2-2 type emulsified asphalt/cement-based piezoelectric sensor and preparation method and application thereof
阅读说明：本技术 一种2-2型乳化沥青/水泥基压电传感器及其制备方法和用途 (2-2 type emulsified asphalt/cement-based piezoelectric sensor and preparation method and application thereof ) 是由 朱兴一 叶方永 庞亚凤 于 2020-07-15 设计创作，主要内容包括：本发明涉及道路工程领域,特别是涉及一种压电传感器及其制备方法和用途。本发明所提供的压电传感器包括封装件、以及封装于封装件中的压电感应元件,所述压电感应元件包括压电材料柱阵列、以及分布于压电材料柱阵列之间的填充相,所述压电材料柱阵列为1*N的矩形矩阵阵列,各压电材料柱的延伸方向一致、且压电材料柱的极化主轴方向与其延伸方向一致,所述压电感应元件还包括两个导电层,所述两个导电层位于压电材料柱阵列表面、且分别与压电材料柱的两极连接。本发明所提供的乳化沥青/水泥基压电传感器,通过对填充基材、封装材料等进行改进,使填充基材与压电材料之间的复合材料结构更加致密,有效提高水泥基压电复合材料的稳定性和兼容性。(The invention relates to the field of road engineering, in particular to a piezoelectric sensor and a preparation method and application thereof. The piezoelectric sensor provided by the invention comprises a packaging part and a piezoelectric sensing element packaged in the packaging part, wherein the piezoelectric sensing element comprises a piezoelectric material column array and filling phases distributed among the piezoelectric material column array, the piezoelectric material column array is a 1 x N rectangular matrix array, the extension direction of each piezoelectric material column is consistent, and the polarization main axis direction of each piezoelectric material column is consistent with the extension direction of the piezoelectric material column, and the piezoelectric sensing element further comprises two conducting layers which are positioned on the surface of the piezoelectric material column array and are respectively connected with two poles of each piezoelectric material column. According to the emulsified asphalt/cement-based piezoelectric sensor provided by the invention, the filling base material, the packaging material and the like are improved, so that the composite material structure between the filling base material and the piezoelectric material is more compact, and the stability and compatibility of the cement-based piezoelectric composite material are effectively improved.)
1. The piezoelectric sensor is characterized by comprising a packaging part and a piezoelectric sensing element packaged in the packaging part, wherein the piezoelectric sensing element comprises a piezoelectric material column array and filling phases distributed among the piezoelectric material column array, the piezoelectric material column array is a 1N rectangular matrix array, N is more than or equal to 2, the extension direction of each piezoelectric material column is consistent, and the polarization main axis direction of each piezoelectric material column is consistent with the extension direction of the piezoelectric material column, and the piezoelectric sensing element further comprises two conducting layers which are located on the surface of the piezoelectric material column array and are respectively connected with two poles of the piezoelectric material column.
2. The piezoelectric sensor according to claim 1, wherein the material of the piezoelectric material pillar is selected from inorganic piezoelectric materials, preferably the inorganic piezoelectric materials are selected from piezoelectric ceramics selected from one or more of lead zirconate titanate piezoelectric ceramics, niobium lithium lead zirconate titanate piezoelectric ceramics, niobium magnesium lead zirconate titanate piezoelectric ceramics.
3. The piezoelectric sensor of claim 1, wherein the piezoelectric material has a density of 6.90 x 103～7.75×103kg/m3A piezoelectric strain constant of 2.25X 10-10～5.95×10-10C/N, the relative dielectric constant is 1050-3500, and the electromechanical coupling coefficient is 0.31-0.76%.
4. The piezoelectric transducer of claim 1, wherein the columns of piezoelectric material have a height of 2 to 7mm and the individual columns of piezoelectric material have a cross-sectional area of 51.3 to 102.9mm2。
And/or the total cross-sectional area of the piezoelectric material column is 360-720 mm2The column spacing is 1-3 mm;
and/or in the cross section of the single piezoelectric material column, the extension length is 30-50 mm, and the width is 1.71-3.43 mm;
and/or in the piezoelectric sensing element, the volume percentage of the piezoelectric material column is 40-80%.
