A single fiber pull-out device and a central non-offset testing method

Abstract

The present invention provides a single fiber pulling-out device and a central non-offset testing method. In the present invention, the first adjusting rod, the second adjusting rod and the third adjusting rod are connected in sequence from bottom to top. The lower end of the first adjusting rod is connected with a base. The upper end of the first adjusting rod is hinged to the lower end of the second adjusting rod through a first connecting member. The upper end of the second adjusting rod is hinged to the lower end of the third adjusting rod through a second connecting member. The upper end of the third adjusting rod is hinged to the bottom surface of a fixing plate, and the top surface of the fixing plate is a connecting surface. The central non-offset testing method is to determine the relationship between the lengths of the first adjusting rod, the second adjusting rod, the third adjusting rod and the thickness value of the X-Y platform according to the testing requirements and the specific type of the single fiber test specimen, and then perform a rotation test on the single fiber test specimen through the cooperation of the first adjusting rod, the second adjusting rod and the third adjusting rod. During the rotation test, relevant test data are obtained while ensuring that the single fiber test specimen is always located on the central axis of the testing machine.

Description

Technical Field

[0001] The present invention specifically relates to a single fiber pulling-out device and a central non-offset testing method. Background Art

[0002] Concrete is one of the most widely used building materials in the field of civil engineering. With the development of science and technology and the continuous improvement of building scale, the performance of concrete is also constantly improving, and a large number of high-performance concretes have emerged. Among them, fiber-reinforced concrete can well overcome the inherent disadvantages of concrete, such as poor tensile performance and low ductility. Fiber concrete is a multiphase material composed of fibers, matrix, and fiber / matrix interface. Among these three, the most important is the bonding performance of the fiber / matrix interface, which determines the macroscopic properties of fiber concrete. And the single fiber pull-out test is one of the most direct and effective methods to study the bonding performance of the fiber / matrix interface.

[0003] At present, there are many experimental cases and invention patents for the single fiber pull-out test. However, these methods are all limited to pulling out the fiber perpendicular to the matrix, which seriously affects the accuracy of the test results. This is because in actual situations, the distribution of fibers in concrete is not perpendicular, but randomly distributed in various positions of the concrete. At the same time, under the stress state, the angle between the fiber and the matrix will directly affect the bonding performance of the fiber / matrix interface. Professor Victor Li of the University of Michigan pointed out that the angle of the fiber will cause a reduction in fiber strength and an enhancement of the interface performance, also known as the "strength reduction effect and friction pulley effect". Therefore, the current test devices cannot well study the bonding performance of the fiber / matrix interface. The single method of pulling out the fiber perpendicular to the matrix cannot comprehensively obtain the complete data of the bonding performance of the fiber / matrix interface. And there are mainly two research methods for the influence of the angle on the fiber / matrix interface:

[0004] The first is to fix a single fiber at a specific angle in the cement matrix during the production of the specimen, and then use the perpendicular pulling-out method for testing. The disadvantage of this method is that the embedding length of the fiber in the matrix is affected by the angle and is not a constant length, which will greatly affect the accuracy of the test results;

[0005] The second is to make conical platforms with different inclination angles and conduct pull-out tests on this basis. The disadvantage of this method is that one angle corresponds to one platform, which will lead to a significant increase in cost. One test may require 4 - 6 platforms. The superposition and cooperation of multiple platforms will also lead to an increase in data errors and affect the accurate acquisition of data. Summary of the Invention

[0006] To overcome the defects of the existing technology, a single-fiber pulling-out device and a central non-offset testing method are provided to solve the above problems.

[0007] A multi-section rotating rod includes an adjusting rod one, an adjusting rod two, an adjusting rod three, a fixing plate and a base. The adjusting rod one, the adjusting rod two and the adjusting rod three are connected in sequence from bottom to top. The lower end of the adjusting rod one is connected with the base. The upper end of the adjusting rod one is hinged to the lower end of the adjusting rod two through a first connecting piece. The upper end of the adjusting rod two is hinged to the lower end of the adjusting rod three through a second connecting piece. The upper end of the adjusting rod three is hinged to the bottom surface of the fixing plate, and the top surface of the fixing plate is a connecting surface.

[0008] As a preferred solution: The upper end of the adjusting rod one is processed with a first narrow-width socket. The lower end of the adjusting rod two is a first sheet-shaped insertion end, and the first sheet-shaped insertion end is inserted into the first narrow-width socket. The first sheet-shaped insertion end is hinged to the inner walls on both sides of the first narrow-width socket through a first connecting piece. The upper end of the adjusting rod two is processed with a second narrow-width socket. The lower end of the adjusting rod three is a second sheet-shaped insertion end, and the second sheet-shaped insertion end is inserted into the second narrow-width socket. The second sheet-shaped insertion end is hinged to the inner walls on both sides of the second narrow-width socket through a second connecting piece.

[0009] As a preferred solution: The first connecting piece is a first connecting shaft, and the second connecting piece is a second connecting shaft.

