CN219348740U

CN219348740U - Flexible multifunctional sensing network

Info

Publication number: CN219348740U
Application number: CN202223031974.5U
Authority: CN
Inventors: 轩福贞; 高阳; 肖彪; 徐维普; 李政霖; 胡越; 李琪
Original assignee: East China University of Science and Technology
Current assignee: East China University of Science and Technology
Priority date: 2022-11-15
Filing date: 2022-11-15
Publication date: 2023-07-14
Anticipated expiration: 2032-11-15

Abstract

The utility model provides a flexible multifunctional sensing network suitable for pressure vessel structural health monitoring, which comprises a network-shaped stretchable flexible substrate layer formed by a plurality of island-shaped members and a plurality of stretchable members, a guided wave signal acquisition unit comprising more than one flexible piezoelectric sensor, a temperature signal acquisition unit comprising more than one patch type temperature sensor, and a plurality of interfaces for being respectively and electrically connected with the guided wave signal acquisition unit and the temperature signal acquisition unit, wherein each flexible piezoelectric sensor and each patch type temperature sensor are distributed on the island-shaped members, the acquired guided wave signals and temperature signals are transmitted to a computer through corresponding interfaces, and the wave speed is corrected based on the temperature signals and combined with the guided wave signals to monitor and position the damage of a pressure vessel. The sensing network has good coupling, considers the influence of temperature fluctuation on the guided wave signal, and can improve the accuracy and reliability of online diagnosis of the damage of the pressure vessel.

Description

Flexible multifunctional sensing network

Technical Field

The utility model relates to the field of guided wave signal acquisition and structural health monitoring, in particular to a flexible multifunctional sensing network which can be used for monitoring and positioning damage to a pressure vessel.

Background

Pressure vessels operating under conditions of high pressure, high temperature, fatigue, vibration, etc. are subject to the threat of severe conditions, which aggravate excessive deformation and cause fracture failure. On-line monitoring is carried out on the in-service pressure vessel, on one hand, the damage of equipment can be found in time, the potential safety hazard is eliminated, and the possibility of failure is reduced; on the other hand, the dynamic development condition of the defects is obtained in real time, so that guidance is provided for a further off-line detection method, the detection efficiency is improved, and the economic loss caused by blind repair and scrapping is reduced.

Hydrogen has attracted attention from many countries in the last decades as a new generation of clean energy, and has great application potential in the field of new energy automobile manufacturing. However, the flammability and explosiveness of hydrogen energy presents a significant potential hazard in its manufacture, storage, transportation, and use. Currently, high pressure vessels play a critical role in the product life cycle of hydrogen energy sources, and therefore their status must be monitored in real time. For the hydrogen pressure container, fatigue cracks can be generated under the long-time working condition, and the transportation process can face collision and impact to generate defects, and the defects can become potential safety hazards for accidents.

At present, the structural health monitoring technology based on ultrasonic guided waves is widely applied to on-line diagnosis and real-time early warning of damage to a pressure container, for example, patent document 1 (CN 107490602A) in the prior art proposes a real-time damage sensing and early warning system for the pressure container, and the method adopts a piezoelectric ceramic plate to monitor the pressure container on line. However, the piezoelectric ceramic is a rigid material, has poor coupling with the pressure vessel and high acoustic impedance, and is easy to crack and degum in the use process, which can bring adverse effects to long-term monitoring of the structural health state of the pressure vessel. Meanwhile, the monitoring means ignores the adverse effects that the temperature change can cause wave velocity disturbance, amplitude disturbance and the like to the guided wave in the using process of the pressure vessel, so that the accuracy and reliability of online diagnosis of the damage of the pressure vessel can be reduced.

Therefore, a sensing network for damage positioning monitoring of a pressure container is required, which has better coupling with the pressure container to improve the defects of easy breakage and high acoustic impedance based on a piezoelectric ceramic transducer, and considers the problem that a guided wave signal is influenced by temperature fluctuation, thereby improving the accuracy and reliability of online diagnosis of the damage of the pressure container.

Disclosure of Invention

In view of the defects in the prior art, the present utility model provides a flexible multifunctional sensing network suitable for pressure vessel structural health monitoring, which has good coupling with a pressure vessel, considers the influence of temperature fluctuation on a guided wave signal and can improve the accuracy and reliability of online pressure vessel damage diagnosis.

The utility model comprises the following technical proposal.

