Method and system for detecting interlayer defects of composite material structure
By using the knocking equipment to generate detection sound signals on the composite structure and matching the feedback feature information through the signal processing equipment, the problem of damage thickness, layer and type identification in the composite structure is solved, and comprehensive detection and rapid identification of the composite structure is achieved.
Patent Information
- Application Number
- CN202411924569.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2025-03-14
AI Technical Summary
The prior art cannot effectively identify damage thickness, damage level and damage type in composite structures, especially in sandwich structures.
The strike device is used to move along the area to be tested, and the surface of the composite structure is tapped at a preset frequency to generate a detection sound signal. Through the signal conversion and processing equipment, the feedback characteristic information is matched to identify the type of damage, the number of damage layers and the degree of damage.
It realizes comprehensive detection of defects between layers of composite structures, can identify damage thickness, layer and type, removes the noise and limitations of traditional C-scan detection, and supports rapid detection of the overall composite material.
Smart Images
Figure CN119619301A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of nondestructive testing, and in particular relates to a method and system for detecting interlayer defects in a composite structure. Background Art
[0002] The aircraft composite structure composed of multiple layers, multiple interfaces and multiple materials has the function of preventing corrosion and damage to the aircraft skin and improving the aircraft survivability and combat effectiveness. During the construction and service process of the composite structure, defects such as cracks, delamination, blistering and shedding are prone to occur, which in turn cause the coating to fall off and threaten flight safety. Therefore, it is very necessary to perform interlayer defect detection on the composite structure.
[0003] The traditional inspection method for aircraft composite structures uses water immersion ultrasonic C-scan imaging technology, usually referred to as C-scan, which uses the composite structure in an ultrasonic medium environment for inspection. When the reflected waves of sound waves in the composite structure are measured to determine whether there are defects in the structure, the overall measurement accuracy is reduced because the reflected waves are often accompanied by noise and clutter, and the type of defects cannot be effectively identified, especially for sandwich structures (such as honeycomb structures and foam structures). In addition, C-scan can only identify damaged areas, but it is difficult to identify damage in terms of thickness and layering. Summary of the invention
[0004] In order to solve the problem that the existing interlayer defect scanning cannot identify the damage thickness, damage level, and composite material damage type, the present application provides a composite structure interlayer defect detection method and system.
[0005] The composite structure interlayer defect detection method and system provided in this application adopts the following technical solutions: The method for detecting interlayer defects of composite structures includes: A knocking device moves along the area to be tested, knocking the surface of the area to be tested at a preset frequency to generate a detection sound signal; the knocking device collects a feedback sound signal reflected by the composite structure from the detection sound signal to generate a feedback electrical signal, and sends the feedback electrical signal to a signal conversion device; The signal conversion device converts the feedback electrical signal into feedback characteristic information and sends it to the signal processing device; The signal processing device matches the closest calibration feature information from a preset damage database according to the feedback feature information, outputs the calibration composite material damage type, the calibration damage layer number, and the calibration damage degree corresponding to the calibration feature information, and performs digital damage contour processing on the feedback feature information to generate and output a detection result image; wherein the preset damage database includes interrelated calibration composite material damage types, calibration damage layer numbers, calibration damage degrees, and calibration feature information.
[0006] By adopting the above technical solution, the moving tapping device can ensure that all areas to be tested are detected. Compared with the C-scan which is limited to the composite structure and cannot perform defect detection on the assembled composite as a whole, the tapping device in this case is free to be positioned, supports the detection of the composite structure and the composite as a whole, and the detection object is no longer limited by the body shape and ultrasonic medium environment.
[0007] Before execution, different composite material damage types, different numbers of damaged layers, and different degrees of damage are calibrated, and these interrelated calibrated composite material damage types, calibrated numbers of damaged layers, calibrated degrees of damage, and calibrated feature information are stored in the preset damage database; during execution, the signal processing device directly finds the closest calibration feature information based on the feedback feature information, thereby determining the composite material damage type, number of damaged layers, degree of damage, and the detection result image processed according to the digital damage contour of the area to be tested by the current tapping device. This case ensures the comprehensiveness of composite material defect detection through comparative reference, and the acoustic wave reflection can solve the detection of intra-layer defects and defect thickness of multi-layer composite materials.
[0008] Optionally, when the knocking device is a handheld knocking head, the knocking device moving along the area to be tested knocks the surface of the area to be tested at a preset frequency to generate a detection sound signal, including: The handheld percussion head determines the preset frequency according to a frequency instruction from a user, and when the handheld percussion head is determined to be in a handheld state, extends a percussion probe at the preset frequency so that the percussion probe contacts the surface of the area to be tested and generates a detection sound signal.
