Real-time in-situ microscopic monitoring method, system and device for microscopic damage of composite material

Abstract

The invention relates to the technical field of test solid mechanics, in particular to a real-time in-situ microscopic monitoring method, system and device for microscopic damage of a composite material. The device comprises an imaging unit for monitoring a preset observation point on a sample in real time; the multi-dimensional adjusting unit is used for being connected with the imaging unit and adjusting the displacement of the imaging unit; the multi-dimensional adjusting unit comprises a guide rail parallel to the expected displacement direction of the observation point; the object placing platform is in sliding connection with the guide rail and used for bearing the imaging unit; the storage platform is connected with the motion controller, and the motion controller adjusts the displacement speed of the imaging unit according to the real-time displacement speed; the real-time displacement speed is calculated through a preset speed formula according to the clamp movement speed received in real time and the first distance, so that the imaging unit is adjusted in real time along with the movement of the to-be-observed point, and the microstructure change of the composite material sample is monitored in real time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of experimental solid mechanics, in particular to a composite material mesoscopic damage real-time in-situ microscopic monitoring method, system and device. BACKGROUND

[0002] In the field of composite material mechanical property testing, tensile, bending, compression and other tests are key means to explore the performance of composite materials. In traditional tests, microscopic observation of the microstructure of the sample mainly relies on post-observation, that is, preset observation positions are set before the test, and then microscopic observation is performed after the loading is completed. However, this method has limitations and cannot capture the real-time microstructure changes of the sample during the loading process. If the sample position deviates during the test, the preset observation point deviates from the microscope observation range, and the observation area cannot accurately reflect the real situation under the stress state, which reduces the accuracy and completeness of the test data, making it difficult to deeply study the initiation and development mechanism of the composite material mesoscopic damage, and limiting the comprehensive understanding of the failure mechanism of the composite material. Therefore, there is an urgent need for a composite material mesoscopic damage real-time in-situ microscopic monitoring method, system and device to realize in-situ real-time monitoring of the microstructure evolution in composite material mechanical testing. SUMMARY

[0003] The purpose of the present application is to solve the technical problem that the observation point deviates from the microscope observation range, making it difficult to accurately reflect the real situation under the stress state. The composite material mesoscopic damage real-time in-situ microscopic monitoring method, system and device provided by the embodiments of the present application can accurately and continuously follow the changes of the preset observation position on the side surface of the sample, and can real-time capture microscopic images, thereby realizing real-time monitoring of the microstructure changes of the composite material sample and providing more detailed and accurate dynamic data of the microstructure for researchers.

[0004] To achieve the above-mentioned purpose of the application, the present application provides the following technical solutions: The composite material mesoscopic damage real-time in-situ microscopic monitoring device comprises: An imaging unit for real-time monitoring of the preset observation point on the sample; A multi-dimensional adjustment unit connected with the imaging unit and used for adjusting the displacement of the imaging unit; the multi-dimensional adjustment unit comprises: A guide rail parallel to the expected displacement direction of the observation point; A placing platform for carrying the imaging unit is slidably connected with the guide rail; the placing platform is connected with a motion controller, and the motion controller adjusts the displacement speed of the imaging unit according to a real-time displacement speed; the real-time displacement speed is calculated according to a real-time received clamp motion speed and a first distance through a preset speed formula, the first distance is a distance between an initial position of the observation point and a fulcrum, the fulcrum is a contact point between the sample and a fixed end of the clamp, and the speed formula is preset according to a test type of the composite material damage.

[0005] The application further provides a composite material microscopic damage real-time in-situ microscopic monitoring system, comprising: The composite material microscopic damage real-time in-situ microscopic monitoring device is used for, after receiving a trigger signal, synchronously adjusting the displacement speed of the imaging unit according to the acquired real-time displacement speed through a motion controller, so as to monitor a preset observation point in real time and obtain image data. The upper computer is used for storing and / or displaying the image data.

[0006] The application provides a composite material microscopic damage real-time in-situ microscopic monitoring method, comprising: Step S1, preparing a sample according to a composite material test standard, and presetting an observation point on the sample; Step S2, monitoring the observation point in real time by using the composite material microscopic damage real-time in-situ microscopic monitoring device; Step S3, receiving image data output by the monitoring device through the upper computer, and storing and / or displaying the image data.

