In-situ phased array ultrasonic structure health monitoring method and system

Abstract

The invention discloses an in-situ phased array ultrasonic structure health monitoring method and system. The method comprises the steps that a coating sensor is manufactured on the surface of a monitoring structure in an in-situ conformal mode, and the coating sensor comprises a plurality of array units; electrodes of all array units of the coating sensor are connected to a multiplexing switch through wires, and the multiplexing switch controls the array units to serve as independent switching of an exciting unit and a receiving unit. The multiplexing switch is arranged to connect the excitation unit with the signal generator and the power amplifier to excite ultrasonic waves, and connect the receiving unit with the oscilloscope to collect ultrasonic signals; traversing all the array units as excitation units and collecting ultrasonic signals, and in the traversing process, when one or more array units serve as excitation unit input voltage, all the array units serve as receiving units at the same time to output signals; and obtaining an imaging result by using the acquired ultrasonic signal in a predetermined imaging mode. The method can accurately monitor the damage condition of the local complex area of the engineering structure.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic sensors, and more particularly to an in-situ phased array ultrasonic structural health monitoring method and system. Background Art

[0002] Large-scale engineering structures often have some local critical parts, such as stiffeners, fastening connections, and adhesive joints. Due to changes in geometric shape or connection methods, local stress concentration occurs, which is prone to damage under cyclic loads during service and causes structural failure. Therefore, it is necessary to develop local health monitoring solutions for these structures to ensure safety. This requires sensors that can conform to complex local morphologies, and diagnostic methods that can achieve high-precision and high-sensitivity damage identification.

[0003] In existing technologies, one approach to structural damage detection combines rigid piezoelectric ceramics with flexible printed circuit boards (FPCs), adhesively bonded to the structure and using phased array ultrasound to image internal defects. This approach uses rigid sensors, which are difficult to conform to complex topography, and FPCs are not suitable for non-extended curved surfaces.

[0004] Another approach involves designing a stretchable phased array sensor based on a 1-3 composite piezoelectric sensor matrix and an island-bridge circuit. This sensor can be attached to complex structures to image internal defects. However, this approach relies on manual bonding, resulting in a complex process and high sensor cost, making it unsuitable for large-area structural health monitoring.

[0005] After analysis, it is found that the current non-destructive testing technology based on mobile ultrasonic probes can achieve high-precision imaging of damage in local inspection areas. However, due to the limitations of human operation and access requirements, it can only be used for offline testing when the structure is in a shutdown state, and even requires disassembly of the structure to access key internal areas. Structural monitoring technology based on in-situ fixed sensors can obtain the damage status of the structure in service state online and in real time. It can be divided into two categories of methods. One is global or large-area monitoring, such as vibration and ultrasonic guided waves. However, this type of method has difficulty in performing high-precision damage monitoring on local complex components of the structure. The other type is local area monitoring, including electromechanical impedance spectroscopy, strain measurement, comparative vacuum monitoring, intelligent coating sensing (resistance), etc. Although these methods can achieve high-sensitivity monitoring of local damage, they lack sufficient quantitative capabilities and find it difficult to achieve high-precision damage imaging. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide an in-situ phased array ultrasonic structural health monitoring method and system.

[0007] According to a first aspect of the present invention, a method for in-situ phased array ultrasonic structural health monitoring is provided. The method comprises the following steps:

[0008] In-situ conformal fabrication of a coating sensor on a surface of a monitoring structure, wherein the coating sensor comprises a plurality of array units;

[0009] Connecting each array unit electrode of the coating sensor to a multiplexing switch via a wire, wherein the multiplexing switch is used to control the individual switching of each array unit as an excitation unit and a receiving unit;

[0010] The multiplexing switch is configured to connect the excitation unit to a signal generator and a power amplifier to excite ultrasonic waves, and to connect the receiving unit to an oscilloscope to collect ultrasonic signals;

[0011] Traversing all array units as excitation units and collecting ultrasonic signals. During the traversal process, when one or more array units are used as excitation units to input voltage, all array units are used as receiving units to output signals at the same time.