The flexible multifunctional sensing network comprises a stretchable flexible substrate layer, a guided wave signal acquisition unit, a temperature signal acquisition unit and a plurality of interfaces which are respectively and electrically connected with the guided wave signal acquisition unit and the temperature signal acquisition unit,

the stretchable flexible substrate layer is in a network shape and is composed of a plurality of island-shaped members at network nodes and a plurality of stretchable members connected with the island-shaped portions,

the guided wave signal acquisition unit comprises more than one flexible piezoelectric sensor which is distributed on the island-shaped member,

the temperature signal acquisition unit comprises more than one patch type temperature sensor which is distributed on the island-shaped component,

the flexible piezoelectric sensor and the patch type temperature sensor are respectively and independently carried on the island-shaped members,

and transmitting the guided wave signals acquired by the guided wave signal acquisition unit and the temperature signals acquired by the temperature signal acquisition unit to a computer through the interface, correcting the wave speed based on the temperature signals, and carrying out damage monitoring and positioning of the pressure vessel by combining the guided wave signals.

The flexible multifunctional sensor network according to item [ 1 ] above, wherein the stretchable flexible base layer is made of a double-sided copper-plated polyimide film having a thickness of 0.1 to 0.5mm, and the island-like members and the stretchable members are produced by laser engraving the double-sided copper-plated polyimide film at room temperature.

The flexible multi-purpose sensor network according to [ 2 ] above, wherein a copper coating layer on a part of the island-like members and a part of the surface of the stretchable member is removed by etching treatment;

the other part of the surface of the stretchable component with the copper coating reserved on the surface is used as a stretchable conductor component to electrically connect the guided wave signal acquisition unit and the temperature signal acquisition unit with corresponding interfaces respectively and is used for transmitting signals acquired by the signal acquisition units.

The flexible multifunctional sensor network according to any one of [ 1 ] to [ 3 ], wherein the stretchable member is a serpentine member.

The flexible multifunctional sensor network according to item [ 1 ] above, wherein the guided wave signal acquisition unit is a piezoelectric sensor array composed of at least 2 flexible piezoelectric sensors, and the temperature signal acquisition unit is a temperature sensor array composed of at least 2 patch type temperature sensors.

The flexible multifunctional sensor network according to [ 1 ] or [ 5 ], wherein the flexible piezoelectric sensor is a piezoelectric thin film sensor, and the patch type temperature sensor is a patch type thin film temperature sensor.

The flexible multifunctional sensor network according to [ 6 ] above, wherein the flexible piezoelectric sensor is a circular polyvinylidene fluoride piezoelectric film transducer.

The flexible multifunctional sensor network according to [ 6 ] above, wherein the patch type temperature sensor is a square platinum patch resistance type temperature sensor.

The flexible multifunctional sensor network according to [ 1 ] above, wherein,

the guided wave signal acquisition unit comprises a first excitation terminal and a first signal receiving terminal, the temperature signal acquisition unit comprises a second signal receiving terminal,

the first excitation terminal, the first signal receiving terminal and the second signal receiving terminal are respectively and electrically connected to corresponding interfaces, and each interface is arranged on a plurality of fixing assemblies for fixing the flexible multifunctional sensing network.

The flexible multifunctional sensor network according to item [ 9 ], wherein the first excitation terminal and the first signal receiving terminal are used interchangeably.

Advantageous effects

Compared with the prior art, the utility model has the following advantages:

(1) The utility model designs the highly integrated flexible multifunctional sensing network as the monitoring device, and the monitoring area can be effectively regulated through the stretching network, so that the device has good universality for pressure containers with different shapes and sizes.

(2) Compared with the traditional structure health monitoring method based on guided waves for the pressure vessel, the flexible piezoelectric sensor is used as the guided wave signal acquisition unit, so that the defects of easy breakage, poor conformal capability with the pressure vessel and high acoustic impedance of the traditional piezoelectric ceramic sheet can be avoided, and the reliability of long-term monitoring is improved.

(3) According to the utility model, the temperature sensor is integrated on the basis of the damage diagnosis technology based on the guided wave, the influence of the disturbance of the guided wave speed caused by the temperature change of the pressure container in the working state, such as the increase of the guided wave amplitude, is considered, and the monitoring precision of the pressure container under different working conditions is improved.

Other aspects, features and advantages of the present utility model will become apparent in the following detailed description.

Drawings

Fig. 1 is a schematic diagram illustrating a flexible multifunctional sensor network according to an embodiment of the present utility model.

Fig. 2 is a schematic exploded view of the guided wave signal acquisition unit in the region a in fig. 1.

Fig. 3 is a schematic exploded view of the temperature signal acquisition unit in the region B in fig. 1.

Fig. 4 is a schematic circuit layout diagram of the flexible multifunctional sensor network shown in fig. 1.

Fig. 5 is a tensile test diagram of a flexible multifunctional sensor network according to an embodiment of the present utility model.

Fig. 6 is a graph showing a temperature change of a pressure vessel (gas cylinder) according to the present utility model during a pressurizing process.

Fig. 7 is a graph showing a comparison of damage positioning results before and after temperature correction of the pressure vessel according to the present utility model, wherein fig. 7 (a) shows the damage positioning results before temperature correction, and fig. 7 (B) shows the damage positioning results after temperature correction.