[0010] As a preferred solution: The upper end of the adjusting rod three is a third sheet-shaped insertion end. Two vertical plates are processed on the bottom surface of the fixing plate. The third sheet-shaped insertion end is clamped between the two vertical plates, and the third sheet-shaped insertion end is hinged to the two vertical plates through a third connecting shaft.

[0011] A single-fiber pulling-out device including the multi-section rotating rod described in the first or second specific implementation manner includes an X-Y platform. The bottom surface of the X-Y platform is detachably connected to the connecting surface, and a single-fiber test specimen is pasted on the X-Y platform.

[0012] As a preferred solution: The single-fiber test specimen includes a matrix and a single fiber. One end of the single fiber is fixed in the matrix, and the other end of the single fiber is a free end.

[0013] As a preferred solution: It includes an upper matching component. The upper matching component includes an upper connecting plate, an upper connecting rod and a force sensor. The top surface of the upper connecting plate is connected to a testing machine through the upper connecting rod and the force sensor in sequence, and the upper connecting plate is bonded to the free end of the single fiber.

[0014] A center non-offset test method implemented by using a single-fiber pulling-out device described in Embodiment 3. The center non-offset test method is to determine the relationship between the lengths of the first adjusting rod, the second adjusting rod, the third adjusting rod, and the thickness value of the X-Y platform according to the test requirements and the specific type of the single-fiber test specimen. Then, under the cooperation of the first adjusting rod, the second adjusting rod, and the third adjusting rod, the single-fiber test specimen is rotated for testing, and relevant test data is obtained while ensuring that the single-fiber test specimen is always located on the central axis of the testing machine during the rotation test.

[0015] As a preferred solution: The process of determining the relationship between the lengths of the first adjusting rod, the second adjusting rod, the third adjusting rod, and the thickness value of the X-Y platform according to the test requirements and the specific type of the single-fiber test specimen is as follows:

[0016] The length of the first adjusting rod is l1, the length of the second adjusting rod is l2, the length of the third adjusting rod is l3, the thickness of the X-Y platform is l4, the position where the first connecting piece is located is the position of node A, the position where the second connecting piece is located is the position of node B, the position where the third connecting shaft is located is the position of node C, and the vertical projection position of the central axis of the testing machine on the single-fiber test specimen is the position of node D;

[0017] According to the angle θ3 required by the test, start rotating nodes A, B, and C respectively. The coordinates of point A are (0, 0);

[0018] When node A rotates by an angle θ1, the coordinates of node B are (l2sinθ1, l2cosθ1);

[0019] When node B is rotated by an angle θ2, the coordinates of node C at this time are obtained as (l2sinθ1 - l3sinθ2, l2cosθ1 + l3cosθ2);

[0020] When node C is rotated by an angle θ3, the coordinates of node D corresponding to the single-fiber test specimen are (l2sinθ1 - l3sinθ2 - l4sinθ3, l2cosθ1 + l3cosθ2 + l4cosθ3). When ensuring that the single-fiber test specimen is always located on the central axis of the testing machine, the X-direction coordinate of node D should be 0, that is, l2sinθ1 - l3sinθ2 - l4sinθ3 = 0;

[0021] Since the thickness l4 of the X-Y platform is a fixed value, the relationship satisfied by the lengths of the second adjusting rod and the third adjusting rod is obtained as:

[0022] l2sinθ1 - l3sinθ2 = l4sinθ3;

[0023] In the above formula, sinθ3 ≤ 1, so l2sinθ1 - l3sinθ2 ≤ l4;

[0024] The rotation angle value ranges of both Node A and Node B are from 0° to 180°;

[0025] The rotation angle value range of Node C is from 0° to 90°;

[0026] The angle range of a single fiber in the matrix in the single - fiber test specimen is from 0° to 90°;

[0027] Turn on the testing machine to ensure that the single - fiber test specimen makes continuous rotational movements under the central axis position of the testing machine, and collect and save the relevant data in real - time when the single - fiber test specimen is in a rotational movement state.

[0028] The beneficial effects of the present invention are as follows:

[0029] In the multi - joint rotating rod of the present invention, through the mutual cooperation among the first adjusting rod, the second adjusting rod, the third adjusting rod, the fixing plate and the base, a structural form of multi - rod multi - angle bending is formed. A three - rotatable - node structural form is formed between the first adjusting rod, the second adjusting rod, the third adjusting rod and the fixing plate. Cooperating with the X - Y platform, a single - fiber pull - out test at any angle can be realized on one platform. The multi - joint rotating rod can also be used in other tests that require multi - angle adjustment.

[0030] The single - fiber pull - out device in the present invention has a reasonable structure and is easy to operate, avoiding the use of multiple platforms in cooperation. Aiming at the limitation that the existing single - fiber pull - out test device can only bear vertical forces, using the design concept of imitating human joints, three rotatable and fixable nodes are adopted. The matrix can rotate to any angle within the range of 0 - 180°, while ensuring that the fiber is at the central axis of the testing machine, realizing a single - fiber pull - out test at any angle, achieving multi - angle and multi - aspect testing and research on the fiber / matrix interface performance. The testing principle is more in line with the actual situation of the fiber / matrix interface, facilitating a better exploration of the bonding performance of the fiber / matrix interface, and cooperating with the testing machine to obtain more accurate relevant data.

