System and method for judging internal damage of composite material based on interlayer sensing data

Abstract

The invention discloses a composite material internal damage judgment system based on interlayer sensing data, and the system comprises a composite material internal interlayer strain calculation module which is used for calculating a composite material internal interlayer strain according to the change of the central wavelength of each fiber grating detected by all optical fiber sensors implanted into each layer in a composite material, calculating the strain of the composite material layer position corresponding to the fiber bragg grating of each fiber sensor; the composite material internal damage degree calculation module is used for dividing the strain corresponding to the same fiber grating position in each layer of the composite material by the strain at the corresponding position of the surface layer of the composite material to obtain the strain relative value of the corresponding position of each layer, and calculating the change rate of the strain relative value of the corresponding position of each layer along with the impact frequency; the damage degree of the corresponding position of each layer of the composite material is obtained. According to the method, the fiber grating sensor is implanted into the material, and the damage of the composite material in the service period is evaluated by monitoring the interlayer physical field of the composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material structure health monitoring, and in particular to a composite material internal damage judgment system and method based on interlayer sensing data. Background Art

[0002] Carbon fiber reinforced resin matrix composite laminates have received great attention in scientific research and engineering applications due to their light weight, high strength, high specific stiffness and other characteristics. Especially in the fields of aerospace, rail transportation, wind power, etc., the proportion of composite materials used has increased year by year, and the proportion of composite materials as load-bearing structures has also gradually increased. However, in the process of preparing and using composite materials, fatigue, equipment falling, impact, shock, lightning strike, corrosion and other factors may cause damage to composite materials that is almost invisible to the naked eye. The generation and expansion of this damage mainly occurs inside the composite material. For composite materials with load-bearing functions, this damage may continue to grow during the load-bearing process, eventually leading to material failure and causing great safety hazards to the overall structure. Therefore, it is very important to judge the internal health status of composite materials in a timely manner in the actual application of composite materials. Traditional detection methods such as visual detection, ultrasonic detection, and radiographic detection cannot achieve real-time monitoring and analysis of the interior of large-scale composite structures. Since the use environment of composite structures is usually more complex, traditional sensors such as surface-mounted strain gauges and piezoelectric sensors are affected by the use environment, unstable, and cannot be implanted inside the material, resulting in insufficient intuitive monitoring of structural health. Summary of the invention

[0003] The purpose of the present invention is to address the defects of the prior art and provide a composite material internal damage judgment system and method based on interlayer sensing data.

[0004] The present invention provides a composite material internal damage judgment system based on interlayer sensing data, comprising:

[0005] The composite material internal interlayer strain calculation module is used to calculate the strain of the composite material layer position corresponding to each fiber grating of all fiber sensors according to the change of the central wavelength of each fiber grating detected by all fiber sensors implanted in each layer of the composite material;

[0006] The internal damage degree calculation module of the composite material is used to divide the strain corresponding to the same fiber grating position in each layer of the composite material by the strain at the corresponding position on the surface of the composite material to obtain the relative strain value of the corresponding position of each layer, and then calculate the rate of change of the relative strain value of the corresponding position of each layer with the number of impacts to obtain the damage degree of the corresponding position of each layer of the composite material.

[0007] Furthermore, it also includes: a composite material health scoring module, which is used to assign weights to the corresponding positions of each fiber grating of all fiber optic sensors, and each weight is multiplied by the degree of damage of the corresponding fiber grating corresponding to the composite material position to characterize the health of the composite material.

[0008] Furthermore, when preparing the composite material, each layer of the composite material includes a base material and a prepreg, the prepreg is laid on the base material, and the optical fiber sensor is flatly fixed on the prepreg, and then the next layer of the base material for preparing the composite material is laid on the prepreg, the optical fiber sensor is composed of a plurality of grating array sensing optical fibers, the grating array sensing optical fibers are engraved with a fiber grating array, the fiber grating array is composed of a plurality of fiber grating strings, and the fiber grating string is composed of a plurality of fiber gratings with different initial center wavelengths.

