A quasi-static transverse compression test device for fiber monofilaments

Abstract

The present invention discloses a quasi-static transverse compression test device for fiber monofilaments, which belongs to the field of material characterization and mechanical experimental technology. The present invention uses piezoelectric ceramic actuators and capacitive displacement sensors to control and measure tiny compression amounts (the displacement accuracy can reach the nanometer level), uses high-precision force sensors to collect the pressure on the fiber monofilaments, and designs a clamp for laying two fiber monofilaments in parallel and equidistantly to reduce the eccentric compression error and achieve uniform compression of tiny fiber materials between two pressing plates. The present invention controls the system gap through the precise design of the overall loading platform, realizes the quasi-static compression mechanical performance characterization of 10-micron-scale high-performance fiber monofilaments, and measures the nominal stress-strain curve of the fiber under quasi-static loading. The characterization method can provide mechanical performance parameters and constitutive models at the fiber scale, and provide guidance for the development of cross-scale mechanical models for fabrics and composite materials and the development of high-performance fiber materials.

Description

Technical Field

[0001] The invention relates to the technical field of material characterization and mechanical experiment, and in particular to a quasi-static transverse compression experiment device for a fiber monofilament. Background Art

[0002] High-performance fibers have extremely high specific strength and specific modulus. Experimental studies have shown that when subjected to high-speed impact, the fiber exhibits a multi-axial failure mode of axial tension and lateral compression. The traditional fiber impact mechanics model based on the tensile fracture assumption deviates greatly from the experimental results in prediction. Therefore, a fiber monofilament lateral compression loading and testing device is urgently needed to characterize the fiber lateral compression mechanical properties and to explore the influence of lateral compression on the fiber axial tensile properties and impact properties.

[0003] At present, the most widely used testing devices for the quasi-static compression mechanical properties of materials are universal testing machines and nanoindenters. However, the diameter of fiber monofilaments is usually on the order of 10 microns, and universal testing machines cannot achieve stable control of loading speed and accurate measurement of loading displacement. On the other hand, the nanoindenter precisely controls the load or displacement to press an indenter with a specific shape into the material being tested, obtains the load-displacement curve during the pressing process, and then calculates the elastic-plastic mechanical properties of the material. Although its loading speed and displacement accuracy can be controlled at the nanometer level, the size of the indenter is also at the nanometer level, and it is impossible to achieve lateral compression loading of micrometer-scale fiber monofilaments. Therefore, the existing quasi-static compression devices for materials are difficult to meet the lateral compression test requirements of fiber monofilaments, and new testing devices need to be specially developed.

[0004] Based on the existing experimental technology, there are two main technical difficulties in the transverse mechanical property test of fiber monofilaments: first, the fiber diameter is usually 5-30 μm, the compressible displacement is small, and it is difficult to accurately control and measure the tiny compression; second, the cylindrical shape of the fiber monofilament, the roughness of the pressure plate surface and the eccentric compression will affect the stability of the loading process. The Chinese invention patent with publication number CN219957112U proposes a loading device for transverse compression of an array circular tube combination structure, which provides a reference for exploring the deformation and energy dissipation mechanical characteristics of the combination tube structure in engineering applications. However, the device is limited to transverse compression testing of large-scale combination structures of XX meters. The Chinese invention patent with publication number CN219957112U uses the pressure head on the cantilever beam to transversely compress the overlapping fiber sample in the polygonal disk, and uses a stepper motor to control the screw rod to achieve compression loading, which makes it difficult to achieve precise control of the loading rate. The prior art has invented a single fiber transverse compression test device. However, during the test, a single fiber is prone to misalignment between the upper and lower compression planes. At the same time, during the initial elastic compression deformation (about 0.5~1.0μm), the mechanical phase of the fiber is greatly affected by the surface roughness of the pressure plate and the eccentric loading. The current technology has designed a single fiber transverse compression device, which reduces the influence of the pressure plate roughness and eccentric loading, but its piezoelectric actuator cannot fully compress the fiber transversely. The maximum nominal strain is only 20%~30%, which is far lower than the actual nominal strain of about 70%~80%. It is necessary to manually adjust the vertical translation of the bottom displacement platform to achieve greater fiber transverse compression. Therefore, the loading method is not stable enough. In addition, the fixing method of the overall device causes it to have a measurement gap of more than 2μm, and the actual measurement is not accurate enough. Summary of the invention

