Friction coefficient testing device and method for dynamically bending fiber bundle under multi-normal load

Abstract

The invention provides a friction coefficient testing device and method for dynamically bending a fiber bundle under multi-normal load, and is applied to the technical field of friction test.The testing device comprises a rack, a traction system, a testing unit, a planar motion system and a loading system.The planar motion system comprises a vertical plate, a guide roller I and a guide roller II; the guiding roller I is installed in the low-position testing area, the guiding roller II is movably installed in the high-position testing area, the testing unit comprises a force measuring device and a balance weight, one end of the fiber bundle is connected with the traction system through the force measuring device, the other end of the fiber bundle bypasses the guiding roller I and the guiding roller II to be connected with the balance weight, and the loading system comprises a force applying component and a pressure sensor. The force application part is used for applying normal load to a sample fiber bundle on the guide roller, the pressure sensor is used for monitoring normal load force in real time, and by exploring a relation model between the bending angle and the combination thereof and the friction coefficient under the condition of multiple normal loads, the test result is more accurate, and the application range is wider.

Description

Technical Field

[0001] This application relates to the field of friction coefficient testing technology, specifically to a friction coefficient testing device and method for dynamically bending fiber bundles under multi-normal loads. Background Technology

[0002] In the preparation of high-performance fiber composites, continuous long filament high-performance fiber bundles are typically used to weave fiber preforms to ensure the strength and performance of the fiber reinforcement phase. While possessing advantages such as high modulus and high strength, high-performance fiber bundles also exhibit brittle properties; examples include ceramic fibers, silicon nitride fibers, and a few high-strength glass fibers. During automated weaving of fiber preforms, high-performance fiber bundles are highly susceptible to weaving defects such as fiber breakage and even yarn breakage under the combined effects of multiple coupled mechanical factors, including bending, friction, and tension. These weaving defects not only lead to severe fuzzing and reduced molding quality of the preform, impairing the mechanical properties of the high-performance fiber composite, but also cause the weaving machine to stagnate, affecting preparation efficiency. Therefore, how to suppress weaving defects in fiber bundles and improve the molding quality of preforms in automated weaving has become a bottleneck problem in the preparation of high-performance fiber-reinforced composites.

[0003] The study of the friction coefficient of fiber bundles during their transport on guide rollers is a key step in identifying and controlling the aforementioned weaving defects. Based on existing literature and patent searches, there are very few devices and methods for simulating the line contact friction between fiber bundles and guide rollers during the weaving process. Furthermore, there is a lack of research on the influence of multiple normal loads on the fiber bundle friction coefficient during the bending changes of the fiber bundle when multiple guide rollers move. These multiple normal loads refer to various normal loads of different magnitudes applied to the fiber bundle under test. The multi-mode testing device and method for fiber bundle friction coefficient proposed by Zhejiang Sci-Tech University (publication number CN 109490190A) establishes a friction simulation test bench to simulate the multi-mode friction of the fiber bundle during weaving, achieving friction performance testing of the fiber bundle under point contact. However, since the fiber bundle rubs against multiple mechanical components during actual weaving, not just a single guide roller, the test bench cannot comprehensively reflect the overall friction behavior of the fiber bundle during the actual weaving process, thus having certain limitations. The fiber friction coefficient testing device proposed by Jiangsu Hengshen Co., Ltd. (publication number CN 212321409 U) can simulate the friction performance test of fiber fabric under curved surface contact and analyze the friction performance between fiber bundle surfaces under various conditions. However, it cannot simulate the dynamic bending of fiber bundles during the weaving process of fiber preforms, which has certain limitations.

[0004] The multi-envelope angle fiber bundle tension and friction coefficient testing device and method proposed by Dalian University of Technology (publication number CN 114993808 A) takes the analysis of the envelope angle between the fiber bundle and the guide roller in the automated weaving process of fiber preform as the starting point. It can perform multi-dimensional model analysis of the changes in the fiber bundle friction coefficient during the preparation process. Although this device and method can study the influence of the envelope angle on the fiber bundle friction coefficient, the size of the envelope angle cannot fully reflect the actual contact condition between the fiber bundle and the guide roller. As mentioned above, the actual contact condition between the fiber bundle and the guide roller is also affected by the normal load applied to the fiber bundle itself. However, the above device and method lacks consideration of the normal load factor. This leads to a certain deviation between the relationship model between the envelope angle and the fiber bundle friction coefficient obtained by the above device and method and the actual working conditions.

[0005] In summary, no device or method has yet been proposed for friction simulation testing of the dynamic bending of fiber bundles under pressure and the friction between multi-guide rollers during the automated weaving process of fiber preforms, which seriously restricts the development of high-performance fiber-reinforced composite material preparation technology. Summary of the Invention

[0006] To address the shortcomings of the existing technology, this invention provides a device and method for testing the friction coefficient of dynamically bent fiber bundles under multi-normal loads.

[0007] The technical concept of this invention is as follows:

[0008] In the automated weaving process of fiber preforms, the contact friction mechanics model of fiber bundles differs from the classical friction mechanics model, and the coefficient of friction of the fiber bundles varies depending on the actual working conditions. When friction occurs between the fiber bundle and the guide roller, the factors that significantly affect the coefficient of friction include the degree of bending, the tension of the fiber bundle, the normal load on the fiber bundle, and the traction speed.

