Measuring device for measuring stress strain of large composite material structure

Abstract

The utility model discloses a measuring device for measuring stress and strain of a large composite material structure. The measuring device comprises a first group of sensors, a second group of sensors, a decoder and a data processing module, the first group of sensors and the second group of sensors are respectively arranged on the surfaces of the composite material structure in the corner area and the periphery of the opening part; the decoder is electrically connected with the first group of sensors and the second group of sensors or is in optical communication with the first group of sensors and the second group of sensors so as to obtain measurement signals acquired by the first group of sensors and the second group of sensors, and the data processing module is in communication connection with the decoder, receives data from the decoder and converts the data into readable stress-strain graphs and / or tables. The measuring device can directly measure the stress strain of the large composite material structure in different states, and the stress strain change of the composite material structure in different states can be obtained by comparing the measurement data in different states, so that the accuracy of the measurement result is greatly improved.

Description

Technical Field

[0001] This disclosure pertains to the technical field of stress and strain measurement, specifically relating to a measuring device for measuring the stress and strain of large composite material structures. Background Technology

[0002] For large composite material structures such as aircraft fuselage panels and wing panels, curing typically relies on molds. Due to differences in the thermal expansion coefficients of the mold materials and the layup design of the structure itself, the structural components often experience unpredictable springback deformation after curing and demolding, deviating from the mold surface. Furthermore, because this springback deformation usually deviates from the theoretical shape, localized assembly forces are typically required during assembly to ensure proper fit and connection with other structures.

[0003] Existing measurement methods generally involve bonding the composite material structure to a dedicated surface inspection mold during the inspection process, applying external force according to inspection requirements, and indirectly judging the internal stress and strain state of the composite material structure caused by springback and assembly force by the magnitude of the applied external force after bonding or the gap value between the structure and the inspection mold.

[0004] Existing technologies also include using springback measurement data from scaled-down verification specimens to correct numerical simulation models, and then using these models to simulate the springback deformation and stress-strain of full-size physical objects. The accuracy of this method is affected by the representativeness of the scaled-down verification specimens and size effects, and it cannot directly obtain the stress and strain generated during springback and assembly from the physical object. Additionally, existing technologies include embedding fiber optic strain sensors inside composite material parts before curing to detect the stress and strain generated from curing onwards. This approach places high demands on the sensors, and because the sensors and their cables are embedded inside the test specimen, their accurate positioning is difficult to guarantee. Sensor failure is difficult to repair, and it can easily have adverse effects on the mechanical properties of the parts. Utility Model Content

[0005] The purpose of this invention is to at least partially avoid or solve the above-mentioned technical problems.

[0006] Specifically, this utility model proposes a measuring device for measuring the stress and strain of large composite material structures, the measuring device comprising:

[0007] The first set of sensors is arranged on the surface of the composite material structure at the corner region of its opening and is configured to acquire measurement signals related to the stress and strain of the corner region.

[0008] The second set of sensors is arranged on the surface of the composite material structure around its opening and is configured to acquire measurement signals of stress and strain around the opening.

[0009] A decoder, electrically connected or optically communicating with the first group of sensors and the second group of sensors respectively, to obtain measurement signals of the composite material structure in different states collected by the first group of sensors and the second group of sensors, and to convert the measurement signals into a readable data format; and

[0010] The data processing module is communicatively connected to the decoder, receives readable data from the decoder, and converts the data into stress-strain graphs and / or tables that are easy for operators to read.

[0011] According to one embodiment of the present invention, the corner region of the composite material structure has an arc structure, and the first set of sensors includes:

[0012] A tangential sensor is disposed on the tangent line at the midpoint of the arc of the circular arc structure to obtain the stress and strain of the corner region along the tangential direction;

[0013] A radial sensor is provided, which is positioned in the radial direction at the midpoint of the arc of the circular arc structure, to obtain the stress and strain in the corner region in the radial direction;

[0014] An oblique sensor is disposed on an oblique line inclined relative to the tangent at the midpoint of the arc structure to obtain the stress and strain of the corner region along the oblique line direction.

[0015] According to one embodiment of the present invention, the tangential sensor, radial sensor and oblique sensor are all fiber optic sensors, and the tangential sensor, radial sensor and oblique sensor are connected in series.

[0016] According to one embodiment of the present invention, the tangential sensor, radial sensor and oblique sensor are integrated into a single unit, which can simultaneously acquire stress and strain measurement signals in three directions.

