CN114518341A - Method for testing fiber orientation of composite material based on light reflection principle - Google Patents

Abstract

The invention discloses a method for testing fiber orientation of composite materials based on the principle of light reflection, which includes operating equipment. The operating device is composed of a workbench, an installation rod, a composite material body, a fixing ring, a fixing plate, a transmitter, a fixing frame, a detector, two fixing rods and two clamping mechanisms. The method for testing the fiber orientation of a composite material based on the principle of light reflection includes the following steps: S1: Fix the composite material body on the operating device through two clamping mechanisms, and keep the surface of the composite material flat. The advantages are: the present invention does not require cutting and sampling from larger samples, avoids damage to composite materials, requires shorter testing time, can effectively ensure success, and uses a fiber orientation algorithm with high precision, so that the testing results can be improved. It is reliable, and since all images are taken under controlled conditions, it is easy to track the reflection intensity at any point through images under different lighting conditions.

Description

A method for testing fiber orientation of composite materials based on the principle of light reflection

technical field

The invention relates to the technical field of fiber orientation testing, in particular to a method for testing fiber orientation of composite materials based on the principle of light reflection.

Background technique

Today, a series of detection and processing techniques have been developed to characterize fiber orientation in composite materials, commonly used methods are: microscopy and X-ray imaging.

Microscopy methods typically rely on cutting out small samples from larger ones, followed by grinding and polishing. This method is often used to reveal cross-sections of material perpendicular to the approximate fiber direction, from which any deviations from the ideal circular fiber shape The ellipses are assumed to be related to the fiber orientation. This geometric analysis method is usually characterized in combination with image analysis methods on a computer. In addition, radiographic methods usually rely on computed tomography (μ-CT) to obtain the necessary resolution. rate to identify individual fiber bundles and generate a 3D representation of the material for subsequent fiber orientation analysis. Under ideal conditions, this method can yield accurate results similar to light microscopy. However, due to the scale limitations of the μ-CT facility, Radiographic samples often still require cutting samples from larger samples, which are time-consuming and do not guarantee success;

In terms of non-destructive methods, the commercially available method on the market is the use of a laser-camera integrated automatic imaging control system, which is capable of scanning the fiber direction from the preformed surface of the composite material through image analysis technology. , but fundamentally, this fiber orientation analysis relies on image filtering techniques and edge detection algorithms that try to identify edge images of fibers or fiber bundles to evaluate fiber orientation, and this analysis method has limited accuracy, Algorithms based on edge detection alone will produce unreliable results.

To sum up, it is urgent to design a method for testing the fiber orientation of composite materials based on the principle of light reflection.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose a method for testing the fiber orientation of composite materials based on the principle of light reflection in order to solve the problems existing in the prior art.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for testing the fiber orientation of composite materials based on the principle of light reflection, including operating equipment, the operating equipment consists of a workbench, a mounting rod, a composite material body, a fixing ring, a fixing plate, a transmitter, a fixing frame, a detector, two The fixing rod and two clamping mechanisms are composed. The method for testing the fiber orientation of composite materials based on the principle of light reflection includes the following steps:

S1: The composite material body is fixed on the operating equipment through two clamping mechanisms, and the surface is kept flat;

S2: Fix the detector on the fixing frame, and make its detection direction perpendicular to the surface of the composite material body;

S3: Fix the transmitter on the fixing plate, and keep its initial light source emission direction perpendicular to the detection direction of the detector;

S4: After completing the initial position adjustment of the composite material body, the detector and the emitter, turn on the detector and the emitter;

S5: Rotate the transmitter relative to the composite material body by 180°, and keep the rotation speed of the transmitter stable during the rotation, so as to complete the first fiber orientation operation;

S6: Check the image captured by the first fiber orientation. By observing the illumination direction that produces the maximum reflection intensity at each point, the direction of the fiber at this point can be inferred, which is recorded as angle a;

S7: After determining the direction of the absolute maximum reflection intensity, restore the transmitter to a 180° rotation relative to the composite material body from the direction in which the absolute maximum reflection intensity was first determined, and the search is approximately opposite to the first maximum value (180° ) in the direction of the second local maximum to complete the second fiber orientation operation;

S8: Check the image captured by the second fiber orientation. By observing the illumination direction that produces the maximum reflection intensity at each point, the direction of the fiber at this point can be inferred, which is recorded as angle b;

S9: According to the angle a obtained by S6 and the angle b obtained by S8, the fiber orientation can be determined to be perpendicular to the average direction of the two angles of the angle a and the angle b.