[0009] From a macroscopic perspective, the fiber bundle, under the traction of the traction system, has line contact with the guide roller. When the position of the guide roller changes, the degree of bending of the fiber bundle changes, leading to a change in the line contact length between the fiber bundle and the guide roller. The length of the line contact is related to the magnitude of the frictional force, and can be characterized by the radian corresponding to the bending angle between the fiber bundle and the guide roller. From a microscopic perspective, the magnitude of the normal load and tension on the fiber bundle affects the stretching state of the individual filaments within the fiber bundle, thus affecting the actual contact area between the fiber bundle and the guide roller. Furthermore, the magnitude of the frictional force generated when the moving fiber bundle contacts the guide roller is closely related to the relative moving speed of the fiber bundle; that is, when the moving speed of the fiber bundle relative to the guide roller changes, the friction condition also changes accordingly. Therefore, investigating the influence of the degree of bending of the fiber bundle on the coefficient of friction under multi-normal load is particularly important. This invention takes two guide rollers as the research object and proposes a device and method for testing the coefficient of friction of dynamically bent fiber bundles under multi-normal load.

[0010] The relationship between the degree of bending of the fiber bundle and the two guide rollers, the normal load on the fiber bundle, and the coefficient of friction can be expressed by the following formula. The influence of the normal load on the fiber bundle and the different positions of guide rollers I and II on the coefficient of friction is as follows:

[0011] like Figure 9 As shown, let the centers of the two guide rollers be A(x) and A(x). A ,y A B(x) B ,y B ), with radii r A r B The point of application of the traction force is G(x) G ,y G The point of application of the normal load is H, the point of connection between the fiber bundle and guide roller I is C, the point of connection is D, the point of connection with guide roller II is E, the point of connection is F, points A1 and A2 are the horizontally movable positions of the center point A of guide roller I, and points A3 and A4 are the vertically movable positions of the center point A of guide roller I.

[0012] Let the equation of the tangent segment DE be y = kx + b, then we can obtain:

[0013]

[0014] The factors are represented as follows:

[0015]

[0016] The bending angle between the fiber bundle and guide roller I is θ1, and the bending angle between the fiber bundle and guide roller II is θ2. θ1 consists of two parts: the angle θ0 between the outlet point D and the horizontal direction, and the angle Δθ between the inlet point C and the horizontal direction, where θ0 and θ2 are equal.

[0017] θ1=θ0-Δθ (3)

[0018] Based on the relationship between the bending angle θ2 of the fiber bundle and guide roller II and the slope k, we can obtain:

[0019]

[0020] As shown in formula (4), the relative positions of points A and B affect the magnitudes of θ0 and θ2. Therefore, the magnitudes of θ0 and θ2 can be precisely controlled by adjusting the relative positions of points A and B. As for the mathematical expression for Δθ, we can assume the angle between GA and the horizontal direction is α, and obtain the slope of the straight line segment GA:

[0021]

[0022] Let β be the angle between segments GA and AC, then we have:

[0023]

[0024] Therefore, the bending angles θ1 and θ2 between the fiber bundle and guide rollers I and II are:

[0025]

[0026] For θ1, there exists a critical state such that θ1 = θ2, which requires the condition Δθ = 0, i.e., α = β, or:

[0027]

[0028] As can be seen from formula (8), the relative positions of point A with points G and B affect the size of the bending angle θ1. Therefore, the bending angle θ1 of guide roller I can be precisely controlled by controlling the position of point A relative to points G and B.

[0029] Let the tension of the fiber bundle in segment GC (between the point of application of traction force G and the point of entry of guide roller I C) be T1, the tension of the fiber bundle in segment DE (between the point of exit of guide roller I D and the point of entry of guide roller II E) be T2, and the tension from point F (the point of exit of guide roller II) to the weight section be T3. Let the coefficients of friction between the fiber bundle and the two guide rollers be μ1 and μ2, respectively. Then, the following Euler equation can be preliminarily established:

[0030]

[0031] Since the fiber bundle in the extended section EH of segment DE is subjected to a normal load, the fiber bundle tension in segment DE is related not only to the coefficient of friction between the fiber bundle and guide roller I, but also to the normal load on the fiber bundle in the extended section EH. Therefore, by introducing a coefficient h, and assuming the normal load on the fiber bundle at point H is T4, we obtain the following formula:

[0032]

[0033] Substituting equation (11) into equation (10), we get:

[0034]

[0035] Eliminating T2, we get:

[0036]

[0037] Simplified to:

[0038]

[0039] Substituting the expressions for bending angles θ1 and θ2 with respect to the positions of points G, A, and B into the Euler equation describing fiber bundle tension and its coefficient of friction, i.e., formula (8), into formula (14), we obtain the following formula:

[0040]

[0041] From formula (15), the expression for the friction coefficient μ(μ1,μ2,h) of the entire system can be obtained by directly substituting the spatial positions of points G, A, and B, the magnitude of the tension at both ends of the fiber bundle, and the magnitude of the normal load on the fiber bundle on guide roller II (measured by a force measuring device).

[0042] To achieve the above objectives, the technical solution proposed by the present invention based on the above technical concept is as follows:

[0043] This specification first provides an embodiment of a friction coefficient testing device for dynamically bending fiber bundles under multi-normal loads, including a frame, a traction system, a testing unit, a planar motion system, and a loading system. The planar motion system includes a vertical plate, guide roller I, and guide roller II. The vertical plate is mounted on the frame and defines a low-level testing area and a high-level testing area arranged vertically offset from each other. Guide roller I is movably mounted in the low-level testing area, and guide roller II is movably mounted in the high-level testing area. The testing unit includes a force measuring device and a counterweight. One end of the fiber bundle is connected to the traction system via the force measuring device, and the other end passes around the lower side of guide roller I and the upper side of guide roller II and is connected to the counterweight. The loading system includes a force-applying component and a pressure sensor. The force-applying component applies a normal load to the sample fiber bundle on guide roller I and / or guide roller II, and the pressure sensor monitors the normal load force in real time.

