CN102495135A - Pressure measurement and crack detection sensor based on nano carbon black and piezoelectric ceramic composite cement - Google Patents

Abstract

The invention relates to a nano-carbon black piezoelectric ceramic composite cement-based sensor, which is a high-strength and high-sensitivity nano-carbon black piezoelectric ceramic composite cement that has good compatibility with concrete, can accurately locate crack positions, and simultaneously measure pressure changes. base sensor. Cement and carbon black were uniformly mixed at a ratio of 5:1 to form a cube, and two pieces of copper wire mesh were added to the cement cube, and three piezoelectric ceramic sheets were implanted, and each piezoelectric ceramic sheet was connected to a wire. The invention utilizes the pressure-sensitive characteristics of nano-carbon black to measure force, and uses piezoelectric ceramic sheets to locate mechanical damage, so that pressure measurement and flaw detection can be realized simultaneously, and can be widely used in the field of engineering monitoring.

Description

A nano-carbon black piezoelectric ceramic composite cement-based force-measuring flaw detection sensor

technical field

The invention relates to the field of sensors, in particular to a nano-carbon black piezoelectric ceramic composite cement-based sensor with high strength and high sensitivity, which has good compatibility with concrete, can accurately locate crack positions, and simultaneously measure pressure changes. the

Background technique

At present, the sensing elements used in the field of civil engineering are generally relatively mature materials that have been used in other fields, such as optical fibers, piezoelectric ceramics, and memory metal alloys. These materials and the most important structural material in the field of civil engineering, concrete, often have obvious compatibility problems, which will cause false signals generated by smart materials, affect the sensing accuracy, and even lead to wrong judgments, which will affect the normal structure of the structure. The use causes great damage. For example, the fiber grating sensor commonly used in engineering has low precision, is easily affected by external stress temperature, and the packaging material and structure form do not match the substrate. As a result, under high-frequency strain, the fiber grating sensor cannot Efficiently track strain changes in the substrate. The invention uses the cement base as the carrier, and the sensor with piezoelectric ceramic sheet and nano-scale carbon black inside has the characteristics of high precision and good compatibility, and can effectively solve this engineering problem. There are sensors that use piezoelectric ceramic sensors for crack location and carbon black pressure-sensitive characteristics for pressure measurement, but they do not effectively combine the two. The present invention effectively combines the characteristics of the two, and can simultaneously perform flaw detection and location. Cement-based transducers for engineering force measurement. the

Contents of the invention

The invention overcomes the obvious compatibility problem between existing sensors and concrete, which leads to the generation of false signals and the reduction of sensing accuracy. The invention provides a high-strength and high-sensitivity nano-carbon black piezoelectric ceramic composite cement-based sensor that has good compatibility with concrete, can accurately locate cracks, and can simultaneously measure pressure changes. It can not only accurately locate the damage, but also analyze the internal force situation at the same time. the

The technical solution adopted by the present invention to solve its technical problems is:

The sensor consists of four parts: cement matrix, piezoelectric ceramic sheet, metal mesh and wire; the cement matrix is a cement cube made by uniformly mixing cement and nano-scale conductive carbon black at a ratio of 5:1; three piezoelectric ceramics The sheets are implanted in the cement cube and are not in the same plane, and the piezoelectric ceramic sheets are connected to the wires respectively; two metal meshes are set in the cement cube, and the signal generated by the carbon particles due to the pressure change is output through the metal mesh. the

Using the cement base as the carrier, the piezoelectric ceramic sheet and carbon particles are applied to the sensor at the same time, and the two substances are used to cooperate to complete the structural performance monitoring work. Use the basic principle of piezoelectric ceramic (PZT) wave propagation method to carry out fine identification of concrete structure damage and defect cracks; use the pressure-sensitive properties of nano-carbon black to judge the pressure on the structure. The piezoelectric material can realize the sensing function according to the positive piezoelectric effect, and can realize the driving function according to the inverse piezoelectric effect. After adding an appropriate amount of nano-carbon black in concrete, the mechanical and electrical properties are improved, and the flexural and compressive strength of concrete is also increased accordingly. the