[0009] Optionally, when the knocking device is a knocking trolley, the knocking device moving along the area to be tested knocks the surface of the area to be tested at a preset frequency to generate a detection sound signal, including: Laying a slide rail along the area to be tested to carry the knocking trolley; When the knocking trolley slides along the slide rail, the preset frequency is determined according to a frequency instruction from a user, and a knocking probe is extended at the preset frequency so that the knocking probe contacts the surface of the area to be tested and generates a detection sound signal.
[0010] Optionally, the signal processing device matches the closest calibration feature information from a preset damage database according to the feedback feature information, and outputs a calibrated composite material damage type, a calibrated number of damaged layers, and a calibrated damage degree corresponding to the calibrated feature information, including: The signal processing device calculates similarity based on the feedback feature information and all calibration feature information, selects two calibration feature information with the highest similarity, and finds the calibration composite material damage type, calibration damage layer number, and calibration damage degree in the corresponding range based on the two calibration feature information.
[0011] Optionally, before the signal processing device matches the closest calibration feature information from a preset damage database according to the feedback feature information, the method further includes building the preset damage database: The knocking device knocks the surface of the test area of the sample collection at the preset frequency to generate a sample detection acoustic signal, and collects a sample feedback acoustic signal generated by the sample detection acoustic signal being fed back by the surface of the test area to generate a sample feedback electrical signal; the collected samples include composite structures with different composite damage types, different damage degrees, and different numbers of damage layers; The signal conversion device converts the sample feedback electrical signal into sample feedback characteristic information and sends it to the signal processing device; The signal processing device stores the sample feedback characteristic information converted by the signal conversion device according to the sample feedback electrical signal into the preset damage database as the calibration characteristic information corresponding to the collected sample, and the composite material damage type, damage degree and number of damaged layers of the collected sample are respectively used as the calibrated composite material damage type, calibrated damage degree and calibrated number of damaged layers.
[0012] Optionally, the performing digital damage contour processing on the feedback feature information to generate a detection result image includes: The feedback characteristic information is digitally processed to generate a digital damage contour image as the detection result image, and the detection result image is used to display the damage contour, damage area, composite material damage type and damage degree of the area to be tested.
[0013] The present invention also provides a composite structure interlayer defect detection system, the system comprising a knocking device, a signal conversion device and a signal processing device; The knocking device comprises a driving unit, a knocking unit and a collecting unit, wherein the driving unit is used to move along the to-be-tested area of the composite structure, the knocking unit is used to knock the surface of the to-be-tested area at a preset frequency to generate a detection sound signal, and the collecting unit is used to collect the feedback sound signal reflected by the composite structure from the detection sound signal to generate a feedback electric signal and send it to the signal processing device through a first data transmission channel; The signal conversion device comprises a signal conversion unit, which is used to convert the feedback electrical signal from the acquisition unit into feedback characteristic information, and send it to the signal processing device through the second data transmission channel; The signal processing device includes a storage unit, a damage assessment unit, and an image processing unit. The storage unit is used to store a preset damage database, and the preset damage database includes mutually related calibrated composite material damage types, calibrated damage layer numbers, calibrated damage degrees, and calibrated feature information; the damage assessment unit is connected to the storage unit, and is used to match the closest calibration feature information from the preset damage database to obtain the calibrated composite material damage type, calibrated damage layer number, and calibrated damage degree corresponding to the calibration feature information; the image processing unit is used to perform digital damage contour processing on the feedback feature information, generate a detection result image, and output it.
[0014] Optionally, the tapping device includes a slide rail assumed along the area to be tested of the composite structure, and a tapping trolley moving along the slide rail, and the driving unit is used to drive the tapping trolley to move along the slide rail according to a control instruction from a user.
[0015] Optionally, the signal processing device further includes a sample input unit; The driving unit is used to move along the area to be tested where the sample is collected, the knocking unit is used to knock the surface of the area to be tested at a preset frequency to generate a sample detection sound signal, and the collecting unit is used to collect the sample detection sound signal and the sample feedback sound signal reflected by the surface of the area to be tested where the sample is collected to generate a sample feedback electric signal and send it to the signal processing device through the first data transmission channel; The sample input unit is used to input the sample feedback characteristic information obtained by converting the sample feedback electrical signal by the signal conversion device, and store the information in the storage unit after associating it with the composite material damage type of the collected sample as the calibrated composite material damage type, the damage degree of the collected sample as the calibrated damage degree, and the number of damaged layers of the collected sample as the calibrated number of damaged layers.