[0031] The center - non - deviation testing method in the present invention provides accurate and reliable structural testing - related limiting parameters for the single - fiber pull - out device. The testing process realized by the single - fiber pull - out device is more accurate, ensuring that the single - fiber pull - out position is reasonable and effective, avoiding repeated operations, saving costs and improving testing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the front - view structural schematic diagram of the multi - joint rotating rod;

[0033] Figure 2 It is the first front - view structural schematic diagram of the single - fiber pull - out device;

[0034] Figure 3 It is the three - dimensional structural schematic diagram of the multi - joint rotating rod;

[0035] Figure 4 Schematic structural diagram of a usage state of a single fiber pull-out device;

[0036] Figure 5 Schematic bottom view structural diagram of a fixing plate;

[0037] Figure 6 Second front view structural diagram of a single fiber pull-out device;

[0038] Figure 7 Schematic front view structural diagram when adjusting rod 1, adjusting rod 2, and adjusting rod 3 are coaxially arranged;

[0039] Figure 8 Single fiber pull-out force - displacement curve graph at 0°, in the graph, the matrix is a cement-based material and the fiber is a polyethylene fiber;

[0040] Figure 9 Single fiber pull-out force - displacement curve graph at 15°, in the graph, the matrix is a cement-based material and the fiber is a polyethylene fiber;

[0041] Figure 10 Single fiber pull-out force - displacement curve graph at 45°, in the graph, the matrix is a cement-based material and the fiber is a polyethylene fiber;

[0042] Figure 11 Single fiber pull-out force - displacement curve graph at 70°, in the graph, the matrix is a cement-based material and the fiber is a polyethylene fiber;

[0043] Figure 12 Single fiber pull-out force - displacement curve graph at 0°, in the graph, the matrix is a cement-based material and the fiber is a polyvinyl alcohol fiber material;

[0044] Figure 13 Single fiber pull-out force - displacement curve graph at 15°, in the graph, the matrix is a cement-based material and the fiber is a polyvinyl alcohol fiber material;

[0045] Figure 14 Single fiber pull-out force - displacement curve graph at 45°, in the graph, the matrix is a cement-based material and the fiber is a polyvinyl alcohol fiber material;

[0046] Figure 15 Single fiber pull-out force - displacement curve graph at 70°, in the graph, the matrix is a cement-based material and the fiber is a polyvinyl alcohol fiber material;

[0047] Figure 16 Schematic structural diagram of the positions of each node in the single fiber pull-out device in Embodiment 3;

[0048] Figure 17 Schematic structural diagram of the angle rotation principle in the single fiber pull-out device in Embodiment 3;

[0049] Figure 18 Schematic diagram for comparing single fiber pull-out force - displacement curves in Embodiment 3

[0050] In the figure: 1 - First adjusting rod; 1 - 1 - First narrow - width socket; 2 - Second adjusting rod; 2 - 1 - First sheet - like insertion end; 2 - 2 - Second narrow - width socket; 3 - Third adjusting rod; 3 - 1 - Second sheet - like insertion end; 3 - 2 - Third sheet - like insertion end; 4 - Fixed plate; 4 - 1 - Vertical plate; 5 - Base; 6 - First connecting piece; 7 - Second connecting piece; 8 - Connecting surface; 9 - X - Y platform; 10 - Single fiber test specimen; 10 - 1 - Matrix; 10 - 2 - Single fiber; 11 - Upper connecting plate; 12 - Upper connecting rod; 13 - Force sensor Specific embodiments

[0051] The following uses specific specific examples to illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention

[0052] Specific Embodiment 1: In combination with Figure 1 , Figure 3 , Figure 4 and Figure 5 describe this embodiment. This embodiment includes a first adjusting rod 1, a second adjusting rod 2, a third adjusting rod 3, a fixed plate 4, and a base 5. The first adjusting rod 1, the second adjusting rod 2, and the third adjusting rod 3 are all stainless - steel alloy rods. The first adjusting rod 1, the second adjusting rod 2, and the third adjusting rod 3 are connected in sequence from bottom to top. The lower end of the first adjusting rod 1 is connected to the base 5. The upper end of the first adjusting rod 1 is hinged to the lower end of the second adjusting rod 2 through a first connecting piece 6. The upper end of the second adjusting rod 2 is hinged to the lower end of the third adjusting rod 3 through a second connecting piece 7. The upper end of the third adjusting rod 3 is hinged to the bottom surface of the fixed plate 4. The top surface of the fixed plate 4 is the connecting surface 8

[0053] In this embodiment, the position where the first connecting piece 6 is located is the position of node A, the position where the second connecting piece 7 is located is the position of node B, and the position where the third connecting shaft is located is the position of node C. The operation process of determining the rotation angles at each node is as follows