5. The piezoelectric transducer according to claim 1, wherein the material of the filler phase is selected from a mixed matrix of emulsified asphalt and cement, and the mixed matrix of emulsified asphalt and cement comprises the following components in parts by weight:
60-100 parts of cement;
20-33 parts of emulsified asphalt;
33-60 parts of water.
6. The piezoelectric sensor of claim 1, wherein the cement is selected from the group consisting of portland cement;
and/or the emulsified asphalt is selected from cationic emulsified asphalt, the cationic emulsified asphalt is quick-cracking cationic emulsified asphalt, the oversize allowance of the cationic emulsified asphalt is more than or equal to 0.1%, and the normal-temperature stability of 1d is less than or equal to 1%.
7. The piezoelectric transducer of claim 1, wherein the material of the package is selected from the group consisting of epoxy asphalt, the epoxy asphalt comprising, in parts by weight: 75-93 parts of matrix asphalt, 1-5 parts of epoxy resin and 6-20 parts of curing agent;
and/or the conducting wire extends out of the package to the conducting layer and is electrically connected with the conducting layer.
8. A method of making a piezoelectric sensor as claimed in any one of claims 1 to 7, comprising:
providing a piezoelectric sensing unit;
packaging a piezoelectric sensing unit to provide the piezoelectric sensor.
9. A road piezoelectric sensing system comprising a road structure and piezoelectric sensors as claimed in any one of claims 1 to 7 distributed in the road structure.
10. A method of road dynamic monitoring, comprising:
pressure data of a road surface is collected by a piezoelectric sensor according to any one of claims 1 to 7 or a piezoelectric sensing system according to claim 8.
Technical Field
The invention relates to the field of road engineering, in particular to a 2-2 type emulsified asphalt/cement-based piezoelectric sensor and a preparation method and application thereof.
Background
With the rapid development of economy, infrastructure makes great progress, the contradiction between the high demand of residents for going out and road infrastructure is increasingly prominent, and the phenomena of traffic jam, airplane-non-conflict, vehicle overload and the like are increasingly frequent. In order to alleviate the phenomenon, the piezoelectric composite material becomes an intelligent sensing component applied to high-grade asphalt pavements in recent years due to the characteristics of good piezoelectric performance, outstanding electromechanical coupling effect, good compatibility with pavements and the like.
In recent years, intelligent transportation is provided, so that a vehicle-road cooperation technology based on people, vehicles, roads and environment widely draws attention of scholars at home and abroad, and compared with an automatic driving technology with single induction at a vehicle end, a vehicle-road integration technology with comprehensive induction at the vehicle end obviously improves the induction efficiency of an internet automobile and improves the reliability and the safety of the operation of the internet automobile. As a part of the road end sensing equipment, the piezoelectric sensor plays an important role in intelligent traffic, and is beneficial to achieving the aims of zero congestion, zero accident, low emission and sustainability. Therefore, developing a piezoelectric sensor with high sensitivity, wide frequency band, sustainability and good compatibility becomes a hot topic of intelligent traffic monitoring at the present stage.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide an emulsified asphalt/cement based piezoelectric sensor, a method for preparing the same, and a use thereof, which solve the problems of the prior art.
In order to achieve the above and other related objects, an aspect of the present invention provides a piezoelectric sensor, including a package and a piezoelectric sensing element packaged in the package, where the piezoelectric sensing element includes an array of piezoelectric material pillars and a filling phase distributed between the array of piezoelectric material pillars, the array of piezoelectric material pillars is a 1 × N rectangular matrix array, where N is greater than or equal to 2, an extending direction of each piezoelectric material pillar is the same, and a polarization main axis direction of the piezoelectric material pillar is the same as the extending direction of the piezoelectric material pillar, and the piezoelectric sensing element further includes two conductive layers located on a surface of the array of piezoelectric material pillars and respectively connected to two electrodes of the piezoelectric material pillar.