[0016] Optionally, the collected samples include composite structures with different composite damage types, damage degrees, and numbers of damaged layers, the number of damaged layers includes single-layer damage and multi-layer damage, and the composite damage types include delamination damage, inclusion damage, bubble damage, and wrinkles.
[0017] Compared with the prior art, the beneficial effects of this application are: 1. The traditional C-scan can only determine whether there is damage and the plane area where the damage is located, but it cannot obtain the detection results of the composite structure in the thickness direction; in this case, since different defects (composite damage type, number of damaged layers, and degree of damage) will affect the rigidity of the composite structure, a detection sound signal is generated by tapping the surface of the area to be tested. The detection sound signal propagates inside the composite structure and is finally reflected to the surface of the area to be tested to generate a feedback sound signal that is collected by the tapping device. After conversion by the signal conversion device and data processing by the signal processing device, the corresponding composite damage type, damage range, number of damaged layers in the thickness direction, and degree of damage are identified based on these different feedback feature information. Therefore, this case solves the problem that the existing C-scan cannot effectively detect sandwich structures and cannot detect multiple layers in the thickness direction.
[0018] 2. In this case, the influence of different faults on the overall stiffness of the composite material is utilized, and the feedback electrical signal corresponding to the acoustic signal is detected for feature collection, thereby realizing free measurement of interlayer defect detection of the composite structure. It is no longer limited to the size of the composite structure, and no longer requires ultrasonic media. The application environment is wider, the detection is more free, and the hardware restrictions on building a water spray system are removed, supporting rapid detection in the installed state.
[0019] 3. Before execution, different composite material damage types, different numbers of damaged layers, and different damage degrees are calibrated, and these interrelated calibrated composite material damage types, calibrated numbers of damaged layers, calibrated damage degrees, and calibrated feature information are stored in the preset damage database; when officially used, the corresponding calibration feature information is directly found according to the feedback feature information, and then the composite material damage type, number of damaged layers, damage degree of the test area detected by the tapping device, and the detection result image obtained by digitizing the damage contour of the feedback feature information are determined to ensure the feasibility of the overall application and the rapid identification and judgment of interlayer defects. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a schematic flow chart of the composite structure interlayer defect detection method provided by the present invention; Figure 2 It is a structural schematic diagram of a composite structure interlayer defect detection system provided by the present invention; Figure 3 It is a schematic diagram of a non-destructive composite structure of the sampling specimen; Figure 4 is a schematic diagram of a composite structure in which the sampling sample is a damaged layer with one number; Figure 5 is a schematic diagram of a composite material structure in which the sampling sample is a damaged layer with two in number; Figure 6 yes Figure 2 Module diagram of the interlayer defect detection system for composite materials. DETAILED DESCRIPTION
[0021] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of 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. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.
[0022] In view of the problems existing in the prior art, the embodiments of the present invention provide a method for detecting interlayer defects in a composite structure. Figure 2 The composite structure interlayer defect system shown in the figure comprises a knocking device 21, a signal conversion device 22, and a signal processing device 23. The signal conversion device 22 is connected to the knocking device 21 through a first data transmission channel 24, and the signal conversion device 22 is connected to the signal processing device 23 through a second data transmission channel 25. Figure 1 , a method for detecting defects between layers of a composite structure, comprising the following steps: Step 101 : The knocking device 21 moves along the area to be tested and knocks the surface of the area to be tested at a preset frequency to generate a detection sound signal.
[0023] Specifically, when testing the composite structure, the knocking device 21 is moved along the area to be tested, and the knocking device 21 in working state knocks the surface of the area to be tested, and a detection sound signal is generated along with the knocking, and the detection sound signal propagates inside the composite structure and changes with the rigidity inside the composite structure. The rigidity inside the composite structure is affected by the interlayer defects of the composite structure.
[0024] In some examples, the tapping device 21 moves along the area to be tested, which is specifically manifested as follows: The knocking device 21 is a handheld knocking head 211. The user holds the handheld knocking head 211 and moves it along the area to be tested of the composite structure. The handheld knocking head is controlled to knock the composite structure at a preset frequency. It is suitable for manual knocking detection in narrow areas, corner areas, and blind spots of an aircraft to determine defects at the location.