[0044] To optimize the above solution, the following technical measures were also adopted:

[0045] Preferably, the traction system includes a slide module, an adjustment plate, and a servo motor. The slide module is vertically mounted on the frame, the adjustment plate is disposed on the slider of the slide module, the servo motor provides power to the slide module to drive the slider to move up and down, and the adjustment plate is connected to a force measuring device.

[0046] Preferably, the planar motion system includes a first slide rail module disposed in the low-position test area, the guide roller I is connected to the first slide rail module through a first pulley, the first slide rail module has a plurality of first snap-fit ​​holes spaced apart, and the first pulley is provided with a first elastic buckle that cooperates with the first snap-fit ​​holes.

[0047] Preferably, the first elastic buckle is configured to disengage from the corresponding first snap-fit ​​hole by elastic deformation in response to the movement of the guide roller I.

[0048] Preferably, the first snap-fit ​​hole is a tapered hole, and the first elastic buckle has a tapered snap-fit ​​portion that mates with the first snap-fit ​​hole.

[0049] Preferably, the planar motion system includes a second slide rail module disposed in the high-level test area, the guide roller II is connected to the second slide rail module through a second pulley, the second slide rail module has a plurality of second snap-fit ​​holes spaced apart, and the second pulley is provided with a second elastic buckle that cooperates with the second snap-fit ​​holes.

[0050] Preferably, the second slide rail module includes a plurality of horizontal and vertical tracks arranged in a vertically staggered manner. The horizontal and vertical tracks are groove-type tracks with the same structure, and the second pulley is operably mounted on the second slide rail module.

[0051] Preferably, the plurality of second snap-fit ​​holes are distributed along the longitudinal track of the second slide rail module, and the frame is provided with a plurality of screw holes corresponding to the plurality of longitudinal tracks. The force-applying component includes a screw rod screwed into the screw hole, and the lower end of the screw rod is adapted to press against the pressure sensor.

[0052] Preferably, the loading system further includes a load block, the upper part of the guide roller II is provided with a vertical guide groove, the lower part of the load block is provided with a guide block adapted to the vertical guide groove, a vertical suction spring is provided between the guide block and the vertical guide groove, the pressure sensor is installed on the upper part of the load block, the force application component is vertically mounted on the frame, and the lower end of the force application component is adapted to press against the pressure sensor.

[0053] This specification also provides an embodiment of a method for testing the friction coefficient of dynamically bent fiber bundles under multi-normal loads, based on the friction coefficient testing device as described in any one of claims 1 to 9, comprising the following steps:

[0054] (1) Build a test device on the frame, construct a coordinate system based on the plane where guide roller I and guide roller II are located, and determine the origin of the coordinate system;

[0055] (2) Preset the bending angle of the fiber bundle of the sample to be tested on guide roller I and guide roller II and the coordinates of the traction end of the fiber bundle of the sample to be tested, and calculate the coordinates of the center point of guide roller I and guide roller II accordingly. Then install the traction end, guide roller I and guide roller II in their respective positions according to the corresponding coordinates.

[0056] (3) Install the fiber bundle of the sample to be tested. After installation, the fiber bundle of the sample to be tested is pulled by the traction system. Then, the normal load is applied to the fiber bundle of the sample to be tested by the loading system, and the values ​​of the force measuring device and the pressure sensor are recorded.

[0057] (4) Substitute the counterweight, bending angle and the above recorded values ​​into the Euler equation describing the fiber bundle tension and its friction coefficient to calculate the friction coefficient of the sample to be tested.

[0058] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least:

[0059] Firstly, this invention focuses on analyzing the bending angle between the fiber bundle and the guide roller and the pressure state of the fiber bundle in the automated weaving process of fiber preforms. It studies the influence of different bending angle combinations and normal loads on the friction coefficient of fiber bundle weaving. By introducing the conditional factor of applying a normal load to the sample fiber bundle, at least the following technical objectives can be achieved:

[0060] (1) By adjusting the normal load parameters, the contact condition between the sample fiber bundle and the corresponding guide roller is improved, making it closer to the actual working condition, so that the relationship model between the bending angle of the sample fiber bundle and the friction coefficient obtained by the test is more accurate.

[0061] (2) By exploring the relationship model between the tension, bending angle and combination of fiber bundles and the traction speed and friction coefficient under multi-normal load conditions, the test results can be applied to a wider range.

[0062] (3) In addition to the influencing factors such as the tension, bending degree and traction speed of the fiber bundle, the normal load factor applied to the fiber bundle is introduced to further modify the existing multi-condition factor and fiber bundle friction coefficient relationship model to make it more accurate, thereby providing a more feasible solution for realizing the low-damage automated weaving preparation process of fiber preforms.

[0063] Furthermore, in this design, the pressure sensor is located between the force-applying component and the load block. This allows the pressure sensor to monitor the normal load force applied to the fiber bundle by the force-applying component in real time. Simultaneously, a suction spring is installed between the load block on guide roller II and the vertical guide groove. The suction spring absorbs the force transmitted in the reverse direction from guide roller II to the pressure sensor, thus avoiding interference from the reverse force on the monitoring status of the pressure sensor. In other words, this design can transmit the pressure of the force-applying component to the sample fiber bundle in real time and accurately, thereby accurately controlling the change of the normal load on the sample fiber bundle on guide roller II, and highly simulating the real stress state of the fiber bundle during the fiber preform weaving process.