In some embodiments of the present invention, the material of the piezoelectric material column is selected from inorganic piezoelectric materials, preferably, the inorganic piezoelectric materials are selected from piezoelectric ceramics, and the piezoelectric ceramics are selected from one or more of lead zirconate titanate piezoelectric ceramics, niobium lithium lead zirconate titanate piezoelectric ceramics, niobium magnesium lead zirconate titanate piezoelectric ceramics.
In some embodiments of the invention, the piezoelectric material has a density of 6.90 × 103～7.75×103kg/m3A piezoelectric strain constant of 2.25
In some embodiments of the invention, the height of the piezoelectric material column is 2-7 mm, and the cross-sectional area of each piezoelectric material column is 51.3-102.9 mm2。
In some embodiments of the present invention, the total cross-sectional area of the piezoelectric material column is 360-720 mm2And the column spacing is 1-3 mm.
In some embodiments of the present invention, the single piezoelectric material pillar has a cross section with an extension length of 30mm to 50mm and a width of 1.71 mm to 3.43 mm.
In some embodiments of the present invention, in the piezoelectric sensing element, the volume percentage of the piezoelectric material column is 40 to 80%.
In some embodiments of the present invention, the material of the filling phase is selected from a mixed base material of emulsified asphalt and cement, and the raw materials of the mixed base material of emulsified asphalt and cement comprise the following components in parts by weight:
60-100 parts of cement;
20-33 parts of emulsified asphalt;
33-60 parts of water.
In some embodiments of the invention, the cement is selected from portland cements.
In some embodiments of the invention, the emulsified asphalt is selected from cationic emulsified asphalt, the cationic emulsified asphalt is quick-breaking cationic emulsified asphalt, the oversize quantity of the cationic emulsified asphalt is more than or equal to 0.1%, and the normal temperature stability of 1d is less than or equal to 1%.
In some embodiments of the present invention, the material of the encapsulation member is selected from epoxy asphalt, and the raw material of the epoxy asphalt comprises, by weight: 75-93 parts of matrix asphalt, 1-5 parts of epoxy resin and 6-20 parts of curing agent.
In some embodiments of the present invention, the package further comprises a wire extending from the package to the conductive layer and electrically connected to the conductive layer.
Another aspect of the present invention provides a method for manufacturing the piezoelectric sensor, including:
providing a piezoelectric sensing unit;
packaging a piezoelectric sensing unit to provide the piezoelectric sensor.
According to another aspect of the present invention, a road piezoelectric sensing system is provided, which comprises a road structure and the piezoelectric sensors distributed in the road structure.
Another aspect of the present invention provides a method for dynamically monitoring a road, including:
the pressure data received by the road surface is collected by the piezoelectric sensor or the piezoelectric sensing system.
Drawings
Fig. 1 is a schematic perspective view of a piezoelectric sensor in example 1 of the present invention.
Fig. 2 is a schematic structural view of a small and medium sized rectangular solid piezoelectric sensor in
Fig. 3 is a schematic view showing preparation of a small and medium sized rectangular solid piezoelectric sensor in example 1 of the present invention.
Fig. 4 is a graph showing the linearity of the piezoelectric sensor calculated in
Fig. 5(a) is a schematic view showing the axle load (80kN axle load) monitoring result of the road vehicle in
Fig. 5(b) is a schematic diagram showing the axle load (120kN axle load) monitoring result of the road vehicle in
Description of the element reference numerals
1 bulk of piezoelectric material
2 polarized positive and negative electrodes
3 piezoelectric material after cutting
4 filling phase
5 base of piezoelectric material
6 conductive layer
7 packaging part
8 conducting wire
9 piezoelectricity buried in road structure
Sensor with a sensor element
10 charge amplifier
11 data acquisition device
12 software processing and computer display equipment
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments, and other advantages and effects of the present invention will be apparent to those skilled in the art from the disclosure of the present specification.
