Composite material hole interference bushing installation damage detection system and method

Abstract

The invention relates to the technical field of composite material hole reinforcement, in particular to a composite material hole interference bushing installation damage detection method, which comprises an interference bushing installation device, a composite material hole periphery strain monitoring system and a composite material hole interference process damage sound signal monitoring device. According to the interference lining installation device, a core rod penetrates through a metal lining in a hydraulic loading mode so that expansion deformation of the lining can be achieved, interference fit is formed between the deformed lining and a composite material hole so that reinforcement of the composite material hole can be achieved, and meanwhile core rod displacement and installation resistance recording in the installation process are achieved through a hydraulic system sensor. The composite material hole circumference strain detection device realizes damage monitoring in the bush expansion process by recording hole circumference strain in the mounting process; the composite material hole interference process damage sound signal monitoring device performs clustering analysis on collected sound signals so as to realize damage type analysis in a bushing expansion process. Through multi-dimensional comprehensive analysis of displacement, resistance, strain and sound signals, comprehensive evaluation of installation damage of the composite material hole interference bushing is realized, and theoretical support is provided for application of an interference strengthening method in the field of composite material hole strengthening.

Description

Technical Field

[0001] This invention relates to the field of composite material hole reinforcement technology, specifically to a composite material hole interference bushing installation damage detection system and method. Background Technology

[0002] Installing metal bushings within the holes of composite material open-hole structures has proven effective in improving the strength and lifespan of composite material connections. However, the poor plasticity and susceptibility of composite materials to damage during interference installation can easily cause peri-hole damage, limiting the application of this method. Several methods exist for installing metal bushings within the holes of composite materials. For example, a composite material structure bushing strengthening method based on electromagnetic loading (202310958660.X) uses electromagnetic loading to strengthen the bushings of composite material structures. This method can calculate the strengthening process parameters for composite material bushings of different structures and sizes, guiding the strengthening of dynamically cold-extruded composite material bushing structures. Furthermore, there is an interference bushing dynamic installation parameter testing method and device based on Hopkinson bar (202411227871.7). This method uses a Hopkinson bar to install the bushing, avoiding inertial forces during installation and improving the accuracy of the test results.

[0003] Existing technologies can install metal bushings in perforated composite material structures and obtain basic installation data. However, there is currently no reliable method to monitor and assess damage during the installation process of interference bushings on composite materials, which severely limits the practical application of this method.

[0004] Therefore, there is a need to provide a method for detecting installation damage of composite material hole interference bushings to solve the above problems. Summary of the Invention

[0005] This invention provides a method for detecting installation damage of composite material hole interference bushings, in order to solve the problem of the lack of damage monitoring and evaluation analysis in the process of installing composite material interference bushings in existing installation methods and technologies.

[0006] The present invention provides a method for detecting installation damage of a composite material hole interference bushing, which adopts the following technical solution: Interference bushing mounting device; A hydraulic loading head with built-in displacement and resistance sensors, one end of which is connected to a mandrel; The mandrel is spindle-shaped, thicker in the middle and thinner at both ends. One end is in close contact with the hydraulic loading head, and the other end is coaxially mounted with the bushing. The bushing is clearance-fitted with the holes in the perforated plate of the composite material, and its lower surface contacts the slotted washer. The perforated plate of composite material has a clearance fit between the perforation and the bushing, and the lower surface is in contact with the slotted washer. The slotted washer has its upper surface in contact with the composite perforated plate and bushing, and its lower surface in contact with the support plate. Its inner hole size is between the outer diameter and the inner diameter of the bushing to provide support during installation and allow the mandrel to pass through smoothly. The support plate has its lower surface fixed to the ground and its upper surface in contact with the slotted washer. Its function is to reserve space for the mandrel to pass through, while reducing the cost of high-precision machining.

[0007] Preferably, the composite material pore circumferential strain detection device includes: The strain gauge comprises two strain gauges, which are bonded to the surface of the perforated plate near the holes in the composite material, respectively perpendicular to and parallel to the +45° layup direction of the surface layer of the composite material perforated plate, in order to enable strain monitoring around the holes.