[0054] The specific process of adjusting the included angle at node A is to adjust the included angle between the length direction of the first adjusting rod 1 and the length direction of the second adjusting rod 2; the specific process of adjusting the included angle at node B is to adjust the included angle between the length direction of the second adjusting rod 2 and the length direction of the third adjusting rod 3. The specific process of adjusting the included angle at node C is to adjust the included angle between the third adjusting rod 3 and the plate surface of the fixed plate 4

[0055] In this embodiment, the upper end of the first adjusting rod 1 is processed with a first narrow-width socket 1-1, the lower end of the second adjusting rod 2 is a first sheet-like insertion end 2-1, the first sheet-like insertion end 2-1 is inserted into the first narrow-width socket 1-1, and the first sheet-like insertion end 2-1 is hinged to the inner walls on both sides of the first narrow-width socket 1-1 through a first connecting member 6; the upper end of the second adjusting rod 2 is processed with a second narrow-width socket 2-2, the lower end of the third adjusting rod 3 is a second sheet-like insertion end 3-1, the second sheet-like insertion end 3-1 is inserted into the second narrow-width socket 2-2, and the second sheet-like insertion end 3-1 is hinged to the inner walls on both sides of the second narrow-width socket 2-2 through a second connecting member 7.

[0056] In this embodiment, the first connecting member 6 is a first connecting shaft, and the second connecting member 7 is a second connecting shaft.

[0057] In this embodiment, the upper end of the third adjusting rod 3 is a third sheet-like insertion end 3-2, two vertical plates 4-1 are processed on the bottom surface of the fixing plate 4, the third sheet-like insertion end 3-2 is clamped between the two vertical plates 4-1, and the third sheet-like insertion end 3-2 is hinged to the two vertical plates 4-1 through a third connecting shaft.

[0058] Specific Embodiment 2: With reference to Figures 1 to 7 This embodiment will be described. The single-fiber pulling-out device in this embodiment includes multiple rotating rods, an X-Y platform 9, and an upper matching assembly. The bottom surface of the X-Y platform 9 is detachably connected to the connecting surface 8, and a single-fiber test specimen 10 is pasted on the X-Y platform 9.

[0059] In this embodiment, the X-Y platform 9 is an existing product, and its working principle is the same as that of an existing X-Y platform.

[0060] In this embodiment, the upper matching assembly includes an upper connecting plate 11, an upper connecting rod 12, and a force sensor 13. The top surface of the upper connecting plate 11 is connected to the testing machine through the upper connecting rod 12 and the force sensor 13 in sequence, and the upper connecting plate 11 is bonded to the free end of a single fiber 10-2. The upper connecting plate 11 provides a connecting position for the free end of the single fiber 10-2 in the single-fiber test specimen 10, and the two are bonded. The upper connecting rod 12 is a single rod body, a solid metal rod body or a plastic rod body with a diameter less than 1 cm, which plays a connecting role. The force sensor 13 is an existing sensor product, and its working process is the same as that of an existing force sensor 13.

[0061] The multi - section rotating rod of this embodiment includes a first adjusting rod 1, a second adjusting rod 2, a third adjusting rod 3, a fixing plate 4 and a base 5. The first adjusting rod 1, the second adjusting rod 2 and the third adjusting rod 3 are connected in sequence from bottom to top. The lower end of the first adjusting rod 1 is connected to the base 5. The upper end of the first adjusting rod 1 is hinged to the lower end of the second adjusting rod 2 through a first connecting member 6. The upper end of the second adjusting rod 2 is hinged to the lower end of the third adjusting rod 3 through a second connecting member 7. The upper end of the third adjusting rod 3 is hinged to the bottom surface of the fixing plate 4, and the top surface of the fixing plate 4 is a connecting surface 8.

[0062] In this embodiment, the upper end of the first adjusting rod 1 is processed with a first narrow - width socket 1 - 1. The lower end of the second adjusting rod 2 is a first sheet - like insertion end 2 - 1. The first sheet - like insertion end 2 - 1 is inserted into the first narrow - width socket 1 - 1, and the first sheet - like insertion end 2 - 1 is hinged to the inner walls on both sides of the first narrow - width socket 1 - 1 through the first connecting member 6. The upper end of the second adjusting rod 2 is processed with a second narrow - width socket 2 - 2. The lower end of the third adjusting rod 3 is a second sheet - like insertion end 3 - 1. The second sheet - like insertion end 3 - 1 is inserted into the second narrow - width socket 2 - 2, and the second sheet - like insertion end 3 - 1 is hinged to the inner walls on both sides of the second narrow - width socket 2 - 2 through the second connecting member 7.

[0063] In this embodiment, the first connecting member 6 is a first connecting shaft, and the second connecting member 7 is a second connecting shaft.

[0064] In this embodiment, the position where the first connecting member 6 is located is the position of node A, the position where the second connecting member 7 is located is the position of node B, the position where the third connecting shaft is located is the position of node C, and the vertical projection position of the central axis of the testing machine on the single - fiber test specimen 10 is the position of node D.