[0009] Furthermore, the initial central wavelength range of the fiber grating is between 1510nm and 1590nm, and the initial wavelength interval between two adjacent fiber gratings in the fiber grating string is between 4nm and 20nm.

[0010] Furthermore, in the composite material internal interlayer strain calculation module, the specific method for calculating the strain of the composite material layer position corresponding to each fiber grating of all fiber sensors according to the change of the central wavelength of each fiber grating detected by all fiber sensors implanted in each layer inside the composite material is:

[0011] According to the change of the central wavelength of each fiber grating, the strain at the corresponding composite material layer position is calculated as:

[0012]

[0013] in, is the strain of the fiber Bragg grating u of the i-th layer of the fiber sensor in the composite material corresponding to the composite material surface position, k is the strain sensitivity coefficient of the fiber Bragg grating, is the central wavelength of the fiber Bragg grating u of the i-th fiber sensor in the composite material during detection, is the initial value of the central wavelength of the fiber Bragg grating u of the i-th layer of optical fiber sensor in the composite material.

[0014] Furthermore, in the internal damage degree calculation module of the composite material, the specific method of dividing the strain corresponding to the same fiber grating position in each layer of the composite material by the strain at the corresponding position on the surface of the composite material to obtain the relative strain value at the corresponding position of each layer is:

[0015] The strain information collected by the i-th layer optical fiber sensor The two-dimensional coordinates of the positions of each fiber grating corresponding to the composite material layer are rearranged into a two-dimensional matrix:

[0016]

[0017] in, is the strain set of all fiber gratings of the i-th layer of fiber optic sensors in the composite material corresponding to the position of the composite material surface, is the strain of the fiber Bragg grating in the mth row and nth column of the i-th layer of the fiber sensor in the composite material corresponding to the position of the composite material surface;

[0018] The relative strain values ​​between the fiber grating positions with the same two-dimensional coordinates on each layer where the fiber optic sensor is implanted:

[0019]

[0020] in, It represents the relative strain value of the fiber Bragg grating in the mth row and nth column of the i-th layer fiber sensor corresponding to the composite material layer position, is the strain of the fiber Bragg grating at the position of the composite material layer corresponding to the mth row and nth column of the i-th fiber sensor, is the strain of the fiber Bragg grating in the mth row and nth column of the first layer of optical fiber sensor corresponding to the composite material layer surface position.

[0021] Furthermore, in the composite material internal damage degree calculation module, the specific method of obtaining the damage degree of the corresponding position of each layer of the composite material by calculating the rate of change of the relative strain value of the corresponding position of each layer with the impact number is as follows:

[0022] Based on the number of impacts, the damage degree is calculated as follows:

[0023]

[0024] in, is the damage degree of the fiber Bragg grating position in the mth row and nth column of the i-th layer fiber sensor after the composite material is subjected to the tth impact, is the relative strain value of the fiber Bragg grating of the mth row and nth column of the i-th fiber sensor corresponding to the composite material surface after the composite material is subjected to the tth impact, is the initial value of the relative strain value of the fiber Bragg grating in the mth row and nth column of the optical fiber sensor of the i-th layer of the composite material corresponding to the composite material surface position.

[0025] A composite material internal damage judgment method based on interlayer sensing data, comprising:

[0026] According to the changes in the central wavelengths of the respective fiber gratings detected by all the fiber optic sensors implanted at each layer inside the composite material, the strains at the positions of the composite material layers corresponding to the respective fiber gratings of all the fiber optic sensors are calculated;

[0027] The strain corresponding to the same fiber grating position in each layer of the composite material is divided by the strain at the corresponding position on the surface of the composite material to obtain the relative strain value at the corresponding position of each layer. Then, by calculating the rate of change of the relative strain value at the corresponding position of each layer with the number of impacts, the degree of damage at the corresponding position of each layer of the composite material is obtained.