[0008] A resistance strain gauge is connected to a strain gauge to collect strain parameters during the installation process. It is also connected to a computer to record the time-domain variation curve of the strain around the hole during the installation process. A computer, with strain parameter processing software installed, is connected to a resistance strain gauge to store and analyze the strain parameters around the hole.

[0009] Preferably, the composite material hole interference process damage acoustic signal monitoring device includes: An acoustic emission sensor is installed on the surface of a perforated composite material plate to monitor acoustic signals emitted by damage to the composite material during installation. An acoustic signal analyzer, which is connected to an acoustic emission sensor, collects acoustic signals and records various acoustic signal parameters. It is connected to a computer to achieve real-time data monitoring and storage. A computer, connected to an acoustic signal analyzer, is installed with acoustic signal processing software to record various acoustic signal parameters and analyze the acoustic signal damage detection results during the installation process.

[0010] Preferably, the comprehensive assessment of installation damage includes; According to the present invention, a composite material hole interference bushing installation damage detection method is used to install the bushing and collect damage parameters. Adjust the installation device: Install the mandrel, bushing, and composite perforated plate coaxially; Adjusting the sensor: Place the acoustic emission sensor close to the perforated plate of the composite material and connect it to the acoustic signal analyzer; install the strain gauge orthogonally on the surface of the perforated plate of the composite material and connect it to the resistance strain gauge; connect the acoustic signal analyzer and the resistance strain gauge to the computer and debug the analysis and recording software to the monitoring state; Set loading parameters: Set the loading parameters of the hydraulic loading head, and set the displacement and resistance sensors of the hydraulic loading head; Loading, installation, and data collection: Start the hydraulic loading head and detection system, and the mandrel completely passes through the bushing to complete one bushing installation; Data processing and analysis: Displacement and resistance parameters during bushing installation are acquired by a hydraulic loading head; circumferential strain data during installation is acquired by a strain acquisition system; and damage data during installation is acquired by an acoustic emission system. The damage data during installation is derived by preprocessing acoustic signals, performing cluster analysis, and combining displacement, resistance, and strain parameters to infer the damage type.

[0011] Preferably, the composite material hole interference bushing installation damage detection method proposed in this invention includes: A comprehensive assessment of installation damage to composite material hole interference bushings is achieved through multi-dimensional integrated analysis of displacement, resistance, strain, and acoustic signals.

[0012] The beneficial effects of this invention are: 1. This invention uses a strain monitoring system to monitor the strain around the hole during the installation of a composite material hole interference bushing. Simultaneously considering the anisotropic characteristics of the composite material, it comprehensively reflects the damage characteristics of the composite material hole caused by bushing expansion, providing data support for subsequent analysis of the actual interference amount of the bushing and damage modeling analysis. It also concretely demonstrates the time-domain stress-strain variation law that previous installation methods could not achieve.

[0013] 2. This invention utilizes an acoustic signal monitoring system to record and classify damage during the installation process of composite material hole interference bushings. Through cluster analysis of the acquired acoustic damage signals during installation, full-time-domain damage characterization and description of the installation process are achieved. This provides damage characterization basis and evidence for analyzing the installation of composite material hole interference bushings, and lays an analytical foundation for subsequent reduction of installation damage and application of installation methods.