Detailed Description

The technical features of the present utility model will be described below with reference to the preferred embodiments and the accompanying drawings, which are intended to illustrate the present utility model, not to limit the present utility model. The figures are greatly simplified for illustration purposes and are not necessarily drawn to scale.

It should be understood that the drawings illustrate only the preferred embodiments of the utility model and are not to be considered limiting of the scope of the utility model. Various obvious modifications, variations, equivalent substitutions of the present utility model may be made by those skilled in the art on the basis of the embodiments shown in the drawings, and the technical features in the different embodiments described below may be arbitrarily combined without contradiction, and all of them fall within the scope of the present utility model.

[ Flexible multifunctional sensor network ]

The configuration and features of the flexible multifunctional sensor network (hereinafter also referred to as "sensor network") of the present utility model will be described in detail below with reference to fig. 1 to 4. Fig. 1 is a schematic diagram illustrating a flexible multifunctional sensor network according to an embodiment of the present utility model. Fig. 2 is a schematic exploded view of the guided wave signal acquisition unit in the region a in fig. 1. Fig. 3 is a schematic exploded view of the temperature signal acquisition unit in the region B in fig. 1. Fig. 4 is a schematic circuit layout diagram of the flexible multifunctional sensor network shown in fig. 1.

The flexible multifunctional sensing network comprises a stretchable flexible substrate layer 1, a guided wave signal acquisition unit 4, a temperature signal acquisition unit 3 and a plurality of interfaces (P1-P20) which are respectively and electrically connected with the guided wave signal acquisition unit and the temperature signal acquisition unit.

As shown in fig. 1, the stretchable flexible substrate layer 1 is in a network shape, and is composed of a plurality of island members 5 at network nodes and a plurality of stretchable members 6 connecting the island portions. For convenience of explanation, the sensing network is set to be in a 5×5 matrix format, the lower left corner of fig. 1 is taken as an origin as a coordinate axis, the transverse direction is taken as an X-axis direction, 5 columns of the sensing network are sequentially marked as X1, X2, X3, X4 and X5 from the origin, the longitudinal direction is taken as a Y-axis direction, and 5 rows of the sensing network are sequentially marked as Y1, Y2, Y3, Y4 and Y5 from the origin. Island members located at network nodes are marked as I (x _i ,y _j ) For example, island-like members located in the 3 rd column and the 1 st row are denoted as islands I (x ₃ ,y ₁ )。

In the present embodiment, the sensor network is set to a 5×5 matrix, but the present utility model is not limited to this, and any matrix such as 6×6, 8×8, 10×10, 100×100, 50×200, etc. may be set as necessary.

Stretchable members 6 connecting the island members to each other are formed between the island members. The stretchable member is preferably a serpentine member so that the network has excellent extensibility, and can reach 350% or more, more preferably 400% or more of the original length after stretching, and the stretchable member is preferably 1000% or less, more preferably 800% or less of the original length after stretching in consideration of the strength of the sensor network and the interval between sensors. The line width of the stretchable member is not particularly limited, and may be 0.5 to 5mm, preferably 1 to 4mm, more preferably 1 to 3mm, and most preferably 1 to 2mm. The line width of the stretchable member is in the above range, laser processing is facilitated and it is ensured that the stretchable member is not easily broken at the time of stretching. The monitoring area and the monitoring area can be effectively adjusted through the stretching network, so that the device has good universality on pressure containers with different shapes and sizes.

In fig. 1, a part of the surface of a stretchable flexible substrate layer 1 is covered with a conductive copper clad layer 2, and the copper clad layer 2 is a black part including a stretchable conductive member and an island-shaped conductive member.

In a preferred embodiment, the stretchable flexible substrate layer 1 is made of a double-sided copper-plated polyimide film having a thickness of 0.1 to 0.5mm, and the island-like members 5 and the stretchable members 6 are prepared by laser engraving the double-sided copper-plated polyimide film at normal temperature. The thickness of the double-sided copper-plated polyimide film is preferably 0.2 to 0.5mm, more preferably 0.25 to 0.4mm. A portion of the island-like members and a portion of the copper cladding on the surface of the stretchable member are removed by etching treatment. By removing part of the copper cladding on both sides of the film, short circuits of the transmission paths can be avoided. In addition, the other part of the surface of the stretchable component with the copper coating reserved on the surface is used as a stretchable conductor component to electrically connect the guided wave signal acquisition unit and the temperature signal acquisition unit with corresponding interfaces respectively, and the stretchable conductor component can be used for transmitting signals acquired by the signal acquisition units.

For example, in FIG. 1Black island-like members (e.g. islands I (x ₁ ,y ₅ )、I(x ₂ ,y ₃ )、I(x ₃ ,y ₂ )、I(x ₃ ,y ₄ )、I(x ₄ ,y ₃ )、I(x ₅ ,y ₃ ) And stretchable means that the surface of the member remains with a copper coating, and island-like members that are white (or hollow) (e.g., islands I (x) ₁ ,y ₁ )、I(x ₁ ,y ₂ )、I(x ₅ ,y ₄ ) Etc.) and the tensile member indicates that the copper coating of the surface of the member has been removed. Furthermore, island-like members shaded in gray (e.g., islands I (x ₂ ,y ₂ )、I(x ₃ ,y ₃ ) Etc.) means that the island-like member carries a guided wave signal acquisition unit or a temperature signal acquisition unit.