[0005] The purpose of the present invention is to solve the problems existing in the prior art and to propose a fiber monofilament quasi-static transverse compression test device.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A fiber monofilament quasi-static transverse compression experimental device, comprising a loading system, a force-displacement data measurement and acquisition system, a fiber sample fixture, and an adjustable loading platform;

[0008] The loading system includes an actuator and an actuator controller. The loading system is fixedly connected to an adjustable loading platform. The actuator controller is connected to a host computer via a data line. The host computer can accurately control the loading motion mode of the actuator through the actuator controller, thereby performing a high-precision and stable compression test on the sample.

[0009] The force-displacement data measurement and acquisition system comprises a displacement measurement part, a force measurement part and a synchronous acquisition part;

[0010] The displacement measurement part is mainly composed of a measuring probe and a displacement sensor controller; the force measurement part is composed of an adapter, a force sensor, a data transfer cable and a double-headed connecting bolt; the synchronous acquisition part includes a data acquisition control box and data analysis software;

[0011] In the displacement measurement part, the measuring probe is connected to the displacement sensor controller, and the displacement sensor controller is connected to the data acquisition control box to accurately record and visualize the measured displacement data. The measuring probe is fixed by a capacitive displacement sensor fixture to measure the displacement of the plug;

[0012] In the force measurement part, the force sensor is connected to the adjustable loading platform and the adapter through a double-headed connecting bolt, the fiber sample fixture is located on the adapter, and the force sensor is connected to the data acquisition control box through a data adapter line to accurately test and record the force value; the data acquisition control box analyzes the data input from the two parts, and finally integrates and installs the data analysis software on the host computer for accurate recording and analysis;

[0013] The fiber sample fixture comprises an upper metal sheet group consisting of two metal sheets, a lower metal sheet group, a metal cylinder, a plugging piece and a U-shaped cardboard, wherein the metal cylinder is equidistantly bonded between the two metal sheets of the upper metal sheet group, the metal cylinder distributes the compressive load to the fiber monofilament, and the plugging piece is connected to the lower sheet of the upper metal sheet group and the upper sheet of the lower metal sheet group;

[0014] The adjustable loading platform includes a Z-axis lifting platform, a capacitive displacement sensor fixing fixture, a transfer base, a three-axis displacement platform and a fixed base, and the three-axis displacement platform is connected to the fixed base through the transfer base.

[0015] Preferably, the downward compression displacement of the plug is used as the actual compression amount of the fiber monofilament, and the U-shaped cardboard is used to fix two fiber monofilament samples and is placed between two metal sheets of the lower metal sheet group.

[0016] Preferably, the Z-axis lifting platform is used to fix the loading system and its height can be adjusted.

[0017] Preferably, the adapter base is connected to a three-axis translation stage for adjusting the position of the sample, and the capacitive displacement sensor fixing fixture is used to fix the measuring probe.

[0018] Preferably, the capacitive displacement sensor fixing fixture can fully reduce the error caused by the system gap and ensure the accuracy of micrometer-scale material measurement.

[0019] Preferably, the U-shaped cardboard realizes fixed clamping and stable and uniform loading of the fiber monofilaments.

[0020] Preferably, the lower metal sheet group ensures that the load is directly and evenly applied above the two fibers, while preventing inaccurate displacement measurement due to bending of the plug sheet.

