CN107796544B - Preparation method of measuring electrode - Google Patents
Preparation method of measuring electrode Download PDFInfo
- Publication number
- CN107796544B CN107796544B CN201710882342.4A CN201710882342A CN107796544B CN 107796544 B CN107796544 B CN 107796544B CN 201710882342 A CN201710882342 A CN 201710882342A CN 107796544 B CN107796544 B CN 107796544B
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- China
- Prior art keywords
- electrode
- base
- top cover
- composite material
- carbon fibers
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/18—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/28—Shaping operations therefor
- B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
- B29C70/34—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/02—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning
- G01L9/06—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning of piezo-resistive devices
Abstract
The invention discloses a preparation method of a measuring electrode. For the novel distributed pressure sensor with the fiber reinforced composite material as a sensitive material, electrodes for wire connection are integrated on carbon fibers inside the material: firstly, in the manufacturing stage of fiber reinforced fabric, fixing a pre-prepared electrode base on a mandrel or a bracket, controlling carbon fibers to be measured to fall on the base, and after the fabric is manufactured, mounting an electrode top cover on the base to fix the carbon fibers; and secondly, in the resin injection molding stage, the surface of the electrode top cover can be completely overlapped with the inner surface of the die, and after the resin is solidified, the residual resin on the surface of the electrode is removed by sand paper, so that wire connection can be performed. The invention can effectively solve the difficulty of preparing the electrode in the composite material, has simple and convenient operation, can be combined with the existing composite material manufacturing process, and can provide long-term effective measurement electrode connection under the condition of basically not changing the integral strength of the composite material.
Description
Technical Field
The invention relates to a preparation method of an electrode, in particular to a preparation method of a measuring electrode on a fiber reinforced composite material.
Background
In the development of the past decades, fiber reinforced composite materials are becoming mature, and the method of adopting fiber reinforced composite materials to replace traditional metals so as to realize light weight is increasingly applied to various departments of national economy, such as the fields of automobiles, ships, aerospace, wind power generation and the like. However, fiber reinforced composites, while gaining wide use, also face a number of challenges, of which safety is a primary concern. Fiber reinforced composites are increasingly replacing metals and are used as structural members in many important links, which are either constantly impacted by themselves or can cause significant safety accidents when damaged.
The composite material is more damaged internally and less deformed externally than the metal material, which makes monitoring of the damage condition inside the composite structural member important during use. The most intuitive and accurate detection method for the damage condition in the composite material is to cut the composite material open for microscopic shooting, but the method can obviously only be used as a means for post analysis, and in order to determine the damage condition in the composite material on the premise of not damaging the structure, researchers in the related field have realized various nondestructive detection methods.
Researchers found that: the characteristic that the resistance value of the carbon fiber in the composite material changes along with the generation of the internal damage of the material is shown in the polymer matrix, and the characteristic of structural function integration enables the carbon fiber resistance measurement method to realize the monitoring of the damage of the composite material without additionally adding a sensor.
The carbon fiber is in the protection of the polymer matrix in the composite material, so that the problem of difficult wiring caused by how to measure the resistance of the carbon fiber is solved. In the experiment, for convenience, the lead wires and the carbon fibers are often connected through conductive silver adhesive, and the outside is protected by an insulating adhesive tape. Such a connection, while simple, is clearly unsuitable for more complex applications requiring long-term stable operation and environments. For this purpose, electroplating technology is applied to the connection of carbon fibers, namely, the surface polymer is removed by a physical and chemical method, the carbon fibers are exposed, a metal layer is formed on the surface of the carbon fibers by electroplating, and finally, the leads are fixed on the surface by a welding method. The wire is made stronger by this method, but the process becomes more complex. The lead connection of the internal fiber is often modified after the composite fiber is formed, so that the defect of difficult wiring exists.
Disclosure of Invention
Aiming at the defect of difficult wiring in the connection of carbon fiber electrodes in the prior fiber reinforced composite material, the method starts from the stage of reinforcing the fabric, and finishes the lead connection at the moment, so that stable lead connection can be obtained, and additional process flows can be reduced. The application provides a simple, convenient and reliable electrode preparation method. The method for preparing the metal electrode on the carbon fiber is compatible with the existing manufacturing process of the fiber reinforced composite material, can reduce the negative influence of the electrode on the overall mechanical property of the composite material, and forms stable and reliable electrode connection.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a preparation method of a measuring electrode, which aims at a novel distributed pressure sensing element with a fiber reinforced composite material as a sensitive material: in the weaving process of the fiber reinforced fabric, fixing the electrode base at a required position on the surface of a supporting structure such as a mandrel or a bracket for maintaining the shape of the fabric; after weaving starts, controlling carbon fibers to be connected with the electrode to fall into a notch on the electrode base; after weaving, the electrode top cover is arranged on the base to ensure that the carbon fibers are fixed in the electrode. In the resin injection stage, a mandrel or a bracket with the surface of which the fiber reinforced fabric is prepared is put into an injection mold, so that the height of the electrode can ensure that the surface of a top cover of the electrode is completely overlapped with the inner surface of the mold; after injection molding, taking out the composite material from the mold after resin is solidified, separating the composite material from the mandrel or the bracket, removing residual resin on the surface of the electrode by using sand paper, and connecting the measuring wire with the electrode by using a welding method.