In addition, according to the circuit layout requirement, a through hole is preferably formed at a specific portion of a part of the island-shaped member by laser processing, and conductive silver paste is poured into the through hole so that the copper cladding layers on the front and back surfaces of the island-shaped member are electrically conducted.

In the flexible multifunctional sensing network, the guided wave signal acquisition unit comprises more than one flexible piezoelectric sensor, and the flexible piezoelectric sensors are distributed on the island-shaped members. The guided wave signal acquisition unit is preferably a piezoelectric sensor array consisting of more than 2 flexible piezoelectric sensors. For example, in FIG. 1, in island I (x ₁ ,y ₄ )、I(x ₃ ,y ₁ )、I(x ₃ ,y ₃ )、I(x ₅ ,y ₂ ) And the surface-mounted temperature sensors are respectively arranged on the substrate to form an array of the surface-mounted temperature sensors.

In addition, in the flexible multifunctional sensing network, the temperature signal acquisition unit comprises more than one patch type temperature sensor, and the patch type temperature sensors are distributed on the island-shaped members. The temperature signal acquisition unit is preferably a temperature sensor array composed of more than 2 patch type temperature sensors. For example, in FIG. 1, in island I (x ₂ ,y ₂ )、I(x ₂ ,y ₄ )、I(x ₄ ,y ₂ )、I(x ₄ ,y ₄ ) On which flexible piezoelectric sensors are respectively arranged to form flexibilityAn array of piezoelectric sensors.

In the flexible multifunctional sensing network, the flexible piezoelectric sensor and the patch type temperature sensor are respectively and independently carried on the island-shaped member. The island-like members are preferably shaped and sized to accommodate the flexible piezoelectric sensor and the patch-type temperature sensor carried thereby.

In the utility model, the flexible piezoelectric sensor is a sensor based on piezoelectric effect and has flexibility, and the sensor is a self-generating type sensor and an electromechanical conversion type sensor and is used for diagnosing and positioning damage. As the flexible piezoelectric sensor, a piezoelectric thin film sensor is preferably used, and a circular polyvinylidene fluoride (PVDF) piezoelectric thin film transducer is particularly preferably used. The piezoelectric film sensor has the characteristics of thinness, light weight, very softness, wide frequency response, large dynamic range, high force point conversion sensitivity, light weight, softness, no brittleness, impact resistance and the like. The thickness of the flexible piezoelectric sensor is 0.05 to 0.5mm, preferably 0.1 to 0.4mm, more preferably 0.2 to 0.3mm. The shape of the flexible piezoelectric sensor is not particularly limited, and may be circular, square, hexagonal, or the like, and is preferably circular. A circular flexible piezoelectric sensor is used in the sensor network shown in fig. 1. The size of the flexible piezoelectric sensor is not particularly limited, and may be selected as required, and in the case of using a circular flexible piezoelectric sensor, for example, the diameter thereof may be 5 to 10mm.

By adopting the flexible piezoelectric sensor as the guided wave signal acquisition unit, the defects of easy breakage, poor conformal capability with a pressure vessel and high acoustic impedance of the traditional piezoelectric ceramic sheet can be avoided, and the reliability of long-term monitoring can be improved.

In addition, in the utility model, the patch type temperature sensor is used for acquiring temperature signals. The patch type temperature sensor has the characteristics of high measurement accuracy and high response speed when being used for measuring the surface temperature of an object. As the patch type temperature sensor, a patch type thin film temperature sensor is preferably used, and a platinum patch resistance type temperature sensor is more preferably used. The platinum patch resistance type temperature sensor has the advantages of high precision, good stability and wide application temperature range. The thickness of the patch type temperature sensor is not particularly limited, and may be 0.05 to 3mm, preferably 0.1 to 1mm. The shape of the patch type temperature sensor is not particularly limited, and may be circular, square, hexagonal, or the like, and is preferably square. A square patch type temperature sensor is used in the sensor network shown in fig. 1. The size of the patch type temperature sensor is not particularly limited, and may be selected as required, and for example, in the case of using a square patch type temperature sensor, the side length thereof may be 5 to 12mm, preferably 8 to 10mm.

The flexible piezoelectric sensor preferably includes a first excitation terminal electrically connected to the corresponding interface and exciting the piezoelectric sensor, and a first signal receiving terminal connected to the corresponding interface and delivering a piezoelectric signal to the computer through the port and the circuit. The first excitation terminal and the first signal receiving terminal in the present utility model may be used interchangeably.