[0021] Preferably, the metal sheets in the fiber sample fixture are all mirror-finished to reduce the influence of roughness on the experimental results. For micrometer-scale fiber monofilament materials, a few micrometers will produce a large error.

[0022] Preferably, the width dimension of the fiber sample fixture determines the length of the compressed section of the fiber monofilament, and the selected width can enable the fiber sample to reach a nominal strain of 70% to 80%.

[0023] Preferably, the length and thickness of the metal sheet in the fiber sample holder are selected based on the mass of the metal sheet itself.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The device for testing the quasi-static transverse compression mechanical properties of micro-scale fiber monofilaments described in the present invention reduces the influence of surface roughness and non-parallel compression by designing a fixture in which two fibers are laid in parallel and equidistantly to achieve sufficiently uniform compression, and the designed loading platform sufficiently reduces the gap of the system; the fiber monofilament sample is accurately loaded by an actuator that can achieve nano-level motion control, and high-precision displacement sensors and force sensors are used to measure data, further ensuring that the system is precise, stable, convenient and miniaturized. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of the main body of a fiber monofilament quasi-static transverse compression test device proposed by the present invention;

[0027] Figure 2 A schematic diagram of the specific layout and connection of a loading system and a force-displacement data measurement and acquisition system in a fiber monofilament quasi-static transverse compression experimental device proposed by the present invention;

[0028] Figure 3 This is a schematic diagram of the structure of a U-shaped cardboard in a fiber monofilament quasi-static transverse compression test device proposed by the present invention;

[0029] Figure 4 This is a schematic diagram of the structure of a fiber sample fixture in a fiber monofilament quasi-static transverse compression test device proposed by the present invention;

[0030] Figure 5 This is a connection relationship diagram of double-headed connecting bolts in a fiber monofilament quasi-static transverse compression test device proposed by the present invention.

[0031] In the figure: 1. Force-displacement data measurement and acquisition system; 2. Fiber sample fixture; 3. Actuator; 4. Actuator controller; 5. Measuring probe; 6. Displacement sensor controller; 7. Adapter; 8. Force sensor; 9. Data adapter cable; 10. Double-headed connecting bolt; 11. Data acquisition control box; 12. Upper metal sheet group; 13. Metal cylinder; 14. Plug; 15. Lower metal sheet group; 16. U-shaped cardboard; 17. Z-axis lifting platform; 18. Capacitive displacement sensor fixing fixture; 19. Adapter base; 20. Three-axis displacement stage; 21. Fixed base. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] Example, see Figures 1 to 5 , a fiber monofilament quasi-static transverse compression test device, such as Figure 1 , which is a schematic diagram of the main structure of a fiber monofilament quasi-static transverse compression experimental device according to an embodiment of the present invention, including a loading system, a force-displacement data measurement and acquisition system 1, a fiber sample fixture 2, and an adjustable loading platform.

[0034] Further, among them, Figure 1 As shown, the loading system is connected to the adjustable loading platform to provide the fiber monofilament with a precise micro-compression amount so that the fiber monofilament can be fully compressed laterally. The loading system specifically includes an actuator 3 and an actuator controller 4. The actuator 3 is tightly connected to the extended platform of the Z-axis lifting platform 17 through bolts to limit its freedom except in the Z direction.

[0035] Further, among them, Figure 1 As shown, the force-displacement data measurement and acquisition system 1 is connected to the fiber sample fixture 2 and the adjustable loading platform, and is used to record the force and displacement data of the transverse compression device. The force-displacement data measurement and acquisition system 1 specifically includes a displacement measurement probe 5, an adapter seat 7, a force sensor 8, and a double-headed connecting bolt 10; wherein the measurement probe 5 is fixed to the adapter seat 7 by a capacitive displacement sensor fixing fixture 18, which can fully reduce the gap of the system, and the force sensor 8 is tightly connected with the adapter seat 7 and the adapter base 19 by the double-headed connecting bolt 10.