The inventor of the invention successfully applies the cement-based piezoelectric composite material to the asphalt pavement main body structure through a large amount of practical researches, improves the compatibility and the stability of the sensor and the pavement main body structure, prolongs the service life of the sensor embedded in the asphalt pavement structure, and improves the modulus matching property of the piezoelectric composite material sensor and the asphalt pavement, thereby completing the invention.
The invention provides a piezoelectric sensor, which comprises a packaging part and a piezoelectric sensing element packaged in the packaging part, wherein the piezoelectric sensing element comprises a piezoelectric material column array and filling phases distributed among the piezoelectric material column array, the piezoelectric material column array is a 1N rectangular matrix array, N is more than or equal to 2, the extension direction of each piezoelectric material column is consistent, and the polarization main axis direction of the piezoelectric material column is consistent with the extension direction of the piezoelectric material column, the piezoelectric sensing element also comprises two conducting layers, and the two conducting layers are positioned on the surface of the piezoelectric material column array and are respectively connected with two poles of the piezoelectric material column. The piezoelectric sensor can be generally arranged in a road structure, the height direction (which is consistent with the direction of a polarization main shaft of each piezoelectric material column) of the piezoelectric sensor is generally matched with the extending direction of a road, namely the stress direction of the road surface is generally consistent with the height direction of the road surface, the compatibility of the pressure sensor can be obviously improved by the mixed base material of emulsified asphalt and cement, when the road surface is stressed, the piezoelectric sensor in the road structure can correspondingly bear certain pressure and can convert the pressure into an electric signal, the electric signal can be transmitted out through a conductive layer in contact with the piezoelectric material and can be received through external equipment, the electric signal output by the piezoelectric sensor generally has proper linearity, and the actual pressure on the road can be accurately monitored.
In the piezoelectric sensor provided by the present invention, the piezoelectric material column may be generally formed by a piezoelectric material, and the piezoelectric material generally refers to a crystal material of a type that generates a voltage between two end surfaces when subjected to a pressure. The material of the piezoelectric material column may be generally an inorganic piezoelectric material, and may preferably be a piezoelectric ceramic or the like. The piezoelectric ceramic generally has the advantages of high response speed, high measurement accuracy and stable performance. Those skilled in the art may select suitable piezoelectric ceramics suitable for use in the piezoelectric sensor, for example, the piezoelectric ceramics may be selected from one or more combinations of lead zirconate titanate piezoelectric ceramics (e.g., PZT-5A, PZT-5H, PZT-4, etc.), lithium niobium lead zirconate titanate piezoelectric ceramics (e.g., PLN, etc.), magnesium niobium lead zirconate titanate piezoelectric ceramics (e.g., PMN, etc.), etc.; for another example, the piezoelectric material may have a density of 6.90 × 103～7.00×103kg/m3、7.00×103～7.10×103kg/m3、7.10×103～7.20×103kg/m3、7.20×103～7.30×103kg/m3、7.30×103～7.40×103kg/m3、7.40×103～7.50×103kg/m3、7.50×103～7.60×103kg/m3、7.60×103～7.70×103kg/m3Or 7.70
In the piezoelectric sensor provided by the present invention, a plurality of piezoelectric material pillars may be disposed in the piezoelectric sensing element, and these piezoelectric material pillars are generally distributed in a rectangular matrix array of 1 × N, that is, each piezoelectric material pillar is generally arranged in a straight line, and when the piezoelectric sensor is used, the direction of arrangement generally coincides with the extending direction of a road, where N is greater than or equal to 2 and N is a positive integer, and N may be specifically 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or a larger positive integer. The piezoelectric material pillars are typically sized to fit