[0025] In one case of this example, the handheld tapping head 211 supports the user to manually tap the surface of the area to be tested at a preset frequency. Since the automatically retractable tapping probe, the driving member for controlling the retraction of the tapping probe, and the power supply for the driving member are omitted, the entire handheld tapping head 211 is smaller in size and more suitable for manual inspection of corners and narrow areas of compliant materials during aircraft manufacturing. It is preferred that the engineer manually control the tapping frequency to maintain it at the preset frequency.
[0026] In another case of this example, the user manually controls the forward trajectory of the knocking head 211, and the handheld knocking head 211 supports automatically knocking the surface of the area to be tested at a preset frequency. The handheld knocking head 211 includes an automatically retractable knocking probe, a driving member that controls the knocking probe to perform retractable movement at a preset frequency, and a power supply to the driving member. Among them, the preset frequency can be a fixed value, which is set by the manufacturer or manually set by the user and remains unchanged; the preset frequency can also be a variable value, and the user can set a value or a numerical change rule at any time.
[0027] In detail, when the knocking device 21 is a handheld knocking head 211, the knocking device moves along the area to be tested, and knocks the surface of the area to be tested at a preset frequency to generate a detection sound signal, including: the handheld knocking head 211 determines the preset frequency according to the frequency instruction from the user, and when the handheld knocking head 211 is determined to be in a handheld state, the knocking probe is extended at the preset frequency, so that the knocking probe contacts the surface of the area to be tested and generates a detection sound signal. Among them, the handheld knocking head 211 is determined to be in a handheld state by the pressure sensor installed on the surface of the handheld knocking head 211 sensing a pressure value reaching a preset value, and it can also be determined by the identity recognition component (such as fingerprint recognition, correct password) installed on the surface of the handheld knocking head 211 to identify the identity of the designated authority (such as fingerprint information, correct password).
[0028] In some examples, the tapping device 21 moves along the area to be tested, which is specifically manifested as follows: The knocking device 21 is a knocking trolley 212 and a track 213. The slide track 213 is laid along the surface of the composite structure in the area to be tested, and the knocking trolley 212 slides on the slide track 213, so that the knocking trolley 212 moves along the area to be tested. The power for the knocking trolley 212 to slide on the slide track 213 can be its own gravity, or it can be additional power applied by the user, or it can be powered by a drive unit installed inside or outside the knocking trolley 212.
[0029] The knocking trolley 212 supports automatically knocking the surface of the area to be tested at a preset frequency, and includes an automatically retractable knocking probe, a driving member that controls the knocking probe to retract at a preset frequency, and a power supply for the driving member. The preset frequency can be a fixed value, which is set by the manufacturer or manually set by the user and remains unchanged; the preset frequency can also be a variable value, which can be set by the user at any time to a value or a value change rule.
[0030] In detail, the knocking device 21 moving along the area to be tested knocks the surface of the area to be tested at a preset frequency to generate a detection sound signal, including: laying a slide rail 213 along the area to be tested to carry the knocking trolley 212; when the knocking trolley 212 slides along the slide rail 213, the preset frequency is determined according to the frequency instruction from the user, and the knocking probe is extended at the preset frequency, so that the knocking probe contacts the surface of the area to be tested and generates a detection sound signal. Among them, the user's frequency instruction can be directly imported by the user into the knocking trolley through a data connection line, or can be input through a wireless communication network, a key on the knocking trolley, etc.
[0031] In step 102 , the striking device 21 collects the feedback acoustic signal reflected by the composite structure from the detection acoustic signal to generate a feedback electrical signal, and sends the feedback electrical signal to the signal conversion device 22 .
[0032] Specifically, after the knocking device 21 knocks on the surface of the test area of the composite structure, the detection sound signal propagates inside the composite structure. Due to the different structures inside the composite structure, the effects of defects on the rigidity of the composite structure are also different, the consumption of the detection sound signal propagating in the composite structure is also different, and the generated feedback sound signal is also different, which causes the wavelength, frequency, power and other characteristics of the feedback sound signal collected by the knocking device 21 to change. In other words, the feedback electrical signal contains characteristics that can represent the rigidity characteristics of the composite structure, and can indirectly reflect the internal structure of the composite structure.
[0033] Step 103: The signal conversion device 22 converts the feedback electrical signal into feedback characteristic information and sends it to the signal processing device.
[0034] Specifically, the signal conversion device 22 extracts features from the feedback electrical signal to obtain feedback feature information, which can fully demonstrate the characteristic properties of the feedback electrical signal. Usually, the signal conversion device 22 is configured as a signal converter.