[0065] The specific process of adjusting the angle at node A is to adjust the angle between the length direction of the first adjusting rod 1 and the length direction of the second adjusting rod 2. The specific process of adjusting the angle at node B is to adjust the angle between the length direction of the second adjusting rod 2 and the length direction of the third adjusting rod 3. The specific process of adjusting the angle at node C is to adjust the angle between the third adjusting rod 3 and the plate surface of the fixing plate 4, so as to realize the three - point angle adjustment process. Finally, the corresponding angle between the upper connecting plate 11 and the single - fiber test specimen 10 is realized. Since the single - fiber test specimen 10 is parallelly pasted to the X - Y platform 9, the above - mentioned process of adjusting the angle is equivalent to adjusting the angle between the upper connecting plate 11 and the X - Y platform 9.

[0066] In this embodiment, the upper end of the third adjusting rod 3 is a third sheet - like insertion end 3 - 2. Two vertical plates 4 - 1 are processed on the bottom surface of the fixing plate 4. The third sheet - like insertion end 3 - 2 is clamped between the two vertical plates 4 - 1, and the third sheet - like insertion end 3 - 2 is hinged to the two vertical plates 4 - 1 through a third connecting shaft.

[0067] There are two connection positions between the device in this embodiment and the testing machine. One position is that the base 5 is connected to the bottom of the testing machine. Specifically, when connecting, the holes in the middle of the base 5 are aligned with the holes of the testing machine, and then they are fixedly connected through pins. The upper end of the testing machine is connected to the upper connecting rod 12. During operation, the upper end of the testing machine drives the upper connecting rod 12 to move, and the force sensor 13 continuously obtains the relevant force signals of the single fiber 10-2 and transmits them to the terminal digital display. Among them, the testing machine is an existing product, and its working principle is the same as that of existing testing machines.

[0068] The testing principle of the single fiber pull-out device in the present invention is:

[0069] The matrix 10-1 is pasted on the X-Y platform 9, and then the single fiber 10-2 is fixedly connected in the matrix 10-1, with a free end exposed. The free end is adhered to the upper connecting plate 11, and then the upper connecting plate 11 is connected to the testing machine through the upper connecting rod 12 and the force sensor 13. As the testing machine moves, the upper connecting rod 12 drives the single fiber 10-2 to move through the upper connecting plate, so as to measure the pull-out force of the fiber through the force sensor 13.

[0070] Specific embodiment three: Combining Figures 1 - 18 To illustrate this embodiment, in this embodiment, the center non-offset testing method is to determine the relationship between the lengths of the first adjusting rod 1, the second adjusting rod 2, the third adjusting rod 3 and the thickness value of the X-Y platform 9 according to the testing requirements and the specific type of the single fiber test specimen 10, and then perform a rotation test on the single fiber test specimen 10 under the cooperation of the first adjusting rod 1, the second adjusting rod 2 and the third adjusting rod 3. During the rotation test, ensure that the single fiber test specimen 10 is always located on the central axis of the testing machine to obtain relevant test data.

[0071] The process of determining the relationship between the lengths of the first adjusting rod 1, the second adjusting rod 2, the third adjusting rod 3 and the thickness value of the X-Y platform 9 according to the testing requirements and the specific type of the single fiber test specimen 10 is as follows:

[0072] The length of the first adjusting rod 1 is l1, the length of the second adjusting rod 2 is l2, the length of the third adjusting rod 3 is l3, the thickness of the X-Y platform 9 is l4, the position where the first connecting piece 6 is located is the node A position, the position where the second connecting piece 7 is located is the node B position, the position where the third connecting shaft is located is the node C position, and the vertical projection position of the central axis of the testing machine on the single fiber test specimen 10 is the node D position;

[0073] According to the angle θ3 required by the test, start rotating nodes A, B and C respectively. The coordinates at point A are 0, 0;

[0074] When the A node rotates by θ1 angle, the coordinates of the B node are l2sinθ1, l2cosθ1;

[0075] When rotating node B by an angle of θ2, the coordinates of node C at this time are l2sinθ1 - l3sinθ2, l2cosθ1 + l3cosθ2;

[0076] When rotating node C by an angle of θ3, the coordinates of node D corresponding to the single - fiber test specimen 10 are l2sinθ1 - l3sinθ2 - l4sinθ3, l2cosθ1 + l3cosθ2 + l4cosθ3. When ensuring that the single - fiber test specimen 10 is always at the central axis position of the testing machine, the X - direction coordinate of node D should be 0, that is, l2sinθ1 - l3sinθ2 - l4sinθ3 = 0;

[0077] Since the thickness l4 of the X - Y platform 9 is a fixed value, it is obtained that the lengths of the second adjusting rod 2 and the third adjusting rod 3 satisfy the relational expression:

[0078] l2sinθ1 - l3sinθ2 = l4sinθ3;

[0079] In the above formula, sinθ3 ≤ 1, so l2sinθ1 - l3sinθ2 ≤ l4;

[0080] The value ranges of the rotation angles of node A and node B are both 0° to 180°;

[0081] The value range of the rotation angle of node C is 0° to 90°;

[0082] The angle range of a single fiber 10 - 2 in the matrix 10 - 1 of the single - fiber test specimen 10 is 0° to 90°, where the matrix 10 - 1 is a cement matrix.