[0028] A computer-readable medium having a computer program / instruction stored thereon, wherein the computer program / instruction executes the above-mentioned composite material internal damage judgment method based on interlayer sensing data when running.

[0029] A computer program product includes a computer program / instruction, wherein when the computer program / instruction is executed by a processor, the method for determining internal damage of a composite material based on interlayer sensing data is implemented.

[0030] The beneficial effects of the present invention are:

[0031] 1. The present invention implants a fiber Bragg grating sensor inside the material, combines it with a three-dimensional fiber Bragg grating sensing network, and monitors the physical field between the layers of the composite material. In particular, according to the relative strain values ​​between the fiber Bragg grating positions with the same two-dimensional coordinates on each layer where the fiber Bragg grating sensor is implanted, the damage of the composite material during service is judged to achieve damage analysis of the composite material structure and safety assessment of the composite material structure.

[0032] 2. Whether the central wavelength of the fiber grating of the optical fiber sensor changes can be detected in real time whether the composite material has been impacted. It has a high degree of real-time performance and can provide timely feedback on the health of the composite material. The strain at that position can be calculated by the change in the central wavelength of the fiber grating before and after the composite material is subjected to force, which can intuitively reflect the damage of the composite material.

[0033] 3. Since the fiber optic sensors are implanted in the composite material in layers, and each fiber grating corresponds to each other in the thickness direction (the two-dimensional coordinates of the fiber gratings in each layer are the same), they together form a three-dimensional sensing network. At the same time, the relative strain value is calculated by ratio to indicate the relative strain size of each layer. This can reflect whether the local strain exceeds the normal range. The degree of damage is calculated by the relative strain value to truly reflect the health status of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a system block diagram of the present invention;

[0035] Figure 2 It is a schematic diagram of the layout of a three-dimensional interlayer sensing network of multi-layer optical fiber sensors;

[0036] Figure 3 Schematic diagram of grating array sensing fiber;

[0037] Figure 4 This is a schematic diagram of the layout of the single-layer grating array sensing optical fiber inside the composite material;

[0038] Figure 5 Schematic diagram of internal damage monitoring system for composite material structure with full-time sensing data between layers;

[0039] Figure 6 Schematic diagram of a three-dimensional interlayer sensor network.

[0040] Description of the accompanying drawings: 1—carbon fiber composite material, 2—optical fiber sensor, 3—optical fiber connector, 4—grating array sensing optical fiber, 5—optical fiber grating, 6—prepreg, 7—grating array sensing optical fiber, 8—connecting optical fiber, 9—optical fiber demodulator. DETAILED DESCRIPTION

[0041] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0042] Example 1

[0043] A composite material internal damage judgment system based on interlayer sensing data, comprising:

[0044] The composite material internal interlayer strain calculation module is used to calculate the strain of the composite material layer position corresponding to each fiber grating of all fiber sensors according to the change of the central wavelength of each fiber grating detected by all fiber sensors implanted in each layer of the composite material;

[0045] The internal damage degree calculation module of the composite material is used to obtain the relative strain value of the corresponding position of each layer by dividing the strain corresponding to the same fiber grating position in each layer of the composite material by the strain at the corresponding position of the surface layer of the composite material, and then obtain the damage degree of the corresponding position of each layer of the composite material by calculating the change rate of the relative strain value of the corresponding position of each layer with the impact number;

[0046] The composite material health scoring module is used to assign weights to the corresponding positions of each fiber grating of all fiber optic sensors. Each weight is multiplied by the damage degree of the corresponding composite material position of the corresponding fiber grating to characterize the health of the composite material.

[0047] (1) When preparing a composite material, each layer of the composite material includes a base material (such as resin-based carbon fiber) and a prepreg, the prepreg is laid on the base material, and the optical fiber sensor is flatly fixed on the prepreg, and then the next layer of the base material for preparing the composite material is laid on the prepreg, the optical fiber sensor is composed of a plurality of grating array sensing optical fibers, the grating array sensing optical fibers are engraved with a fiber grating array, the fiber grating array is composed of a plurality of fiber grating strings, and the fiber grating string is composed of a plurality of fiber gratings with different initial center wavelengths.