[0036] Further, among them, Figure 1As shown, the fiber sample fixture 2 is used to fix two fiber monofilaments and lay them in parallel and equidistantly, reducing the non-parallel compression error and the influence of roughness, and realizing the uniform compression of tiny fiber materials between two pressing plates. The fiber sample fixture 2 specifically includes: an upper metal sheet group 12 composed of two metal sheets, a lower metal sheet group 15, a metal cylinder 13, and a plug sheet 14. The metal cylinder 13 is equidistantly bonded between the two metal sheets of the upper metal sheet group 12, and the metal cylinder 13 can better distribute the compression load to the fiber monofilament. The plug sheet 14 is connected to the lower sheet of the upper metal sheet group 12 and the upper sheet of the lower metal sheet group 15, and the downward compression displacement of the plug sheet 14 is used as the actual compression amount of the fiber monofilament, wherein all metal sheets are mirror-finished to reduce the influence of roughness.

[0037] Further, among them, Figure 1 As shown, the adjustable loading platform is used to fix the loading system and the position of the sample. The adjustable loading platform specifically includes a Z-axis lifting platform 17, a capacitive displacement sensor fixing fixture 18, an adapter base 19, a three-axis displacement platform 20, and a fixed base 21; the Z-axis lifting platform 17 mainly fixes the loading system, and its height can be adjusted to adjust the loading position of the actuator 3; the adapter base 19 connects the three-axis displacement platform 20 and the force sensor 8, and is used to adjust the position of the sample; the capacitive displacement sensor fixing fixture 18 is fixed on the adapter seat 7, and the capacitive displacement sensor fixing fixture 18 is used to fix the measuring probe 5 of the capacitive displacement sensor. By using the adjustable loading platform, the overall device can be convenient for adjusting the position of the sample and the loading system.

[0038] like Figure 2 FIG. 1 is a schematic diagram of the specific layout and connection of the loading system and the force-displacement data measurement and acquisition system 1 described in the embodiment of the present invention, which mainly includes a loading system, a displacement measurement part, and a force measurement part.

[0039] Further, among them, Figure 2 As shown, in the loading system, the actuator controller 4 is connected to the host computer, i.e., the user's computer, via a data line. The actuator controller 4 can accurately control the loading motion mode of the actuator 3, thereby performing a high-precision and stable compression test on the sample.

[0040] Further, among them, Figure 2 As shown, the displacement measurement part is used for contactless measurement of the compression of the fiber monofilament. The measuring probe 5 is connected to the adjustable loading platform through the capacitive displacement sensor. The capacitive displacement sensor is a precision measuring instrument based on the non-contact capacitance principle. The appropriate measuring distance is adjusted and it is aligned with the plug 14. The precise measurement of the compression of the fiber monofilament can be achieved by measuring the distance the plug 14 moves downward. The measuring probe 5 is connected to the data acquisition control box 11 through the displacement sensor controller 6 to collect displacement data.

[0041] Further, among them, Figure 2 As shown, the force measurement part is used to measure the transverse compression force on the fiber monofilament. The force sensor 8 is connected to the data acquisition control box 11 through the data adapter 9 to accurately test and record the force value. The data acquisition control box 11 analyzes the data input from the two parts and finally integrates them into the data analysis software installed on the host computer for accurate recording and analysis.

[0042] like Figure 3 , which is a schematic diagram of the planar structure of the U-shaped cardboard 16 described in an embodiment of the present invention.

[0043] Furthermore, the U-shaped cardboard 16 is used to fix two fiber monofilament samples, which are placed between the two metal sheets of the lower metal sheet group 15 to fix and clamp the samples. The rectangular size of the middle opening is consistent with the size of the lower metal sheet group 15, and the spacing between the fiber monofilaments fixed by tape should be consistent with the spacing between the metal cylinders 13, so as to ensure that the force is applied to the fiber more evenly.