[0083] Turn on the testing machine, ensure that the single - fiber test specimen 10 makes continuous rotational movements under the condition of being at the central axis position of the testing machine, and collect and save the relevant data of the single - fiber test specimen 10 during the rotational movement in real - time.

[0084] The single - fiber pulling - out device in this embodiment includes multiple rotating rods, an X - Y platform 9 and an upper matching component. The bottom surface of the X - Y platform 9 is detachably connected to the connecting surface 8, and the single - fiber test specimen 10 is pasted on the X - Y platform 9.

[0085] The upper matching component in this embodiment includes an upper connecting plate 11, an upper connecting rod 12 and a force sensor 13. The top surface of the upper connecting plate 11 is connected to the testing machine through the upper connecting rod 12 and the force sensor 13 in sequence, and the bottom surface of the upper connecting plate 11 is closely attached to the top surface of the single - fiber test specimen 10.

[0086] In this embodiment, the upper connecting plate 11 is an aluminum plate, and the upper connecting rod 12 is an aluminum rod. Such a setting is because the force for single fiber pull-out is usually very small, so the measuring range of the force sensor is also very small. The commonly used measuring range is 5N or 10N. The self-weight of the aluminum material is relatively small, about 50g, which indicates that the combination of the aluminum plate and the aluminum rod will not exceed the measuring range of the force sensor, will not affect the test results, and is conducive to obtaining more accurate data.

[0087] In this embodiment, both the upper connecting rod 12 and the force sensor 13 are connected and fixed to the testing machine by bolts, or can also be connected to the testing machine by clamping. The base 5, the first adjusting rod 1, the second adjusting rod 2, the third adjusting rod 3 and the fixing plate 4 are arranged from bottom to top. An X-Y platform 9 is connected to the fixing plate 4. The base 5 is connected to the X-Y platform 9 through three joints, and the first connecting shaft, the second connecting shaft and the third connecting shaft are fixed by bolts at the joints. When the matrix 10-1 in the single fiber test specimen 10 is a cement matrix, the cement matrix is adhered to the X-Y platform 9 by double-sided adhesive. The diameter and length of a single fiber 10-2 in the matrix 10-1 are several or dozens of micrometers. The single fiber 10-2 is adhered to the aluminum plate by glue. The aluminum plate is connected by bolts and the aluminum rod. As the testing machine starts to work, the crossbeam of the testing machine will drive the fiber to move upward, and the bonding friction force at the fiber / matrix interface is measured by the sensor, and the data is recorded in real time.

[0088] The X-Y platform 9 in this embodiment is an existing product that can be adjusted and moved in the X-axis and Y-axis directions.

[0089] The multi-section rotating rod in this embodiment includes the first adjusting rod 1, the second adjusting rod 2, the third adjusting rod 3, the fixing plate 4 and the base 5. The first adjusting rod 1, the second adjusting rod 2 and the third adjusting rod 3 are connected in sequence from bottom to top. The lower end of the first adjusting rod 1 is connected to the base 5. The upper end of the first adjusting rod 1 is hinged to the lower end of the second adjusting rod 2 through a first connecting member 6. The upper end of the second adjusting rod 2 is hinged to the lower end of the third adjusting rod 3 through a second connecting member 7. The upper end of the third adjusting rod 3 is hinged to the bottom surface of the fixing plate 4, and the top surface of the fixing plate 4 is the connecting surface 8.

[0090] In this embodiment, a connecting vertical plate, bolts or other connecting members are arranged in cooperation on the connecting surface 8 for connecting different forms of existing platform products in cooperation. The X-Y platform 9 or a platform with other structural forms can be connected to the connecting surface 8 by bonding or detachable connection.

[0091] In this embodiment, the upper end of the first adjusting rod 1 is machined with a first narrow-width socket 1-1, and the lower end of the second adjusting rod 2 is a first sheet-shaped insertion end 2-1. The first sheet-shaped insertion end 2-1 is inserted into the first narrow-width socket 1-1, and the first sheet-shaped insertion end 2-1 is hinged to the inner walls on both sides of the first narrow-width socket 1-1 through a first connecting member 6; the upper end of the second adjusting rod 2 is machined with a second narrow-width socket 2-2, and the lower end of the third adjusting rod 3 is a second sheet-shaped insertion end 3-1. The second sheet-shaped insertion end 3-1 is inserted into the second narrow-width socket 2-2, and the second sheet-shaped insertion end 3-1 is hinged to the inner walls on both sides of the second narrow-width socket 2-2 through a second connecting member 7.

[0092] In this embodiment, the first connecting member 6 is a first connecting shaft, and the second connecting member 7 is a second connecting shaft.

[0093] In this embodiment, the upper end of the third adjusting rod 3 is a third sheet-shaped insertion end 3-2. Two vertical plates 4-1 are machined on the bottom surface of the fixing plate 4. The third sheet-shaped insertion end 3-2 is clamped between the two vertical plates 4-1, and the third sheet-shaped insertion end 3-2 is hinged to the two vertical plates 4-1 through a third connecting shaft.