[0017] According to one embodiment of the present invention, the overall unit is a strain gauge, which is capable of simultaneously acquiring stress and strain measurement signals in three directions.

[0018] According to one embodiment of the present invention, the extending direction of the oblique sensor forms a 45° angle with the extending direction of the tangential sensor.

[0019] According to one embodiment of the present invention, the opening is configured as an open opening structure, and the second set of sensors are sequentially arranged on the edge of the composite material structure located on one side of the opening, the periphery of the opening, and the edge located on the other side of the opening.

[0020] According to one embodiment of the present invention, the opening is configured as a closed opening structure, and the second set of sensors is arranged on the surface of the composite material structure located around the opening.

[0021] According to one embodiment of the present invention, the second group of sensors includes one sensor or at least two sensors connected in series.

[0022] According to one embodiment of the present invention, the measuring device further includes a third set of sensors, which are configured at the connection point when the composite material structure is connected to a component or structure on an aircraft, for collecting stress and strain measurement signals at the connection point.

[0023] According to one embodiment of the present invention, the measuring device further includes an electronic device, which integrates the data processing module. The electronic device includes, but is not limited to, a computer, tablet computer, mobile phone, and industrial control computer.

[0024] According to one embodiment of the present invention, the different states include any one of the following states of the composite material structure: before demolding, after demolding, lifting, transportation and assembly process, and the measuring device can obtain the stress and strain changes of the composite material structure under different states by comparing the measurement data under different states.

[0025] The positive effects of this utility model are as follows:

[0026] The measuring device provided by this utility model for measuring the stress and strain of large composite material structures can directly measure the stress and strain data of large composite material structures such as aircraft fuselage panels and wing panels under different conditions. Furthermore, by comparing the measurement data under different conditions, the measuring device can obtain the stress and strain changes of the composite material structure under different conditions, which greatly improves the accuracy of the measurement results.

[0027] The first, second, and third sets of sensors in the aforementioned measuring device are directly fixed to the surface of the composite material structure. This facilitates sensor maintenance and allows for easy removal of the sensors after measurement, without affecting the subsequent use of the composite material structure. Furthermore, the decoder and electronic equipment with integrated data processing modules in this measuring device do not require constant electrical or optical communication with the sensors; an electrical or signal connection is only needed during measurement to transmit signals or data. This simplifies the structure of the measuring device and improves its ease of use. Attached Figure Description

[0028] Figure 1 This is a schematic diagram showing the position of the composite material structure according to this utility model on an aircraft;

[0029] Figure 2 This is a schematic diagram of the connection between the first group of sensors, the second group of sensors, the third group of sensors and the decoder in a preferred embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram of the sensor arrangement on a composite material structure according to a preferred embodiment of the present invention;

[0031] Figure 4 and Figure 5 They are respectively Figure 3 Schematic diagram of the structure of the first group of sensors at points A and B in the middle;

[0032] Figure 6 This is a schematic diagram of the sensor arrangement on a composite material structure according to another preferred embodiment of the present invention.

[0033] The reference numerals in the attached figures are explained as follows:

[0034] 10. First composite material structure;

[0035] 20. Second composite material structure;

[0036] 310. Opening; 320. Corner area;

[0037] 410. First group of sensors; 411. Tangential sensor; 412. Radial sensor; 413. Oblique sensor; 420. Second group of sensors; 430. Third group of sensors;

[0038] 500, decoder; 510, optical fiber. Detailed Implementation

[0039] In the following description, preferred embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Although preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0040] Unless the context requires otherwise, throughout the specification and claims, the word “comprising” and its variations, such as “including” and “having”, shall be understood to have an open, inclusive meaning, that is, to be interpreted as “including, but not limited to”.

[0041] Throughout this specification, references to "one embodiment" or "some embodiments" indicate that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Therefore, the appearance of "in one embodiment" or "in some embodiments" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any way in one or more embodiments.

[0042] Furthermore, the terms "first," "second," etc., used in the specification and claims are used merely for clarity of description to distinguish various objects, and do not limit the size, quantity, or other order of the objects described. Directional terms indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are used solely for the purpose of describing this application, not to indicate or imply that the objects referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this application.