In the above-mentioned method for testing fiber orientation of composite materials based on the principle of light reflection, the two fixing rods are respectively fixed and installed on the left and right sides of the upper surface of the workbench, and the installation rods are fixedly installed between the two fixing rods , the two clamping mechanisms are respectively installed on the workbench and the installation rod, the composite material body is fixed between the two clamping mechanisms, the fixing ring is fixedly installed between the middle sections of the two fixing rods, the The fixing plate is installed on the fixing ring through a sliding mechanism, the transmitter is fixedly installed on the fixing plate, the fixing frame is fixedly installed on the worktable, and the detector is fixedly installed on the fixing frame.

In the above-mentioned method for testing the fiber orientation of composite materials based on the principle of light reflection, the clamping mechanism is composed of a bidirectional screw rod, two clamping plates, two chutes and four sliders, and the two chutes are Opened on the upper surface of the workbench, the four sliding blocks are slidably connected in two chutes respectively, and the two clamping plates are respectively fixed and installed between the sliding blocks corresponding to the two left and right positions. The lead screw is rotatably connected to the worktable, and one end of the two-way lead screw located in one of the sliding grooves is threadedly connected with the corresponding two sliding blocks.

In the above-mentioned method for testing the fiber orientation of composite materials based on the principle of light reflection, the sliding mechanism is composed of an annular groove and a moving block, the annular groove is opened on the inner wall of the fixed ring, and the moving block is slidably connected to the annular groove. In the groove, the moving block is fixedly connected with the fixing plate.

In the above-mentioned method for testing the fiber orientation of composite materials based on the principle of light reflection, the upper end of the moving block is fixedly installed with a protruding rod, and the upper side wall of the fixing ring is provided with an annular moving groove matched with the protruding rod, The annular moving groove communicates with the annular groove, and a control board is fixedly installed on the upper end of the protruding rod.

In the above-mentioned method for testing the fiber orientation of composite materials based on the principle of light reflection, the control board is fixedly mounted on the pointer, and the upper surface of the fixing ring is provided with an angle scale matched with the pointer.

Compared with the prior art, the advantages of the present invention are:

1: There is no need to cut and sample from a larger sample, which avoids damage to the composite material, and the test takes a short time, and the success can be effectively ensured.

2: By identifying two peak reflectance values at one point (due to opposite lighting conditions), and taking the direction perpendicular to their average value as the fiber direction, this algorithm has high accuracy and reliable results.

3: Since all images are taken under controlled conditions, it is easy to trace the reflection intensity at any point through images under different lighting conditions, and by looking at the direction of illumination that produces the greatest reflection intensity at each point , the orientation of the fibers at this point can be inferred.

To sum up, the present invention does not require cutting and sampling from larger samples, avoids damage to composite materials, requires shorter testing time, can effectively ensure success, and uses a high-precision fiber orientation algorithm, so that The test results are reliable, and since all images were taken under controlled conditions, it is easy to trace the reflection intensity at any point through images under different lighting conditions.

Description of drawings

1 is a schematic diagram of an example of single-point fiber orientation analysis based on reflection intensities in different directions in a method for testing composite fiber orientation based on the principle of light reflection proposed by the present invention;

2 is a general process flow diagram of a method for testing fiber orientation of composite materials based on the principle of light reflection proposed by the present invention;

3 is a schematic structural diagram of an operating device used in a method for testing fiber orientation of composite materials based on the principle of light reflection proposed by the present invention;

Fig. 4 is the top view of Fig. 3;

FIG. 5 is an enlarged schematic view of the structure of part A in FIG. 3 .

In the picture: 1 worktable, 2 fixed rod, 3 installation rod, 4 splint, 5 composite material body, 6 slider, 7 chute, 8 two-way screw, 9 fixed ring, 10 annular groove, 11 moving block, 12 fixed Plate, 13 launcher, 14 fixed frame, 15 detector, 16 annular moving groove, 17 protruding rod, 18 control board.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

1-5, a method for testing the fiber orientation of composite materials based on the principle of light reflection, including operating equipment, the operating equipment consists of a workbench 1, a mounting rod 3, a composite material body 5, a fixing ring 9, a fixing plate 12, and a transmitter 13. The fixing frame 14, the detector 15, the two fixing rods 2 and the two clamping mechanisms are composed. The method for testing the fiber orientation of the composite material based on the light reflection principle includes the following steps:

S1: The composite material body 5 is fixed on the operating device through two clamping mechanisms, and the surface is kept flat;

S2: The detector 15 is fixedly installed on the fixing frame 14, and its detection direction is perpendicular to the surface of the composite material body 5;

S3: Fix the emitter 13 on the fixing plate 12, and keep its initial light source emission direction perpendicular to the detection direction of the detector 15;

S4: After adjusting the initial positions of the composite material body 5, the detector 15 and the transmitter 13, turn on the detector 15 and the transmitter 13;

S5: rotate the transmitter 13 relative to the composite material body 5 by 180°, and keep the rotation speed of the transmitter 13 stable during the rotation, so as to complete the first fiber orientation operation;

