AU2020104038A4

AU2020104038A4 - A single fibre pulling-out matrix device and a method for measuring that pull-out force

Info

Publication number: AU2020104038A4
Application number: AU2020104038A
Authority: AU
Inventors: Kunfu Chen; Hongwen JING; Mingyang Li; Longyang WU; Lei Yue
Original assignee: China University of Mining and Technology CUMT
Current assignee: China University of Mining and Technology CUMT
Priority date: 2020-12-13
Filing date: 2020-12-13
Publication date: 2021-02-25
Anticipated expiration: 2028-12-13

Abstract

The invention discloses a device for performing single fibre pull-out test and a method for measuring that pull-out force, which comprises a test specimen, an actuating mechanism, a clamping mechanism for clamping the test specimen, a force sensor and a testing machine rack. Wherein, the force sensor is connected in series with a fibre chuck processed by lightweight aluminium, so that sufficient clamping force can be guaranteed to be given to the fibre, and the change of the pulling-out force during the fibre pulling-out from the matrix can be effectively measured, so as to overcome the problem that the traditional testing machine does not match the range and precision of the single fibre pulling-out experiment. Besides, the selected 5N range sensor is equipped with proper range and high precision. Made of light aluminium, the fibre chuck is light in weight, which ensures that its series connection with the sensor will not make the sensor exceed the range, thereby solving the problems existing in the testing device and method during the implementation of the single fibre pull-out experiment with low cost, especially realizes the possibility of carrying out single fibre pull-out experiment on the traditional testing machine. 2/2 1 2 4 3 75 6 8 Figure 3 An exploded schematic diagram of the device for pulling out a single fibre from a matrix according to the present invention

Description

2/2

1

2

4 3

75

6

8

Figure 3 An exploded schematic diagram of the device for pulling out a single fibre

from a matrix according to the present invention

A single fibre pulling-out matrix device and a method for measuring that pull

out force

TECHNICAL FIELD

[01] The invention relates to a device for performing single fibre pull-out test and a method for measuring that pull-out force, in particular to a device and a method for determining the pull-out force when PVA (polyvinyl alcohol) fibre is pulled out from a cementitious matrix.

BACKGROUND

[02] At present, the mechanical behaviour of fibre in matrix includes friction and adhesive force between them, and most of the researches are based on single fibre pull out experiment. The embedded depth required by relevant research is 1mm. In terms of shapes and fabrications of matrixes of single fibre pull-out specimens, the related researches are not the same. In addition, the devices used in the single fibre pull-out experiment in different research institutes are different, and the cost is generally high, which raises the threshold of the experiment. This situation also leads to the difficult implement of single fibre pull-out experiment in most studies and limits the related research of fibre reinforced composites.

SUMMARY

[03] The technical problem to be solved by the invention is to standardize the single fibre pull-out experiment, reduce the cost of testing instruments and ensure the accuracy of measurement data.

[04] In view of the shortcomings of the prior art, a device for performing single fibre pull-out test and a method for measuring the pull-out force are provided, so as to realize real-time monitoring of the change of the pull-out force and displacement between the fibre and the matrix during the pull-out process.

[05] To solve the above technical problems, the technical scheme adopted by the invention is as follows.

[06] A single fibre pull-out device is characterized by comprising a test specimen, an actuating mechanism, a clamping mechanism for clamping the test specimen, a force sensor and a testing machine rack.

[07] Wherein, the test specimen comprises a matrix and a single fibre. Further, one end of that fibre is inserted into the matrix, and the other end extends out of the matrix to be exposed.

[08] The actuating mechanism is fixedly and longitudinally installed in the middle part of the testing machine rack, and the actuating mechanism is parallel with the ground.

[09] The clamping mechanism comprises a matrix chuck and a fibre chuck which are arranged separately. The fixed end of the matrix chuck is connected with the power output end of the actuating mechanism, and the clamping end of the matrix chuck can clamp and fix the matrix of the test specimen. The fixed end of the fibre chuck is connected with the force sensor in series, and the force sensor is fixedly installed below the top of the testing machine rack. The fixed end of the fibre chuck is transversely adjusted to ensure that the single fibre is in a vertical state. In the testing process, the actuating mechanism acts on the matrix chuck to promote the single fibre to be pulled out from the matrix, and the force sensor tests the tensile force bome by the single fibre when being pulled out.