[0007] Compared with the prior art, the application has the following beneficial effects: The composite material microscopic damage real-time in-situ microscopic monitoring device provided by the application has the advantages of simple structure, accurate control, and the like, realizes in-situ real-time monitoring of microscopic structure evolution in composite material testing by fusing motor control, multi-axis collaborative tracking and high-resolution imaging technology, and combining a mechanical testing machine, solves the problem that in traditional mechanical property testing, microscopic monitoring of a sample is dependent on post-observation and it is difficult to capture real-time microscopic changes of the sample in a stress process, and is beneficial to improving the accuracy and integrity of composite material data analysis. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 It is a shaft side view of the structure of the composite material microscopic damage real-time in-situ microscopic monitoring device; Figure 2 It is a side view of the imaging unit and the placing platform in the monitoring device; Figure 3 It is a connection schematic view of the communication structure of the monitoring device and the mechanical testing machine; Figure 4A flowchart of a method for real-time in-situ microscopic monitoring of composite micro-damage; The figure marks: 1-imaging unit, 11- objective, 12- light source, 13- continuous zoom lens, 14- automatic focusing camera, 2- multi-dimensional adjustment unit, 20- guide rail, 21- object platform, 22- displacement platform group, 221- first displacement platform, 222- second displacement platform, 23- groove, 24- displacement plate, 25- bearing plate, 26- first reinforcing beam, 27- second reinforcing beam, 3- motion controller, 4- motor, 5- guide rail base body, 6- rotary table, 7- mechanical testing machine, 8- conversion interface. DETAILED DESCRIPTION

[0009] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application.

[0010] Therefore, the following detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but merely represents some embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application.

[0011] It should be noted that the embodiments in the present application and the features and technical solutions in the embodiments can be combined with each other without conflict.

[0012] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0013] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly placed when the product of the present application is used, or the orientation or positional relationship commonly understood by those skilled in the art, such terms are only for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used for differentiation, and cannot be understood as indicating or implying relative importance.

[0014] In the present embodiment, for example Figures 1-3As shown, the composite material microscopic damage real-time in-situ microscopic monitoring device provided by the application is used for adjusting the displacement speed of the imaging unit along the guide rail according to the clamp movement speed of the mechanical testing machine and the distance between the initial position of the preset observation point and the fulcrum, and sliding the imaging unit along the displacement direction of the observation point, so as to focus on the observation point in real time, realize real-time microscopic monitoring of the observation point, and obtain image data.

[0015] It should be noted that in the embodiment, the mechanical testing machine 7 is a vertical testing machine, that is, when the clamp clamps the sample for testing, the displacement direction of the clamp is set as the vertical direction. However, in another embodiment, the mechanical testing machine 7 can also be a horizontal testing machine, that is, the displacement direction of the clamp is set as the horizontal direction.

[0016] The monitoring device comprises an imaging unit 1 and a multi-dimensional adjustment unit 2.

[0017] The imaging unit 1 is used for microscopic imaging and real-time monitoring of the preset observation point on the composite material. Preferably, the imaging unit 1 is provided with an objective lens 11 at one end away from the guide rail 20 and an automatic focusing camera 14 at one end close to the guide rail 20. A light source 12 and a continuous zoom lens 13 are sequentially arranged between the objective lens 11 and the automatic focusing camera 14. The light source 12 can adjust the light intensity to meet different observation requirements. The continuous zoom lens 13 and the objective lens 11 are combined to realize continuous zoom of the field of view, so that the field of view covers the entire observation point section, to provide a flexible field of view range, and the automatic focusing camera 14 can quickly focus when the composite material sample produces damage and is out of focus, to ensure clear image recording.

[0018] The multi-dimensional adjustment unit 2 is used for connecting with the imaging unit 1 and adjusting the displacement of the imaging unit 1 along the guide rail 20. Preferably, the multi-dimensional adjustment unit 2 is connected with a flat plate at the bottom. A plurality of locking countersunk holes are arranged on the flat plate to facilitate connection with the multi-dimensional adjustment unit 2 through screws and nuts, so as to facilitate fixing or disassembling and separating. A base is arranged at the bottom of the flat plate and connected through screws and nuts, to provide a stable foundation for the entire monitoring system. In the embodiment, the base is arranged as a rectangular truss. It should be noted that in other embodiments, the base can also be arranged as a rectangular box structure or a column with a flat support seat at the bottom.