The outstanding effect of the present invention compared with prior art is:

One: Good compatibility with concrete. The present invention is made of cement-based piezoelectric composite material with good compatibility with concrete as the sensing unit, which is wrapped by cement block. The sensor has good compatibility with the most commonly used concrete materials in civil engineering, such as similar acoustic impedance, equivalent shrinkage rate and similar thermal expansion coefficient, etc.; it is buried in concrete, and there is no difference between it and the surrounding concrete. The continuous interface problem will not change the characteristics of the structure, nor will there be a sudden change in stress. the

Second: high strength, good durability, nano-carbon black material, excellent electrical conductivity, small size, large specific surface area, and excellent interface properties. Some researchers have applied it to concrete to improve the microstructure of concrete materials and mechanics. the

Third: High sensing sensitivity, fully combining the advantages of piezoelectric ceramics and nano-carbon black, can accurately locate damage, and use the pressure-sensitive characteristics of materials to analyze internal force conditions. the

Fourth: It can accurately locate the damage and analyze the internal stress situation at the same time. Use the basic principle of piezoelectric ceramic (PZT) wave propagation method to carry out fine identification of concrete structure damage and defect cracks; use the pressure-sensitive properties of nano-carbon black to judge the pressure on the structure. the

Description of drawings

Figure 1 is a schematic diagram of the overall appearance of the nano-carbon black piezoelectric ceramic composite cement-based sensor. the

Fig. 2 is a schematic cross-sectional structure diagram of nano-carbon black piezoelectric ceramic composite cement-based sensor. the

Fig. 3 is a schematic diagram of the perspective structure of the nano-carbon black piezoelectric ceramic composite cement-based sensor. the

In the figure: 1 wire; 2 nanometer conductive carbon black; 3 piezoelectric ceramic sheet; 4 metal mesh. the

Detailed ways

Specific embodiments of the present invention will be described in detail below in conjunction with technical solutions and accompanying drawings. the

Mix cement and nano-scale conductive carbon black at a ratio of 5:1 with a dispersant to make a cube of 5cm×5cm×5cm, add two pieces of copper wire mesh to the cement cube, and implant 3 pieces that are not on the same plane. The piezoceramic sheets inside and connected to the wires respectively, and use the wires to transmit the acoustic emission signal to the outside. The carbon black adopts surface-treated or untreated nano-scale conductive carbon black, and the dispersant is a water-based dispersant. the

The prepared cement matrix can be made into cubes of various sizes as required, and can also adopt other non-cubic shapes, all within the protection scope of this patent. the

Claims (3)

1. nano carbon black piezoelectric ceramics complex cement base dynamometry flaw detection sensor, it is characterized in that: this sensor comprises four parts: cement matrix, piezoelectric ceramic piece, wire netting and lead; Cement matrix is cement and nano-level conducting carbon black in the even mixed cement that the makes cube block of 5: 1 ratio; Three piezoelectric ceramic piece implantation cement cube blocks are interior and not in same plane, each piezoelectric ceramic piece links to each other with lead respectively; Two wire nettings are set in cement cube block, change the signal that produces owing to pressure through wire netting output carbon granule.

2. a kind of nano carbon black piezoelectric ceramics complex cement base dynamometry flaw detection sensor according to claim 1 is characterized in that, with cement and the nano-level conducting carbon black cube block in the even mixing manufacture 5cm * 5cm of ratio * 5cm of 5: 1.

3. a kind of nano carbon black piezoelectric ceramics complex cement base dynamometry flaw detection sensor according to claim 1 and 2, cube block that it is characterized in that utilizing spreading agent that mixed uniformly cement and nano-level conducting carbon black are made into.

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