[010] Furthermore, a servo motor is arranged on the base of the testing machine and a screw rod communicated with the servo motor is arranged in the gantry. A moving beam is suspended parallel with the ground, whose two ends are connected with the screw rod in a threaded way. Besides, the moving beam is communicated by a control acquisition panel outside the testing machine.

[011] Furthermore, the material of the fibre chuck is lightweight aluminium, and the material of the matrix chuck is steel.

[012] Furthermore, the force sensor is a 5N range force sensor, with resolution of +0.001N.

[013] Furthermore, the matrix chuck and the fibre chuck are U-shaped, and they are internally provided with fixed clamping blocks for clamping the test specimen.

[014] Furthermore, the size of the matrix of the specimen is lOx10x20mm, and the length of the part that the fibre is embedded in the matrix is 1 mm. In addition, the fibre exposed outside the fibre chuck is pasted with a layer of special paper with instant cyanoacrylate glue, and the pasted special paper is in sheet form.

[015] Further, the special paper for the test specimen is electrostatic printing paper with a mass of 80g per square meter.

[016] Further, the glue used is ALTECO glue of ALTECO Technology (Wuxi) Co., Ltd.

[017] The test method is as follows.

[018] Adjusting the position of the testing device to align the centre of the force sensor with the centre of the fibre when the fibre chuck clamps the fibre, so as to ensure that the fibre is vertically pulled. During the test, the moving beam of the testing machine drives the matrix chuck and the matrix to move, thereby obtaining the displacement data. The fibre pull-out force during the pull-out process is determined by the force sensor. With the help of the data collected by the control panel, the pull-out length and pull-out force of the fibre relative to the matrix at each time during the pull out process can be displayed.

[019] The invention has the following beneficial effects.

[020] In above mentioned technical scheme, the force sensor is connected in series with the fibre chuck so that sufficient clamping force can be guaranteed to be given to the fibre, and the change of the pulling-out force during thefibre pulling-out from the matrix can be effectively measured, so as to overcome the problem that the traditional testing machine does not match the range and precision of the single fibre pulling-out experiment. Besides, the selected 5N force sensor is equipped with proper range and high precision. Made of light aluminium, the fibre chuck is light in weight, which ensures that its series connection with the sensor will not make the sensor exceed the range, thereby solving the problems existing in the testing device and method during the implementation of the single fibre pull-out experiment with low cost, especially realizes the possibility of carrying out single fibre pull-out experiment on the traditional testing machine.

BRIEF DESCRIPTION OF THE FIGURES

[021] Figure 1 is a schematic structural diagram of the device for performing single fibre pull-out from matrix test according to the present invention.

[022] Figure 2 is a perspective view of the structure of the test specimen of the present invention.

[023] Figure 3 is an exploded schematic diagram of the device for pulling out a single fibre from a matrix according to the present invention.

[024] In figures, 1- 5N force sensor, 2- fibre chuck base, 3- fibre chuck elastic nut, 4- fibre chuck clamping block, 5- matrix chuck base, 6- matrix chuck elastic nut, 7- matrix chuck clamping block, 8- fixing nut of matrix chuck, 9- moving beam, 10 matrix clamp connecting beam, 11- gantry, 12- matrix, 13- fibre.

DESCRIPTION OF THE INVENTION

[025] The present invention will be further explained in detail with reference to the attached figures and specific preferred embodiment.

[026] In the description of the present invention, it should be understood that the orientations or positional relationships indicated by the terms "left", "right", "upper" and "lower" are based on the orientations or positional relationships shown in the figures, which are only for the convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred devices or elements must have a specific orientation and be constructed and operated in a specific orientation. "First", "second" and the like do not indicate the importance of the components, so they cannot be understood as a limitation of the invention. The specific size adopted in the embodiment is only to illustrate the technical scheme and does not limit the protection scope of the invention.

[027] As shown in figs.1 and 3, the single fibre pull-out device consists of a test specimen, an actuating mechanism, a clamping mechanism for clamping the test specimen, a force sensor and a testing machine.