[0019] Further, the multi-dimensional adjustment unit 2 comprises: The guide rail 20 is parallel to the expected displacement direction of the preset observation point on the sample. In the embodiment, the expected displacement direction of the observation point is the same as the displacement direction of the clamp of the mechanical testing machine 7. A placing platform 21 for carrying the imaging unit 1 is slidably connected to the guide rail 20. A displacement platform group 22 is arranged on the placing platform 21 and is displaced in a direction perpendicular to the expected displacement direction. The imaging unit 1 is arranged above the displacement platform group 22 and moves with the displacement platform group 22 in a plane perpendicular to the guide rail 20, so that the objective lens 11 of the imaging unit 1 is preliminarily aligned with the observation point of the sample.

[0020] Specifically, the side of the guide rail 20 away from the imaging unit 1 is connected with a guide rail base 5 for improving the stability of the guide rail 20. The guide rail base 5 is arranged as a rectangular frame, the plane of which is parallel to the plane of the guide rail 20. The two ends of the guide rail 20 are connected with the upper and lower edges of the guide rail base 5 to improve the stability of the guide rail 20 in the direction perpendicular to the axial direction of the imaging unit 1. The side of the guide rail base 5 away from the guide rail 20 is connected with a support beam perpendicular to the plane of the guide rail base 5 to improve the stability of the guide rail 20 in the axial direction of the imaging unit 1. The lower part of the support beam is arranged as a rectangle and is connected with the flat plate. The upper part of the support beam is arranged as a trapezoid. The beam body of the support beam is provided with an opening, and a reinforcing rib perpendicular to the plane of the guide rail base 5 is arranged in the opening. In another embodiment, the guide rail base 5 can also be a trapezoidal frame, and the shape thereof is not limited in the embodiment.

[0021] In another embodiment, the guide rail 20 can be directly connected with the flat plate. A screw hole is arranged at one end of the guide rail 20, and the guide rail 20 is connected with the flat plate by a screw and is vertically arranged above the flat plate. The fixing mode of the guide rail 20 is not limited in the embodiment.

[0022] Further, the placing platform 21 is provided with a carrying plate 25 perpendicular to the guide rail 20, and the displacement platform group 22 is arranged above the carrying plate 25. When the placing platform 21 slides along the guide rail 20, the placing platform 21 is affected by the gravity of the placing platform 21, the inertia of the placing platform 21 itself, and the force for displacing the placing platform 21 in the sliding direction, and the placing platform 21 has a problem of vibration in the sliding direction, which increases the time for stable imaging when the imaging unit 1 tracks the observation point in real time.

[0023] Therefore, preferably, the object platform 21 is further provided with a displacement plate 24 in sliding connection with the guide rail 20, and the side of the displacement plate 24 in contact with the guide rail 20 is provided with a sliding groove matching the width of the guide rail 20. The displacement plate 24 is provided with locking counterbores for connection with the side walls of a groove 23 through nuts and screws. The first reinforcing beam 26 for improving the stability of the vertical displacement of the imaging unit 1 is connected between the two side walls of the groove 23, and the first reinforcing beam 26 is perpendicular to the two side walls and the bottom of the groove 23. In another embodiment, the first reinforcing beam 26 can also be connected with the bottom of the groove 23. The bearing plate 25 is arranged on the side wall of the groove 23 away from the guide rail 20, preferably at the upper end of the side wall. The second reinforcing beam 27 is further arranged between the bearing plate 25 and the side wall connected therewith. The second reinforcing beam 27 is perpendicular to the bearing plate 25 and / or the side wall of the groove 23. The imaging unit 1 is arranged above the bearing plate 25. The greater the distance between the objective lens 11 and the connection point of the imaging unit 1 and the displacement platform group 22, the greater the moment formed, and when the imaging unit 1 slides along the guide rail 20 with the object platform, the objective lens 11 is more likely to vibrate greatly. By connecting the bearing plate 25 and the displacement plate 24 on the guide rail 20 through the groove 23, not only the arrangement depth of the imaging unit 1 in the axial direction is increased, which is conducive to reducing the moment of the objective lens 11, but also the bearing strength of the imaging unit 1 in the axial direction is increased through the first reinforcing beam 26 arranged in the groove 23 and the second reinforcing beam 27 between the bearing plate 25 and the side wall of the groove 23, which is conducive to reducing the vibration of the imaging unit 1 and improving the stability of the imaging of the objective lens 11.

[0024] In another embodiment, the object platform 21 can be provided only with the bearing plate 25 perpendicular to the guide rail 20, and the imaging unit 1 is arranged on one side of the bearing plate 25. The bearing plate 25 is provided with a through hole matching the shape of the outer circumferential surface of the radial section of the guide rail 20, and the guide rail 20 passes through the through hole during installation, so that the bearing plate 25 can slide along the guide rail 20.