[0035] Step 104: the signal processing device 23 matches the closest calibration feature information from the preset damage database according to the feedback feature information, and outputs the calibrated composite material damage type, the calibrated number of damaged layers, and the calibrated damage degree corresponding to the calibrated feature information.
[0036] Specifically, before executing step 104, a preset damage database needs to be built, which specifically includes: S0-1, set the collection samples of different composite material structures according to the composite material damage type, damage degree and number of damaged layers, and the composite material damage type, damage degree and number of damaged layers of the collected samples are used as the calibration composite material damage type, calibration damage degree and calibration number of damaged layers respectively; S0-2, the knocking device 21 knocks the surface of the area to be tested where the sample is collected at a preset frequency to generate a sample detection sound signal, and obtains a sample feedback sound signal generated by the sample detection sound signal being fed back by the surface of the area to be tested where the sample is collected to generate a sample feedback electrical signal; S0-3, the signal conversion device 22 converts the sample feedback electrical signal into sample feedback characteristic information and sends it to the signal processing device 23; S0-4, the signal conversion device 22 converts the sample feedback electrical signal into sample feedback characteristic information and sends it to the signal processing device 23; S0-5, the signal processing device 23 uses the feedback characteristic information as the calibration characteristic information corresponding to the collected sample, and stores the calibrated composite material damage type, calibrated damage degree, calibrated number of damaged layers and calibration characteristic information of the collected sample into a preset damage database.
[0037] In this case, the exhaustive method is adopted to select composite structures with different composite damage types, damage degrees, and number of damaged layers as calibrated composite structures, also known as collection samples; these collection samples are normally tested, and the test results obtained are used as calibration to determine which of these collection samples different feedback characteristic information corresponds to in the actual application process, and then determine the internal interlayer defects of the composite structure currently being measured.
[0038] In step 0-1, the composite material damage types include delamination, inclusion, bubble, wrinkle, etc., the damage degree includes low, medium, and severe, and the number of damaged layers includes 0 damaged layers, 1 damaged layers, 2 damaged layers, and more than 2 damaged layers. The composite material structure includes a laminate 41 and a core material 42. For the composite material damage type of delamination between the laminate 41 and the core material 42, the following are set: Figure 3 The number of damaged layers shown is 0 (i.e. no damage), Figure 4 The number of damaged layers shown is 1 (i.e., single layer delamination), Figure 5The number of damaged layers shown is 2 (i.e., two-layer delamination) and the number of damaged layers shown is n (n>2) for multi-layer delamination. Then, according to the number of damaged layers and the degree of damage, different composite structures are selected as collection samples to achieve calibration. When the collection sample of S0-1 is undamaged, the feedback feature information and calibration feature information in S0-4 and S0-5 are both signal modes for calibration of undamaged; when the collection sample of S0-1 is single-layer delamination, the feedback feature information and calibration feature information in S0-4 and S0-5 are both signal modes for single-layer delamination defects; when the collection sample of S0-2 is two-layer delamination, the feedback feature information and calibration feature information of S0-4 and S0-5 are both signal modes for the two-layer delamination defects; when the collection sample of S0-2 is multi-layer delamination, the feedback feature information and calibration feature information of S0-4 and S0-5 are both signal modes for the multi-layer delamination defects.
[0039] When step 104 is executed, the signal processing device 23 calculates the similarity based on the feedback feature information and all the calibration feature information, selects the two calibration feature information with the highest similarity, determines the corresponding calibration interval based on the two calibration feature information, and finds the corresponding calibration composite material damage type, calibration damage layer number and calibration damage degree based on the calibration interval. The calibration interval of the currently detected composite material structure is determined by the two most similar calibration feature information to ensure accurate interval determination, and then accurately find the corresponding calibration composite material damage type, calibration damage layer number and calibration damage degree. To realize the knock detection of the aircraft structure, the obtained feedback special information (digital form) is compared with the calibration feature information in the database to judge the composite material damage type, damage degree and number of damage layers.
[0040] Step 105: the signal processing device 23 performs digital damage contour processing on the feedback feature information, generates a detection result image, and outputs it.
[0041] Specifically, as the striking device moves along the area to be tested, the digital damage contour image becomes more and more comprehensive. The feedback feature information is digitally processed to generate a digital damage contour image as a detection result image, and the detection result image is used to display the damage contour, damage area, composite material damage type and damage degree of the area to be tested. The detection result image supports display in the form of an image on the signal processing device 23.