The temperature signal acquisition unit preferably comprises a second signal receiving terminal for electrically connecting with a corresponding interface and for transmitting the received temperature signal to a computer.

In some preferred embodiments, the interfaces (P1 to P20) corresponding to the first excitation terminal, the first signal receiving terminal, and the second signal receiving terminal are provided on a plurality of fixing members of the flexible multifunctional sensor network, and the fixing members are used for fixing the flexible multifunctional sensor network to the pressure vessel. For convenience of description, the fixed components are denoted by reference numerals corresponding to the interfaces (P1 to P20).

The sensing network transmits the guided wave signals acquired by the guided wave signal acquisition unit and the temperature signals acquired by the temperature signal acquisition unit to the computer through a plurality of interfaces, corrects the wave speed based on the temperature signals, and combines the temperature signals with the guided wave signals to monitor and position the damage of the pressure vessel.

The connection and operation of each constituent element of the sensor network according to the preferred embodiment of the present utility model will be further described below with reference to fig. 2 to 3.

Fig. 2 shows a schematic structural exploded view of the guided wave signal acquisition unit of the region a in fig. 1, the region a including an island I (x 2, y 2), an island I (x 2, y 1), and a stretchable member connecting the two islands, wherein a circular PVDF piezoelectric film transducer (hereinafter also abbreviated as PVDF piezoelectric film) is carried on the island I (x 2, y 2). As can be seen from fig. 2, the frontside of the islands I (x 2, y 1) and stretchable members are white, indicating that the copper cladding on the frontside of the copper-clad polyimide film 11 is removed, but the backside of the copper-clad polyimide film 11 remains with the copper cladding 12 for electrical connection with the PVDF piezoelectric film and transmission of electrical signals.

The whole guided wave signal acquisition unit has a stacked structure, is clamped between the upper layer and the lower layer of copper-clad polyimide film 11, is formed by bonding the upper side and the lower side of the PVDF piezoelectric film 14 with the copper-clad layer 12 on the copper-clad polyimide film 11 through the z-axis conductive adhesive tape layer 13 of 10-30 mu m respectively, thereby realizing electric connection and mechanical connection, and an electric signal is transmitted from the island I (x 2, y 1) to the positive electrode of the PVDF piezoelectric film 14 at the island I (x 2, y 2) through a stretchable member. The island I (x 2, y 1) is formed by closely bonding the copper-clad layers 12 of the two-layered copper-clad polyimide 11 via the z-axis conductive tape, thereby achieving electrical and mechanical connection, and outputting piezoelectric signals collected from the PVDF piezoelectric film to the corresponding interfaces.

Fig. 3 is a schematic exploded view of the temperature signal acquisition unit in the region B in fig. 1. The region B comprises an island I (x 3, y 1) and stretchable members connected with two sides of the island I (x 3, y 1), wherein the upper part of the island I is the front surface of the island I (x 3, y 1), the lower part of the island I is the back surface of the island I (x 3, y 1), and the middle part of the island I is a structural exploded view of the temperature signal acquisition unit. In the island-like member and the stretchable member in fig. 3, white portions indicate that the copper clad layer on the surface of the copper-clad polyimide film 21 is removed, and black portions indicate that the copper clad layer 22 on the surface of the copper-clad polyimide film 21 remains as a wire.

A through hole 23 with a pore diameter of about 1-2 mm formed by laser processing is arranged at a specific part of the island I (x 3, y 1), and conductive silver paste 24 is poured into the through hole 23 to form a conductive path for conducting copper cladding layers on two sides of the copper-clad polyimide film. A patch type temperature sensor 25 for acquiring a temperature signal is carried on the island I (x 3, y 1). As shown in the exploded view of fig. 3, the positive electrode 26 and the negative electrode 27 of the patch type temperature sensor are adhered to the copper clad of the copper-clad polyimide film via the z-axis conductive tape 28, wherein the negative electrode is conducted with the copper clad on the other side of the copper-clad polyimide film through the conductive path of the through-hole portion to form a conductive path. And transmitting electric signals to the patch type temperature sensor through the positive electrode and the negative electrode of the patch type temperature sensor and transmitting the acquired temperature signals to a corresponding interface.

The circuit layout of the flexible multifunctional sensor network according to the preferred embodiment of the present utility model will be described with reference to fig. 4.

In the flexible multifunctional sensing network of the present utility model, the temperature signal acquisition unit 3 and the guided wave signal acquisition unit 4 are arranged in a distributed manner on a plurality of island-shaped members, and the island-shaped members are interconnected with each other by stretchable members. The temperature signal acquisition unit 3 and the guided wave signal acquisition unit 4 are connected with the outside (for example, a computer) through corresponding interfaces (P1-P20). The sensor network is arranged on the surface of the pressure vessel through a fixing component at the interface after stretching. In fig. 4, the gray route is the back trace of the sensor network, the black route is the front trace, and the node where the black and gray meet is the junction electrically conducted through the conductive silver paste of the through hole.