[0048] See also Figure 2-Figure 6 The fiber sensor 2 is composed of a plurality of grating array optical fibers 4. The grating array sensing optical fiber is engraved with a fiber grating array. The fiber grating array is composed of a plurality of fiber gratings 5 ​​of different wavelengths, and the central wavelength range is between 1510nm and 1590nm. The length of each fiber grating string is L1, and the interval between the fiber grating strings is L2. Each fiber grating string contains 5 fiber gratings 5 ​​of different wavelengths. The initial wavelength interval between two adjacent fiber gratings in the fiber grating string is between 4nm and 20nm. The included fiber gratings are evenly distributed at intervals of L3, which ensures that the fiber gratings do not interfere with each other, while retaining a larger detection range.

[0049] For the laying method of single-layer optical fiber sensor 2, see Figure 5 After the prepreg 6 is laid, the grating array sensing optical fiber is laid flat and fixed on top. The fiber grating in the grating array sensing optical fiber 7 is arranged parallel to the fiber direction of the prepreg 6. In order to form a grating sensing network, the fiber grating string is used to space the optical fiber and wrap around at the edge. The parallel spacing is set to L3, and the fiber grating 5 before and after the wrapping is kept symmetrical to ensure the formation of a uniform rectangular grating sensing array. The lead-out end of the grating array sensing optical fiber 7 is connected to the optical fiber connector 3.

[0050] After the single-layer fiber optic sensor is laid out, continue to lay the composite material prepreg, and implant the fiber optic sensor 4 into the composite material 1 at the designed fiber optic sensor 2 position according to the above steps, and ensure that the fiber optic layout between the layers of each fiber optic sensor 2 is consistent, the fiber optic Bragg grating 5 corresponds one to one along the longitudinal position, and the lead-out end of each layer of grating array sensor fiber 7 is connected to the fiber optic connector 3 respectively.

[0051] (2) In the composite material internal interlayer strain calculation module, the specific method for calculating the strain of the composite material layer position corresponding to each fiber grating of all fiber sensors according to the change of the central wavelength of each fiber grating detected by all fiber sensors implanted in each layer of the composite material is:

[0052] According to the change of the central wavelength of each fiber grating, the strain at the corresponding composite material layer position is calculated as:

[0053]

[0054] in, is the strain of the fiber Bragg grating u of the i-th layer of the fiber sensor in the composite material corresponding to the composite material surface position, k is the strain sensitivity coefficient of the fiber Bragg grating, is the central wavelength of the fiber Bragg grating u of the i-th fiber sensor in the composite material during detection, is the initial value of the central wavelength of the fiber Bragg grating u of the i-th layer of optical fiber sensor in the composite material.

[0055] By checking whether the central wavelength of the fiber Bragg grating of the optical fiber sensor changes, it is possible to detect in real time whether the composite material has been impacted. It has a high degree of real-time performance and can provide timely feedback on the health of the composite material. It can also calculate the strain at that position through the change in the central wavelength of the fiber Bragg grating before and after the composite material is subjected to force, and intuitively reflect the damage to the composite material.

[0056] (3) In the composite material internal damage degree calculation module, the specific method of dividing the strain corresponding to the same fiber grating position in each layer of the composite material by the strain at the corresponding position on the surface of the composite material to obtain the relative strain value at the corresponding position of each layer is:

[0057] The strain information collected by the i-th layer optical fiber sensor The two-dimensional coordinates of the positions of each fiber grating corresponding to the composite material layer are rearranged into a two-dimensional matrix:

[0058]

[0059] in, is the strain set of all fiber gratings of the i-th layer of fiber optic sensors in the composite material corresponding to the position of the composite material surface, is the strain of the fiber Bragg grating in the mth row and nth column of the i-th layer of the fiber sensor in the composite material corresponding to the position of the composite material surface;

[0060] The relative strain values ​​between the fiber grating positions with the same two-dimensional coordinates on each layer where the fiber optic sensor is implanted:

[0061]

[0062] in, It represents the relative strain value of the fiber Bragg grating in the mth row and nth column of the i-th layer fiber sensor corresponding to the composite material layer position, is the strain of the fiber Bragg grating at the position of the composite material layer corresponding to the mth row and nth column of the i-th fiber sensor, is the strain of the fiber Bragg grating in the mth row and nth column of the first layer of optical fiber sensor corresponding to the composite material layer surface position.