Further, as preferable:
the electrode can be designed and manufactured by the following method: the electrode material is made of metal copper or aluminum, and is designed into a base part and a top cover part.
The electrode base is connected with the surface of the mandrel or the bracket, the shape of the lower surface of the bottom of the electrode base is consistent with the position of the surface where the electrode needs to be arranged, and the electrode base and the surface are adhered by a double-sided adhesive tape; the upper part of the base is a cylinder with threads on the surface, and a vertical notch divides the cylinder into a left half and a right half; when the electrode base is installed, the incision direction is required to be ensured to be consistent with the axial direction of the carbon fiber, so that the carbon fiber can smoothly fall into the incision in the weaving process. The electrode top cover is connected with the inner surface of the injection mold, so that the shape of the upper surface of the top cover is consistent with the position where the inner surface of the mold is contacted; the lower portion of the cap is a cylinder with an inner surface Hu Luowen and the threads are each sized to threadably mate with the base. After the electrode base and the top cover are installed together, the carbon fiber can be fixed in the notch, the base is fixed on the surface of the mandrel or the bracket, and the upper surface of the top cover is attached to the inner surface of the die.
The electrode surface needs to be treated as follows: the upper surface of the bottom of the electrode base, the lower surface of the top of the electrode top cover and the outer surface of the cylinder are sprayed with insulating paint so as to prevent the electrode from being accidentally contacted with surrounding adjacent carbon fibers, thereby causing measurement errors.
The invention has the beneficial effects that:
the invention starts from the stage of reinforcing the fabric, and directly prepares the carbon fiber electrode on the woven fiber fabric before the injection molding process, so that the process is simple, stable and reliable, and the influence of the electrode on the strength of the structural member can be reduced to an acceptable range after reasonable position design.
Drawings
FIG. 1 is a schematic illustration of an electrode configuration for a composite tube;
FIG. 2 is a schematic illustration of the integration of electrodes on a fiber reinforced fabric;
fig. 3 is a typical contact resistance measurement.
In the figure: 1. insulating paint, 2, electrode top cover upper portion, 3, electrode top cover cylinder, 4, electrode top cover, 5, incision, 6, electrode base cylinder, 7, electrode base bottom, 8, electrode base, 9, electrode, 10, kevlar-29 fiber, 11, carbon fiber.
Detailed Description
The invention is further illustrated by the following figures and examples.
Fig. 1 shows a set of measuring electrode structures for carbon fibers on a fiber reinforced composite tube. The electrode base bottom 7 is used for fixing the cylindrical core surface, and the shape of the upper surface of the electrode top cover 4 is the same as that of the cylindrical inner surface of the die. The whole electrode body is 5mm in height and consistent with the thickness of the pipe fitting, and the upper surface of the top cover can be ensured to be just coincident with the inner surface of the die. The central incision 5 of the electrode base cylinder 6 has the width of 1 mm, carbon fibers can pass through the central incision, the surface of the electrode base cylinder 6 is provided with M4 threads, and the M4 threads are matched with the threads on the inner surface of the electrode top cover cylinder 3; in the above structure, the electrode top cover upper part 2 and the electrode top cover cylinder 3 form an electrode top cover 4, the notch 5, the electrode base cylinder 6 and the electrode base bottom 7 form an electrode base 8, a cylindrical groove is arranged in the middle of the electrode base cylinder 6, and when the electrode base 8 and the electrode top cover 4 are installed, the electrode top cover cylinder 3 is inserted into the cylindrical groove. As shown in fig. 1, an insulating paint 1 is sprayed on the upper surface of the electrode base bottom 7, the outer surface of the electrode top cover cylinder 3 and the lower surface of the electrode top cover upper part 2 so as to prevent measurement errors caused by contact of other carbon fibers with the electrode.