[0044] The following takes the fiber monofilament quasi-static transverse compression test device described in the first embodiment of the present invention as an example to specifically describe the actual operation process of the device:

[0045] First, the loading system, force-displacement data measurement and acquisition system 1, fiber sample fixture 2, and adjustable loading platform are as follows Figure 1 Install as shown; loading system, force-displacement data measurement and acquisition system 1 according to Figure 2 Layout and connect; select the fiber monofilament samples and place them according to Figure 3 It is fixed in the Hui-shaped cardboard 16.

[0046] Second, the rationality of the system is verified. Without placing the sample, the fiber sample fixture 2 is aligned and placed on the adapter 7. The position of the measuring probe 5 of the capacitive displacement sensor is adjusted to be within the measuring range. The position of the actuator 3 is adjusted through the adjustable loading platform to make its probe initially contact with the fiber sample fixture 2. The analysis software of the force-displacement data measurement and acquisition system 1 is opened, and the loading rate and loading waveform are input through the actuator controller 4 to start loading. At the same time, the output force-displacement curve is recorded. The data is analyzed to determine that the system's own clearance is very small and within a reasonable range.

[0047] Third, after confirming the rationality of the system, place the U-shaped cardboard 16 with the sample between the two metal sheets of the lower metal sheet group 15, clamp the sample, repeat the steps in the second step, and record the force-displacement curve of the lateral compression of the fiber monofilament. The compressed sample can be observed by a scanning electron microscope to determine its uniform compression, and its nominal stress-nominal strain curve can be obtained through data processing and analysis.

[0048] The operation implementation steps included in the above embodiment are only for reference. For those skilled in the art, the logical relationship of the installation sequence can be changed according to actual needs.

[0049] Compared with the prior art, the present invention has the following advantages and outstanding effects: 1. The device reduces the influence of surface roughness and eccentric compression through the designed double fiber monofilament clamp, and further realizes fully uniform compression. 2. The device accurately loads the fiber monofilament sample through the actuator 3 that can realize nano-level motion control, and uses high-precision displacement sensors and force sensors 8 to measure data, solving the problem of accurate control and measurement of tiny compression amounts. 3. Through the designed adjustable loading platform, the measuring device is precisely connected, and the gap can be fully reduced while the position of the sample and the loading system can be accurately adjusted, solving the problem of inconvenient adjustment of the loading position of micro-scale samples.

[0050] In summary, the system and method use the actuator 3 to accurately load the sample, and combine the high-precision force sensor 8 and the capacitive displacement sensor to study the static transverse compression mechanical properties of the micron-level fiber monofilament sample. Under the premise of obtaining accurate loading and measurement, the uniformity of sample compression is ensured by the design of the fixture. The device and method have the functions and characteristics of miniaturization, high energy conversion rate, stability, easy adjustment, and convenience for repeated tests. In addition to fiber monofilaments, experimental research can also be carried out on a series of micron-level materials such as PDMS films and micro-metamaterials.