[0063] In the composite material internal damage degree calculation module, the specific method of obtaining the damage degree of each layer of the composite material at the corresponding position by calculating the change rate of the relative strain value of each layer at the corresponding position with the impact number is as follows:

[0064] Based on the number of impacts, the damage degree is calculated as follows:

[0065]

[0066] in, is the damage degree of the fiber Bragg grating position in the mth row and nth column of the i-th layer fiber sensor after the composite material is subjected to the tth impact, is the relative strain value of the fiber Bragg grating of the mth row and nth column of the i-th fiber sensor corresponding to the composite material surface after the composite material is subjected to the tth impact, is the initial value of the relative strain value of the fiber Bragg grating in the mth row and nth column of the optical fiber sensor of the i-th layer of the composite material corresponding to the composite material surface position.

[0067] like Figure 6 As shown in the figure, since the fiber optic sensors are implanted in the composite material layer by layer, and each fiber grating corresponds to each other in the thickness direction (the fiber grating two-dimensional coordinates of each layer are the same), they together form a three-dimensional sensing network. At the same time, the relative strain value is calculated by ratio to indicate the relative strain size of each layer. Only in this way can it be reflected whether the local strain exceeds the normal range. Then, the damage degree is calculated by the relative strain value to truly reflect the health status of the composite material. Whether the local strain exceeds the normal range involves specific values ​​related to the application scenario of the composite material and the properties of the material itself, and cannot be generalized.

[0068] Example 2

[0069] A composite material internal damage judgment method based on interlayer sensing data, comprising:

[0070] According to the changes in the central wavelengths of the respective fiber gratings detected by all the fiber optic sensors implanted at each layer inside the composite material, the strains at the positions of the composite material layers corresponding to the respective fiber gratings of all the fiber optic sensors are calculated;

[0071] The strain corresponding to the same fiber grating position in each layer of the composite material is divided by the strain at the corresponding position on the surface of the composite material to obtain the relative strain value at the corresponding position of each layer, and then the damage degree at the corresponding position of each layer of the composite material is obtained by calculating the change rate of the relative strain value at the corresponding position of each layer with the impact number;

[0072] Weights are assigned to the corresponding positions of each fiber grating of all fiber optic sensors, and each weight is multiplied by the damage degree of the corresponding fiber grating corresponding to the composite material position to characterize the health of the composite material.

[0073] (1) When preparing a composite material, each layer of the composite material includes a base material (such as resin-based carbon fiber) and a prepreg, the prepreg is laid on the base material, and the optical fiber sensor is flatly fixed on the prepreg, and then the next layer of the base material for preparing the composite material is laid on the prepreg, the optical fiber sensor is composed of a plurality of grating array sensing optical fibers, the grating array sensing optical fibers are engraved with a fiber grating array, the fiber grating array is composed of a plurality of fiber grating strings, and the fiber grating string is composed of a plurality of fiber gratings with different initial center wavelengths.

[0074] During the preparation of the carbon fiber composite material 1, the optical fiber sensor 2 is implanted between the composite material layers according to the material design requirements, and is connected to the optical fiber connector 3 for signal transmission.