[0014] 3. This invention collects displacement and resistance parameters during bushing installation using a hydraulic loading head. Combined with strain analysis and acoustic signal damage analysis, it achieves multi-dimensional recording and analysis of damage to the composite material perforated plate during bushing installation. This enables a comprehensive assessment of installation damage to composite material perforated bushings. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the overall method for detecting installation damage of a composite material hole interference bushing according to the present invention; Figure 2 This is a schematic diagram of the sensor position in a composite material hole interference bushing installation damage detection method according to the present invention; Figure 3 This is a flowchart illustrating the specific implementation steps of a composite material hole interference bushing installation damage detection method according to the present invention; Figure 4 This is an example of the time-domain variation curve of the strain around the hole during the installation process of a composite material hole interference bushing installation damage detection method according to the present invention; In the figure: 1. Acoustic emission sensor; 2. Hydraulic loading head; 3. Mandrel; 4. Bushing; 5. Strain gauge; 6. Slit washer; 7. Resistance strain gauge; 8. Computer; 9. Acoustic signal analyzer; 10. Support plate; 11. Perforated plate of composite material. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] An embodiment of the present invention for detecting installation damage of a composite material hole interference bushing, as shown below. Figure 1 As shown, it includes an interference bushing mounting device; Specifically, the hydraulic loading head 2 has a built-in displacement and resistance sensor, and one end of it is connected to the mandrel 3; the mandrel 3 is spindle-shaped with a thicker middle and thinner ends, one end of which is tightly attached to the hydraulic loading head 2, and the other end is coaxially installed with the bushing 4; the bushing 4 is fitted with the hole in the composite material perforated plate 11 with a clearance fit, and its lower surface is in contact with the slotted washer 6; the perforated plate 11 of the composite material is fitted with the bushing 4 with a clearance fit, and its lower surface is in contact with the slotted washer 6; the slotted washer 6 has its upper surface in contact with the composite material perforated plate 11 and the bushing 4, and its lower surface in contact with the support plate 10, and its inner hole size is between the outer diameter and the inner diameter of the bushing 4, so as to provide support during the installation process and allow the mandrel 3 to pass through smoothly; the support plate 10 has its lower surface fixed to the ground, and its upper surface in contact with the slotted washer 6, and its function is to reserve space for the mandrel to pass through, while reducing the cost of high-precision processing.

[0020] This includes a device for detecting the circumferential strain of pores in composite materials; Specifically, such as Figure 2As shown, it includes strain gauge 5, which comprises two strain gauges, bonded to the surface of the perforated plate 11 near the hole, respectively perpendicular to and parallel to the +45° layup direction of the surface layer of the perforated plate 11, so as to realize strain monitoring around the hole.

[0021] Specifically, such as Figure 1 The resistance strain gauge 7 shown is connected to the strain gauge 5 to collect strain parameters during the installation process. It is also connected to the computer 8 to record the time-domain variation curve of the strain around the hole during the installation process. The computer 8 has strain parameter processing software installed inside it and is connected to the resistance strain gauge 7 to store and analyze the strain parameters around the hole.

[0022] This includes a device for monitoring acoustic signals of damage during the interference process of composite material holes; Specifically, such as Figure 2 As shown. Acoustic emission sensor 1 is installed on the surface of the perforated composite material plate (11) to monitor the acoustic signals emitted by damage to the composite material during installation; Specifically, the acoustic signal analyzer 9 is connected to the acoustic emission sensor 1 to collect acoustic signals and record various acoustic signal parameters. It is connected to the computer 8 to realize real-time data monitoring and storage. The computer 8 is connected to the acoustic signal analyzer 9 and has acoustic signal processing software installed to record various acoustic signal parameters and analyze the acoustic signal damage detection results during the installation process.

[0023] Among them, such as Figure 3 The diagram shows the specific implementation steps of a method for detecting installation damage of a composite material hole interference bushing. S301. Adjust the installation device: Install the mandrel, bushing and composite material perforated plate coaxially; S302. Adjust the sensor: Place the acoustic emission sensor close to the perforated plate of the composite material and connect it to the acoustic signal analyzer; install the strain gauge orthogonally on the surface of the perforated plate of the composite material and connect it to the resistance strain gauge; connect the acoustic signal analyzer and the resistance strain gauge to the computer and debug the analysis and recording software to the monitoring state. S303, Set loading parameters: Set the loading parameters of the hydraulic loading head, and set the displacement and resistance sensors of the hydraulic loading head; S304. Loading, installation and data acquisition: Start the hydraulic loading head and detection system. The mandrel passes completely through the bushing to complete one bushing installation. S305. Data Processing and Analysis: Displacement and resistance parameters during bushing installation are acquired by the hydraulic loading head; circumferential strain data during installation is acquired by the strain acquisition system; and damage data during installation is acquired by the acoustic emission system. The damage data during installation is derived by preprocessing acoustic signals, performing cluster analysis, and combining displacement, resistance, and strain parameters to infer the damage type.

