A method for detecting defects in hydraulic structures in deep water environments based on piezoelectric sensor arrays

Abstract

The present invention discloses a method for detecting defects in hydraulic structures in deepwater environments based on a piezoelectric sensor array, comprising the steps of: preparing a flexible piezoelectric sensor array; assembling a detection device: installing the piezoelectric sensor array on an ROV robot, loading a sonar positioning system, and then performing waterproofing and deepwater negative pressure treatment; remotely controlling the detection device for underwater detection; and data processing and defect identification. The flexible piezoelectric sensor array of the device is placed in a flexible power generation layer, which can achieve self-power supply, greatly reducing the number of maintenance times and increasing the service life of the equipment. The method and equipment are flexible and highly sensitive, and can achieve unmanned nondestructive detection of damage and deformation of hydraulic structures in deepwater environments.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater structure defect detection, and specifically to a method for detecting defects of hydraulic structures in a deep water environment based on a piezoelectric sensor array. Background Art

[0002] Hydraulic structures have an impact on controlling and regulating water flow, flood discharge, power generation, irrigation, etc. It is inevitable that some parts of hydraulic structures will be placed underwater. Long-term scouring of water flow and corrosion of some pollutants in the water will cause some hydraulic structures to have holes, which will directly affect the quality and safety of the buildings and also greatly affect the service life of hydraulic structures. Therefore, during the service life of hydraulic structures, it is necessary to regularly detect and inspect the deformation, damage, defects, etc. of the buildings.

[0003] Due to the large negative pressure at the bottom of hydraulic structures, the deep underwater environment cannot be easily detected, and some safety factors make it not suitable for humans to detect it by themselves. However, it is also difficult to detect some hole defects in deep underwater hydraulic structures with just some ordinary tools.

[0004] Based on the above problems, there are currently several methods for detecting hole defects in underwater buildings:

[0005] (1) Infrared nondestructive testing: Based on the intrinsic relationship between the infrared radiation, surface temperature and material properties of an object, an infrared thermal imager is used to convert the infrared radiation from the target into a visible thermal image. By analyzing the characteristics of the thermal image, it is possible to infer whether there are defects inside the object. However, its disadvantage is that it has poor penetration and can only measure the surface of the material.

[0006] (2) X-ray inspection: X-ray equipment is used to transmit the step standard gauge and the target object to obtain clear images of the step standard gauge and the target object. The size of the holes on the step layer of the same thickness as the target object in the step standard gauge in the clear image is visually compared with the size of the holes on the target object one by one to obtain the size of the holes on the target object and the sealing degree of the target object. However, the presence of volume defects and area defects makes the inspection very uncertain.

[0007] (3) Microwave detection: Use microwave vector network analyzer to detect buildings, obtain a series of signals such as reflection peaks, calculate time domain signals through inverse Fourier transform, and draw conclusions by comparison. However, the cost is high and the process is cumbersome, which brings inconvenience to the detection of hole defects in a large number of hydraulic structures.

[0008] The above three detection methods all have some problems, so it is necessary to develop better methods for detecting hole defects in hydraulic structures in deepwater environments. Summary of the invention

[0009] The purpose of the present invention is to provide a method for detecting defects in hydraulic structures in deepwater environments based on a piezoelectric sensor array, so as to solve the technical problem that it is difficult to detect hole defects in deepwater hydraulic structures in the prior art.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] The method for detecting defects of hydraulic structures in deep water environment based on piezoelectric sensor array comprises the following steps:

[0012] Step 1: Prepare flexible piezoelectric sensor array:

[0013] The flexible piezoelectric sensor array comprises a flexible protective film, a flexible insulating layer and a piezoelectric sensor array layer; the piezoelectric sensor array layer is arranged on the flexible protective film to eliminate stress concentration of external pressure and realize smooth transition of piezoelectric signals of each sensor element; the flexible insulating film encapsulates the piezoelectric sensor array layer and the flexible protective film to realize watertight sealing and electrical signal insulation in a deep water environment;

[0014] Step 2: Assemble the detection equipment:

[0015] Install the piezoelectric sensor array on the ROV robot, load the sonar positioning system, and then do waterproofing and deep-water negative pressure treatment;

[0016] Step 3: Remotely control the detection equipment for underwater detection:

[0017] The ROV robot carrying the piezoelectric sensor array is controlled by a remote control platform to descend to the deep-water area to be detected and approach the deep-water structure; the sonar positioning system is used to assist in determining the macroscopic outline of the underwater hydraulic structure, and then determine the fixed or hovering position of the detection equipment, as well as the location of the structure where defects need to be detected, and waterproofing is done to extend the service life of the sonar, robot and piezoelectric array, deep-water negative pressure treatment is done well, and the water pressure reference value is recorded to avoid detection errors. The ROV robot is a prior art and will not be described in detail.

[0018] The robot's mechanical arm drives the piezoelectric sensor array to touch the part of the building to be detected. When a certain position of the underwater building is sunken in the middle, the pressure of each piezoelectric element in the piezoelectric sensor array when in contact with the building will be different. The difference is converted into an electrical signal by the piezoelectric effect of the piezoelectric sensor element and transmitted to the controller terminal.