the road structure so that the pressure from the road surface is adequately sensed without affecting the stability of the road structure and the stability of the device itself. For example, in the piezoelectric sensing element, the height of the piezoelectric material column (piezoelectric material column)The height direction of the piezoelectric sensor is the same as the height direction of the piezoelectric sensor) may be 2 to 7mm, 2 to 3mm, 3 to 4mm, 4 to 5mm, 5 to 6mm, or 6 to 7 mm; as another example, the cross-sectional area of a single column of piezoelectric material may be 51.3 to 102.9mm 2、51.3～60mm2、60～70mm2、70～80mm2、80～90mm2Or 90 to 102.9mm2(ii) a For another example, the total cross-sectional area of the piezoelectric material column may be 360-720 mm2、360～420mm2、420～480mm2、480～540mm2、540～600mm2、600～660mm2Or 660 to 720mm2(ii) a For another example, the distance between the columns may be 1 to 3mm, 1 to 1.5mm, 1.5 to 2mm, 2 to 2.5mm, or 2.5 to 3 mm; as another example, the shape and size of each piezoelectric material column may be substantially the same. In the cross section of the piezoelectric sensing element, each pillar of piezoelectric material generally extends straight from one side of the piezoelectric sensing element to the other side to form a rectangular matrix of 1 × N, so as to enhance the robustness of signal output, for example, in the cross section of a single pillar of piezoelectric material (i.e., a cross section perpendicular to the extending direction of each pillar of piezoelectric material), the extending length of the pillar of piezoelectric material is generally substantially the same as the dimension of the piezoelectric sensing element in the extending direction, and specifically may be 30mm to 50mm, 30mm to 35mm, 35mm to 40mm, 40mm to 45mm, or 45mm to 50 mm; for another example, the width of the single piezoelectric ceramic column may be 1.71-3.43 mm, 1.71-2.03 mm, 2.03-2.33 mm, 2.33-3.63 mm, 2.63-2.93 mm, 2.93-3.13 mm, or 3.13-3.43 mm in the cross section.
In the piezoelectric sensor provided by the invention, the piezoelectric material column generally needs to have a proper volume ratio in the piezoelectric sensing element, so that certain gaps can be distributed among column materials, and the materials can be ensured to fully sense the pressure applied to a road surface, for example, in the piezoelectric sensing element, the volume percentage of the piezoelectric material column can be 40-80%, 40-50%, 50-60%, 60-70%, or 70-80%. The overall dimensions of the piezoelectric sensing element generally correspond to the overall arrangement of the piezoelectric material pillars, for example, since the piezoelectric material pillar array is a 1 × N rectangular matrix array, the overall shape of the piezoelectric sensing element is generally a rectangular parallelepiped; for another example, the dimension of the piezoelectric sensing element in the height direction may be 2mm to 4mm, 2mm to 2.5mm, 2.5mm to 3mm, 3mm to 3.5mm, or 3.5mm to 4mm (i.e., the direction that coincides with the height direction of the piezoelectric sensor), the dimension in the length direction (i.e., the direction that coincides with the extending direction of the cross section of a single piezoelectric material column) may be 30mm to 50mm, 30mm to 35mm, 35mm to 40mm, 40mm to 45mm, or 45mm to 50mm, and the dimension in the width direction may be 30mm to 50mm, 30mm to 35mm, 35mm to 40mm, 40mm to 45mm, or 45mm to 50 mm; as another example, the cross-section of the piezoelectric sensor may be square.
In the piezoelectric sensor provided by the invention, the existence of the filling phase can improve the defects of large brittleness, small limit strain, poor compatibility and the like of a single piezoelectric material. The material of the filler phase may be selected from a mixed matrix of emulsified bitumen and cement, which generally requires better adhesion to the piezoelectric phase. The mixed base material of the emulsified asphalt and the cement comprises the following raw materials in parts by weight: 60-100 parts of cement; 20-33 parts of emulsified asphalt; 33-60 parts of water.
The mixed base material of the emulsified asphalt and the cement may include 60 to 100 parts, 60 to 70 parts, 70 to 80 parts, 80 to 90 parts, or 90 to 100 parts of the cement. The cement is typically used as a cementitious material in the filler phase. The cement may typically be a portland cement, e.g., grade 42.5 portland cement, and the like.