[0042] In summary, this case calibrates different composite material damage types, different numbers of damaged layers, and different degrees of damage, and stores these interrelated calibrated composite material damage types, calibrated numbers of damaged layers, calibrated degrees of damage, and calibrated feature information into a preset damage database; when it is officially used, the corresponding calibration feature information is directly found based on the feedback feature information, so that the types of intra-layer defects and the number of damaged layers in the thickness direction of the corresponding composite structure are identified by comparing these different feedback feature information with the calibrated preset damage database, where the types of layer defects of the composite structure include composite material damage type, damage range, and damage degree. The test result image is obtained by digitizing the damage contour of the feedback feature information. The traditional method of adding a spray system to perform C-scan detection is abandoned, making the overall measurement environment more free. Not only can the components of the composite structure be inspected, but also the entire assembly can be inspected. The detection range is larger, more flexible, and more comprehensive, realizing the rapid identification and judgment of interlayer defects.
[0043] The step division of the above-mentioned methods is only for the purpose of clear description. When implemented, they can be combined into one step or some steps can be split and decomposed into multiple steps. As long as they include the same logical relationship, they are all within the scope of protection of this patent. Adding insignificant modifications or introducing insignificant designs to the algorithm or process without changing the core design of the algorithm and process are all within the scope of protection of this patent.
[0044] The present invention also provides a composite structure interlayer defect detection system. Figure 2 and Figure 6 As shown, the composite structure interlayer defect detection system includes a knocking device 21, a signal conversion device 22, a signal processing device 23, a first data transmission channel 24 and a second data transmission channel 25.
[0045] The knocking device 21 includes a driving unit 216, a knocking unit 214 and a collection unit 215. The driving unit 216 is used to move along the area to be tested of the composite structure, the knocking unit 214 is used to knock the surface of the area to be tested at a preset frequency to generate a detection sound signal, and the collection unit 215 is used to collect the feedback sound signal reflected by the composite structure from the detection sound signal to generate a feedback electric signal and send it to the signal processing device 22 through the first data transmission channel 24.
[0046] The knocking device 21 includes two types: a handheld knocking head 211 and a knocking trolley 212 matched with a track 213. When the knocking device 21 is a handheld knocking head 211, the handheld knocking head 211 includes a driving unit 216, a knocking unit 214 and a collection unit 215; the driving unit 216 is usually set as the handheld part of the handheld knocking head, so that the user can hold the handheld knocking head 211 body, so that the position change of the handheld knocking head 211 can be controlled by the user himself. Preferably, the driving unit 216 of the handheld knocking head 211 is provided with a sensor for sensing whether the handheld knocking head 211 is currently in a handheld state and thus controlling whether the knocking unit 214 and the collection unit 215 are working or not. The sensor can be a fingerprint sensor or a pressure sensor, etc.; the knocking unit 213 can be a fixed position sensor. A predetermined knocking probe is provided so that the user can manually knock on the surface of the test area of the composite structure to be tested at a preset frequency to generate a detection sound signal. The knocking unit 213 can also be an integral body composed of an automatically retractable knocking probe, a driving member that controls the knocking probe to perform retractable movement at a preset frequency, and a power supply to the driving member, so that the user can manually control the position of the handheld knocking head 211 and control the knocking unit 213 to automatically knock on the surface of the test area of the composite structure to be tested to generate a detection sound signal; the collection unit 215 is used to collect the feedback sound signal reflected by the composite structure of the detection sound signal to generate a feedback electrical signal and send it to the signal processing device 22 through the first data transmission channel 24.
[0047] When the knocking device 21 is a knocking trolley 212 matched with the track 213, the track 213 is laid along the surface of the composite structure to be tested, and the knocking trolley 212 includes a driving unit 216, a knocking unit 214 and a collection unit 215; the driving unit 216 can be a force-bearing part of the knocking trolley 212, which is used to receive an external force from the user to drive the trolley 212 to move along the track 213 in a predetermined direction. The driving unit 216 can also be a whole composed of a power supply and a driving motor. The user starts the driving motor so that the driving motor drives the trolley on the track. The knocking unit 214 can be an integral body consisting of an automatically retractable knocking probe, a driving member that controls the knocking probe to retract at a preset frequency, and a power supply that supplies power to the driving member, so that the knocking trolley 212 can automatically knock on the surface of the test area of the composite structure to be tested while moving along the track 213 to generate a detection sound signal; the collection unit 215 is used to collect the feedback sound signal reflected by the composite structure from the detection sound signal to generate a feedback electrical signal and send it to the signal processing device 22 through the first data transmission channel 24.