[0019] Step 4: Data processing and defect identification:

[0020] The controller terminal receives the electrical signal transmitted by the piezoelectric sensor array, and reconstructs the surface morphology of the hydraulic structure through signal denoising, compensation and array analysis, restores the shape of the underwater structure, and compares the design drawings of the hydraulic structure by analyzing and comparing the damage and deformation of the overall and detailed structures, thereby obtaining more specific and accurate information such as the location and shape of the hole defects, thereby realizing defect identification.

[0021] Further improvement, the piezoelectric sensor array layer is composed of m rows and n columns, a total of m×n piezoelectric electret thin film sensor elements, each sensor element is fixed on a flexible substrate, and m and n are both positive integers greater than or equal to 3;

[0022] The upper and lower surfaces of each piezoelectric sensor element are symmetrically covered with conductive electrodes, and each electrode is connected to a signal receiver through a wire.

[0023] Further improvement, the analysis of the electrical signal in step 4 is based on the function model f(x, a, b, c, d), such as the following functional relationship (1),

[0024] Ψ(y)=ax+bx 2 +csinx+dlnx (1)

[0025] Where x is the feedback electrical signal, Ψ(y) is the deformation variable, and a, b, c, d are coefficients;

[0026] The function model is constructed by fitting a large amount of experimental data, and the coefficients a, b, c and d in the functional relationship (1) are calculated using the least squares method, so as to determine the functional relationship between the electrical signal fed back by the piezoelectric sensor array and the object deformation under deep water conditions.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The flexible piezoelectric sensor array of the device is placed in the flexible power generation layer, which can achieve self-power supply, greatly reducing the number of maintenance times and extending the service life of the equipment.

[0029] 2. The equipment for this method is relatively simple to manufacture and has low cost. It reduces the economic burden of the necessary requirement of regularly detecting hole defects in hydraulic structures and also provides technical support.

[0030] 3. This method has flexible equipment and high sensitivity, and can realize unmanned nondestructive detection of damage and deformation of hydraulic structures in deepwater environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the structure of the flexible piezoelectric sensor array described in the present invention.

[0032] Figure 2The present invention is a schematic diagram of the principle of detecting defects in hydraulic structures using the detection equipment of the present invention.

[0033] Figure 3 Flowchart of the detection method of the present invention. DETAILED DESCRIPTION

[0034] The following is a clear and complete description of the technical solution in the present invention in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] like Figure 1-3 As shown, the method for detecting defects of hydraulic structures in deep water environment based on piezoelectric sensor array comprises the following steps:

[0036] Step 1: Prepare flexible piezoelectric sensor array:

[0037] like Figure 1 As shown, the flexible piezoelectric sensor array 1 includes a flexible protective film 12, a flexible insulating layer 13 and a piezoelectric sensor array layer 11; the piezoelectric sensor array layer is arranged on the flexible protective film to eliminate stress concentration caused by external pressure and achieve smooth transition of piezoelectric signals of each sensor element; the flexible insulating film encapsulates the piezoelectric sensor array layer and the flexible protective film to achieve water-proof sealing and electrical signal insulation in deep water environment.

[0038] The piezoelectric sensing array layer includes a flexible substrate and a plurality of thin film transistors formed by stacking multiple inorganic layers and multiple metal layers on the flexible substrate, wherein at least one inorganic layer is patterned to form a plurality of island structures containing thin film transistors, and an organic layer having a bending performance greater than that of the inorganic layer is filled between adjacent island structures, so that when the flexible array substrate is bent, adjacent island structures have gaps for stress release. The flexible substrate also includes a planarization layer covering the island structures, which is an organic layer and fills the gaps between the island structures.

[0039] Step 2: Assemble the detection equipment:

[0040] Install the piezoelectric sensor array 1 on the ROV robot, load the sonar positioning system, and then perform waterproofing and deep-water negative pressure treatment.

[0041] Step 3: Remotely control the detection equipment for underwater detection:

[0042] The ROV robot carrying the piezoelectric sensor array is controlled by a remote control platform to descend to the deep-water area to be detected and approach the deep-water structure; the sonar positioning system is used to assist in determining the macroscopic outline of the underwater hydraulic structure, and then determine the fixed or hovering position of the detection equipment, as well as the location of the structure where defects need to be detected, and waterproofing is done to extend the service life of the sonar, robot and piezoelectric array, deep-water negative pressure treatment is done well, and the water pressure reference value is recorded to avoid detection errors. The ROV robot is a prior art and will not be described in detail.

[0043] like Figure 2 As shown, the robot's mechanical arm 2 drives the piezoelectric sensor array to touch the part to be detected of the building 4. When a certain position of the underwater building is concave in the middle, there will be a difference in pressure when each piezoelectric element in the piezoelectric sensor array contacts the building. The difference is converted into an electrical signal by the piezoelectric effect of the piezoelectric sensor element and transmitted to the controller terminal 3.