The mixed base material of the emulsified asphalt and the cement can comprise 20-33 parts, 20-24 parts, 24-28 parts or 28-33 parts of emulsified asphalt, the emulsified asphalt is generally liquid asphalt which is formed by asphalt and an emulsifier under the action of a certain process and generates oil-in-water or water-in-oil, and the existence of the emulsified asphalt can improve the connection characteristic between a filling phase and a functional phase (a piezoelectric material column), thereby improving the flexibility and the stability of the whole material, prolonging the service life of the piezoelectric sensor, and providing the sensitivity, the durability and the compatibility with a main structure of a pavement when the piezoelectric sensor is used. The emulsified asphalt can be cationic emulsified asphalt, more preferably can be fast-cracking cationic emulsified asphalt, the fast-cracking type is generally corresponding to the demulsification speed of the emulsified asphalt, the fast-cracking, the medium-cracking or the slow-cracking is generally determined qualitatively according to the state after the emulsified asphalt is mixed with mineral aggregates and the like, and the test method of the qualitative characterization can be tested according to T6058. In addition, the oversize can be more than or equal to 0.1 percent, the 1d normal temperature stability can be less than or equal to 1 percent, and the JTG F40-2004 can be referred to as the measurement method of the oversize and the 1d normal temperature stability.
The mixing base material of the emulsified asphalt and the cement can also comprise a proper amount of water, and the amount of the water used in the mixing base material can be adjusted by a person skilled in the art according to the needs, and for example, the water can comprise 33-60 parts, 33-36 parts, 36-40 parts, 40-45 parts, 45-50 parts, 50-55 parts or 55-60 parts.
In the piezoelectric sensor provided by the invention, the material of the filling phase can generally comprise other additives, such as a water reducing agent and the like. The water reducing agent can be mainly used for reducing the water-cement ratio on the basis of ensuring the fluidity of the cement emulsified asphalt slurry so as to obtain an emulsified asphalt cement-based material with higher strength as far as possible to adapt to the high strength of the piezoelectric ceramics.
In the piezoelectric sensor provided by the invention, the packaging part needs to have good insulation and mechanical properties (such as mechanical strength, flexibility and the like), and needs to have good uniformity and stability, so that the piezoelectric sensor not only can play good roles of supporting, protecting and packaging the piezoelectric composite material main body in the packaging part, but also can remarkably improve the compatibility of the traditional cement-based piezoelectric sensor and a road surface structure. The material of the encapsulation may preferably be selected from epoxy asphalt, which is typically a mixture of epoxy resin, curing agent and matrix asphalt chemically modified. For example, the raw materials of the epoxy asphalt can comprise the following components in parts by weight: 75-93 parts of matrix asphalt, 1-5 parts of epoxy resin and 6-20 parts of curing agent.
The epoxy asphalt may include 75 to 93 parts, 75 to 78 parts, 78 to 81 parts, 81 to 84 parts, 84 to 87 parts, 87 to 90 parts, or 90 to 93 parts. The base asphalt generally needs to be a base asphalt with a penetration grade of No. 70, for example, the penetration of the base asphalt can be 60-80, 60-65, 65-70, 70-75, or 75-80.
The epoxy asphalt can comprise 1-5 parts, 1-2 parts, 2-3 parts, 3-4 parts or 4-5 parts of epoxy resin. The epoxy resin can be E51 epoxy resin, and the epoxy equivalent can be 185-192, 185-186, 186-188, 188-190, or 190-192. In one embodiment of the present invention, the epoxy resin has an epoxy equivalent of 189.
The epoxy asphalt can comprise 6-20 parts, 6-8 parts, 8-10 parts, 10-12 parts, 12-14 parts, 14-16 parts, 16-18 parts or 18-20 parts of curing agent. The curing agent may specifically be an acid complex curing agent, and may specifically be methylhexahydrophthalic anhydride (MTHPA), for example.