[0025] Preferably, the maximum sliding displacement distance of the object platform 21 along the guide rail 20 , wherein H test is the maximum lifting distance of the clamp of the mechanical testing machine 7. The maximum movement distance of one end of the objective lens 11 of the imaging unit 1 along the direction perpendicular to the axial direction of the imaging unit 1 , wherein W test is the distance between the two columns of the mechanical testing machine 7. The displacement speed of the object platform 21 satisfies , wherein is the minimum displacement speed of the clamp; and the displacement accuracy of the imaging unit 1 and the object platform 21 satisfies , The displacement resolution of the fixture chuck of the mechanical testing machine. In this way, the imaging unit 1 meets the observation requirements of different positions and ensures real-time tracking of the position change of the sample observation point in the mechanical property test.

[0026] Further, the displacement platform group 22 is provided with a plurality of overlapping displacement platforms. In this embodiment, the displacement platform group 22 includes a first displacement platform 221 and a second displacement platform 222, wherein the first displacement platform 221 moves in the axial direction of the imaging unit 1, and the second displacement platform 222 moves perpendicular to the axial direction, so that the objective lens 11 approaches the observation point of the sample, and then adjusts the imaging to be clear through the imaging unit 1, and makes the observation point located in the center of the field of view through the automatic focusing camera 14.

[0027] In an embodiment, a slide rail is arranged below the first displacement platform 221 and the second displacement platform 222. Before starting real-time monitoring, the first displacement platform 221 and the second displacement platform 222 are moved by manual adjustment to preliminarily adjust the position of the imaging unit 1, so that the objective lens 11 is aligned with the observation point. In another embodiment, the mechanism of ball nut and screw can also be arranged below the first displacement platform 221 and the second displacement platform 222, and the displacement platform connected with the ball nut is moved by rotating the screw through the hand wheel installed at one end of the screw.

[0028] Further, the multi-dimensional adjustment unit 2 further includes a motion controller 3. In an embodiment, as shown in the figure, Figure 3 The motion controller 3 is in communication connection with the mechanical testing machine 7 through the conversion interface 8 to receive the fixture motion speed and the first distance from the mechanical testing machine 7. After starting the test, the mechanical testing machine 7 sends a trigger signal, and the motion controller 3 establishes connection with the mechanical testing machine 7 after receiving the trigger signal. The mechanical testing machine 7 sends the real-time collected fixture motion speed and the first distance to the motion controller 3. The motion controller 3 calculates the real-time displacement speed of the imaging unit 1 when monitoring the observation point according to the real-time received fixture motion speed and the first distance from the mechanical testing machine 7 through the preset speed formula, so as to realize the synchronous displacement of the imaging unit 1 and the observation point. The direction of the real-time displacement speed is the same as the expected displacement direction, and the first distance is the distance between the initial position of the observation point and the fulcrum. The fulcrum is the contact point between the sample and the fixed end of the fixture. Specifically, in an embodiment, the motion controller 3 is electrically connected with the motor 4, and the motor 4 is in transmission connection with the placement platform 21, so that the motion controller 3 adjusts the torque output of the motor 4 to realize that the placement platform 21 real-time tracks the observation point at different displacement speeds or at a constant speed according to the expected displacement direction.

[0029] In another embodiment, the speed of the clamp movement of the mechanical testing machine 7 needs to be kept constant. The motion controller 3 is used to directly receive the real-time displacement speed. After the tester reads the speed of the clamp movement and the first distance from the mechanical testing machine 7, the real-time displacement speed is calculated through the speed formula and set to the motion controller 3. After the test starts, the mechanical testing machine 7 sends a trigger signal, and after the motion controller 3 receives the trigger signal, it controls the imaging unit 1 to slide according to the expected displacement direction of the observation point according to the set real-time displacement speed, so as to realize the synchronous displacement of the imaging unit 1 and the observation point.

[0030] Specifically, the tester obtains the spatial function by reasoning through the material mechanics formula according to the first distance and the test type of the composite material, and presets a plurality of spatial functions corresponding to a plurality of test types in the motion controller 3 or other storage devices. Before monitoring starts, the tester selects the corresponding spatial function according to the current test type; after starting monitoring, the motion controller 3 calculates the real-time displacement speed by taking the clamp movement speed and the spatial function as the factors of the speed formula; the speed formula is as follows: ; Wherein, k is a preset dimensionless correction coefficient; v test is the speed of the clamp movement; x is the first distance; L is the characteristic length of the sample; is the spatial function.

