure is perpendicular to the axial direction (length direction) of the negative Poisson's ratio beam.

[0035] The negative Poisson's ratio unit composed of the left and right members of the M-shape naturally has two recesses located in the middle of the two sides. The width of the left and right members of the M-shape gradually increases from both ends, which matches the recesses. Therefore, when adjacent negative Poisson's ratio arrays are arranged alternately, the left and right members of the M-shape can perfectly fill the adjacent left and right members, so that the space of the recesses is filled by the adjacent left and right members.

[0036] like Figure 9 As shown in the figure, the dimensions of the negative Poisson's ratio element are as follows, and the widest width of the negative Poisson's ratio element is shown in the figure. w =13mm, longest length is l =11.6mm, element wall thickness T2=1.6mm, connecting layer thickness T1=1mm, element concave angle θ=60°. Element wall refers to the wall where negative Poisson's ratio elements in different negative Poisson's ratio arrays contact each other; connecting layer refers to the part where negative Poisson's ratio elements in the same negative Poisson's ratio array contact each other.

[0037] like Figure 8 As shown, the width of the negative Poisson's ratio bottom layer is adjusted using rectangular or tapered cropping.

[0038] In this embodiment, the negative Poisson's ratio substrate is shaped to further optimize bending deformation behavior and reduce resonant frequency, such as... Figure 8The diagram shows two clipping methods: rectangular and tapered. W1 represents the initial width of the negative Poisson's ratio layer. Figure 8 As shown in a; W2 = (0.5~0.8) W1 is the result of using a rectangular cropping method, such as Figure 8 As shown in b, the material is cut to the same width from the fixed end 1 to both sides of the free end to achieve a width of W2; the negative Poisson's ratio bottom layer remains the same width on both sides after cutting. W3 = (0.5~0.7)W1 is achieved using a tapered cutting method, such as... Figure 8 As shown in Figure c, the width W1 of the fixed end 1 remains unchanged and is gradually reduced towards the free end to form a width of W1 at one end and W3 at the other end.

[0039] like Figure 1 , Figure 3 , Figure 5 , Figure 7 As shown, the width of the middle waist plate 7 is less than that of the upper wing plate 6 or the lower wing plate 8, and the upper wing plate 6 and the lower wing plate 8 have the same width.

[0040] The width of the negative Poisson's ratio intermediate layer is smaller than the width of the negative Poisson's ratio surface layer or the negative Poisson's ratio bottom layer, and the width of the negative Poisson's ratio surface layer is larger than the width of the negative Poisson's ratio bottom layer.

[0041] In this embodiment, the width of the intermediate waist plate 7 is smaller than that of the upper flange 6 and the lower flange 8, and the width of the negative Poisson's ratio intermediate layer is smaller than that of the negative Poisson's ratio surface layer or the negative Poisson's ratio bottom layer, making the middle part smaller than the adjacent parts, forming a pseudo-I-shaped structure. The initial dimensions of the negative Poisson's ratio cantilever beam are length × width × thickness = 85mm × 30mm × 4mm; the width of the upper flange 6 is 30mm, and the thickness is 1.5mm; the width of the negative Poisson's ratio surface layer is 30mm, and its thickness transitions uniformly from 1.5mm at the fixed end 1 to 1mm at the free end. The width of the intermediate waist plate 7 and the negative Poisson's ratio intermediate layer are both 15mm, and the thickness is both 1.5mm. The width of the lower flange 8 is 30mm, and the thickness is 1mm; the width of the negative Poisson's ratio bottom layer is W1 = 30mm, W3 = 18mm, and the thickness transitions uniformly from 1mm at the fixed end 1 to 1.5mm at the free end.

[0042] The piezoelectric acquisition unit includes a piezoelectric ceramic sheet 3 and a copper sheet 4. The copper sheet 4 is bonded to the negative Poisson's ratio beam with epoxy resin, and the piezoelectric ceramic sheet 3 is symmetrically bonded to the copper sheet 4 with epoxy resin. The piezoelectric ceramic sheets 3 are electrically connected to each other.

[0043] In this embodiment, a copper sheet 4 is bonded to the negative Poisson's ratio surface of the negative Poisson's ratio beam with epoxy resin. Two piezoelectric ceramic sheets 3 are symmetrically arranged on the copper sheet 4 with epoxy resin. The piezoelectric ceramic sheets 3 generate current after sensing the deformation of the negative Poisson's ratio beam below.

[0044] Two piezoelectric ceramic plates 3 are designated as PZT-1 and PZT-2, respectively. Each piezoelectric ceramic plate 3 is polarized in the thickness direction, and both its upper and lower surfaces are coated with a conductive silver layer. The selected piezoelectric ceramic plate 3 is a flanged electrode (positive and negative electrodes on the same side). The specific series connection method is as follows: the negative electrode of PZT-1 is soldered to the positive electrode of PZT-2 via a wire; a wire is soldered from the positive electrode of PZT-1 to serve as the positive electrode of the output terminal; a wire is soldered from the negative electrode of PZT-2 to serve as the negative electrode of the output terminal.

[0045] A thin copper sheet 4 (60mm long, 30mm wide, and 0.2mm thick) and two piezoelectric ceramic sheets 3 (25mm long, 25mm wide, and 0.2mm thick) are bonded together using epoxy resin. Guide wires are attached to the surface of the piezoelectric ceramic sheets 3, and the two sheets are connected in series. When the fixed end of the cantilever beam is subjected to vibration excitation, the piezoelectric cantilever beam will bend and deform under the assistance of the end mass block; the piezoelectric ceramics bonded to it will generate polarized charges in the thickness direction due to the positive piezoelectric effect, which are collected by electrodes to form an alternating voltage output.