In the temperature signal and guided wave signal acquisition process, current flows in from a signal input end, flows through a temperature acquisition unit (a patch type temperature sensor) and a guided wave acquisition unit (a flexible piezoelectric sensor) and flows out from a circuit cathode. The circuit layout is flexibly designed according to the number of sensors and the installation positions, and the preferred arrangement of the circuit paths of each signal acquisition unit is described by taking a 5×5 matrix multifunctional sensor network as an example shown in fig. 4.

All the similar sensors are connected by adopting a common negative electrode, so that the potential of the whole negative electrode surface is the same and can be regarded as the common ground. Wherein the temperature sensor is at the common ground I (x 1, y 3) -I (x 1, y 2) -I (x 1, y 1) -I (x 2, y 1) -I (x 3, y 1) -I (x 4, y 1) -I (x 5, y 1), this entire common ground path being designated Gt. The piezoelectric sensor is co-grounded as I (x 2, y 4) -I (x 3, y 4) -I (x 4, y 3) -I (x 4, y 2) -I (x 3, y 2) -I (x 2, y 3) -I (x 5, y 3), and the whole common ground path is named Gg.

The circuit layout of each temperature sensor (T1 to T5) is as follows:

T1:7→P15→I(x1,y5)→T1→Gt→P5→10

T2:7→P13→I(x3,y5)→I(x3,y4)→T2→Gt→P5→10

T3:7→P7→T3→Gt→P5→10

T4:7→P3→T4→Gt→P5→10

the circuit layout of each piezoelectric sensor (PT 1 to PT 5) is as follows:

PT1:8→P14→I(x2,y5)→PT1→Gg→P8→9

PT2:8→P12→I(x4,y5)→PT2→Gg→P8→9

PT3:8→P4→I(x4,y1)→PT3→Gg→P8→9

PT4:8→P2→I(x2,y1)→PT4→Gg→P8→9

the circuit layout of each sensor of the temperature signal acquisition unit and the guided wave signal acquisition unit is only a preferred embodiment, and the utility model is not limited thereto, and one of ordinary skill in the art can make any modification and combination according to the actual requirements on the premise that the operation of the sensor and the signal acquisition and transmission can be realized.

[ method for manufacturing flexible multifunctional sensor network ]

The preferred flexible multifunctional sensor network of the present utility model can be manufactured by the following method.

The flexible double-sided copper-plated polyimide film is tiled on the plane of a workbench, a pre-designed conductive path is printed by an ink-jet printer, the printing ink is left to stand for curing, and after the curing is finished, an unnecessary copper coating is etched and removed by ferric chloride etching liquid (step S1). In this step, the curing temperature is preferably room temperature, the curing time is preferably 12 to 24 hours, and the etching time is preferably 5 to 20 minutes.

Next, the polyimide film obtained is laid on a laser work table, unnecessary portions of the polyimide film are removed by laser engraving according to a pre-designed program and a base pattern, a network-like stretchable flexible substrate composed of a plurality of island members at network nodes and a plurality of stretchable members connecting the island portions is formed, and laser processing is performed at specific positions of part of the island members to form through holes (step S2). In this step, the stretchable member is preferably processed into a serpentine member. Further, it is preferable to further spray an insulating material on the surfaces of the island-like member and the stretchable member having the copper coating layer on the surfaces thereof for electromagnetic shielding. As the insulating material, an insulating material such as silicone three-proofing glue is preferably used.

Next, pouring conductive silver paste into the through hole and curing to form a conductive path; installing flexible piezoelectric sensors on more than 1 island-shaped members to form guided wave signal acquisition units, and arranging interfaces corresponding to the guided wave signal acquisition units so that the positive and negative poles of the guided wave signal acquisition units are electrically connected with the corresponding interfaces through stretchable members with copper coating on the surfaces; mounting patch type temperature sensors on more than 1 island-shaped members to form a temperature signal acquisition unit, and providing interfaces corresponding to the temperature signal acquisition unit, so that the temperature signal acquisition unit is electrically connected with the corresponding interfaces through a stretchable member with a copper coating on the surface (step S3). In this step, the curing condition of the conductive silver paste is preferably curing at 100 to 150 ℃ for 5 minutes to 8 hours. In addition, the flexible piezoelectric sensor and the patch temperature sensor are preferably bonded to the island member by z-axis conductive tape to achieve electrical conduction and mechanical connection. In addition, as the flexible piezoelectric sensor, a PVDF piezoelectric film transducer is preferably used, and as the patch-type temperature sensor, a platinum patch-type resistance-type temperature sensor is preferably used.

Examples

The constitution of the present utility model and its advantages are further described below by way of examples, but it should be understood that the following examples are merely illustrative of the practice of the present utility model and are not intended to limit the scope of the present utility model.