[0012] The collected ultrasound signals are used in a predetermined imaging manner to obtain imaging results.

[0013] According to a second aspect of the present invention, an in-situ phased array ultrasonic structural health monitoring system is provided. The system comprises a coating sensor, a multiplexing switch, a signal generator, a power amplifier, an oscilloscope, and an imaging module, wherein:

[0014] The coating sensor is conformally manufactured in situ on the surface of the monitoring structure, and the coating sensor includes a plurality of array units;

[0015] Connecting each array unit electrode of the coating sensor to a multiplexing switch via a wire, wherein the multiplexing switch is used to control the individual switching of each array unit as an excitation unit and a receiving unit;

[0016] The multiplexing switch is configured to connect the excitation unit to a signal generator and a power amplifier to excite ultrasonic waves, and to connect the receiving unit to an oscilloscope to collect ultrasonic signals;

[0017] The imaging module is used to perform: traversing all array units as excitation units. During the traversal process, when one or more array units are used as excitation units to input voltage, all array units simultaneously output signals as receiving units; and using a predetermined imaging method to obtain imaging results using the collected ultrasonic signals.

[0018] Compared with the existing technology, the advantage of the present invention is that it realizes damage monitoring of complex local areas of engineering structures by combining the conformal manufacturing characteristics of sprayed piezoelectric sensors with the high precision and high sensitivity advantages of ultrasonic non-destructive testing and the in-situ and online information acquisition advantages of structural health monitoring.

[0019] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0021] Figure 1 is a flow chart of an in-situ phased array ultrasonic structural health monitoring method according to one embodiment of the present invention;

[0022] Figure 2 is a schematic diagram of an in-situ conformal manufacturing process of a spray-coated piezoelectric sensor structure according to one embodiment of the present invention;

[0023] Figure 3 is a schematic diagram of an in-situ phased array ultrasonic structural health monitoring system according to one embodiment of the present invention;

[0024] Figure 4 FIG. 4 is a schematic diagram of a phased array all-focusing imaging algorithm according to an embodiment of the present invention.

[0025] Figure 5 2. This is a schematic diagram of the imaging effect of a flat aluminum block with a transverse through hole according to an embodiment of the present invention;

[0026] Figure 6 Schematic diagram of the imaging effect of a curved aluminum block with a transverse through hole according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention.

[0028] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0029] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0030] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0031] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0032] See also Figure 1 As shown, in general, the provided in-situ phased array ultrasonic structural health monitoring method includes: step S110, in-situ conformal manufacturing of a coating sensor on the surface of the monitoring structure, the coating sensor including a plurality of array units; step S120, connecting each array unit electrode of the coating sensor to a multiplexing switch via a wire, the multiplexing switch being used to control the individual switching of each array unit as an excitation unit and a receiving unit; step S130, the multiplexing switch is configured to connect the excitation unit to a signal generator and a power amplifier to excite ultrasonic waves, and connect the receiving unit to an oscilloscope to collect ultrasonic signals; step S140, traversing all array units as excitation units and collecting ultrasonic signals, and during the traversal process, when one or more array units are input as excitation units, all array units simultaneously output signals as receiving units; step S150, using the collected ultrasonic signals in a predetermined imaging manner to obtain imaging results.

[0033] Figure 2 The figure is a schematic diagram of the in-situ conformal manufacturing process of the sprayed piezoelectric sensor on the structure, which mainly includes the following steps:

[0034] Step 1: Use a robotic arm to control the nozzle to prepare the sensing layer coating to obtain a coating specimen.

[0035] For example, the piezoelectric polymer (PVDF-TrFE) is dissolved in an organic solvent (acetone / DMF=1:1) and a robotic arm is used to control the nozzle to move in a follow-up manner to prepare a sensor coating.

[0036] Step 2: heating and annealing the coated specimen.

[0037] For example, the coated specimen is heated to 130-140 degrees Celsius for 2 hours using a bottom heating stage to complete annealing. The heating temperature and duration can be set as needed.

[0038] Step 3: Operate the high-voltage electrostatic gun to polarize the coated specimen.