[0048] The signal conversion device 22 includes a signal conversion unit 221 , which converts the feedback electrical signal from the acquisition unit 215 into feedback characteristic information, and sends the feedback characteristic information to the signal processing device 23 through the second data transmission channel 25 .
[0049] The signal processing device 23 includes a storage unit 231, a damage assessment unit 232, and an image processing unit 233. The storage unit 231 is used to store a preset damage database, which includes interrelated calibrated composite material damage types, calibrated damage layer numbers, calibrated damage degrees, and calibrated feature information; the damage assessment unit 232 is connected to the storage unit 231, and matches the calibrated feature information closest to the feedback feature information from the preset damage database to obtain the calibrated composite material damage type, calibrated damage layer number, and calibrated damage degree corresponding to the calibrated feature information. The image processing unit 233 performs digital damage contour processing on the feedback feature information, generates a detection result image, and outputs it.
[0050] In some examples, continue to refer to Figure 6 , the signal processing device 23 also includes a sample input unit 234.
[0051] In the knocking device 21, the driving unit 216 is used to move along the test area of the collected sample, the knocking unit 214 is used to knock the surface of the test area at a preset frequency to generate a sample detection sound signal, and the collection unit 215 is used to collect the sample detection sound signal, the sample feedback sound signal reflected by the surface of the test area of the collected sample generates a sample feedback electric signal and sends it to the signal processing device 22 through the first data transmission channel 24; wherein the collected samples include composite structures with different composite damage types, damage degrees, and numbers of damaged layers, the number of damaged layers includes single-layer damage and multi-layer damage, and the composite damage types include delamination damage, inclusion damage, bubble damage, and wrinkles; The sample input unit 234 is used to input the sample feedback characteristic information converted by the signal conversion device 22 from the sample feedback electrical signal and transmitted through the second data transmission channel 25, and associate it with the composite material damage type of the collected sample as the calibrated composite material damage type, the damage degree of the collected sample as the calibrated damage degree, and the number of damaged layers of the collected sample as the calibrated number of damaged layers, and then store it in the storage unit 231.
[0052] Other implementation details and working methods of the composite structure interlayer defect detection system disclosed in the present application are the same or similar to the composite structure interlayer defect detection method described above, and will not be repeated here.
[0053] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.
Claims
1. A method for detecting interlayer defects in a composite structure, characterized in that: The method comprises: A knocking device moves along the area to be tested, knocking the surface of the area to be tested at a preset frequency to generate a detection sound signal; the knocking device collects a feedback sound signal reflected by the composite structure from the detection sound signal to generate a feedback electrical signal, and sends the feedback electrical signal to a signal conversion device; The signal conversion device converts the feedback electrical signal into feedback characteristic information and sends it to the signal processing device; The signal processing device matches the closest calibration feature information from a preset damage database according to the feedback feature information, outputs the calibration composite material damage type, the calibration damage layer number, and the calibration damage degree corresponding to the calibration feature information, and performs digital damage contour processing on the feedback feature information to generate and output a detection result image; The preset damage database includes interrelated calibrated composite material damage types, calibrated numbers of damaged layers, calibrated damage degrees and calibrated feature information.
2. The method for detecting interlayer defects of a composite structure according to claim 1, characterized in that: When the knocking device is a handheld knocking head, the knocking device moving along the area to be tested knocks the surface of the area to be tested at a preset frequency to generate a detection sound signal, including: The handheld percussion head determines the preset frequency according to a frequency instruction from a user, and when the handheld percussion head is determined to be in a handheld state, extends a percussion probe at the preset frequency so that the percussion probe contacts the surface of the area to be tested and generates a detection sound signal.
3. The method for detecting interlayer defects of a composite structure according to claim 1, characterized in that: When the knocking device is a knocking trolley, the knocking device moving along the area to be tested knocks the surface of the area to be tested at a preset frequency to generate a detection sound signal, including: Laying a slide rail along the area to be tested to carry the knocking trolley; When the knocking trolley slides along the slide rail, the preset frequency is determined according to a frequency instruction from a user, and a knocking probe is extended at the preset frequency so that the knocking probe contacts the surface of the area to be tested and generates a detection sound signal.