[028] Specifically, the testing machine comprises a base, a gantry (11) and a moving beam (9). Wherein, a servo motor is arranged on the base of the testing machine and the gantry (11) is vertical to the ground, and the screw rod in the gantry (11) is connected with the servo motor. The moving beam (9) is suspended parallel with the ground, whose two ends are connected with the screw rod in a threaded way. Besides, the moving beam (9) is communicated by a control acquisition panel outside the testing machine.

[029] The force sensor (1) is a 5N range sensor with a resolution of 0.001N. Wherein, the upper end of the force sensor (1) is fixed on the top beam of the testing machine, and the lower end bolt is connected in series with the upper end of the fibre chuck base. Fibre chuck is made of lightweight aluminium, which can clamp fibre. The matrix chuck is installed on the moving beam (9) of the testing machine, which is made of steel and can clamp the matrix with a thickness of 10 mm.

[030] The matrix chuck sequentially comprises a fixing nut (8), a connecting beam (10), a matrix chuck base (5), a clamping block (7) and an elastic nut (6) from bottom to top.

[031] The connecting beam (10) is U-shaped, both open ends of which are fixed on the moving beam (9), and there is a hollow gap in the middle of the upper end of the connecting beam (10) for adjusting the position of the matrix chuck base (5) on the connecting beam (10). The matrix chuck base (5) is also U-shaped, fixed on the connecting beam (10) by the fixing nut (8). The matrix chuck base (5) provides the matrix clamping reaction force, and then the matrix chuck clamping block (7) is pushed by the matrix chuck elastic nut (6) to give the matrix clamping force. After the chuck clamping block (7) is inserted into the opening of the matrix chuck base (5), the elastic nut (6) is threaded through the matrix chuck base (5) from the outside to clamp the chuck clamping block (7) into the matrix chuck base (5).

[032] The fibre chuck is located above the matrix chuck, which includes a fibre chuck elastic nut (3), a fibre chuck base (2) and a fibre chuck block (4) from outside to inside. Specifically, the shapes, structures and connection directions of the fibre chuck elastic nut (3), the fibre chuck base (2) and the fibre chuck block (4) are completely consistent with those of the matrix chuck elastic nut (6), the matrix chuck base (5) and the matrix chuck clamping block (7). The fibre chuck base (2) is used to provide clamping reaction force, the fibre chuck elastic nut (3) is used to adjust the fibre clamping force, and the fibre chuck block (4) is pushed by the fibre chuck elastic nut (3) to give fibre clamping force.

[033] Preparing the matrix specimen of single fibre pull-out test as shown in fig. 2. The matrix (12) is 10x10x20mm, the length of the part where the fibre (13) is embedded into the matrix is 1mm, and a layer of special paper is pasted on the fiber exposed outside the matrix. It should be noted that the special paper and the fibre are stuck with instant cyanoacrylate glue, wherein the length of special paper is equal to the exposed length of fiber, and the width is 10 mm. After the exposed fiber are pasted at 1/4 of the length of the special paper and parallel with the width of the special paper, the special paper is folded in half along the length center line. The instant cyanoacrylate glue used to process the specimen is ATECO glue of ATECO Technology (Wuxi) Co., Ltd. The selected special paper is electrostatic special paper with a mass of 80g per square meter.

[034] Using the single fibre pulling-out matrix device in fig.1 to measure the change of pulling-out force during the pulling-out process. The specific steps are as follows.

[035] Clamping the processed matrix specimen for fibre pulling-out test in the matrix chunk.

[036] (2) Moving the fibre chuck to make the fibre enter the fibre clamp.

[037] (3) Loosening the fixing nut of the matrix chuck and adjusting the position of the matrix chuck in the horizontal plane to align the fibre with the fibre chuck base and ensure the vertical tension of the fibre.

[038] (4) After the fibre is aligned, tightening the fixing nut of the matrix clamp.

[039] (5) Tightening the elastic nut of the fibre chuck to clamp the fibre.

[040] (6) Making the moving beam to load according to the displacement at a rate of 0.05mm/min, and then starting the test.

[041] (7) The change of pull-out force in the experiment is measured by the 5N range sensor, and the change of pull-out length is measured by a displacement sensor in the moving beam as well.

[042] (8) After the fibre is pulled out, stopping the testing machine and saving the data obtained in the experiment.