[0031] In a specific embodiment, the test type is set according to the composite material mechanical property test standard, such as ASTM D3039 or GB / T 3355. In this embodiment, the spatial functions selected by the three commonly used test cases are as follows: When performing uniaxial tensile test or uniaxial compression test, the spatial function formula is as follows: ; Wherein, x is the first distance, and L0 is the original length of the sample.

[0032] When performing three-point bending test, the spatial function formula is as follows: ; Wherein, x is the first distance, and L1 is the distance between the two contact points of the sample and the fixed end.

[0033] It should be noted that the clamp of the mechanical testing machine 7 includes a fixed end and a moving end, the fixed end is used to keep the sample position, and the moving end is used to apply test force to the sample to make the sample deform. Among them, the fixed end can be multiple, so that the sample of the composite material is provided with multiple contact points to meet different test requirements, for example, in the three-point bending test, the sample has two contact points to realize the moving end to apply force to the preset observation point between the contact points to bend the sample.

[0034] It should be noted that when there are multiple fixed ends, the first distance is the minimum distance between the initial position of the observation point and the multiple fulcrums.

[0035] In an embodiment, the motion controller 3 is electrically connected with the motor 4 arranged at the top end of the guide rail 20. The motor 4 is drivingly connected with the placement platform 21 through chain transmission or belt transmission, so as to drive the displacement plate 24 to slide along the guide rail 20.

[0036] Further, the bottom end of the guide rail 20 is also provided with a rotating table 6, which is connected with the flat plate, so that the imaging unit 1 can rotate in a plane perpendicular to the guide rail 20, for observing a sample with an arc-shaped or pitted surface. Rotating the imaging unit 1 can make it easier for the autofocus camera 14 to focus on the arc surface, and adjust the illumination angle of the light source 12, so as to improve the imaging quality.

[0037] In an embodiment, the guide rail 20 is arranged above the rotating table 6 and connected with the rotating table 6. The rotating table 6 and the flat plate are connected through nuts and screws passing through locking counterbores. The rotating table 6 rotates, so that the imaging unit 1 rotates synchronously with the guide rail 20. In another embodiment, the guide rail 20 is a cylinder. The rotating table 6 is provided with a through hole matching the diameter of the outer circumferential surface of the guide rail 20. The guide rail 20 passes through the through hole of the rotating table 6, and the flat plate is connected through nuts and screws passing through locking counterbores. The rotating table 6 rotates, so that the imaging unit 1 rotates around the guide rail 20. In this embodiment, the rotating angle of the rotating table 6 is satisfies .

[0038] In an embodiment of the present application, the composite material microscopic damage real-time in-situ microscopic monitoring system provided by the present application comprises: The monitoring device is used to receive a trigger signal from the mechanical testing machine 7, and then adjust the displacement speed of the imaging unit 1 synchronously according to the acquired real-time displacement speed through the motion controller 3, so as to monitor the preset observation point in real time and obtain image data. The upper computer is used to store and / or display the image data.

[0039] Further, the monitoring device comprises: The imaging unit 1 is used to perform microscopic imaging and real-time monitoring on the observation point.

[0040] The multi-dimensional adjustment unit 2 is used to adjust the imaging unit 1 to slide along the guide rail 20 synchronously with the offset of the observation point, so that the observation point is located at the center of the field of view of the imaging unit 1.

[0041] The motion controller 3 is used to adjust the displacement speed of the imaging unit (1) according to the real-time displacement speed; the real-time displacement speed is calculated by using a preset speed formula based on the clamp movement speed and the first distance obtained from the mechanical testing machine 7 in real time. The first distance is the distance between the initial position of the observation point and the fulcrum; the fulcrum is the contact point between the sample and the fixed end of the clamp.

[0042] In one embodiment, the motion controller 3 includes a data acquisition submodule, a speed acquisition submodule, and an adjustment submodule.

[0043] The data acquisition submodule is used to acquire preset fixture movement speed, initial position of observation point and first distance between fulcrum and support point from the mechanical testing machine 7 via conversion interface 8, and preset test type, where the support point is the contact point between the specimen and the fixed end of the fixture. Conversion interface 8 is used for communication connection between the mechanical testing machine 7 and the motion controller 3.

[0044] The speed acquisition submodule is used to receive the fixture's movement speed and first distance in real time, and calculate the real-time displacement speed using a preset speed formula. In another embodiment, after the tester reads the fixture's movement speed and first distance from the mechanical testing machine 7, the real-time displacement speed is calculated using a speed formula; the speed acquisition submodule can directly receive the real-time displacement speed set by the tester.