[0064] Furthermore, in the testing method of this scheme, the bending angle change of the sample fiber bundle on guide rollers I and II is simulated by the change of the spatial position of the sample fiber bundle traction end, guide roller I and guide roller II in the device coordinate system. When arranging different bending angle combination tests, the desired bending angle and its combination can be quickly obtained by changing the spatial position of guide roller I and guide roller II, thereby quickly performing friction tests on the sample fiber bundle and improving testing efficiency. Attached Figure Description

[0065] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0066] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of this application;

[0067] Figure 2 This is a schematic diagram of the back structure of Embodiment 1 of this application;

[0068] Figure 3 This is a schematic diagram of the traction system in Embodiment 1 of this application;

[0069] Figure 4 This is a schematic diagram of the test unit in Embodiment 1 of this application;

[0070] Figure 5 This is a schematic diagram of the low-plane motion system in Embodiment 1 of this application;

[0071] Figure 6 yes Figure 5 A cross-sectional view of the connection between the middle guide roller I and the first slide rail module;

[0072] Figure 7 This is a schematic diagram of the high-plane motion system in Embodiment 1 of this application;

[0073] Figure 8 yes Figure 7 A cross-sectional view of the connection between the middle guide roller II and the second slide rail module;

[0074] Figure 9 This is a schematic diagram of the testing method of the present invention.

[0075] In the picture:

[0076] 1. Frame; First column 11; Second column 12;

[0077] 2. Traction system; 21. Servo motor; 22. Slide module; 23. Adjustment plate; 24. Lifting eye bolt;

[0078] 3. Testing unit; 31. Force measuring device; 32. Sample fiber bundle; 33. Weights;

[0079] 4. Low-plane motion system; 41. First vertical plate; 42. First slide rail module; 43. Guide roller I; 44. First pulley; 45. First elastic buckle; 451. Snap-fit ​​part; 452. Pressure spring; 46. First snap-fit ​​hole;

[0080] 5. High-plane motion system; 51. Second vertical plate; 52. Second slide rail module; 53. Guide roller II; 54. Second pulley; 55. Second elastic buckle; 56. Second snap-fit ​​hole; 57. Vertical guide groove;

[0081] 6. Loading system; 61. Mounting plate; 62. Helical rod; 63. Loading block; 631. Guide block; 64. Pressure sensor; 65. Suction spring; Detailed Implementation

[0082] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0083] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0084] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0085] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0086] This specification presents a device and method for testing the friction coefficient of dynamically bent fiber bundles under multi-normal loads. The aim is to address the lack of investigation and testing of the influence of normal loads on the fiber bundle's friction coefficient in existing devices and methods, resulting in discrepancies between the measured envelope angle and the actual working conditions. This new method not only makes the measured relationship between the fiber bundle bending angle and the friction coefficient more accurate but also allows for a wider range of applications by exploring the relationship between tension, bending angle and its combination, and traction speed and the friction coefficient under multi-normal loads. Furthermore, it provides a more feasible solution for achieving low-damage automated weaving fabrication processes for fiber preforms.

[0087] The technical solutions provided by the various embodiments of this application are described below with reference to the accompanying drawings.

[0088] Example 1

[0089] like Figures 1 to 8 As shown in the embodiment of this specification, a friction coefficient testing device for dynamically bending fiber bundles under multi-normal loads is provided. The device includes a frame 1, a traction system 2, a testing unit 3, a planar motion system, and a loading system 6. The frame 1 includes a platform, a first column 11, and a second column 12. The platform is constructed from horizontally arranged columnar aluminum profiles. The first column 11 and the second column 12 are connected to the platform and are spaced apart laterally. The planar motion system includes a vertical plate, guide roller I 43, and guide roller II 53. The vertical plate is mounted on the frame 1 and defines a low-position test area and a high-position test area arranged vertically in a staggered manner. The test area refers to a planar area containing multiple test positions. Preferably, the plane of the planar area is a vertical plane, and the low-position test area and the high-position test area are in the same vertical plane. The test positions are determined according to the testing requirements. The guide rollers can be positioned at any test location as needed. Positioning methods include snap-fit ​​positioning and threaded connection positioning. Snap-fit ​​positioning, for example, involves the guide rollers being snapped into snap-fit ​​holes at the test positions by snap-fit ​​parts on the guide rollers. Guide roller I 43 is movably mounted in the lower test area, and guide roller II 53 is movably mounted in the higher test area. As disclosed herein, "movable" clearly means "movable in a plane," and guide roller I 43 and guide roller II 53 are movable in the same plane. Mobility not in the same plane is not within the scope defined by this embodiment. Test unit 3 includes a force measuring device 31, a sample fiber bundle 32, and a counterweight. The counterweight may be, for example, a weight 33, a ballast water tank, a sandbox, or any object on which weight can be applied and can be suspended from the lower end of the sample fiber bundle 32 to apply end tension to the sample fiber bundle 32.

[0090] When installing the sample fiber bundle 32, one end of the fiber bundle is connected to the traction system 2 via the force measuring device 31, and the other end passes over the lower side of guide roller I 43 and the upper side of guide roller II 53 and is connected to the counterweight. The loading system 6 includes a force-applying component and a pressure sensor 64. The force-applying component is used to apply a normal load to the sample fiber bundle 32 on guide roller I 43 and / or guide roller II 53, and the pressure sensor 64 is used to monitor the normal load force in real time. By setting the loading system 6, a normal load can be applied to the sample fiber bundle 32, thereby introducing the conditional factor of "normal load" into the model of the relationship between the parameters of each device and the friction coefficient of the sample fiber bundle 32. Thus: firstly, by adjusting the normal load parameters, the contact condition between the sample fiber bundle and the corresponding guide roller can be improved, making it closer to the actual working condition, thereby making the model of the relationship between the bending angle of the sample fiber bundle and the friction coefficient obtained by the test more accurate. Secondly, by exploring the relationship model between the tension, bending angle and its combination, and traction speed and friction coefficient of the fiber bundle under multiple normal load conditions, the application range of the test results can be broadened. Furthermore, in addition to factors such as the tension, bending degree, and traction speed of the fiber bundle, a normal load factor applied to the fiber bundle is introduced. This further refines the existing model relating multiple working conditions to the fiber bundle friction coefficient, making it more accurate. This provides a more feasible solution for achieving a low-damage automated weaving process for fiber preforms. It should be noted that this embodiment only illustrates the solution by applying a normal load to the sample fiber bundle on guide roller II using the loading system 6. However, this should not be considered a limitation on the scope of protection of this invention. In fact, applying a normal load to the sample fiber bundle on guide roller I and applying a normal load to the sample fiber bundle on guide roller II are two specific manifestations of the inventive concept, which will not be elaborated upon here.