[0075] See also Figure 2-Figure 6 The fiber sensor 2 is composed of a plurality of grating array optical fibers 4. The grating array sensing optical fiber is engraved with a fiber grating array. The fiber grating array is composed of a plurality of fiber gratings 5 ​​of different wavelengths, and the central wavelength range is between 1510nm and 1590nm. The length of each fiber grating string is L1, and the interval between the fiber grating strings is L2. Each fiber grating string contains 5 fiber gratings 5 ​​of different wavelengths. The initial wavelength interval between two adjacent fiber gratings in the fiber grating string is between 4nm and 20nm. The included fiber gratings are evenly distributed at intervals of L3, which ensures that the fiber gratings do not interfere with each other, while retaining a larger detection range.

[0076] For the laying method of single-layer optical fiber sensor 2, see Figure 5 After the prepreg 6 is laid, the grating array sensing optical fiber is laid flat and fixed on top. The fiber grating in the grating array sensing optical fiber 7 is arranged parallel to the fiber direction of the prepreg 6. In order to form a grating sensing network, the fiber grating string is used to space the optical fiber and wrap around at the edge. The parallel spacing is set to L3, and the fiber grating 5 before and after the wrapping is kept symmetrical to ensure the formation of a uniform rectangular grating sensing array. The lead-out end of the grating array sensing optical fiber 7 is connected to the optical fiber connector 3.

[0077] After the single-layer fiber optic sensor is laid out, continue to lay the composite material prepreg, and implant the fiber optic sensor 4 into the composite material 1 at the designed fiber optic sensor 2 position according to the above steps, and ensure that the fiber optic layout between the layers of each fiber optic sensor 2 is consistent, the fiber optic Bragg grating 5 corresponds one to one along the longitudinal position, and the lead-out end of each layer of grating array sensor fiber 7 is connected to the fiber optic connector 3 respectively.

[0078] (2) According to the changes in the central wavelengths of the respective fiber gratings detected by all the fiber optic sensors implanted at each layer inside the composite material, the specific method for calculating the strain of the composite material layer position corresponding to the fiber gratings of all the fiber optic sensors is as follows:

[0079] According to the change of the central wavelength of each fiber grating, the strain at the corresponding composite material layer position is calculated as:

[0080]

[0081] in, is the strain of the fiber Bragg grating u of the i-th layer of the fiber sensor in the composite material corresponding to the composite material surface position, k is the strain sensitivity coefficient of the fiber Bragg grating, is the central wavelength of the fiber Bragg grating u of the i-th fiber sensor in the composite material during detection, is the initial value of the central wavelength of the fiber Bragg grating u of the i-th layer of optical fiber sensor in the composite material.

[0082] By checking whether the central wavelength of the fiber Bragg grating of the optical fiber sensor changes, it is possible to detect in real time whether the composite material has been impacted. It has a high degree of real-time performance and can provide timely feedback on the health of the composite material. It can also calculate the strain at that position through the change in the central wavelength of the fiber Bragg grating before and after the composite material is subjected to force, and intuitively reflect the damage to the composite material.

[0083] (3) The specific method of dividing the strain corresponding to the same fiber grating position in each layer of the composite material by the strain at the corresponding position on the surface of the composite material to obtain the relative strain value at the corresponding position of each layer is:

[0084] The strain information collected by the i-th layer optical fiber sensor The two-dimensional coordinates of the positions of each fiber grating corresponding to the composite material layer are rearranged into a two-dimensional matrix:

[0085]

[0086] in, is the strain set of all fiber gratings of the i-th layer of fiber optic sensors in the composite material corresponding to the position of the composite material surface, is the strain of the fiber Bragg grating in the mth row and nth column of the i-th layer of the fiber sensor in the composite material corresponding to the position of the composite material surface;

[0087] The relative strain values ​​between the fiber grating positions with the same two-dimensional coordinates on each layer where the fiber optic sensor is implanted:

[0088]

[0089] in, It represents the relative strain value of the fiber Bragg grating in the mth row and nth column of the i-th layer fiber sensor corresponding to the composite material layer position, is the strain of the fiber Bragg grating at the position of the composite material layer corresponding to the mth row and nth column of the i-th fiber sensor, is the strain of the fiber Bragg grating in the mth row and nth column of the first layer of optical fiber sensor corresponding to the composite material layer surface position.