[0045] Specifically, the clamp's movement speed and the first distance are substituted into a preset speed formula to calculate the real-time displacement speed v. The speed formula is as follows: ; Where k is a preset dimensionless correction coefficient; v test denoted as _x_, where _x is the speed of the clamp movement; _x_ is the first distance; and _L_ is the characteristic length of the specimen. It is a spatial function, which is derived by the testers using material mechanics formulas based on the first distance and the test type.

[0046] In specific implementations, the test types are set according to composite material mechanical property testing standards, such as ASTM D3039 or GB / T 3355. In this embodiment, the spatial functions for selecting three commonly used test case types are as follows: When performing uniaxial tensile or uniaxial compression tests, the space function formula is as follows: ; Where x is the first distance and L0 is the original length of the sample.

[0047] The space function formula for the three-point bending test is as follows: ; Where x is the first distance, and L1 is the distance between the two support points that contact the sample with the fixed end.

[0048] The adjustment submodule is used to adjust the current of motor 4 according to the real-time displacement speed, and adjust the torque output of motor 4 by adjusting the current to adjust the real-time displacement speed of the storage platform 21 connected to motor 4.

[0049] In one embodiment of this application, for example Figure 4 The diagram shows a flowchart of the real-time in-situ microscopic monitoring method for microscopic damage in composite materials provided by this invention. For example, using carbon fiber reinforced polymer (CFRP) composites as samples for uniaxial tensile testing, the monitoring method provided by this invention is used for real-time microscopic monitoring, including: Step S1: Prepare the specimen according to the ASTM D3039 standard for testing the mechanical properties of composite materials and determine the observation point location. In this embodiment, the area where the optical fiber is embedded is used as the observation point location. It should be noted that the specimen observation point can also be a cross-section of the composite material without any embedded impurities; the optical fiber used in this embodiment is only one of many external embeddings used in the mechanical testing of composite materials, and other materials can also be embedded. A single-mode optical fiber with a diameter of 155 μm and a polyimide coating is pre-embedded in the middle layer of the carbon fiber reinforced polymer (CFRP) laminate to observe the damage propagation trend of the CFRP after the optical fiber is embedded. The fiber laying direction is perpendicular to the direction of the reinforcing fibers in the adjacent layers. The laminate is processed into 250 × 25 × 1.5 mm according to the ASTM D3039 testing standard. 3 Tensile specimens were prepared. Reinforcing plates, each measuring 30 × 25 × 1 mm, were adhered to the four edges of the specimen. 3 The embedded area of ​​the optical fiber is the preset observation point. In this embodiment, the observation point is set at the center of the sample length. The cross-section of the composite material sample into which the optical fiber is embedded is polished one by one using 1000-grit sandpaper, 2000-grit sandpaper, and polishing cloth to reduce scratches and improve the quality of the microscopic imaging.

[0050] The two ends of the carbon fiber reinforced composite (CFRP) specimen are clamped by the clamps of the mechanical testing machine 7, so that the axial direction of the CFRP specimen is parallel to the tensile direction.

[0051] Step S2: Use the monitoring device to monitor the observation point in real time.

[0052] Step S3: Receive image data output by the monitoring device via a host computer for storage and / or display.

[0053] As one monitoring scheme of this application, step S2 includes: Step S21: Adjust the displacement platform group 22 so that the objective lens 11 of the imaging unit 1 is initially aligned with the fiber embedding area of ​​the intermediate layer of the carbon fiber reinforced polymer (CFRP) sample. Preferably, in this embodiment, two displacement platforms are used, including a first displacement platform 221 and a second displacement platform 222. The first displacement platform 221 moves along the axial direction of the imaging unit 1, and the second displacement platform 222 moves perpendicular to the axial direction, bringing the objective lens 11 closer to the observation point of the sample. After the imaging unit 1 adjusts the image to be clear, the autofocus camera 14 centers the observation point in the field of view.

[0054] The first displacement platform 221 is manually adjusted to move along the axial direction of the imaging unit 1, and the second displacement platform 222 is manually adjusted to move perpendicular to the axial direction. The displacement plate 24 is adjusted by the motor 4 to slide along the guide rail 20, so that the objective lens 11 of the imaging unit 1 is initially close to the observation point, and the vertical distance between the objective lens 11 and the surface of the carbon fiber reinforced composite (CFRP) sample is maintained at 2 mm.