S6: Check the image captured by the first fiber orientation. By observing the illumination direction that produces the maximum reflection intensity at each point, the direction of the fiber at this point can be inferred, which is recorded as angle a;

S7: After determining the direction of the absolute maximum reflection intensity, restore the transmitter 13 to rotate 180° relative to the composite material body 5 from the direction in which the absolute maximum reflection intensity was determined for the first time, and the search is approximately opposite to the first maximum value ( 180°) in the direction of the second local maximum to complete the second fiber orientation operation;

S8: Check the image captured by the second fiber orientation. By observing the illumination direction that produces the maximum reflection intensity at each point, the direction of the fiber at this point can be inferred, which is recorded as angle b;

S9: According to the angle a obtained by S6 and the angle b obtained by S8, the fiber orientation can be determined to be perpendicular to the average direction of the two peaks of angle a and angle b.

It is worth noting the above:

1. The arrangement of the emitter 13, the detector 15 and the installation position of the composite material body 5 is to ensure that the composite material surface can be photographed under lighting conditions in different directions (timed intervals from 0° to 360° or within a constant radius). A series of images, in this technique, the detector 15 will directly face the surface of the composite body 5, and the emitter 13 is illuminated from a shallow angle of incidence to the surface of the composite body 5 (helps to eliminate the composite material Body 5 surface reflection and fiber surface reflection).

2. The above method first determines the direction of the absolute maximum reflected intensity, and then searches for the direction of a second local maximum approximately opposite (180°) to the first maximum. According to the example shown in Figure 1, once the two local maxima of the points to be tested are determined, the fiber direction is determined to be perpendicular to the average of these two peaks. In this case, the maximum reflection intensity for a given pixel observes a light direction of 15°, and the second maximum reflection intensity observes 235°. Therefore, the fiber orientation was determined to be 125°, perpendicular to the average direction of these two peaks (35°).

3. When the fiber orientation of the points to be tested has been determined, identified and stored, the pictures taken will use the periodic HSV (Hue Saturation Value) color model to best visualize the results, which will give 0° Any oriented fiber between 180° and 180° has a unique color value.

4. The detector 15 can use a camera, and the transmitter 13 can use one of light waves or electromagnetic waves.

5. Any configuration of emitter 13 (light source) and detector 15 (camera) designed to isolate reflections obtained from cylindrical fibers from standard surface reflections for fiber localization and quality assurance analysis.

6. The above method can be implemented in a range of different physical configurations where the position, movement and properties of the detector 15 (camera), emitter 13 (light/electromagnetic wave) and composite body 5 may all be different, however, In all cases, the basic principle of interpreting the fiber orientation in terms of the variation in the reflection intensity in the different emitter 13 directions is the same.

3-5, two fixing rods 2 are fixedly installed on the left and right sides of the upper surface of the workbench 1, respectively, the installation rod 3 is fixedly installed between the two fixing rods 2, and the two clamping mechanisms are respectively installed on the workbench 1 And on the installation rod 3, the composite material body 5 is fixed between the two clamping mechanisms, the fixing ring 9 is fixedly installed between the middle sections of the two fixing rods 2, the fixing plate 12 is installed on the fixing ring 9 through the sliding mechanism, and the transmitter 13 is fixedly installed on the fixing plate 12 , the fixing frame 14 is fixedly installed on the workbench 1 , and the detector 15 is fixedly installed on the fixing frame 14 .

It is worth noting the above:

1. The clamping mechanism is composed of a bidirectional screw 8, two clamping plates 4, two sliding grooves 7 and four sliding blocks 6. The two sliding grooves 7 are all set on the upper surface of the worktable 1, and the four sliding blocks 6 are Two-by-two sliding connections are made in the two chute 7, the two clamping plates 4 are respectively fixedly installed between the two sliders 6 corresponding to the left and right positions, the two-way screw 8 is rotatably connected to the worktable 1, and the two-way screw 8 One end located in one of the sliding grooves 7 is connected with the corresponding two sliders 6 by screw threads, and the two-way screw 8 is rotated to allow the two clamping plates 4 to approach each other, thereby completing the fixation of the composite material body 5 .

2. The sliding mechanism consists of an annular groove 10 and a moving block 11. The annular groove 10 is opened on the inner wall of the fixed ring 9, the moving block 11 is slidably connected in the annular groove 10, and the moving block 11 is fixedly connected with the fixed plate 12.

3. The upper end of the moving block 11 is fixedly installed with a protruding rod 17, and the upper side wall of the fixed ring 9 is provided with an annular moving groove 16 that cooperates with the protruding rod 17, and the annular moving groove 16 communicates with the annular groove 10. The upper end of the protruding rod 17 The control board 18 is fixedly installed, and by moving the control board 18, the angle of the transmitter 13 relative to the composite material body 5 can be changed, and the operation method is simple.