[0091] like Figure 3 As shown, in this embodiment, the traction system 2 includes a slide module 22, an adjusting plate 23, and a servo motor 21. The slide module 22 is vertically mounted on the frame 1. The adjusting plate 23 is disposed on the slider of the slide module 22. The servo motor 21 provides power to the slide module 22 to drive the slider to move up and down. The adjusting plate 23 is connected to the force measuring device 31. The position of the fiber bundle traction end is adjusted by changing the position of the adjusting plate 23. Specifically, the slide module 22 is mounted on the first column 11. The slide module 22 is a lead screw slide module. The output shaft of the servo motor 21 is connected to the slide module 22 through a lead screw drive. The slider of the slide module 22 moves up and down driven by the lead screw. A lifting eye bolt 24 is connected to the lower part of the adjusting plate 23. One end of the force measuring device 3 is hung on the lifting eye bolt 24, and the other end is connected to the sample fiber bundle 32.

[0092] like Figures 5 to 8As shown, the planar motion system includes a low-plane motion system 4 and a high-plane motion system 5. The structure of the low-plane motion system 4 is as follows: Figures 5 to 6 As shown, the structure of the high-plane motion system 5 is as follows: Figures 7 to 8 As shown. The low-plane motion system 4 includes a first slide rail module 42 disposed within the low-position test area. A guide roller I 43 is connected to the first slide rail module 42 via a first pulley 44. Here, the first pulley 44 can be fixed to the guide roller I 43 and can slide along the first slide rail module 42. Specifically, the upright plate includes a first upright plate 41 disposed within the low-position test area. The first upright plate 41 is disposed on the platform of the frame 1, and the first slide rail module 42 is disposed on the first upright plate 41. A plurality of first locking holes 46 are distributed at intervals on the first slide rail module 42, and the first pulley 44 is provided with a first elastic buckle 45 that cooperates with the first locking holes 46.

[0093] like Figure 5 and Figure 6 As shown, the first slide rail module 42 includes several interleaved transverse and longitudinal tracks. In this embodiment, the first slide rail module 42 includes two relatively parallel transverse tracks (upper and lower) and three relatively spaced and parallel longitudinal tracks. Multiple first snap-fit ​​holes 46 are distributed at corresponding test positions within these tracks. The guide roller I 43 moves along any track in the first slide rail module 42 via the first pulley 44, thereby adjusting the test position as needed. Limiting posts are also provided at both ends of the transverse tracks to prevent the guide roller I 43 from detaching from the track during movement.

[0094] The guide roller I 43 is locked in position by engaging the first elastic buckle 45 on the first pulley 44 with the corresponding first engaging hole 46. When it is necessary to unlock, the guide roller I 43 can be moved on the first slide rail module 42 by disengaging the first elastic buckle 45 from the first engaging hole 46. Here, there are various possible structural forms for the first elastic buckle 45, such as the commonly used press-type spring buckle structure. Specifically, the side of the first pulley 44 is provided with a cylindrical groove extending radially. A cylindrical locking part 451 is slidably connected in the cylindrical groove. A pressure spring 452 is connected between the locking part 451 and the bottom surface of the cylindrical groove. When the first pulley 44 moves along the first slide rail module 4, the pressure spring 452 retracts into the cylindrical groove. When the test position is reached, the pressure spring 452 pushes the locking part 451 out of the groove and engages with the first locking hole 46 at that location, locking the position of the first pulley 44, and thus locking the position of the guide roller I 43. At this time, the first snap-fit ​​hole 46 can be configured to penetrate the first vertical plate 41. Then, by applying a pressing operation to the snap-fit ​​part 451 in the first snap-fit ​​hole 46, the snap-fit ​​part 451 can be disengaged from the first snap-fit ​​hole 46. Then, the position of the guide roller I 43 in the first slide rail module 42 can be adjusted. However, this method is relatively inconvenient to operate.

[0095] Therefore, this embodiment provides another implementation method in which the first elastic buckle 45 is configured to disengage from the corresponding first locking hole 46 through elastic deformation in response to the movement operation of the guide roller I 43. Specifically, the first locking hole 46 is a tapered hole, and the first elastic buckle 45 has a tapered locking portion 451 that cooperates with the first locking hole 46. In this way, when the guide roller I 43 is moved, the tapered slope of the first locking hole 46 can press the locking portion 451 of the first elastic buckle 45 upward, forcing the locking portion 451 to disengage from the corresponding first locking hole 46, thereby making the adjustment operation of the guide roller I 43 more convenient. Here, when the locking portion 451 is engaged with the first locking hole 46, the pressure spring 452 is in a compressed state, and the pressure of the pressure spring 452 needs to be configured to resist the pressure of the fiber bundles on the guide roller I 43 during operation, so that the locking portion 451 is always kept in the first locking hole 46.