[0051] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A fiber monofilament quasi-static transverse compression test device, characterized in that: It includes a loading system, a force-displacement data measurement and acquisition system (1), a fiber sample fixture (2), and an adjustable loading platform; The loading system comprises an actuator (3) and an actuator controller (4); the loading system is fixedly connected to an adjustable loading platform; the actuator controller (4) is connected to a host computer via a data line; the host computer accurately controls the loading motion mode of the actuator (3) via the actuator controller (4), thereby performing a high-precision and stable compression test on the sample; The force-displacement data measurement and acquisition system (1) comprises a displacement measurement part, a force measurement part and a synchronous acquisition part; The displacement measurement part is composed of a measuring probe (5) and a displacement sensor controller (6); the force measurement part is composed of an adapter (7), a force sensor (8), a data adapter cable (9) and a double-headed connecting bolt (10); and the synchronous acquisition part includes a data acquisition control box (11) and data analysis software; In the displacement measurement part, the measuring probe (5) is connected to the displacement sensor controller (6), and the displacement sensor controller (6) is connected to the data acquisition control box (11) to accurately record and visualize the measured displacement data. The measuring probe (5) is fixed by a capacitive displacement sensor fixture to measure the displacement of the plug; In the force measurement part, the force sensor (8) is connected to the adjustable loading platform and the adapter (7) via a double-headed connecting bolt (10), the fiber sample fixture (2) is located on the adapter (7), and the force sensor (8) is connected to the data acquisition control box (11) via a data adapter cable (9) to accurately test and record the force value; the data acquisition control box (11) analyzes the input data of the two parts, and finally integrates and installs the data analysis software on the host computer to accurately record and analyze; The fiber sample fixture (2) comprises an upper metal sheet group (12) consisting of two metal sheets, a lower metal sheet group (15), a metal cylinder (13), a plugging sheet (14) and a U-shaped cardboard (16), wherein the metal cylinder (13) is equidistantly bonded between the two metal sheets of the upper metal sheet group (12), the metal cylinder (13) distributes the compressive load to the fiber monofilaments, and the plugging sheet (14) is connected to the lower sheet of the upper metal sheet group (12) and the upper sheet of the lower metal sheet group (15); The adjustable loading platform comprises a Z-axis lifting platform (17), a capacitive displacement sensor fixing fixture (18), a transfer base (19), a three-axis displacement platform (20) and a fixed base (21), wherein the fixed base (21) is arranged below the three-axis displacement platform (20); The displacement of the plug (14) when compressed downward is used as the actual compression amount of the fiber monofilament. The U-shaped cardboard (16) is used to fix two fiber monofilament samples and is placed between two metal sheets of the lower metal sheet group (15) to fix and clamp the samples. The size of the rectangular opening in the middle is consistent with the size of the lower metal sheet group (15). The spacing between the fiber monofilaments fixed by adhesive tape should be consistent with the spacing between the metal cylinders (13). The Z-axis lifting platform (17) is used to fix the loading system and adjust its height to adjust the loading position of the actuator (3); The adapter base (19) is connected to the three-axis displacement stage (20) and the force sensor (8) and is used to adjust the position of the sample. The capacitive displacement sensor fixing fixture (18) is fixed on the adapter base (7). The capacitive displacement sensor fixing fixture (18) is used to fix the measuring probe (5). The adjustable loading platform is used to fix the loading system and the position of the sample. The adjustable loading platform can realize the overall device to facilitate the position adjustment of the sample and the loading system.

2. A fiber monofilament quasi-static transverse compression test device according to claim 1, characterized in that: The capacitive displacement sensor fixing fixture (18) fully reduces the error caused by the system gap, thereby ensuring the accuracy of micrometer-scale material measurement.

3. The fiber monofilament quasi-static transverse compression test device according to claim 1, characterized in that: The U-shaped cardboard (16) achieves fixed clamping and stable and uniform loading of the fiber monofilaments.

4. The fiber monofilament quasi-static transverse compression test device according to claim 1, characterized in that: The lower metal sheet group (15) ensures that the load is directly and evenly applied above the two fibers, while preventing inaccurate displacement measurement due to bending of the plug sheet (14).

5. The fiber monofilament quasi-static transverse compression test device according to claim 1, characterized in that: The metal sheets in the fiber sample fixture (2) are all mirror-finished.

6. The fiber monofilament quasi-static transverse compression test device according to claim 1, characterized in that: The width of the fiber sample fixture (2) determines the length of the compressed section of the fiber monofilament, and the selected width can enable the fiber sample to reach a nominal strain of 70% to 80%.

7. The fiber monofilament quasi-static transverse compression test device according to claim 1, characterized in that: The selection of the length and thickness of the metal sheet in the fiber sample fixture (2) depends on the mass of all the metal sheets themselves.

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