[0043] Aircraft fuselage panels and wing panels mostly use large composite material structures. These composite material structures are usually formed by mold processing. However, due to the difference in thermal expansion coefficient between the mold material and the composite material, as well as the layer design of the structure itself, the composite material structure will experience stress and strain changes due to springback before and after demolding, during lifting, transportation and assembly, as well as stress and strain changes due to possible straightening and forced assembly.

[0044] The measuring device provided by this utility model for measuring the stress and strain of large composite material structures can directly measure the stress and strain of large composite material structures such as aircraft fuselage panels and wing panels under different conditions. The different conditions include before demolding, after demolding, lifting, transportation and assembly processes of the composite material structure. Furthermore, the measuring device can obtain the stress and strain changes of the composite material structure under different conditions by comparing the measurement data under different conditions.

[0045] The specific embodiments of this utility model will be described in detail below. Figure 1 As shown, in the preferred embodiment of this utility model, the composite material structure includes a first composite material structure 10 and a second composite material structure 20. The first composite material structure 10 and the second composite material structure 20 are aircraft fuselage panels with curvature and large openings. The first composite material structure 10 is the connection part between the aircraft fuselage and the wing, and the second composite material structure 20 is the boarding door part of the aircraft.

[0046] In a preferred embodiment, such as Figure 2 and 3 As shown, an opening 310 is formed on the first composite material structure 10 at the connection between the fuselage and the wing of the aircraft. The opening 310 is an open structure. Two corner regions 320 are formed around the opening 310 and recessed into the main body of the first composite material structure 10. Both corner regions 320 are designed as arc structures.

[0047] The present invention provides a measuring device for measuring stress and strain in large composite material structures, comprising a first set of sensors 410, a second set of sensors 420, a decoder 500, and a data processing module (not shown in the figure). The first set of sensors 410 is arranged on the surface of the first composite material structure 10 at the corner region 320, and is used to collect stress and strain measurement signals in the corner region 320. The second set of sensors 420 is arranged on the surface of the first composite material structure 10 around the opening 310, and is used to collect stress and strain measurement signals around the opening 310.

[0048] The decoder 500 is electrically connected or optically communicated with the first set of sensors 410 and the second set of sensors 420 respectively. The data processing module is communicatively connected to the decoder 500. The first set of sensors 410 and the second set of sensors 420 transmit the measurement signals of the first composite material structure 10 under different states to the decoder 500. The decoder 500 converts the measurement signals into a data format that can be read by the data processing module. The data processing module receives the readable data from the decoder 500 and converts the data into stress and strain graphs and / or tables that are easy for operators to read. Operators can directly read the measured stress and strain values ​​of the first composite material structure 10 under different states through the graphs and / or tables.

[0049] Furthermore, the measuring device also includes an electronic device that integrates the aforementioned data processing module. The electronic device includes, but is not limited to, a computer, tablet computer, mobile phone, or industrial control computer. The communication connection between the electronic device and the decoder 500 includes, but is not limited to, serial communication, USB, Wi-Fi, and Bluetooth. The electronic device can intuitively display the aforementioned stress-strain graphs and / or tables.

[0050] like Figure 4 and 5 As shown, the first set of sensors 410 includes a tangential sensor 411, a radial sensor 412, and an oblique sensor 413. The first set of sensors 410 forms a centralized layout in the corner region 320 of the first composite material structure 10, thereby enabling simultaneous acquisition of stress and strain measurement signals in the corner region 320 along the tangential, radial, and oblique directions. Specifically, the tangential sensor 411 is positioned on the tangent line at the midpoint of the arc of the corner region 320's arc structure, and is used to acquire stress and strain in the corner region 320 along the tangential direction. The radial sensor 412 is positioned in the radial direction at the midpoint of the arc of the corner region 320's arc structure, and is used to acquire stress and strain in the radial direction of the corner region 320. The oblique sensor 413 is positioned on an oblique line inclined relative to the tangent line at the midpoint of the arc of the corner region 320's arc structure, and is used to acquire stress and strain in the corner region 320 along the oblique direction. Preferably, the extension direction of the oblique sensor 413 forms a 45° angle with the extension direction of the tangential sensor 411, which facilitates accurate measurement of the stress and strain of the first composite material structure 10 located in the corner region 320.

[0051] It should be noted that, in this preferred embodiment, the tangential sensors 411 in the first group of sensors 410 located at points A and B of the composite material structure are arranged in positions other than... Figure 4 and 5 The arrangement shown is on the tangent line of the arc structure located on one side of the arc midpoint, or it can be arranged on the tangent line of the arc structure located on the other side of the arc midpoint. Accordingly, the position of the oblique sensor 413 will also change with the position of the tangential sensor 411.