In the piezoelectric sensor provided by the invention, the package part can be usually wrapped on the periphery of the piezoelectric material to form a piezoelectric sensor with a proper size, for example, the size of the piezoelectric sensor in the length direction can be 40-100 mm, 40-50 mm, 50-60 mm, 60-70 mm, 70-80 mm, 80-90 mm or 90-100 mm, the size of the piezoelectric sensor in the width direction can be 40-100 mm, 40-50 mm, 50-60 mm, 60-70 mm, 70-80 mm, 80-90 mm or 90-100 mm, and the size of the piezoelectric sensor in the height direction can be 8-10 mm, 8-8.5 mm, 8.5-9 mm, 9-9.5 mm or 9.5-10 mm. The thickness of the package on the surface of the piezoelectric material is usually required to be appropriate, so as to provide an appropriate protection effect for the internal piezoelectric sensing element, for example, the thickness of the package on the surface of the piezoelectric material may be 1 to 5mm, 1 to 2mm, 2 to 3mm, 3 to 4mm, or 4 to 5mm, for example, the thickness of the package on the surface of the piezoelectric material may be 4.5 to 5.5mm, 4.5 to 4.7mm, 4.7 to 4.9mm, 4.9 to 5.1mm, 5.1 to 5.3mm, or 5.3 to 5.5mm in the length and width directions of the piezoelectric sensor; for another example, the thickness of the package on the surface of the piezoelectric material in the height direction of the piezoelectric sensor may be 1.8 to 2.2mm, 1.8 to 1.9mm, 1.9 to 2.0mm, 2.0 to 2.1mm, or 2.1 to 2.2 mm.
In the piezoelectric sensor provided by the invention, the conducting layer is generally positioned on the surface of the piezoelectric material column array and is connected with two poles of each piezoelectric material column. Generally, the piezoelectric transducer may include at least two conductive layers, the two conductive layers may be respectively disposed at two poles of the array of columns of piezoelectric material so as to be connected to two poles of each column of piezoelectric material, and the conductive layers may extend in a direction generally matching the array of columns of piezoelectric material, for example, in a direction perpendicular to a principal axis of polarization of each column of piezoelectric material in the array. The thickness of the conductive layer is usually very thin, and it is necessary to achieve a proper conductive function. The conductive layer can be made of a material selected by those skilled in the art, for example, the conductive layer can be made of a conductive silver paste, and the conductive layer can be formed after the paste is cured.
The piezoelectric sensor provided by the invention can further comprise a lead, wherein the lead can extend out of the package to the conductive layer and is electrically connected with the conductive layer, so that an electric signal generated by the piezoelectric material can be led out, and the lead can be further transmitted to external equipment, wherein the external equipment can be an electric signal acquisition instrument and the like, and specifically can be an oscilloscope, a dynamic signal acquisition instrument and the like.
A second aspect of the present invention provides a method for manufacturing a piezoelectric sensor provided in the first aspect of the present invention, including:
providing a piezoelectric sensing unit;
packaging a piezoelectric sensing unit to provide the piezoelectric sensor.
The preparation method of the piezoelectric sensor provided by the invention can comprise the following steps: a piezoelectric sensing unit is provided. The person skilled in the art may select a suitable method for providing the piezoelectric sensing unit, which may for example comprise: providing a piezoelectric material column array, filling raw materials of a filling phase between the piezoelectric material column arrays, solidifying, and coating conducting layers on two poles of the piezoelectric material column array to provide the piezoelectric sensing unit. The piezoelectric material column array can be obtained by appropriately cutting the piezoelectric material, and in the process of preparing the piezoelectric sensing unit, the cutting of the piezoelectric material can be performed in sequence with the filling of the raw material of the filling phase, and can also be performed simultaneously and alternately. Because the filling phase is a mixed base material of emulsified asphalt and cement, and the raw materials have good fluidity, the piezoelectric material column array can be placed in a mould during filling, and the piezoelectric material column array can be filled. In the filling process, the raw materials are generally required to be fully distributed among the piezoelectric material column arrays, for example, air in the filler can be removed by methods of vacuumizing, vibrating and the like, so as to improve the bonding strength between a matrix phase and a functional phase interface and enhance the compactness of the emulsified asphalt/cement-based composite slurry. After the filling is finished, after the raw materials of the filling phase are cured, the raw materials of the conducting layer can be coated on the two electrodes to form the conducting layer and provide the piezoelectric sensing unit.