(manufacture of flexible multifunctional sensor network)

A flexible double-sided copper-plated polyimide film with a thickness of 0.25mm was laid flat on a table plane, then a pre-designed conductive path was printed by an inkjet printer, then the ink was allowed to stand at room temperature for 12 hours to cure, and after curing was completed, etching was performed by an etching solution of ferric chloride (20% by mass of ferric chloride-aqueous solution) for 10 minutes to remove an unnecessary copper clad layer.

Next, the obtained polyimide film was tiled on a laser work platform (Stone MMEPU-355-5, tianjin Mei Man laser technology limited company), and unnecessary portions of the polyimide film were removed by laser engraving (laser power 5w, laser spot size 25 μm, engraving rate 10 mm/s) according to a pre-designed program and base pattern, to form a 5×5 array-type sensor network shown in fig. 1 composed of a plurality of island-like members at network nodes and a plurality of stretchable members connecting the island-like portions, the stretchable members being formed in a serpentine structure with a line width of 1mm, and laser processing was performed at specific positions of part of the island-like members to form through holes with a hole diameter of 1mm. And further spraying organosilicon three-proofing glue serving as an insulating material on the surfaces of the island-shaped member and the stretchable member with the copper coating on the surfaces for electromagnetic protection.

Next, a conductive silver paste (SINWE 3701) was poured into the through hole and cured at 150 ℃ for 5 minutes to form a conductive via; a square platinum patch resistance type temperature sensor (with a side length of 10mm, a thickness of 0.1mm and an initial resistance of 100 omega at 25 ℃) is adhered and mounted on the 4 island-shaped members by using a z-axis anisotropic conductive adhesive tape to form a temperature sensor array; circular PVDF piezoelectric film piezoelectric transducers (thickness 0.2mm, diameter 9mm, sampling center frequency 200 kHz) were bonded and mounted on the 4 island members using z-axis anisotropic conductive tape, respectively, to form an array of piezoelectric film piezoelectric transducers, the specific arrangement of which is shown in FIG. 1. Interfaces corresponding to the temperature sensors and the piezoelectric thin film piezoelectric transducers are arranged, a stretchable serpentine member with a copper coating on the surface is electrically connected with the corresponding interfaces, and the sensors are communicated according to the circuit layout line shown in fig. 4.

(tensile test of Flexible multifunctional sensor network)

The serpentine structure portion of the flexible multifunctional sensor network prepared as above was fixed to an upper limit stretcher (ESM 750S american mark-10) for a uniaxial stretching experiment, and force-length data as shown in fig. 5 was obtained. As can be seen from fig. 5, when the serpentine length is stretched to 390% of the original length, the force changes dramatically, indicating that the serpentine breaks. Namely, the serpentine structure part has high extensibility which can be stretched to 390% of the original length, and the flexible multifunctional sensing network can flexibly adjust the monitoring area and the area, has excellent extensibility and has good universality for pressure containers with different shapes and sizes.

(temperature variation during inflation and deflation of pressure vessel)

The prepared flexible multifunctional sensing network is stretched and arranged on the surface of a gas cylinder (pressure vessel). The temperature signals of the platinum patch resistance type temperature sensors are collected by the multichannel data collection card, and the input port 7 and the output port 10 of the temperature sensors are respectively connected to the multichannel data collection card NI-9273 (National Instruments, U.S.). And setting the sampling voltage to be 1v and the sampling frequency to be 20Hz for the output port and the input port, automatically collecting the multichannel current signals, and exporting the data to a computer for recording. The method is characterized in that gas cylinder temperature signals in the pressurizing process are collected, the pressurizing parameters are that the inflating speed is 0.8Mpa/s, the deflating speed is 10Mpa/s, the peak gas pressure is 20Mpa, and the peak holding time is 0s. The temperature acquisition result is shown in fig. 6, and the acquisition capability of the temperature sensor array on temperature is shown.

The principle of temperature-modified ultrasonic guided wave is related to the propagation mechanism of ultrasonic guided wave, guided wave is generally divided into transverse wave and longitudinal wave, and the wave speed of the longitudinal wave propagating along the tubular structure is shown in formula (1):

the transverse wave propagates along the tubular structure as shown in equation (2):

wherein E is the Young's modulus of the material; ρ is the material density; sigma is poisson's ratio; g is the modulus of rigidity. It can be seen that the wave velocity of the guided wave is related to the intrinsic performance of the material, the Young modulus and the rigidity modulus of the material are greatly influenced by temperature fluctuation, the change relation of the rigidity modulus of the solid elastic modulus along with the temperature is generally obtained by adopting a statistical fitting method based on experiments, and then the wave velocity is corrected based on the relation, so that the positioning precision can be improved.