4. The control board 18 is fixedly mounted on the pointer. The upper surface of the fixing ring 9 is provided with an angle scale matched with the pointer. The cooperation of the pointer and the angle scale can improve the accuracy of the angle adjustment of the transmitter 13 .

Claims (6)

1. A method for testing the fiber orientation of a composite material based on a light reflection principle is characterized by comprising an operating device, wherein the operating device consists of a workbench (1), a mounting rod (3), a composite material body (5), a fixing ring (9), a fixing plate (12), an emitter (13), a fixing frame (14), a detector (15), two fixing rods (2) and two clamping mechanisms, and the method for testing the fiber orientation of the composite material based on the light reflection principle comprises the following steps:

s1: fixing the composite material body (5) on an operating device through two clamping mechanisms, and keeping the surface of the composite material body smooth;

s2: fixedly mounting a detector (15) on the fixed frame (14), and enabling the detection direction of the detector to be vertical to the surface of the composite material body (5);

s3: fixing the emitter (13) on the fixing plate (12) and keeping the initial light source emission direction vertical to the detection direction of the detector (15);

s4: after the initial position adjustment of the composite material body (5), the detector (15) and the emitter (13) is completed, the detector (15) and the emitter (13) are opened;

s5: rotating the emitter (13) relative to the composite material body (5) by 180 degrees, and keeping the rotating speed of the emitter (13) stable in the rotating process so as to finish the first fiber orientation operation;

s6: looking at the image taken at the first fiber orientation, by observing the illumination direction that produces the maximum reflection intensity at each point, the direction of the fiber at that point can be inferred and recorded as angle a;

s7: after the direction of the absolute maximum reflection intensity is determined, the emitter (13) is turned 180 degrees relative to the composite material body (5) from the direction of the absolute maximum reflection intensity determined for the first time, and the direction of a second local maximum which is approximately opposite (180 degrees) to the first maximum is searched, so that the fiber orientation operation for the second time is completed;

s8: looking at the image taken at the second fiber orientation, by observing the illumination direction that produces the maximum reflection intensity at each point, the direction of the fiber at this point can be inferred and recorded as angle b;

s9: from the angle a obtained at S6 and the angle b obtained at S8, the fiber orientation can be determined to be perpendicular to the average of the two angles, angle a and angle b.

2. The method for testing the fiber orientation of the composite material based on the light reflection principle according to claim 1, it is characterized in that the two fixed rods (2) are respectively and fixedly arranged at the left side and the right side of the upper surface of the workbench (1), the mounting rod (3) is fixedly arranged between the two fixing rods (2), the two clamping mechanisms are respectively arranged on the workbench (1) and the mounting rod (3), the composite material body (5) is fixed between the two clamping mechanisms, the fixing ring (9) is fixedly arranged between the middle sections of the two fixing rods (2), the fixing plate (12) is arranged on the fixing ring (9) through a sliding mechanism, the emitter (13) is fixedly arranged on the fixing plate (12), the fixing frame (14) is fixedly arranged on the workbench (1), and the detector (15) is fixedly arranged on the fixing frame (14).

3. The method for testing the fiber orientation of the composite material based on the light reflection principle according to claim 2, wherein the clamping mechanism is composed of a bidirectional screw rod (8), two clamping plates (4), two sliding grooves (7) and four sliding blocks (6), the two sliding grooves (7) are formed in the upper surface of the workbench (1), the four sliding blocks (6) are respectively connected into the two sliding grooves (7) in a two-to-two sliding mode, the two clamping plates (4) are respectively fixedly installed between the two sliding blocks (6) corresponding to the left position and the right position, the bidirectional screw rod (8) is rotatably connected onto the workbench (1), and one end of the bidirectional screw rod (8) located in one sliding groove (7) is in threaded connection with the two corresponding sliding blocks (6).

4. The method for testing the fiber orientation of the composite material based on the light reflection principle as claimed in claim 2, wherein the sliding mechanism is composed of an annular groove (10) and a moving block (11), the annular groove (10) is formed on the inner wall of the fixed ring (9), the moving block (11) is slidably connected in the annular groove (10), and the moving block (11) is fixedly connected with the fixed plate (12).

5. The method for testing the fiber orientation of the composite material based on the light reflection principle as claimed in claim 4, wherein a protruding rod (17) is fixedly installed at the upper end of the moving block (11), an annular moving groove (16) matched with the protruding rod (17) is formed in the upper side wall of the fixing ring (9), the annular moving groove (16) is communicated with the annular groove (10), and a control board (18) is fixedly installed at the upper end of the protruding rod (17).

6. The method for testing the fiber orientation of the composite material based on the light reflection principle is characterized in that the control plate (18) is fixedly installed on a pointer, and the upper surface of the fixing ring (9) is provided with an angle scale matched with the pointer.

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