[0039] Specifically, a robotic arm is used to control a high-voltage electrostatic gun to move along the coating surface at a certain height, and non-contact corona polarization is achieved by ionizing the air.

[0040] Step 4: Perform electrode printing.

[0041] For example, conductive silver paste is screen-printed on the coating surface to prepare an array electrode, thereby obtaining a spray-on sensor, or a coating sensor.

[0042] Figure 3 This is a schematic diagram of an in-situ phased array ultrasonic structural health monitoring system, which includes a spray sensor, a multiplexer switch, an oscilloscope, a power amplifier, and a signal generator. Specifically, during the phased array ultrasonic imaging of localized internal damage, the collected data includes:

[0043] Step 2: Connect each array unit electrode of the coating sensor to a multiplexing switch through a wire to achieve independent switching of the excitation and reception functions of all units.

[0044] Step 2: The multiplexing switch connects the excitation unit to the signal generator and the power amplifier to excite ultrasonic waves, and connects the receiving unit to the oscilloscope to collect ultrasonic signals.

[0045] Step 3: When one or more units serve as excitation units T to input voltage, all units including the unit serve as receiving units R to output signals at the same time; all units are traversed as excitation units.

[0046] Step 4: All collected signals are processed through an algorithm for damage imaging.

[0047] In one embodiment, see Figure 4 As shown, the all-focus imaging algorithm is expressed as:

[0048]

[0049] Where I(x,z) is the pixel value at the post-focus point (x,z), and H is the signal envelope curve obtained by Hilbert transform of the time domain signal. is the excitation unit point, is the receiving unit position. C is the wave speed. For the sensing path from the excitation unit T n To receiving unit R n The ultrasonic signal obtained, Δt(x,z) is the ultrasonic wave from the excitation unit point To the back-focusing spatial point (x, z) and then to the receiving unit point The transit time. n is the unit number. Unit width L e and spacing L p It can be flexibly changed, depending on the ultrasonic frequency and wavelength used and the required accuracy of the specific damage.

[0050] It should be noted that those skilled in the art may make appropriate changes or modifications to the above embodiments without departing from the spirit and scope of the present invention. For example, the present invention relates to fully focused imaging in phased array ultrasound, a "back-focusing" technique. Other phased array imaging techniques, such as "front-focusing" based on electronically delayed beam deflection, can also be implemented. This is because the prepared phased array sensor does not need to be modified; only the input voltage signal needs to be changed to achieve different functions.

[0051] To further validate the effectiveness of the present invention, numerical simulations and experiments were conducted. In the experiment, an aluminum block was used to fabricate a transverse through hole (SDH) as an internal simulated defect. The imaging region (ROI) included surfaces such as flat, concave, and convex surfaces. Figure 5 This is a schematic diagram of the imaging effect of a flat aluminum block with a transverse through hole, where Figure 5 (a) is a flat aluminum block with a horizontal through hole. Figure 5 (b) is the finite element simulation imaging result, Figure 5 (c) is the local imaging effect. Figure 6 This is a schematic diagram of the imaging effect of a curved aluminum block with a transverse through hole, where Figure 6 (a) is a curved aluminum block with a horizontal through hole. Figure 6 (b) is the local concave imaging result, Figure 6 (c) is the local convex imaging result. Figure 5 and Figure 6 It can be seen that the finite element and / or experimental imaging results can accurately show the defect location.

[0052] In summary, the present invention provides an in-situ phased array ultrasonic structural health monitoring technology based on conformal manufacturing of sprayed piezoelectric sensors. The sensors are ultra-light, ultra-thin, and flexible, and can conform to the surface of complex structures. In addition, the cost is much lower than that of commercial ultrasonic phased array probes, and they can be used in large quantities to monitor structures. The present invention solves the problem of high-precision and high-sensitivity damage monitoring in local critical areas (usually stress concentration areas) of engineering structures during service, and can ensure the health and safety of the structure.