[043] (9) Loosening the elastic nut of the fibre chuck first, then adjusting the moving beam to an easy-to-operate height. Finally, loosening the elastic nut of the matrix clamp and removing the specimen.

[044] In the above embodiment, the shape of the matrix chuck and the fibre chuck can be U-shaped, but it is not limited to U-shaped, and any other shape can be used as long as there are channels running through the specimen up and down inside the matrix chuck and the fibre chuck.

[045] In the above embodiment, when the matrix chuck and the fibre chuck clamp the test specimen, they are fixedly connected by nuts, or otherfixed connections, such as snap connections.

[046] Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms, in keeping with the broad principles and the spirit of the invention described herein.

[047] The present invention and the described embodiments specifically include the best method known to the applicant of performing the invention. The present invention and the described preferred embodiments specifically include at least one feature that is industrially applicable

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A single fibre pull-out device is characterized by comprising a test specimen, an actuating mechanism, a clamping mechanism for clamping the test specimen, a force sensor and a testing machine rack.

Wherein, the test specimen comprises a matrix and a single fibre. Further, one end of that fibre is inserted into the matrix, and the other end extends out of the matrix to be exposed.

The actuating mechanism is fixedly installed in the testing machine rack.

The clamping mechanism comprises a matrix chuck and a fibre chuck which are arranged separately. The fixed end of the matrix chuck is connected with the power output end of the actuating mechanism, and the clamping end of the matrix chuck can clamp and fix the matrix of the test specimen. The fixed end of the fibre chuck is connected with the force sensor in series, and the force sensor is fixedly installed below the top of the testing machine rack. The fixed end of the fibre chuck is transversely adjusted to ensure that the single fibre is in a vertical state. In the testing process, the actuating mechanism acts on the matrix chuck to promote the single fibre to be pulled out from the matrix, and the force sensor tests the tensile force borne by the single fibre when being pulled out.

2. According to claim 1, the single fibre pull-out device is characterized in that the actuating mechanism is composed of a moving beam and screw rods. Specifically, a servo motor is arranged on the base of the testing machine and screw rods are arranged on two side of the testing machine rack. The screw rods are connected with the servo motor and the moving beam is suspended parallel with the ground, whose two ends are connected with the screw rod in a threaded way. Besides, the moving beam is controlled by a control acquisition panel outside the testing machine to move in the vertical direction.

3. According to claim 1, the single fibre pull-out device is characterized in that the matrix chuck and the fibre chuck are U-shaped, and they are internally provided with fixed clamping blocks for clamping the test specimen.

4. According to claim 1, the single fibre pull-out device is characterized in that the material of the fibre chuck is lightweight aluminium, and the material of the matrix chuck is steel.

5. According to claim 1, the single fibre pull-out device is characterized in that the force sensor is a 5N range sensor, with resolution of O.OOIN.

6. According to claim 1, the single fibre pull-out device is characterized in that the size of the matrix of the specimen is OxOx2Omm, and the length of the part that the fibre is embedded in the matrix is 1 mm. In addition, the fibre exposed outside the fibre chuck is pasted with a layer of special paper with instant cyanoacrylate glue, and the pasted special paper is in sheet form.

7. According to claim 6, the single fibre pull-out device is characterized in that the special paper for the test specimen is electrostatic printing paper with a mass of 80g per square meter.

8. According to claim 6, the single fibre pull-out device is characterized in that the glue used is ALTECO glue of ALTECO Technology (Wuxi) Co., Ltd.

9. The detection method of using the single fibre pull-out device based on claims 1-9, is characterized by following specific detection steps.

(1) Clamping the processed matrix specimen for fibre pulling-out test in the matrix chunk.

(2) Moving the fibre chuck to make the fibre enter the fibre clamp.

(3) Adjusting the position of the matrix chuck in the horizontal plane to align the fibre with the fibre chuck base and ensure the vertical tension of thefibre.

(4) After the fiber is aligned, it is fixed in the fiber chuck, and the positions of the matrix chuck and the fiber chuck are also fixed.

(5) Making the moving beam to load according to the displacement at a rate of 0.05mm/min.

(6) Starting the test. The change of pull-out force in the experiment is measured by the force sensor, and the change of pull-out length is measured by a displacement sensor in the testing machine as well.

(8) After the fibre is pulled out, stopping the testing machine and saving the obtained data.