(guided wave-based damage localization test)

And stretching the manufactured flexible multifunctional sensing network to a proper size along a transverse and longitudinal axis, and fixing the flexible multifunctional sensing network on the surface of the gas cylinder by using an adhesive. And the PVDF piezoelectric transducer terminal used for collecting the guided wave signals in the sensing network is subjected to sweep frequency experiments to obtain the center frequency and the bandwidth of the guided wave signal collecting terminal, wherein the center frequency is selected to be 200Khz, and the bandwidth is 30db. The guided wave signal is generated by a signal generator, is input into the positive electrode of the excitation terminal through the signal attenuator by the input port 8, is received by the receiving terminal, is output to the signal amplifier by the output port 9, and finally displays the waveform on the oscilloscope to complete the single-channel guided wave signal acquisition. And finally, carrying out lesion localization imaging by using an ellipse algorithm. As shown in fig. 7 (a), the imaging results when the temperature correction was not performed are that the pressure vessel damage position was close to the imaging position, and the positioning accuracy on the abscissa before the temperature correction was not performed was 91% and 92%, respectively. In contrast, the wave velocity was corrected based on the acquired temperature signal, and the damage detection and positioning results were obtained with the corrected abscissa positioning accuracy of 95.2% and 96.7%, respectively, as shown in fig. 7 (B). Therefore, the guided wave signal acquisition unit and the temperature signal acquisition unit comprising the temperature sensor are arranged in the flexible multifunctional sensing network, influences such as guided wave speed disturbance caused by temperature change of the pressure container in a working state are considered, the guided wave speed is corrected based on the acquired temperature signals, and the monitoring precision of damage positioning of the pressure container under different working conditions can be remarkably improved.

Finally, it should be understood that the description of the embodiments and examples above is illustrative in all respects, not limiting of the utility model, and that various modifications could be made by those of ordinary skill in the art without undue burden without departing from the spirit of the utility model. The scope of the utility model is indicated by the claims rather than by the foregoing description or examples. The scope of the utility model also includes all modifications within the meaning and scope equivalent to the claims.

Furthermore, while the foregoing description and related drawings describe example embodiments with respect to certain example combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and/or functions other than those explicitly described above are also contemplated as may be set forth in some of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Industrial applicability

The flexible multifunctional sensing network has excellent stretching ductility, integrates the guided wave signal acquisition unit and the temperature signal acquisition unit, can flexibly and adjustably set the monitoring area, is integrated on the surface of the pressure container to realize on-line monitoring, and has good application prospect in the field of accurately positioning the damage defects.

Claims

1. A flexible multifunctional sensing network is characterized by comprising a stretchable flexible substrate layer, a guided wave signal acquisition unit, a temperature signal acquisition unit and a plurality of interfaces which are respectively and electrically connected with the guided wave signal acquisition unit and the temperature signal acquisition unit,

the stretchable flexible substrate layer is in a network shape and is composed of a plurality of island-shaped members at network nodes and a plurality of stretchable members connecting the island-shaped portions,

the temperature signal acquisition unit comprises more than one patch type temperature sensor which is distributed on the island-shaped member,

the flexible piezoelectric sensor and the patch type temperature sensor are respectively and independently carried on the island-shaped members.

2. The flexible multifunctional sensor network of claim 1, wherein the stretchable flexible substrate layer is made of a double-sided copper-plated polyimide film with a thickness of 0.1-0.5 mm,

the island-like members and the stretchable members are made of double-sided copper-plated polyimide film laser-engraved at normal temperature.

3. The flexible multi-function sensor network of claim 2, wherein a portion of the island-like members and a portion of the copper cladding on the surface of the stretchable member are etched away;

4. A flexible multifunctional sensing network according to any of claims 1-3, characterized in that the stretchable member is a serpentine member.

5. The flexible multifunctional sensor network of claim 1, wherein the guided wave signal acquisition unit is a piezoelectric sensor array composed of more than 2 flexible piezoelectric sensors, and the temperature signal acquisition unit is a temperature sensor array composed of more than 2 patch type temperature sensors.

6. The flexible multi-functional sensor network of claim 1 or 5, wherein the flexible piezoelectric sensor is a piezoelectric film sensor and the patch-type temperature sensor is a patch-type film temperature sensor.

7. The flexible multi-functional sensor network of claim 6, wherein the flexible piezoelectric sensor is a polyvinylidene fluoride piezoelectric film transducer.

8. The flexible multi-function sensor network of claim 6, wherein the patch-type temperature sensor is a platinum patch-type resistive temperature sensor.

9. The flexible multi-function sensor network of claim 1,

the flexible piezoelectric sensor comprises a first excitation terminal and a first signal receiving terminal, the patch type temperature sensor comprises a second signal receiving terminal,

the first excitation terminal, the first signal receiving terminal and the second signal receiving terminal are respectively and electrically connected to corresponding interfaces, and each interface is arranged on a plurality of fixing components for fixing the flexible multifunctional sensing network.

10. The flexible multi-function sensor network of claim 9, wherein the first excitation terminal and the first signal receiving terminal are used interchangeably.