The preparation method of the piezoelectric sensor provided by the invention can further comprise the following steps: packaging a piezoelectric sensing unit to provide the piezoelectric sensor. The piezoelectric sensing element may be encapsulated by a suitable method selected by those skilled in the art, for example, the piezoelectric sensing element may be placed in a mold, and the conductive wires may be connected to the conductive layer, and an encapsulating material may be poured in the mold for encapsulation, and the piezoelectric sensor may be provided after curing.
A third aspect of the invention provides a road piezoelectric sensing system comprising a road structure and piezoelectric sensors as provided in the first aspect of the invention distributed in the road structure. The direction of extension of each column of piezoelectric material generally coincides with the direction of the compressive force bearing force of the road structure, and for an array of columns of piezoelectric material, the positive side may be located closer to the road surface or farther away from the road surface. The road structure is generally an asphalt pavement structure, which may include an asphalt pavement, a base layer, a sub-base layer, and a roadbed, and further the asphalt pavement is composed of an upper surface layer, a middle surface layer, and a lower surface layer. The piezoelectric sensors can be generally distributed in a surface layer structure of an asphalt pavement structure, for example, the piezoelectric sensors can be arranged at a distance of 1-3 cm, 1-1.5 cm, 1.5-2 cm, 2-2.5 cm or 2.5-3 cm from the surface layer of the pavement according to the thickness of the upper surface layer of the pavement; for another example, at least 2 piezoelectric sensors may be arranged in the cross section of a single lane, and the specific distribution amount may be determined by combining the actual road material, traffic conditions and the comprehensive response of the piezoelectric sensors; for another example, the piezoelectric sensors may be generally spaced apart from each other in the extending direction of the road, and the specific distribution distance may be the distance between the axles. When the piezoelectric sensor is located in a road structure, the piezoelectric pillars are arranged in the direction of the extension of the road as a 1 × N rectangular matrix array of pillars, so that when a load is not fully applied directly above the element, a portion of the area of each pillar is still directly exposed to the load.
The fourth aspect of the present invention provides a road dynamic monitoring method, including: by the piezoelectric sensor provided by the first aspect of the present invention or the piezoelectric sensing system provided by the third aspect of the present invention, pressure data received by a road surface is collected. As described above, when the road surface is subjected to pressure, the piezoelectric sensor in the road structure is correspondingly subjected to a certain pressure, and can convert the pressure into an electrical signal, the electrical signal can be transmitted through the conductive layer in contact with the piezoelectric material, and the electrical signal can be received through the external device, so that the pressure actually applied to the road can be accurately monitored, and the conditions to be monitored on the road, such as traffic flow monitoring of people and vehicles, dynamic weighing monitoring of vehicles and the like, can be reflected.
According to the emulsified asphalt/cement-based piezoelectric sensor provided by the invention, the filling base material, the packaging material and the like are improved, so that the composite material structure between the filling base material and the piezoelectric material is more compact, the stability and compatibility of the cement-based piezoelectric composite material are effectively improved, the sensitivity of the sensor can be improved, the sensor has the advantages of wide frequency band, strong anti-interference capability and the like, and the signal-to-noise ratio is also effectively improved. In addition, the emulsified asphalt/cement-based piezoelectric sensor is simple and feasible in preparation steps and low in cost, and has a good industrialization prospect in the field of dynamic monitoring of roads.
The invention of the present application is further illustrated by the following examples, which are not intended to limit the scope of the present application.
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