[0096] Preferably, the first vertical plate 41 is provided with coordinate scales to calibrate the specific coordinate position of the guide roller I 43 in the low-position test area on the first vertical plate 41.

[0097] like Figure 7 and Figure 8As shown, the high-plane motion system 5 includes a second slide rail module 52 disposed within the high-level test area. A guide roller II 53 is connected to the second slide rail module 52 via a second pulley 54. Specifically, the upright plate also includes a second upright plate 51 disposed within the high-level test area. The second upright plate 51 is mounted on the second column 12. Figure 1 and 2 As shown, the second slide rail module 52 is mounted on the second upright plate 51. Preferably, the second upright plate 51 is provided with coordinate scales to calibrate the specific coordinate position of the guide roller II 53 within the low-level test area on the second upright plate 51. In this way, the spatial position changes of the sample fiber bundle 32 traction end, guide roller I 43, and guide roller II 53 in the device coordinate system can be visualized, allowing the tester to quickly adjust their positions. These positional changes can simulate the bending angle changes of the sample fiber bundle on guide roller I 43 and guide roller II 53. In other words, when arranging different bending angle combinations for testing, the desired bending angle and its combination can be obtained by quickly adjusting the spatial positions of guide roller I 43 and guide roller II 53, thereby rapidly performing friction tests on the sample fiber bundle and improving testing efficiency.

[0098] In this embodiment, a plurality of second locking holes 56 are spaced apart on the second slide rail module 52, and a second elastic buckle 55 is provided on the second pulley 54 to cooperate with the second locking holes 56. Figure 8 As shown, the second elastic buckle 55 and the first elastic buckle 45 can adopt the same specific structural form to facilitate the adjustment of the position of the guide roller II 53 on the second slide rail module 52, which will not be described in detail here.

[0099] like Figure 7 and Figure 8As shown, the second slide rail module 52 includes several horizontal and vertical tracks arranged in a vertically staggered pattern. In this embodiment, the second slide rail module 52 includes three horizontal tracks and three vertical tracks. Both the horizontal and vertical tracks are groove-type tracks, and the groove cross-section of the groove-type track is, for example, a C-shaped cross-section. The second pulley 54 is operably mounted on the second slide rail module 52. Similarly, limiting posts are also provided at both ends of the horizontal tracks. Unlike the low-plane motion system 4, here, multiple second snap-fit ​​holes 46 are distributed along the longitudinal tracks of the second slide rail module 52. A mounting plate 61 is provided at the top of the second upright plate 51, extending horizontally outward from one side of the second upright plate 51. The mounting plate 61 has screw holes corresponding to several longitudinal tracks. In this embodiment, there are three longitudinal tracks, therefore three screw holes are correspondingly provided, and each screw hole is aligned longitudinally with its corresponding longitudinal track. The force-applying component includes a screw rod 62 screwed into the screw hole, the lower end of which is adapted to press against the pressure sensor 64. Thus, as the guide roller II 53 switches positions between different longitudinal tracks, the screw rod 62 can also switch to the corresponding screw hole, ensuring that a normal load force can be applied to the sample fiber bundle on the guide roller II 53 through the screw rod 62.

[0100] Specifically, the loading system also includes a load block 63, a vertical guide groove 57 on the upper part of the guide roller II 53, and a guide block 631 adapted to the vertical guide groove 57 on the lower part of the load block 63. Here, the guide block 631 is elongated and is configured to extend radially upward along the guide roller II 53. A vertical suction spring 65 is provided between the guide block 631 and the vertical guide groove 57. A pressure sensor 64 is installed on the upper part of the load block 63, and the force-applying component, i.e., the screw rod 62, is adapted to press against the pressure sensor 64.

[0101] As shown in the figure, the upper end of the screw rod 62 has a cross-shaped rotating handle. When it is necessary to apply a normal load to the sample fiber bundle on the guide roller II 53, the screw rod 62 is rotated through the cross-shaped rotating handle. The screw rod 62 moves downward in the screw hole, passes through the corresponding longitudinal track on the second slide rail module 52, and presses against the pressure sensor 64. The load block 63 at the lower part of the pressure sensor 64 overcomes the elastic force of the suction spring 65 and presses against the sample fiber bundle 32 on the upper part of the guide roller II 53. Here, the pressure sensor 64 is located between the force-applying component and the load block 63. The pressure sensor 64 can monitor the normal load force applied to the fiber bundle from the force-applying component in real time. At the same time, a suction spring 65 is installed between the load block 63 on the guide roller II 53 and the vertical guide groove 57. The suction spring 65 can absorb the force transmitted to the pressure sensor 64 in the reverse direction from the guide roller II 53, thereby avoiding interference from the reverse force on the monitoring state of the pressure sensor 64. In other words, this solution can transmit the pressure of the force-applying component to the sample fiber bundle in real time and accurately, thereby accurately controlling the change of the normal load on the sample fiber bundle on the guide roller II 53, and highly simulating the real stress state of the fiber bundle during the fiber preform weaving process.

[0102] Preferably, the servo motor 21 is controlled by a PLC system, and the data from the force measuring device 31 and the pressure sensor 64 are fed back to the computer.

[0103] Preferably, the entire apparatus also includes a lifting platform for supporting the weights 33 during the testing of the sample fiber bundle 32.

[0104] Example 2

[0105] This embodiment discloses a method for testing the friction coefficient of dynamically bent fiber bundles under multi-normal loads, based on the friction coefficient testing device in Embodiment 1 above, including the following steps:

[0106] (1) Construct the testing device on the frame 1. Specifically, first place the entire device on the horizontal platform of the workbench (not shown in the figure), then fix it, so that the first vertical plate 41 and the second vertical plate 51 are suspended above the edge of the platform. Construct a coordinate system based on the plane where the guide roller I 43 and guide roller II 53 are located, and determine the origin of the coordinate system, such as... Figure 1 and Figure 5 As shown, the upper left corner of the first upright plate 41 is defined as the origin (0,0).