[0090] In the composite material internal damage degree calculation module, the specific method of obtaining the damage degree of each layer of the composite material at the corresponding position by calculating the change rate of the relative strain value of each layer at the corresponding position with the impact number is as follows:

[0091] Based on the number of impacts, the damage degree is calculated as follows:

[0092]

[0093] in, is the damage degree of the fiber Bragg grating position in the mth row and nth column of the i-th layer fiber sensor after the composite material is subjected to the tth impact, is the relative strain value of the fiber Bragg grating of the mth row and nth column of the i-th fiber sensor corresponding to the composite material surface after the composite material is subjected to the tth impact, is the initial value of the relative strain value of the fiber Bragg grating in the mth row and nth column of the optical fiber sensor of the i-th layer of the composite material corresponding to the composite material surface position.

[0094] like Figure 6 As shown in the figure, since the fiber optic sensors are implanted in the composite material layer by layer, and each fiber grating corresponds to each other in the thickness direction (the fiber grating two-dimensional coordinates of each layer are the same), they together form a three-dimensional sensing network. At the same time, the relative strain value is calculated by ratio to indicate the relative strain size of each layer. Only in this way can it be reflected whether the local strain exceeds the normal range. Then, the damage degree is calculated by the relative strain value to truly reflect the health status of the composite material. Whether the local strain exceeds the normal range involves specific values ​​related to the application scenario of the composite material and the properties of the material itself, and cannot be generalized.

[0095] Example 3

[0096] A computer readable medium having a computer program / instruction stored thereon, wherein the computer program / instruction executes the composite material internal damage judgment method based on interlayer sensor data in embodiment 2 when the computer program / instruction is run

[0097] Example 4

[0098] A computer program product includes a computer program / instruction, wherein when the computer program / instruction is executed by a processor, the method for determining internal damage of a composite material based on interlayer sensing data in Example 2 is implemented.

[0099] The contents not described in detail in this specification belong to the prior art known to those skilled in the art. It should be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0100] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0101] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0102] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the pending claims of the invention.

Claims

1. A composite material internal damage judgment system based on interlayer sensing data, characterized in that: include: The composite material internal interlayer strain calculation module is used to calculate the strain of the composite material layer position corresponding to each fiber grating of all fiber sensors according to the change of the central wavelength of each fiber grating detected by all fiber sensors implanted in each layer of the composite material; The internal damage degree calculation module of the composite material is used to divide the strain corresponding to the same fiber grating position in each layer of the composite material by the strain at the corresponding position on the surface of the composite material to obtain the relative strain value of the corresponding position of each layer, and then calculate the rate of change of the relative strain value of the corresponding position of each layer with the number of impacts to obtain the damage degree of the corresponding position of each layer of the composite material.

2. The composite material internal damage judgment system based on interlayer sensing data according to claim 1 is characterized in that: Also includes: The composite material health scoring module is used to assign weights to the corresponding positions of each fiber grating of all fiber optic sensors. Each weight is multiplied by the damage degree of the corresponding composite material position of the corresponding fiber grating to characterize the health of the composite material.

3. The composite material internal damage judgment system based on interlayer sensing data according to claim 1 is characterized in that: When preparing a composite material, each layer of the composite material includes a base material and a prepreg, the prepreg is laid on the base material, and the optical fiber sensor is flatly fixed on the prepreg, and then the next layer of the base material for preparing the composite material is laid on the prepreg, the optical fiber sensor is composed of a plurality of grating array sensing optical fibers, the grating array sensing optical fibers are engraved with a fiber grating array, the fiber grating array is composed of a plurality of fiber grating strings, and the fiber grating string is composed of a plurality of fiber gratings with different initial center wavelengths.

4. The composite material internal damage judgment system based on interlayer sensor data according to claim 3 is characterized in that: The initial central wavelength range of the fiber grating is between 1510nm and 1590nm, and the initial wavelength interval between two adjacent fiber gratings in the fiber grating string is between 4nm and 20nm.