[0055] Step S22: Adjust the parameters of the continuous zoom lens 13 so that the autofocus camera 14 focuses on the observation point. Fine-tune the parameters along the axial direction of the imaging unit 1 using the first displacement platform 221, and fine-tune them along the axial direction perpendicular to the imaging unit 1 using the second displacement platform 222. Set the continuous zoom lens 13 to 20x magnification mode. Position the optical fiber in the real-time image of the autofocus camera 14 so that the observation point is located at the center of the field of view of the autofocus camera 14.

[0056] Adjust the intensity of light source 12 to 800 lux to make the image in the autofocus camera 14 clear. Set the continuous zoom lens 13 to 100x magnification mode, covering the field of view of eight laminates, making the fiber coating layer and resin-rich area clearly visible. Set the parameters of the autofocus camera 14, including: exposure time 1 / 500 s, contrast enhancement mode, video recording specification 1080p@60fps, and enable autofocus to cope with defocusing during the stretching process.

[0057] Step S23: Set the test parameters of the mechanical testing machine 7, such as the initial value of the clamp movement speed; select the test type, set the space function according to the test type, and determine the speed formula used for calculation.

[0058] Based on the test parameters of the mechanical testing machine 7, the accuracy range of the displacement of the imaging unit in the motion controller 3 is set, including but not limited to a maximum displacement distance of 100 mm, a displacement speed range of 0-5 mm / min, and a rotation angle range of (0, π).

[0059] After monitoring begins, the mechanical testing machine 7 sends a trigger signal. Upon receiving the trigger signal, the motion controller 3 establishes a connection with the mechanical testing machine 7. The motion controller 3 receives the fixture movement speed and first distance from the mechanical testing machine 7 in real time through the conversion interface 8, and calculates the real-time displacement velocity of the imaging unit 1 based on the fixture movement speed and spatial function.

[0060] In another embodiment, before monitoring begins, the operator reads the clamp movement speed and first distance from the mechanical testing machine 7, calculates the real-time displacement speed of the imaging unit 1 using the speed formula, and then sets the real-time displacement speed to the motion controller 3. After monitoring begins, the motion controller 3 receives the trigger signal from the mechanical testing machine 7 and adjusts the imaging unit 1 to slide at a constant speed along the expected displacement direction at the real-time displacement speed.

[0061] In this embodiment, according to the ASTM D3039 standard, the test type is a uniaxial tensile test, and the fixture movement speed is v. test With a speed of 2 mm / min and L0 of 200 mm, the formula for the spatial function corresponding to the uniaxial tensile test is selected as follows: ; Where x is the initial distance between the observation point and the fulcrum, and the fulcrum is the contact point between the specimen and the fixed end of the fixture; L0 is the original length of the carbon fiber reinforced polymer (CFRP) specimen. The real-time displacement velocity v to be set for motion controller 3 varies depending on the test type. The real-time displacement velocity v is calculated based on the fixture movement speed and the spatial function corresponding to the first distance. The velocity formula used for calculation is as follows: ; Where k is a preset dimensionless correction coefficient, which is set to 1 in this embodiment; v test denoted as , where is the clamping speed; x is the first distance; and L is the length of the sample. In this embodiment, x is measured as 100 mm, and v is calculated to be 1 mm / min.

[0062] In step S24, the motion controller 3 adjusts the current of the motor 4 according to the real-time displacement speed, changes the torque of the motor 4, and adjusts the sliding distance of the displacement plate 24 through the motor 4, so that the imaging unit 1 slides synchronously with the displacement of the observation point and tracks the offset of the observation point in real time.

[0063] The motion controller 3 acquires real-time displacement velocity and adjusts the current of the motor 4 to change its torque, thereby altering the motor 4's rotational speed and adjusting the displacement velocity of the imaging unit 1. This ensures that the observation point remains centered in the field of view during the carbon fiber reinforced polymer (CFRP) tensile test. The tensile program of the mechanical testing machine 7 is initiated, and communication signals, including the clamp separation speed, are input to the motion controller 3 via the conversion interface 8. The motion controller 3 then operates synchronously with the start of the mechanical test. The video recording function of the autofocus camera 14 is activated. The imaging unit 1 adjusts its position synchronously with the displacement of the specimen's observation point, capturing in real-time the matrix crack initiation, fiber debonding, and interface damage evolution processes of the CFRP surrounding the optical fiber. The recorded video is stored in real-time to a host computer connected to the autofocus camera 14.

[0064] After the tensile test, the power to the light source 12, the continuous zoom lens 13, and the motion controller 3 was turned off in sequence. The video data was imported into the analysis software to compare the microscopic damage at different times to verify the failure mechanism of the composite material.