[0107] (2) Preset the bending angle of the fiber bundle 32 of the sample to be tested on guide roller I 43 and guide roller II 53, as well as the coordinates of the traction end of the fiber bundle 32 of the sample to be tested. Based on this, calculate the coordinates of the center points of guide roller I 43 and guide roller II 53, and then install the traction end, guide roller I 43, and guide roller II 53 into position according to their corresponding coordinates. Specifically, as follows... Figure 8 As shown, the bending angle θ1 of the fiber bundle 32 of the sample to be tested on guide roller I 43 and the bending angle θ2 on guide roller II 53 are pre-set to determine the radius r of guide roller I. A The radius r of guide roller II B Due to the eye bolt's eye vertex G(x) G ,y G The slide module 22 will move vertically, and its upper and lower limit positions are defined as points G0 and G1, respectively. The default initial point G is the midpoint of the travel path G0G1, and the coordinates of point G are denoted as (x, y, y). G ,y G The center point A(x) of guide roller I is calculated using the following formula. A ,y A ) and the center point B(x) of guide roller II B ,y B The exact location of )

[0108]

[0109] Then, start the servo motor 21, adjust the vertical height of the adjustment base plate 23 so that the lifting eye apex G of the lifting eye bolt 24 is the position obtained in step (2), use the first slide rail module 42 to adjust the horizontal and vertical installation positions of the guide roller I 43 on the first vertical plate 41 to the positions obtained in step (2), and then turn off the servo motor 21.

[0110] Furthermore, the installation position of guide roller II 53 on the second vertical plate 51 is adjusted using the second slide rail module 52 to the position obtained in step (2) and locked. The positions of the lifting eye apex G of the lifting eye bolt 24, the center point A of guide roller I 43, and the center point B of guide roller II 53 are recorded.

[0111] (3) Install the fiber bundle 32 of the sample to be tested. After installation, the fiber bundle 32 of the sample to be tested is pulled by the traction system 2. Then, the normal load is applied to the fiber bundle 32 of the sample to be tested by the loading system 6, and the values ​​of the force measuring device 31 and the pressure sensor 64 are recorded.

[0112] Specifically, a new test sample fiber bundle 32 is taken, one end is fixed on the force measuring device 31, and the other end is passed around the lower side of guide roller I 43 and the upper side of guide roller II 53 before being connected to the weight 33. At the same time, the bottom of the weight 33 is supported by the lifting platform to counteract its gravity and make the sample fiber bundle in a relaxed state.

[0113] Then, the lifting platform is lowered, so that the sample fiber bundle 32 is taut under the gravity of the weight 33. Then, the servo motor 21 is started again, and the slider of the slide module 22 is moved upward, pulling the sample fiber bundle 32 to be tested to move on the guide roller. During this process, the screw rod 62 on the operating mounting plate 61 is moved downward, acting on the pressure sensor 64, thereby causing the load block 63 to press against the sample fiber bundle, so that the sample fiber bundle 32 is under pressure. The values ​​of the force measuring device 31 and the pressure sensor 64 are recorded during the process. Then, the servo motor 21 is turned off, and the sample fiber bundle is removed, numbered and stored.

[0114] (4) Substitute the counterweight weight, bending angles θ1 and θ2, and the recorded values ​​into the Euler equation describing the fiber bundle tension and its coefficient of friction to calculate the coefficient of friction of the sample to be tested. Obviously, the changes in bending angles θ1 and θ2 can be defined by the coordinate values ​​of the center point A of guide roller I 43, the center point B of guide roller II 53, and the coordinate values ​​of the lifting eye vertex G of lifting eye bolt 24. The counterweight weight is the tension T3 from the guide roller II contact point to the counterweight in formula (15).

[0115] Depending on the testing requirements, the following steps may also be added:

[0116] (5) Change only the mass of the weight 33, that is, change the tension on the sample fiber bundle 32, and then jump to step (3). Repeat steps (3) to (4) until all the required tension values ​​are tested.

[0117] (6) Change only the speed of the servo motor 21, that is, change the magnitude of the traction speed, and then jump to step (3). Repeat steps (3) to (4) until all the required traction speed values ​​are tested.

[0118] (7) Change only the distance that the cross screw 62 moves down, that is, change the normal load on the sample fiber bundle 32, and then jump to (3) and repeat steps (3) to (4) until all the required normal load values ​​are completed.

[0119] (8) Change only the combination of bending angles θ1 and θ2, that is, change the relative positions of the lifting eye apex G of the lifting eye bolt, the center point A of guide roller I and the center point B of guide roller II, and repeat steps (2) to (4) until all required bending angle combinations are tested.

[0120] In summary, the testing method provided in this embodiment takes the analysis of the bending angle between the fiber bundle and the guide roller and the pressure state of the fiber bundle in the automated weaving process of fiber preforms as the starting point. It studies the influence of different bending angle combinations and normal loads on the friction coefficient of fiber bundle weaving, providing a feasible method for better realizing the low-damage automated weaving process of fiber preforms. The method explores the dynamic bending angle of the fiber bundle under different normal loads, different traction speeds and different tensions in the actual manufacturing process, making the evaluation of the friction performance of the fiber bundle more comprehensive and in-depth. This allows for the acquisition of the corresponding friction coefficient variation law of the fiber bundle, providing richer and more accurate evidence for the research and development and improvement of high-performance fiber materials.