[0094] The following embodiments are described in combination with the beneficial effects of the present invention:

[0095] Example 1: In combination with Figures 1 - 11 Describe this embodiment: In this embodiment, the single-fiber test specimen 10 is a cement-based material specimen, and the matrix is a cement-based material. Its mix ratio is 505 kg / m3 of cement, 621 kg / m 3 , 536 kg / m of quartz sand (0.06 mm - 0.2 mm) 3 , 338 kg / m of water 3 , and 0.1% of water reducer. The fiber used is a polyethylene fiber. The diameter of the polyethylene fiber is 20 microns, the density is 0.97 kg / m3, and the tensile strength and elastic modulus are 3800 MPa and 3 GPa respectively. First, according to the requirements of the test, the joints A, B, and C are adjusted by certain angles respectively. Finally, the angles between the upper connecting plate 11 and the single-fiber test specimen 10 are 15°, 45°, and 70°. These three angles are respectively corresponding to three tests. Whether each angle is adjusted in place can be determined by a magnetic protractor. As Figure 4 shown, the single-fiber test specimen 10 is adhered to the X-Y platform 9 and then connected to the testing machine. Through fine adjustment of the X-Y platform 9, it is ensured that the polyethylene fiber is at the central axis of the testing machine, so as to ensure that the position of the single-fiber test specimen 10 under the axial force is reasonable and conducive to accurately obtaining the test data. Then the polyethylene fiber is adhered to the upper pressing plate 11. After the glue solidifies, the test is started. The force-displacement curve during the single-fiber pulling-out process is collected through the 10N force sensor 13 and the displacement sensor of the testing machine itself. AsFigures 8 - 11 As shown, the interfacial frictional force between the fiber and the matrix is calculated, and the calculation formula is as follows.

[0096]

[0097] In the formula, τ 0 is the interfacial frictional force between the fiber and the matrix, P max is the maximum force in the force-displacement curve, d f is the diameter of the fiber, l e is the embedding depth of the fiber in the matrix.

[0098] Table 1 gives the interfacial frictional forces between polyethylene fibers and the matrix at different angles, and it can be seen that the angle has a great influence on the interfacial properties. Therefore, it is very necessary to conduct the single-fiber pull-out test at an angle to study the fiber / matrix interfacial properties.

[0099] Table 1

[0100] angle 0° 15° 45° 70° <![CDATA[Fiber / matrix interfacial frictional force τ 0]]> 1.23 MPa 1.28 MPa 2.35 MPa 2.84 MPa

[0101] Example 2: Combined with Figures 12 - 15 To illustrate this example, the same cement mix ratio as in Example 1 is used, and the fiber used is polyvinyl alcohol fiber. The length of the polyvinyl alcohol fiber is 12 mm, the diameter is 39 μm, the ultimate tensile strength is 1600 MPa, and the density is 1300 kg / m 3 , and the elastic modulus is 42 GPa. Similar to Example 1, each node is rotated so that the X-Y platform 9 forms corresponding angles, which are 0, 15, 45, and 70 degrees respectively, that is, the included angles at nodes A, B, and C are adjusted respectively. Finally, the corresponding angle is formed between the central axis of the testing machine and the X-Y platform 9. Since the single fiber 10-2 is parallel to the central axis of the testing machine and the matrix 10-1 is parallel to the X-Y platform 9, the corresponding angle formed between the central axis of the testing machine and the X-Y platform 9 can specifically be the angle between the central axis of the testing machine and the single-fiber test specimen 10, the angle between the single fiber 10-2 and the X-Y platform 9, and the angle between the central axis of the testing machine and the X-Y platform 9. Both the device and method in the present invention can be realized, and the subsequent process is the same as that in Example 1. The final test results show that due to the low strength of the polyvinyl alcohol fiber, it is shown that the single fiber 10-2 has broken.

[0102] Example 3: Combined with Figures 16 - 18Description of this embodiment: The cement mix ratio is the same as that of the first and second embodiments, and the fibers used are the same as those of the first embodiment. In this embodiment, the lengths of the first adjusting rod 1, the second adjusting rod 2, and the third adjusting rod 3 are all 500 mm, and the height of the X-Y platform 9 is 50 mm. The purpose of the test is to conduct a single-fiber pull-out test at 45°, so the angles of nodes A, B, and C need to be adjusted. According to the center non-offset test method, the lengths of the second adjusting rod 2 and the third adjusting rod 3 satisfy the relationship: l2sinθ1 - l3sinθ2 = l4sinθ3. The first angle combination is to adjust θ1, θ2, and θ3 to 30°, 25.42°, and 45° respectively; the other angle combination is: adjust θ1, θ2, and θ3 to 45°, 34.05°, and 45°. Then, a magnetic protractor can be used to determine whether each angle is adjusted in place. After determining that each angle is adjusted in place, the single-fiber test specimen 10 is adhered to the X-Y platform 9, and then connected to the testing machine. Through fine adjustment of the X-Y platform 9, ensure that the polyethylene fiber is at the central axis of the testing machine, so as to ensure that the position of the single-fiber test specimen 10 under the axial force is reasonable, which is conducive to accurately obtaining the test data. Then, the polyethylene fiber is adhered to the upper pressure plate 11. After the glue solidifies, the test begins. The force-displacement curve during the single-fiber pull-out process is collected through the 10N force sensor 13 and the displacement sensor of the testing machine itself, so as to calculate the interfacial friction force between the fiber / matrix. The final test results show that the single-fiber pull-out test results are basically the same at different θ1 and θ2 angles. The structures, connection relationships, and operation methods not mentioned in this embodiment are the same as those of the third specific implementation manner.