[0065] This invention enables in-situ dynamic monitoring of micron-level damage around observation points in carbon fiber reinforced polymer (CFRP) composites during uniaxial tensile testing under ASTM D3039 standards. The monitoring device stably tracks the observation points for 5 minutes, clearly recording interface delamination and crack propagation processes with a displacement tracking error of less than 15 μm. The microscopic observation results are superior to traditional offline observation methods, providing effective technical support for the study of microscopic damage in composite materials.

[0066] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0067] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described herein. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the specific embodiments described above. Therefore, any modifications or equivalent substitutions to the present invention, as well as all technical solutions and improvements that do not depart from the spirit and scope of the invention, are covered within the scope of the claims of the present invention.

Claims

1. A real-time in-situ microscopic monitoring device for microscopic damage in composite materials, characterized in that, include: An imaging unit (1) for real-time monitoring of preset observation points on a sample; A multidimensional adjustment unit (2) is used to connect to the imaging unit (1) and adjust the displacement velocity of the imaging unit (1); the multidimensional adjustment unit (2) includes: A guide rail (20) parallel to the expected displacement direction of the observation point; A platform (21) for supporting the imaging unit (1) is slidably connected to the guide rail (20); the platform (21) is connected to the motion controller (3); the motion controller (3) adjusts the displacement speed of the imaging unit (1) according to the real-time displacement speed of the observation point; the real-time displacement speed is calculated by a preset speed formula based on the real-time received clamp movement speed and the first distance, the first distance being the distance between the initial position of the observation point and the fulcrum, and the fulcrum being the contact point between the sample and the fixed end of the clamp.

2. The apparatus as claimed in claim 1, characterized in that, The placement platform (21) is provided with a displacement platform group (22) that moves along a direction perpendicular to the expected displacement direction; the imaging unit (1) is located above the displacement platform group (22) and moves with the displacement platform group (22) in a plane perpendicular to the guide rail (20).

3. The apparatus as described in claim 1, characterized in that, The placement platform (21) is provided with a support plate (25) perpendicular to the guide rail (20), and the imaging unit (1) is located above the support plate (25).

4. The apparatus as described in claim 3, characterized in that, The placement platform (21) is also provided with a displacement plate (24) that is slidably connected to the guide rail (20). The displacement plate (24) is connected to the side wall of a groove (23). A first reinforcing beam (26) for improving the stability of the imaging unit (1) is connected between the two side walls of the groove (23). The bearing plate (25) is provided on the side wall of the groove (23) away from the guide rail (20).

5. The apparatus as described in claim 4, characterized in that, A second reinforcing beam (27) is also provided between the support plate (25) and the side wall connected thereto to improve the stability of the imaging unit (1).

6. The apparatus as claimed in claim 1, characterized in that, A rotating platform (6) is provided at the bottom of the guide rail (20) so that the imaging unit (1) can rotate in a plane perpendicular to the guide rail (20).

7. A real-time in-situ microscopic monitoring system for microscopic damage in composite materials, characterized in that, include: The real-time in-situ microscopic monitoring device for microscopic damage of composite materials as described in any one of claims 1-6 is used to adjust the displacement speed of the imaging unit (1) synchronously according to the real-time displacement speed obtained by the motion controller (3) after receiving the trigger signal, so as to monitor the preset observation point in real time and obtain image data. The host computer is used to store and / or display the image data.

8. The system as described in claim 7, characterized in that, The monitoring device includes: The imaging unit (1) is used to observe the observation point; A multidimensional adjustment unit (2) is used to adjust the imaging unit (1) to slide synchronously with the offset distance of the observation point, so that the observation point is located at the center of the field of view of the imaging unit (1); The motion controller (3) is used to adjust the displacement speed of the imaging unit (1) according to the real-time displacement speed; the real-time displacement speed is calculated by a preset speed formula based on the real-time acquired clamp movement speed and the first distance, the first distance being the distance between the initial position of the observation point and the fulcrum; the fulcrum being the contact point between the sample and the fixed end of the clamp.

9. A method for real-time in-situ microscopic monitoring of microscopic damage in composite materials, characterized in that, include: Step S1: Prepare a sample according to the composite material testing standard and set observation points on the sample. Step S2: Use the real-time in-situ microscopic monitoring device for microscopic damage of composite materials as described in any one of claims 1-6 to monitor the observation point in real time; Step S3: Receive the image data output by the monitoring device through the host computer, and store and / or display the image data.

Images