[0052] Furthermore, it should be noted that the composite material structure in this preferred embodiment has an arc-shaped structure as a whole. Therefore, the tangential sensor 411, radial sensor 412, and oblique sensor 413 can be understood as being fixed on the surface of the composite material structure in a generally tangential, radial, and oblique direction. In addition to the midpoint of the arc, the tangential, radial, and oblique directions of other points on the arc are also possible, but the midpoint of the arc is preferred.

[0053] Tangential sensor 411, radial sensor 412, and oblique sensor 413 are all fiber optic sensors, and they are connected in series via fiber optic cable 510 to acquire stress and strain measurement signals of the corner region 320 along the tangential, radial, and oblique directions. (See also: [link to relevant documentation]) Figure 2As shown, the first set of sensors 410, which are set at each corner region 320 of the composite material structure, are connected to the decoder 500 through optical fiber 510, so as to transmit the measurement signals collected by the first set of sensors 410 to the decoder 500.

[0054] Alternatively, the tangential sensor 411, radial sensor 412, and oblique sensor 413 are integrated into a single unit, which is a strain gauge. This strain gauge can simultaneously acquire stress and strain measurement signals in the corner region 320 along the tangential, radial, and oblique directions. The strain gauges of the composite material structure located at each corner region 320 are electrically connected to the decoder 500, thereby transmitting the measurement signals acquired by the first set of sensors 410 to the decoder 500.

[0055] See back Figure 2 and 3 As shown, the second set of sensors 420 includes one sensor, which is sequentially arranged on the edge of the first composite material structure 10 on one side of the opening 310, around the periphery of the opening 310, and on the edge on the other side of the opening 310. The second set of sensors 420 forms a distributed layout around the opening 310, thereby acquiring the stress and strain measurement signals around the opening 310. Furthermore, the second set of sensors 420 maintains a distance of 25-50 mm from the edge of the first composite material structure 10 and the periphery of the opening 310 to avoid the influence of the irregular cut contours of the edge of the first composite material structure 10 and the periphery of the opening 310 on the measurement results.

[0056] Alternatively, the second set of sensors 420 includes at least two sensors arranged in series on the edge of the first composite material structure 10 on one side of the opening 310, the periphery of the opening 310, and the edge on the other side of the opening 310, so as to acquire the stress and strain measurement signal of the periphery of the opening 310.

[0057] See back Figure 2 and 3 As shown, the measuring device also includes a third set of sensors 430, which are arranged at the connection points where the first composite material structure 10 is connected to components or structures on the aircraft. The third set of sensors 430 forms a distributed layout at these connection points to collect measurement signals of stress and strain at the connection points. Figure 2 and 3As shown, the first composite material structure 10 includes three connection points that need to be connected to the aircraft frame. The third group of sensors 430 includes at least three sensors, which are respectively arranged at the three connection points. One sensor or at least two sensors connected in series are arranged at each connection point, and the at least three sensors are connected in series with each other.

[0058] It should be noted that the connection points when the composite material structure of this utility model is connected to the components or structures on the aircraft are not limited to the above three points. The number of connection points can be any other number. It should also be understood that, based on the number of connection points of the composite material structure, the third group of sensors 430 includes at least a corresponding number of sensors, and the at least corresponding number of sensors are connected in series to collect the stress and strain measurement signals of the connection points.

[0059] Preferably, the closest distance between the second group of sensors 420 and the third group of sensors 430 is maintained at a spacing of 25 to 50 mm, so as to avoid mutual interference between the two groups of sensors during measurement and to collect stress and strain measurement signals over a wider range as much as possible.

[0060] The sensors in the second group of sensors 420 and the third group of sensors 430 mentioned above are preferably fiber optic sensors. (See also: [link to previous section]) Figure 2 As shown, the sensors are connected in series via optical fiber 510, and the second group of sensors 420 and the third group of sensors 430 are also connected in series via optical fiber 510. They are then connected to the decoder 500 via optical fiber 510, thereby transmitting the measurement signals collected by the second group of sensors 420 and the third group of sensors 430 to the decoder 500.

[0061] It should be noted that the sensors used in the first group of sensors 410, the second group of sensors 420 and the third group of sensors 430 are not limited to fiber optic sensors, but can also be any other type of sensor.