[0044] Step 4: Data processing and defect identification:

[0045] The controller terminal 3 receives the electrical signal transmitted by the piezoelectric sensor array 1, and reconstructs the surface morphology of the hydraulic structure through signal denoising, compensation and array analysis, restores the shape of the underwater structure, and compares the design drawings of the hydraulic structure by analyzing and comparing the damage and deformation of the overall and detailed structures, thereby obtaining more specific and accurate information such as the location and shape of the hole defects, thereby realizing defect identification.

[0046] In this embodiment, the piezoelectric sensor array layer is composed of m rows and n columns, with a total of m×n piezoelectric electret thin film sensor elements, each of which is fixed on a flexible substrate, and m and n are both positive integers greater than or equal to 3;

[0047] The upper and lower surfaces of each piezoelectric sensor element are symmetrically covered with conductive electrodes, and each electrode is connected to a signal receiver through a wire.

[0048] In this embodiment, the array analysis is as follows: Based on the least squares principle, the function model f(x, a, b, c, d) can be obtained as shown in the following functional relationship (1). According to the measured electrical signal and the obtained object deformation depth, the functional relationship (1) between the electrical signal difference and the deformation amount is introduced. A simulation experiment is designed, and a large number of experiments are performed to fit the function. The coefficients a, b, c, d in the functional relationship (1) are calculated using the least squares method. The parameters a, b, c, d are selected so that the residual ek of the fitting model and the actual observation value at each point is equal to y. k -f(x k , the weighted square sum of a, b, c, d) is minimized, thereby determining the functional relationship between the electrical signal fed back by the piezoelectric sensor array and the deformation of the object under deep water conditions;

[0049] Ψ(y)=ax+bx 2 +csinx+dlnx (1)

[0050] Where x is the feedback electrical signal, Ψ(y) is the deformation variable, and a, b, c, d are coefficients;

[0051] The least square fitting curve is obtained by fitting the function, and the shape of the underwater building is restored. By comparing with the design drawings, the damage and deformation of the overall and detailed structure are analyzed and compared, so as to obtain more specific and accurate information such as the location of hole defects and the shape of the hole.

[0052] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting defects in hydraulic structures in deep water environments based on a piezoelectric sensor array, characterized in that: The steps include: Step 1: Prepare flexible piezoelectric sensor array: The flexible piezoelectric sensor array comprises a flexible protective film, a flexible insulating layer and a piezoelectric sensor array layer; the piezoelectric sensor array layer is arranged on the flexible protective film, and the flexible insulating film encapsulates the piezoelectric sensor array layer and the flexible protective film to achieve water-proof sealing and electrical signal insulation in a deep water environment; Step 2: Assemble the detection equipment: Install the piezoelectric sensor array on the ROV robot, load the sonar positioning system, and then do waterproofing and deep-water negative pressure treatment; Step 3: Remotely control the detection equipment for underwater detection: The ROV robot carrying the piezoelectric sensor array is controlled by a remote control platform to descend to the deep-water area to be detected and approach the deep-water buildings; the sonar positioning system is used to assist in determining the macroscopic outline of the hydraulic structures in the underwater environment, and then determine the fixed or hovering position of the detection equipment. The robot's mechanical arm drives the piezoelectric sensor array to touch the part of the building to be detected. When a certain position of the underwater building is concave in the middle, the pressure of each piezoelectric element in the piezoelectric sensor array when in contact with the building will be different. The difference is converted into an electrical signal by the piezoelectric effect of the piezoelectric sensor element and transmitted to the controller terminal; Step 4: Data processing and defect identification: The controller terminal receives the electrical signal transmitted by the piezoelectric sensor array, and reconstructs the surface morphology of the hydraulic structure through signal denoising, compensation and array analysis, restores the shape of the underwater structure, and compares the design drawings of the hydraulic structure by analyzing and comparing the overall and detailed damage and deformation of the structure, thereby obtaining more specific and accurate information on the location and shape of the hole defects and realizing defect identification.

2. The method for detecting defects of hydraulic structures in deep water environments based on a piezoelectric sensor array according to claim 1, characterized in that: The piezoelectric sensor array layer is composed of m rows and n columns, with a total of m×n piezoelectric electret thin film sensor elements, each of which is fixed on a flexible substrate, and m and n are both positive integers greater than or equal to 3; The upper and lower surfaces of each piezoelectric sensor element are symmetrically covered with conductive electrodes, and each electrode is connected to a signal receiver through a wire.

3. The method for detecting defects of hydraulic structures in deep water environments based on a piezoelectric sensor array according to claim 1 or 2, characterized in that: The analysis of the electrical signal in step 4 is based on the function model f(x, a, b, c, d), as shown in the following functional relationship (1): (1)； Where x is the feedback electrical signal, is the shape variable, a, b, c, d are coefficients; The function model is constructed by fitting a large amount of experimental data, and the coefficients a, b, c and d in the functional relationship (1) are calculated using the least squares method, thereby determining the functional relationship between the electrical signal fed back by the piezoelectric sensor array and the object deformation under deep water conditions.

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