5. The composite material internal damage judgment system based on interlayer sensing data according to claim 1 is characterized in that: In the composite material internal interlayer strain calculation module, the specific method for calculating the strain of the composite material layer position corresponding to each fiber grating of all fiber sensors according to the change of the central wavelength of each fiber grating detected by all fiber sensors implanted in each layer of the composite material is: According to the change of the central wavelength of each fiber grating, the strain at the corresponding composite material layer position is calculated as: in, is the strain of the fiber Bragg grating u of the i-th layer of the fiber sensor in the composite material corresponding to the composite material surface position, k is the strain sensitivity coefficient of the fiber Bragg grating, is the central wavelength of the fiber Bragg grating u of the i-th layer of optical fiber sensor in the composite material during detection, is the initial value of the central wavelength of the fiber Bragg grating u of the i-th layer of optical fiber sensor in the composite material.

6. The composite material internal damage judgment system based on interlayer sensing data according to claim 1 is characterized in that: In the composite material internal damage degree calculation module, the specific method of dividing the strain corresponding to the same fiber grating position in each layer of the composite material by the strain at the corresponding position on the surface of the composite material to obtain the relative strain value at the corresponding position of each layer is: The strain information collected by the i-th layer optical fiber sensor The two-dimensional coordinates of the positions of each fiber grating corresponding to the composite material layer are rearranged into a two-dimensional matrix: in, is the strain set of all fiber gratings of the i-th layer of fiber optic sensors in the composite material corresponding to the position of the composite material surface, is the strain of the fiber Bragg grating in the mth row and nth column of the i-th layer of the fiber sensor in the composite material corresponding to the position of the composite material surface; The relative strain values ​​between the fiber grating positions with the same two-dimensional coordinates on each layer where the fiber optic sensor is implanted: in, It represents the relative strain value of the fiber Bragg grating in the mth row and nth column of the i-th layer fiber sensor corresponding to the composite material layer position, is the strain of the fiber Bragg grating at the position of the composite material layer corresponding to the mth row and nth column of the i-th fiber sensor, is the strain of the fiber Bragg grating in the mth row and nth column of the first layer of optical fiber sensor corresponding to the composite material layer surface position.

7. The composite material internal damage judgment system based on interlayer sensing data according to claim 6 is characterized in that: In the composite material internal damage degree calculation module, the specific method for calculating the damage degree of the position corresponding to the relative strain value according to the relative strain value is as follows: Based on the number of impacts, the damage degree is calculated as follows: in, is the damage degree of the fiber Bragg grating position in the mth row and nth column of the i-th layer fiber sensor after the composite material is subjected to the tth impact, is the relative strain value of the fiber Bragg grating of the mth row and nth column of the i-th fiber sensor corresponding to the composite material surface after the composite material is subjected to the tth impact, is the initial value of the relative strain value of the fiber Bragg grating in the mth row and nth column of the optical fiber sensor of the i-th layer of the composite material corresponding to the composite material surface position.

8. A composite material internal damage judgment method based on interlayer sensing data, characterized in that: include: According to the changes in the central wavelengths of the respective fiber gratings detected by all the fiber optic sensors implanted at each layer inside the composite material, the strains at the positions of the composite material layers corresponding to the respective fiber gratings of all the fiber optic sensors are calculated; The strain corresponding to the same fiber grating position in each layer of the composite material is divided by the strain at the corresponding position on the surface of the composite material to obtain the relative strain value at the corresponding position of each layer. Then, by calculating the rate of change of the relative strain value at the corresponding position of each layer with the number of impacts, the degree of damage at the corresponding position of each layer of the composite material is obtained.

9. A computer-readable medium having a computer program / instruction stored thereon, wherein the computer program / instruction, when run, executes the composite material internal damage judgment method based on interlayer sensing data as claimed in claim 8.

10. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the method for determining internal damage of a composite material based on interlayer sensing data as described in claim 8 is implemented.

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