[0121] Furthermore, by introducing the conditional factor of applying a normal load to the sample fiber bundle, the contact condition between the sample fiber bundle and the corresponding guide roller is improved, making it closer to the actual working conditions. This allows for a more accurate model of the relationship between the bending angle and the coefficient of friction of the sample fiber bundle obtained from the test. Moreover, by exploring the relationship model between the tension, bending angle and its combination, and traction speed and the coefficient of friction of the fiber bundle under multiple normal load conditions, the application range of the test results is broadened. In addition, the existing relationship model between multiple working conditions and the coefficient of friction of the fiber bundle can be further modified to make it more accurate. This provides a more feasible solution for realizing a low-damage automated weaving process for fiber preforms.

[0122] In this specification, the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the descriptions of the embodiments described later are relatively simple, and relevant parts can be referred to the descriptions of the foregoing embodiments.

[0123] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A device for testing the friction coefficient of dynamically bent fiber bundles under multi-normal loads, characterized in that, It includes a frame, traction system, test unit, planar motion system, and loading system; among which, The planar motion system includes a vertical plate, guide roller I and guide roller II. The vertical plate is mounted on the frame and defines a low-position test area and a high-position test area that are staggered in the vertical direction. Guide roller I is movably mounted in the low-position test area and guide roller II is movably mounted in the high-position test area. The testing unit includes a force measuring device and a counterweight. One end of the fiber bundle is connected to the traction system through the force measuring device, and the other end passes around the lower side of guide roller I and the upper side of guide roller II and is connected to the counterweight. The loading system includes a force-applying component and a pressure sensor. The force-applying component is used to apply a normal load to the sample fiber bundle on guide roller I and / or guide roller II, and the pressure sensor is used to monitor the normal load force in real time.

2. The friction coefficient testing device for dynamically bent fiber bundles under multi-normal loads according to claim 1, characterized in that, The traction system includes a slide module, an adjustment plate, and a servo motor. The slide module is vertically mounted on the frame, the adjustment plate is mounted on the slider of the slide module, the servo motor provides power to the slide module to drive the slider to move up and down, and the adjustment plate is connected to a force measuring device.

3. The friction coefficient testing device for dynamically bent fiber bundles under multi-normal loads according to claim 1, characterized in that, The planar motion system includes a first slide rail module set in the low-position test area. The guide roller I is connected to the first slide rail module through a first pulley. The first slide rail module has a plurality of first snap-fit ​​holes spaced apart. The first pulley is provided with a first elastic buckle that cooperates with the first snap-fit ​​holes.

4. The friction coefficient testing device for dynamically bent fiber bundles under multi-normal loads according to claim 3, characterized in that, The first elastic buckle is configured to disengage from the corresponding first snap-fit ​​hole by elastic deformation in response to the movement of the guide roller I.

5. The friction coefficient testing device for dynamically bent fiber bundles under multi-normal loads according to claim 4, characterized in that, The first snap-fit ​​hole is a tapered hole, and the first elastic buckle has a tapered snap-fit ​​portion that mates with the first snap-fit ​​hole.

6. The friction coefficient testing device for dynamically bent fiber bundles under multi-normal loads according to claim 1, characterized in that, The planar motion system includes a second slide rail module set in the high-level test area. The guide roller II is connected to the second slide rail module through a second pulley. The second slide rail module has a plurality of second locking holes spaced apart. The second pulley is provided with a second elastic buckle that cooperates with the second locking holes.

7. The friction coefficient testing device for dynamically bent fiber bundles under multi-normal loads according to claim 6, characterized in that, The second slide rail module includes several horizontal and vertical tracks arranged in a vertically staggered pattern. The horizontal and vertical tracks are groove-type tracks with the same structure. The second pulley is operably mounted on the second slide rail module.

8. The friction coefficient testing device for dynamically bent fiber bundles under multi-normal loads according to claim 7, characterized in that, The plurality of second snap-fit ​​holes are distributed along the longitudinal track of the second slide rail module. The frame is provided with a plurality of screw holes corresponding to the plurality of longitudinal tracks. The force-applying component includes a screw rod screwed into the screw hole. The lower end of the screw rod is adapted to press against the pressure sensor.

9. The friction coefficient testing device for dynamically bent fiber bundles under multi-normal loads according to claim 1, characterized in that, The loading system also includes a load block, the upper part of the guide roller II is provided with a vertical guide groove, the lower part of the load block is provided with a guide block adapted to the vertical guide groove, a vertical suction spring is provided between the guide block and the vertical guide groove, the pressure sensor is installed on the upper part of the load block, the force application component is vertically mounted on the frame, and the lower end of the force application component is adapted to press against the pressure sensor.

10. A method for testing the friction coefficient of dynamically bent fiber bundles under multi-normal loads, based on the friction coefficient testing device as described in any one of claims 1 to 9, characterized in that, Includes the following steps: (1) Build a test device on the frame, construct a coordinate system based on the plane where guide roller I and guide roller II are located, and determine the origin of the coordinate system; (2) Preset the bending angle of the fiber bundle of the sample to be tested on guide roller I and guide roller II and the coordinates of the traction end of the fiber bundle of the sample to be tested, and calculate the coordinates of the center point of guide roller I and guide roller II accordingly. Then install the traction end, guide roller I and guide roller II in their respective positions according to the corresponding coordinates. (3) Install the fiber bundle of the sample to be tested. After installation, the fiber bundle of the sample to be tested is pulled by the traction system. Then, the normal load is applied to the fiber bundle of the sample to be tested by the loading system, and the values ​​of the force measuring device and the pressure sensor are recorded. (4) Substitute the counterweight, bending angle and the above recorded values ​​into the Euler equation describing the fiber bundle tension and its friction coefficient to calculate the friction coefficient of the sample to be tested.

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