[0024] In this embodiment, the steps for acoustic signal preprocessing, cluster analysis, and damage type determination are as follows: During bushing installation, 12 signal features were acquired using acoustic emission sensors. Principal component analysis (PCA) was employed to reduce the dimensionality of the acoustic emission feature matrix and simplify the data structure. The N principal components were retained when their cumulative variance exceeded 85%, as they effectively represented most of the damage-related information of the overall connection structure.

[0025] Specifically, Principal Component Analysis (PCA) primarily focuses on reducing the dimensionality of the dataset by minimizing variance, without explicitly considering the correlations between individual features. To address this limitation and further optimize feature selection, the Pearson correlation coefficient is employed. This method helps reduce the risk of overfitting and enhances the generalization ability of subsequent models. The formula for calculating the Pearson correlation coefficient is as follows:

[0026] in, Represents the original acoustic emission data matrix and the reduced matrix and Covariance between and Represents random variables and The mean, and and That is the corresponding standard deviation.

[0027] Specifically, before clustering the AE features, it is necessary to determine the optimal number of damage categories related to bushing installation. This study selects the SI coefficient and DB coefficient as evaluation indicators to determine the appropriate number of clusters. The SI coefficient assesses the compactness and separation of clusters; a higher SI value indicates better clustering performance. The DB coefficient assesses clustering efficiency; a lower SI value indicates better partitioning results.

[0028] The SI coefficient is defined as:

[0029] in, This represents the average intra-class distance of the samples. Indicates sample The minimum average distance between it and all other classes to which it does not belong. This indicates the total number of data samples.

[0030] The DB coefficient is defined as:

[0031] in, This represents the total number of classes (i.e., damage categories). and Representation Class and The average intra-class distance (i.e., class diameter). Representation Class and The distance between the centers of mass.

[0032] This also includes a specific example from this embodiment: Specifically, such as Figure 4 As shown, strain changes during bushing installation were monitored in real time, with strain gauges placed around the holes at positions parallel and perpendicular to the fiber direction. The recorded strain-time curves show that the parallel strain was consistently higher than the perpendicular strain.

[0033] Specifically, after principal component analysis, the cumulative variance of the first five principal components all exceeded 85%, indicating that the dimensionality-reduced dataset has good consistency and representativeness. The first five principal components selected were peak amplitude (PA), rise time (RT), duration (H), total frequency (GF), and peak frequency (PF).

[0034] Specifically, when selecting the optimal number of damage categories, a larger SI coefficient and a lower DB coefficient result in better clustering. When the number of categories is set to 4, both evaluation indicators reach satisfactory values, indicating that the classification scheme is reliable. In addition, based on literature and damage observation results, the damage patterns observed during the installation of the bushing can be divided into four categories. These damage patterns include: (1) matrix breakage, (2) fiber bending, (3) delamination, and (4) bushing deformation.

[0035] Specifically, peak amplitude (PA), centroid frequency (GF), and peak frequency (PF) were selected to visualize the clustering results of the specimens. The fuzzy c-means (FCM) clustering algorithm was used to divide the data into single clusters and meta-clusters, thereby enhancing the interpretability and robustness of the damage characterization process.

[0036] Specifically, the clustered data points were further analyzed by examining the relationship between gravity frequency (GF) and time. The specimens exhibited significant damage throughout the installation process. Fiber bending and delamination continued throughout the installation, while matrix damage was primarily concentrated in the early stages or near the mandrel inlet.

Claims

1. A composite material hole interference bushing mounting damage detection system, characterized in that, The system includes: Interference bushing mounting device, composite material hole circumferential strain detection device, composite material hole interference process damage acoustic signal monitoring device, and installation damage comprehensive assessment device; The interference bushing mounting device is used to realize the installation process of the interference bushing; The composite material hole circumferential strain detection device is used to detect the hole circumferential strain data of composite material holes during the installation of interference bushings; The composite material hole interference process damage acoustic signal monitoring device is used to detect acoustic signal damage data of composite material holes during the installation of interference bushings; The device is used to install a comprehensive damage assessment system for storing and analyzing the perimeter strain parameters, as well as for recording various acoustic signal parameters and analyzing the acoustic signal damage detection results during the installation process.