In this example, 24 strands of Kevlar-29 fibers 10 were woven on a cylindrical mandrel with a diameter of 25mm by an annular weaving method, and 4 stockholder T700-12K carbon fibers 11 were used as axial yarns and woven into the fabric as sensing fibers, with copper electrodes at each end of each strand. Before the knitting starts, all the electrode bases are fixed at the positions where the spindle yarns are to be knitted by using double-sided adhesive tapes, and the cuts 5 are consistent with the knitting direction of the spindle yarns (namely, the axial direction of the spindle). The braiding is then started, during which it is ensured that carbon fibres fall into the cut 5, other fibres being wound around the cylinder. After the weaving is completed, the electrode top cover 4 is mounted on the electrode base 8, so that the carbon fibers are tightly connected with the electrodes, as shown in fig. 2. And then placing the reinforced fabric and the mandrel into a cylindrical mold, carrying out resin injection molding, taking out the composite material after curing, and removing the mandrel. If the resin remains on the upper surface of the electrode top cover 4, the resin is removed by using fine sand paper, and the exposed metal surface can be connected by wires. Fig. 3 shows the measurement results of the resistance between each electrode and the initial position electrode mounted on 4 strands of carbon fibers 11, the electrode spacing is 10cm, the number of electrodes on each carbon fiber is five, the data are linearly fitted, and the intersection point of the fitted straight line and the Y axis is the theoretical contact resistance value.
Claims (2)
1. A method of manufacturing a measuring electrode, comprising the steps of:
(1) Fixing the electrode base at a required position on the surface of the supporting structure in the weaving process of the fiber reinforced fabric; after weaving starts, controlling carbon fibers to be connected with the electrode to enable the carbon fibers to fall into a clamping groove on the electrode base; after weaving, the electrode top cover is arranged on the base, and the carbon fiber is ensured to be fixed in the electrode;
(2) In the resin injection stage, placing the support structure with the surface of the fiber reinforced fabric prepared into an injection mold, and ensuring that the height of the electrode can ensure that the surface of the top cover and the inner surface of the mold are completely overlapped; after injection molding is finished, taking out the composite material from the mold and separating the composite material from the supporting structure after resin is solidified, then removing residual resin on the surface of the electrode by using sand paper, and connecting a measuring wire with the electrode;
the electrode can be designed and manufactured by the following method:
(1) The electrode material is metal copper or aluminum, and comprises a base and a top cover;
(2) The electrode base is connected with the surface of the supporting structure, and the shape of the lower surface of the bottom of the electrode base is consistent with the position of the surface where the electrode needs to be arranged; the upper part of the base is a cylinder with threads on the surface, and the cylinder is divided into a left half and a right half by a vertical incision; the vertical incision direction is consistent with the carbon fiber axial direction so as to ensure that the carbon fiber can smoothly fall into the incision in the weaving process;
(3) The electrode top cover is connected with the inner surface of the injection mold, and the shape of the upper surface of the top cover is consistent with the shape of the position to be contacted with the inner surface of the mold; the lower part of the top cover is a cylinder with threads on the inner surface, and the threads can be matched with the threads of the base in each size;
(4) The electrode base and the top cover are mounted together, the initial position of the carbon fiber is fixed in the notch, the base is fixed on the surface of the supporting structure, and the upper surface of the top cover is attached to the inner surface of the die;
the electrode surface is required to be treated as follows: and insulating paint is sprayed on the upper surface of the bottom of the electrode base, the lower surface of the top of the electrode top cover and the outer surface of the cylinder.
2. The method for manufacturing a measuring electrode according to claim 1, wherein: the supporting structure is a mandrel or a bracket.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710882342.4A CN107796544B (en) | 2017-09-26 | 2017-09-26 | Preparation method of measuring electrode |
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| CN201710882342.4A CN107796544B (en) | 2017-09-26 | 2017-09-26 | Preparation method of measuring electrode |
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| CN107796544A CN107796544A (en) | 2018-03-13 |
| CN107796544B true CN107796544B (en) | 2023-07-18 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109177207A (en) * | 2018-07-09 | 2019-01-11 | 黄河科技学院 | Para-aramid fiber enhances unsaturated-resin board making and stress measuring method |
| CN110736669B (en) * | 2019-10-30 | 2022-02-22 | 浙江理工大学 | Impact detection method for carbon fiber reinforced composite material based on piezoelectric fibers |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US4715235A (en) * | 1985-03-04 | 1987-12-29 | Asahi Kasei Kogyo Kabushiki Kaisha | Deformation sensitive electroconductive knitted or woven fabric and deformation sensitive electroconductive device comprising the same |
| CN1187761C (en) * | 2003-08-22 | 2005-02-02 | 武汉理工大学 | Self diagnostic intellgient structure of fiber reinforced resin base composite material and method for self diagnosis |
| CN102797185B (en) * | 2012-07-10 | 2014-12-10 | 东南大学 | Intelligent FRP (Fiber Reinforced Polymer) composite rib based on carbon fiber distribution type sensing and large-scale production process thereof |
| DE102015120369B3 (en) * | 2015-11-25 | 2016-11-03 | Pilz Gmbh & Co. Kg | Step mat for securing a technical system |
| CN105819662B (en) * | 2016-04-12 | 2019-01-25 | 蔡永辉 | A kind of electro-osmosis belt squeezing sludge dewatering equipment |
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