[0046] Moment of inertia of the section of a simulated I-beam cantilever beam I It relates to the stiffness of the overall structural system fr External resonant frequency k With respect to the surface stress level of piezoelectric ceramics .

[0047] in M Indicates bending moment, y Indicates the distance from the fixed end. k For the overall structural stiffness, E It represents the overall elastic modulus of the structure. L This is the total length of the cantilever beam. m Indicates the overall mass of the structure.

[0048] The optimized I-beam-like cantilever beam structure reduces the moment of inertia and stiffness of the structural section, leading to a lower resonant frequency and increased bending surface stress. This allows for better matching with low-frequency environmental vibrations and improves piezoelectric energy harvesting efficiency. Furthermore, the I-beam-like structure significantly alters the surface stress distribution during bending vibrations. With the cooperation of the upper and lower flanges and the central waist plate, stress concentration at the fixed end is effectively avoided, improving the overall utilization rate of the piezoelectric material and extending the structure's cycle life. The upper and lower flanges and waist plate of the I-beam-like cantilever beam structure employ negative Poisson's ratio array structural units, eliminating the bidirectional strain cancellation problem of traditional piezoelectric cantilever beam surface piezoelectric patches. This achieves synchronous positive gain of piezoelectric strain, further improving the mechanical energy to electrical energy conversion level.

[0049] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A piezoelectric energy harvesting device for a cantilever beam based on negative Poisson's ratio, the device being installed on an existing structure for converting, harvesting, and storing vibration energy, characterized in that, The device includes a matching mass block (5), a piezoelectric acquisition unit, and a negative Poisson's ratio cantilever beam (2). The negative Poisson's ratio cantilever beam (2) includes a free end and a layered negative Poisson's ratio beam body and a fixed end (1). The fixed end (1) and the free end are located at the two ends of the negative Poisson's ratio beam body, respectively. The piezoelectric acquisition unit is set on the negative Poisson's ratio beam body, the matching mass block (5) is set on the free end, and the fixed end (1) is fixedly set on the existing structure. The negative Poisson's ratio beam is subjected to external vibration excitation, causing it to bend and deform. The piezoelectric acquisition unit generates corresponding polarization charges, collects and processes them, and outputs them.

2. The cantilever beam piezoelectric energy harvesting device based on negative Poisson's ratio according to claim 1, characterized in that, The negative Poisson's ratio beam body includes a negative Poisson's ratio surface layer, a negative Poisson's ratio intermediate layer, and a negative Poisson's ratio bottom layer arranged in sequence. The fixed end (1) includes an upper flange (6), a middle waist plate (7), and a lower flange (8) arranged in sequence in an I-shape. The two ends of the negative Poisson's ratio surface layer are connected to the free end and the upper flange (6), the two ends of the negative Poisson's ratio intermediate layer are connected to the free end and the middle waist plate (7), and the two ends of the negative Poisson's ratio bottom layer are connected to the free end and the lower flange (8).

3. The cantilever beam piezoelectric energy harvesting device based on negative Poisson's ratio according to claim 2, characterized in that, The negative Poisson ratio surface layer, negative Poisson ratio intermediate layer, and negative Poisson ratio bottom layer are all composed of multiple columns of negative Poisson ratio arrays arranged alternately.

4. The cantilever beam piezoelectric energy harvesting device based on negative Poisson's ratio according to claim 3, characterized in that, The negative Poisson's ratio array includes negative Poisson's ratio units composed of left and right components, which are arranged sequentially end to end, with the ends of the left and right components aligned and connected.

5. The cantilever beam piezoelectric energy harvesting device based on negative Poisson's ratio according to claim 4, characterized in that, Both the left and right components have M-shaped longitudinal sections.

6. The cantilever beam piezoelectric energy harvesting device based on negative Poisson's ratio according to claim 4, characterized in that, The end of the left or right member is located at the waist of the left or right member in the adjacent negative Poisson's ratio array.

7. The cantilever beam piezoelectric energy harvesting device based on negative Poisson's ratio according to claim 2, characterized in that, The width of the negative Poisson's ratio bottom layer can be adjusted using rectangular or tapered cropping.

8. The cantilever beam piezoelectric energy harvesting device based on negative Poisson's ratio according to claim 2, characterized in that, The width of the middle waist plate (7) is less than that of the upper wing plate (6) or the lower wing plate (8), and the upper wing plate (6) and the lower wing plate (8) have the same width.

9. A cantilever beam piezoelectric energy harvesting device based on negative Poisson's ratio according to claim 2, characterized in that, The width of the negative Poisson's ratio intermediate layer is smaller than the width of the negative Poisson's ratio surface layer or the negative Poisson's ratio bottom layer, and the width of the negative Poisson's ratio surface layer is larger than the width of the negative Poisson's ratio bottom layer.

10. The cantilever beam piezoelectric energy harvesting device based on negative Poisson's ratio according to claim 1, characterized in that, The piezoelectric acquisition unit includes epoxy resin, piezoelectric ceramic sheet (3) and copper sheet (4). The copper sheet (4) is bonded to the negative Poisson's ratio beam by epoxy resin. The piezoelectric ceramic sheet (3) is symmetrically bonded to the copper sheet (4) by epoxy resin. The piezoelectric ceramic sheets (3) are electrically connected to each other.

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