[0062] In another preferred embodiment, such as Figure 6As shown, an opening 310 is formed on the second composite material structure 20 located at the boarding door of the aircraft. This opening 310 is a closed structure, and four corner regions 320 recessed into the main body of the second composite material structure 20 are formed around the periphery of the opening 310. Each of the four corner regions 320 is designed as an arc. This preferred embodiment differs from the previously described preferred embodiment in that the second set of sensors 420 includes one sensor, which is arranged on the surface of the second composite material structure 20 around the opening 310. The second set of sensors 420 forms a distributed layout around the opening 310, thereby acquiring measurement signals of stress and strain around the opening 310. Furthermore, a distance of 25-50 mm is maintained between the second set of sensors 420 and the periphery of the opening 310 to avoid the influence of irregular cut contours around the opening 310 on the measurement results.

[0063] Alternatively, the second set of sensors 420 includes at least two sensors arranged in series on the surface of the second composite material structure 20 around the opening 310, thereby acquiring measurement signals of stress and strain around the opening 310.

[0064] Preferably, the first group of sensors 410, the second group of sensors 420, and the third group of sensors 430 are fixed to the surface of the composite material structure by means of fast-curing adhesive after the composite material structure has been cured and before demolding. According to actual needs, after the measuring device has completed the stress and strain measurement, the sensors can be directly removed without affecting the subsequent use of the composite material structure.

[0065] The following is a detailed description of a measurement method using a measuring device according to a preferred embodiment of the present invention. The measurement method includes the following steps:

[0066] S1. Arrange sensors: After the composite material structure is cured and before demolding, according to the structural characteristics of the composite material structure, arrange the first set of sensors 410, the second set of sensors 420 and the third set of sensors 430 on the surface of the opening 310, the corner area 320 and the connecting part of the composite material structure respectively.

[0067] S2. Calibrate the measurement reference. Before measurement, establish communication between the electronic equipment, decoder 500 and the above sensors. Then, measure the stress and strain of the composite material structure before demolding and calibrate the current measurement as the measurement reference A0.

[0068] S3. Continuous measurement in the first stage: Continuous measurement begins after the composite material structure is demolded and continues until the composite material structure is transferred to the bracket. The measurement result is recorded as B1. The measurement result B1 is compared with the measurement benchmark A0 in step S2 to monitor and determine whether harmful strain has been generated during the lifting, transportation and other processes after demolding.

[0069] S4. Support state measurement: After the composite material structure is placed and stabilized on the horizontal bracket, support state measurement is performed. The measurement result is recorded as A1. The measurement result A1 is compared with the measurement reference A0 in step S2 to obtain the strain generated by the rebound inside the composite material structure under the influence of gravity.

[0070] S5. Second stage of continuous measurement: After the composite material structure is removed from the bracket, select individual states, such as different transportation states and lifting states from step S3, for measurement. The measurement result is recorded as B2. The measurement result B2 is compared with the measurement result A1 in step S4 and the measurement benchmark A0 in step S2 to obtain the additional stress and strain generated during lifting and transportation.

[0071] S6. After assembly, measure the assembly state of the composite material structure. Record the measurement result as A2. Compare the measurement result A2 with the measurement reference A0 in step S2. After deducting the gravity factor, the stress and strain generated in the composite material structure under the combined action of springback and assembly operation can be obtained.

[0072] S7. Measurement complete, remove sensor.

[0073] The measuring device provided by this utility model for measuring the stress and strain of large composite material structures can directly measure the stress and strain of large composite material structures such as aircraft fuselage panels and wing panels under different conditions. The different conditions specifically include before demolding, after demolding, lifting, transportation and assembly processes. Furthermore, by comparing the measurement data under different conditions, the measuring device can obtain the stress and strain changes of the composite material structure under different conditions, which greatly improves the accuracy of the measurement results.

[0074] The first set of sensors 410, the second set of sensors 420, and the third set of sensors 430 in the aforementioned measuring device are directly fixed to the surface of the composite material structure. This facilitates sensor maintenance and allows for direct removal of the sensors after measurement, without affecting the subsequent use of the composite material structure. Furthermore, the decoder 500 and the electronic equipment with integrated data processing modules in this measuring device do not require constant electrical or optical communication with the sensors; an electrical or signal connection is only needed during measurement to transmit signals or data. This simplifies the structure of the measuring device and improves its ease of use.