4. The method for detecting interlayer defects of a composite structure according to claim 1, characterized in that: The signal processing device matches the closest calibration feature information from a preset damage database according to the feedback feature information, and outputs the calibrated composite material damage type, the calibrated number of damaged layers, and the calibrated damage degree corresponding to the calibrated feature information, including: The signal processing device calculates similarity based on the feedback feature information and all calibration feature information, selects two calibration feature information with the highest similarity, and finds the calibration composite material damage type, calibration damage layer number, and calibration damage degree in the corresponding range based on the two calibration feature information.
5. According to the composite structure interlayer defect detection method of claim 1, before the signal processing device matches the closest calibration feature information from the preset damage database according to the feedback feature information, the method further comprises building the preset damage database: The knocking device knocks the surface of the test area of the sample collection at the preset frequency to generate a sample detection acoustic signal, and collects a sample feedback acoustic signal generated by the sample detection acoustic signal being fed back by the surface of the test area to generate a sample feedback electrical signal; the collected samples include composite structures with different composite damage types, different damage degrees, and different numbers of damage layers; The signal conversion device converts the sample feedback electrical signal into sample feedback characteristic information and sends it to the signal processing device; The signal processing device stores the sample feedback characteristic information converted by the signal conversion device according to the sample feedback electrical signal into the preset damage database as the calibration characteristic information corresponding to the collected sample, and the composite material damage type, damage degree and number of damaged layers of the collected sample are respectively used as the calibrated composite material damage type, calibrated damage degree and calibrated number of damaged layers.
6. The method for detecting interlayer defects of a composite structure according to claim 1, characterized in that: The step of performing digital damage contour processing on the feedback feature information to generate a detection result image includes: The feedback characteristic information is digitally processed to generate a digital damage contour image as the detection result image, and the detection result image is used to display the damage contour, damage area, composite material damage type and damage degree of the area to be tested.
7. Composite structure interlayer defect detection system, characterized in that: The system includes a striking device, a signal conversion device and a signal processing device; The knocking device comprises a driving unit, a knocking unit and a collecting unit, wherein the driving unit is used to move along the to-be-tested area of the composite structure, the knocking unit is used to knock the surface of the to-be-tested area at a preset frequency to generate a detection sound signal, and the collecting unit is used to collect the feedback sound signal reflected by the composite structure from the detection sound signal to generate a feedback electric signal and send it to the signal processing device through a first data transmission channel; The signal conversion device comprises a signal conversion unit, which is used to convert the feedback electrical signal from the acquisition unit into feedback characteristic information, and send it to the signal processing device through the second data transmission channel; The signal processing device includes a storage unit, a damage assessment unit, and an image processing unit. The storage unit is used to store a preset damage database, and the preset damage database includes mutually related calibrated composite material damage types, calibrated damage layer numbers, calibrated damage degrees, and calibrated feature information; the damage assessment unit is connected to the storage unit, and is used to match the closest calibration feature information from the preset damage database to obtain the calibrated composite material damage type, calibrated damage layer number, and calibrated damage degree corresponding to the calibration feature information; the image processing unit is used to perform digital damage contour processing on the feedback feature information, generate a detection result image, and output it.
8. The composite structure interlayer defect detection system according to claim 7, characterized in that: The knocking device includes a slide rail assumed along the area to be tested of the composite structure, and a knocking trolley moving along the slide rail, and the driving unit is used to drive the knocking trolley to move along the slide rail according to a control instruction from a user.
9. The composite structure interlayer defect detection system according to claim 7, characterized in that: The signal processing device also includes a sample entry unit; The driving unit is used to move along the area to be tested where the sample is collected, the knocking unit is used to knock the surface of the area to be tested at a preset frequency to generate a sample detection sound signal, and the collecting unit is used to collect the sample detection sound signal and the sample feedback sound signal reflected by the surface of the area to be tested where the sample is collected to generate a sample feedback electric signal and send it to the signal processing device through the first data transmission channel; The sample input unit is used to input the sample feedback characteristic information obtained by converting the sample feedback electrical signal by the signal conversion device, and store the information in the storage unit after associating it with the composite material damage type of the collected sample as the calibrated composite material damage type, the damage degree of the collected sample as the calibrated damage degree, and the number of damaged layers of the collected sample as the calibrated number of damaged layers.
10. The composite structure interlayer defect detection system according to claim 9, characterized in that: The collected samples include composite material structures with different composite material damage types, damage degrees, and numbers of damaged layers. The number of damaged layers includes single-layer damage and multi-layer damage. The composite material damage types include delamination damage, inclusion damage, bubble damage, and wrinkles.