[0053] The flowcharts and block diagrams in the accompanying drawings show the possible implementation architecture, functions and operations of the systems, methods and computer program products according to multiple embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, program segment or part of an instruction, and the module, program segment or part of the instruction contains one or more executable instructions for implementing the specified logical function. In some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system that performs the specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions. It is well known to those skilled in the art that implementation by hardware, implementation by software, and implementation by a combination of software and hardware are all equivalent.

[0054] While various embodiments of the present invention have been described above, the foregoing description is intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein. The scope of the present invention is defined by the appended claims.

Claims

1. An in-situ phased array ultrasonic structural health monitoring method, comprising the following steps: In-situ conformal manufacturing of a coating sensor on the surface of a monitoring structure, wherein the coating sensor includes a plurality of array units; Connecting each array unit electrode of the coating sensor to a multiplexing switch via a wire, the multiplexing switch is used to control the individual switching of each array unit as an excitation unit and a receiving unit; The multiplexing switch is configured to connect the excitation unit with a signal generator and a power amplifier to excite ultrasonic waves, and to connect the receiving unit with an oscilloscope to collect ultrasonic signals; Traversing all array units as excitation units and collecting ultrasonic signals, during the traversal process, when one or more array units are used as excitation units to input voltage, all array units are used as receiving units to output signals at the same time; The collected ultrasound signal is used in a predetermined imaging manner to obtain an imaging result.

2. The method according to claim 1, characterized in that The in-situ conformal fabrication of coated sensors The following steps are involved: The piezoelectric polymer is dissolved in an organic solvent, and a robot arm is used to control the nozzle to move in a shape-following manner to prepare a sensor coating to obtain a coated specimen; The coated specimen is heated to a set temperature range by a heating table and maintained for a period of time, thereby performing an annealing treatment; Use a robotic arm to control the high-voltage electrostatic gun to move along the coating surface at a set height, and perform non-contact corona polarization by ionizing the air; Conductive silver paste is used to prepare array electrodes on the surface of the coating by screen printing to obtain the coating sensor.

3. The method according to claim 2, characterized in that The piezoelectric polymer is PVDF-TrFE.

4. The method according to claim 2, characterized in that: The organic solvent is acetone / DMF=1:1, the set temperature range is 130-140 degrees Celsius, and the period of time is 2 hours.

5. The method according to claim 1, characterized in that The predetermined imaging mode includes rear-focus imaging and front-focus imaging.

6. The method according to claim 1, characterized in that The predetermined imaging mode is full-focus imaging, which is expressed as: Among them, I(x,z) is the pixel value at the post-focusing spatial point (x,z), H is the signal envelope curve, which is obtained by Hilbert transform of the time domain signal. is the excitation unit point, is the receiving unit point, C is the wave speed, f TnRn (Δt) is the ultrasonic signal obtained from the sensing path from the excitation unit Tn to the receiving unit Rn, and Δt(x,z) is the ultrasonic signal from the excitation unit point To the post-focusing spatial point (x, z) and then to the receiving unit point The transit time of , n is the unit number.

7. The method according to claim 1, characterized in that The surface of the monitoring structure includes a flat surface, a concave surface and a convex surface.

8. The method according to claim 1, characterized in that: Also includes: The imaging results are used to identify defects in the monitoring structure.

9. An in-situ phased array ultrasonic structural health monitoring system, comprising a coating sensor, a multiplexing switch, a signal generator, a power amplifier, an oscilloscope and an imaging module, wherein: The coating sensor is conformally manufactured in-situ on the surface of the monitoring structure, and the coating sensor includes a plurality of array units; Connecting each array unit electrode of the coating sensor to a multiplexing switch via a wire, the multiplexing switch is used to control the individual switching of each array unit as an excitation unit and a receiving unit; The multiplexer switch is configured to connect the excitation unit to a signal generator and a power amplifier to excite ultrasonic waves, and to connect the receiving unit to an oscilloscope to collect ultrasonic signals; The imaging module is used to execute: traversing all array units as excitation units, during the traversal process, when one or more array units are used as excitation units to input voltage, all array units simultaneously output signals as receiving units; using the collected ultrasound signal using a predetermined imaging method to obtain an imaging result.

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