[0075] It should be noted that the features or combinations of features described above according to the present utility model, as well as the features and combinations of features mentioned and / or shown only in the accompanying drawings, can be used not only in the given combinations, but also in other combinations or individually, without departing from the scope of the present utility model.

[0076] This utility model has been described through the above embodiments. However, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit this utility model to the scope of the described embodiments. Those skilled in the art should understand that many more changes and modifications can be made based on the teachings of this utility model, and all such changes and modifications fall within the protection scope of this utility model.

Claims

1. A measuring device for measuring stress and strain in large composite material structures, characterized in that, The measuring device includes: The first set of sensors (410) is arranged on the surface of the composite material structure at the corner region (320) of its opening (310) and is configured to acquire measurement signals of stress and strain in relation to the corner region (320). The second set of sensors (420) is arranged on the surface of the composite material structure around its opening (310) and is configured to acquire measurement signals of stress and strain around the opening (310). A decoder (500) is electrically connected or optically communicated with the first group of sensors (410) and the second group of sensors (420) respectively to obtain measurement signals of the composite material structure in different states collected by the first group of sensors (410) and the second group of sensors (420), and converts the measurement signals into a readable data format; and The data processing module is communicatively connected to the decoder (500), receives readable data from the decoder (500), and converts the data into stress-strain graphs and / or tables that are easy for operators to read.

2. The measuring device for measuring stress and strain in large composite material structures according to claim 1, characterized in that, The corner region (320) of the composite material structure has an arc structure, and the first set of sensors (410) includes: A tangential sensor (411) is disposed on the tangent at the midpoint of the arc of the circular arc structure to obtain the stress and strain of the corner region (320) along the tangential direction; A radial sensor (412) is disposed in the radial direction at the midpoint of the arc of the arc structure to obtain the stress and strain of the corner region (320) in the radial direction; An oblique sensor (413) is disposed on an oblique line inclined to the tangent at the midpoint of the arc structure to obtain the stress and strain of the corner region (320) along the oblique line direction.

3. The measuring device for measuring stress and strain in large composite material structures according to claim 2, characterized in that, The tangential sensor (411), radial sensor (412), and oblique sensor (413) are all fiber optic sensors, and the three sensors are connected in series.

4. The measuring device for measuring stress and strain in large composite material structures according to claim 2, characterized in that, The tangential sensor (411), radial sensor (412), and oblique sensor (413) are integrated into a single unit, which can simultaneously acquire stress and strain measurement signals in three directions.

5. The measuring device for measuring stress and strain in large composite material structures according to claim 4, characterized in that, The overall unit is a strain gauge, which can simultaneously acquire stress and strain measurement signals in three directions.

6. The measuring device for measuring stress and strain in large composite material structures according to claim 2, characterized in that, The extension direction of the oblique sensor (413) forms a 45° angle with the extension direction of the tangential sensor (411).

7. The measuring device for measuring stress and strain in large composite material structures according to claim 1, characterized in that, The opening (310) is configured as an open opening structure, and the second set of sensors (420) are arranged sequentially on the edge of the composite material structure on one side of the opening (310), the periphery of the opening (310), and the edge on the other side of the opening (310).

8. The measuring device for measuring stress and strain in large composite material structures according to claim 1, characterized in that, The opening (310) is configured as a closed opening structure, and the second set of sensors (420) are arranged on the surface of the composite material structure located around the opening (310).

9. The measuring device for measuring stress and strain in large composite material structures according to claim 7 or 8, characterized in that, The second group of sensors (420) includes one sensor or at least two sensors connected in series.

10. The measuring device for measuring stress and strain in large composite material structures according to claim 1, characterized in that, The measuring device also includes a third set of sensors (430), which are configured at the connection point when the composite material structure is connected to a component or structure on the aircraft, for collecting stress and strain measurement signals at the connection point.

11. The measuring device for measuring stress and strain in large composite material structures according to claim 1, characterized in that, The measuring device also includes electronic equipment, which integrates the data processing module. The electronic equipment includes, but is not limited to, computers, tablets, mobile phones, and industrial control computers.

12. The measuring device for measuring stress and strain in large composite material structures according to claim 1, characterized in that, The different states include any of the following states of the composite material structure: before demolding, after demolding, lifting, transportation and assembly process, and the measuring device can obtain the stress and strain changes of the composite material structure under different states by comparing the measurement data under different states.

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