2. The composite material hole interference bushing installation damage detection system according to claim 1, characterized in that, The interference bushing mounting device includes: The hydraulic loading head (2) has a built-in displacement and resistance sensor, one end of which is connected to the mandrel (3); The mandrel (3) is spindle-shaped with a thick middle and thin ends. One end of it is in close contact with the hydraulic loading head (2), and the other end is coaxially installed with the bushing (4). The bushing (4) is clearance-fitted with the hole in the perforated plate (11) of the composite material, and its lower surface is in contact with the slotted washer (6); The perforated plate (11) of the composite material has a clearance fit with the bushing (4) at the opening and the lower surface is in contact with the slotted washer (6); The slotted washer (6) has its upper surface in contact with the composite perforated plate (11) and bushing (4), and its lower surface in contact with the support plate (10). The support plate (10) has its lower surface fixed to the ground and its upper surface in contact with the slotted washer (6). Its function is to reserve space for the mandrel to pass through.

3. The composite material hole interference bushing installation damage detection system according to claim 2, characterized in that, The inner diameter of the slotted washer (6) is between the outer diameter and the inner diameter of the bushing (4) to provide support during installation and allow the mandrel (3) to pass through smoothly.

4. The composite material hole interference bushing installation damage detection system according to claim 1, characterized in that, The composite material pore circumferential strain detection device includes: Strain gauge (5), comprising two strain gauges, is bonded to the surface of the hole near the perforated plate (11) of the composite material; A resistance strain gauge (7) is connected to a strain gauge (5) to collect strain parameters during the installation process. It is also connected to a computer (8) to record the time-domain variation curve of the strain around the hole during the installation process. A computer (8) with strain parameter processing software installed inside it is connected to a resistance strain gauge (7) for storing and analyzing the strain parameters around the hole.

5. The composite material hole interference bushing installation damage detection system according to claim 1, characterized in that, The two strain gauges are perpendicular and parallel to the +45° layup direction of the surface layer of the perforated composite plate (11), respectively.

6. The composite material hole interference bushing installation damage detection system according to claim 1, characterized in that, A device for monitoring acoustic signals of damage during the interferometric process of composite materials includes: An acoustic emission sensor (1) is installed on the surface of a composite perforated plate (11) to monitor the acoustic signals emitted by damage to the composite material during the installation process. The acoustic signal analyzer (9) is connected to the acoustic emission sensor (1) to collect acoustic signals and record various acoustic signal parameters. It is connected to the computer (8) to realize real-time data monitoring and storage. The computer (8) is connected to the acoustic signal analyzer (9) and has acoustic signal processing software installed to record various acoustic signal parameters and analyze the acoustic signal damage detection results during the installation process.

7. The composite material hole interference bushing installation damage detection system according to claim 1, characterized in that, The installation damage comprehensive assessment device achieves a comprehensive assessment of the installation damage of composite material hole interference bushings through multi-dimensional comprehensive analysis of displacement, resistance, strain and acoustic signals.

8. A method for detecting installation damage of a composite material hole interference bushing, implemented using the system described in any one of claims 1-6, the method comprising: Adjust the installation device: Install the mandrel (3), bushing (4) and composite material perforated plate (11) coaxially; Adjust the sensor: Place the acoustic emission sensor (1) close to the perforated plate (11) of the composite material and connect it to the acoustic signal analyzer (9); install the strain gauge (5) orthogonally on the surface around the hole of the perforated plate (11) of the composite material and connect it to the resistance strain gauge (7); connect the acoustic signal analyzer (9) and the resistance strain gauge (7) to the computer (8) and debug the analysis and recording software to the monitoring state; Set loading parameters: Set the loading parameters of the hydraulic loading head (2), and set the displacement and resistance sensors of the hydraulic loading head (2); Loading and data collection: Start the hydraulic loading head (2) and detection system, and the mandrel (3) passes through the bushing (4) completely to complete one bushing installation; Data processing and analysis: Displacement and resistance parameters during bushing installation are obtained by hydraulic loading head (2), strain data around the hole during installation is obtained by strain acquisition system, and damage data during installation is obtained by acoustic emission system.

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