Claims

1. A single fiber pulling-out device, characterized in that: It includes a multi-section rotating rod and an X-Y platform (9). The multi-section rotating rod includes a first adjusting rod (1), a second adjusting rod (2), a third adjusting rod (3), a fixing plate (4) and a base (5). The first adjusting rod (1), the second adjusting rod (2) and the third adjusting rod (3) are connected in sequence from bottom to top. The lower end of the first adjusting rod (1) is connected with the base (5). The upper end of the first adjusting rod (1) is hinged to the lower end of the second adjusting rod (2) through a first connecting member (6). The upper end of the second adjusting rod (2) is hinged to the lower end of the third adjusting rod (3) through a second connecting member (7). The upper end of the third adjusting rod (3) is hinged to the bottom surface of the fixing plate (4). The top surface of the fixing plate (4) is a connecting surface (8). The upper end of the first adjusting rod (1) is processed with a first narrow-width socket (1-1). The lower end of the second adjusting rod (2) is a first sheet-shaped insertion end (2-1). The first sheet-shaped insertion end (2-1) is inserted into the first narrow-width socket (1-1). The first sheet-shaped insertion end (2-1) is hinged to the inner walls on both sides of the first narrow-width socket (1-1) through the first connecting member (6). The upper end of the second adjusting rod (2) is processed with a second narrow-width socket (2-2). The lower end of the third adjusting rod (3) is a second sheet-shaped insertion end (3-1). The second sheet-shaped insertion end (3-1) is inserted into the second narrow-width socket (2-2). The second sheet-shaped insertion end (3-1) is hinged to the inner walls on both sides of the second narrow-width socket (2-2) through the second connecting member (7). The upper end of the third adjusting rod (3) is a third sheet-shaped insertion end (3-2). Two vertical plates (4-1) are processed on the bottom surface of the fixing plate (4). The third sheet-shaped insertion end (3-2) is clamped between the two vertical plates (4-1). The third sheet-shaped insertion end (3-2) is hinged to the two vertical plates (4-1) through a third connecting shaft. The bottom surface of the X-Y platform (9) is detachably connected to the connecting surface (8). A single-fiber test specimen (10) is pasted on the X-Y platform (9). The position where the first connecting member (6) is located is the position of node A. The position where the second connecting member (7) is located is the position of node B. The position where the third connecting shaft is located is the position of node C. The range of the rotation angle of node A and node B is both 0° to 180°. The range of the rotation angle of node C is 0° to 90°.

2. The single fiber pulling-out device according to claim 1, characterized in that: The first connecting member (6) is a first connecting shaft, and the second connecting member (7) is a second connecting shaft.

3. The single fiber pulling-out device according to claim 1, characterized in that: The single-fiber test specimen (10) includes a matrix (10-1) and a single fiber (10-2). One end of the single fiber (10-2) is fixed in the matrix (10-1), and the other end of the single fiber (10-2) is a free end.

4. The single fiber pulling-out device according to claim 3, characterized in that: It includes an upper matching component. The upper matching component includes an upper connecting plate (11), an upper connecting rod (12) and a force sensor (13). The top surface of the upper connecting plate (11) is connected to a testing machine through the upper connecting rod (12) and the force sensor (13) in sequence. The upper connecting plate (11) is bonded to the free end of the single fiber (10-2).

5. A center non-offset testing method implemented by using the single fiber pulling-out device according to claim 4, characterized in that: The described center non-offset test method determines the relationship between the lengths of the first adjusting rod (1), the second adjusting rod (2), the third adjusting rod (3), and the thickness value of the X-Y platform (9) based on the test requirements and the specific type of the single-fiber test specimen (10). Then, with the cooperation of the first adjusting rod (1), the second adjusting rod (2), and the third adjusting rod (3), a rotation test is carried out on the single-fiber test specimen (10). During the rotation test, relevant test data are obtained while ensuring that the single-fiber test specimen (10) is always at the central axis position of the testing machine.

6. The center non-offset testing method according to claim 5, characterized in that: The process of determining the relationship between the lengths of the first adjusting rod (1), the second adjusting rod (2), the third adjusting rod (3), and the thickness value of the X-Y platform (9) based on the test requirements and the specific type of the single-fiber test specimen (10) is as follows: The length of the first adjusting rod (1) is l1, the length of the second adjusting rod (2) is l2, the length of the third adjusting rod (3) is l3, the thickness of the X-Y platform (9) is l4. The position where the first connecting piece (6) is located is the position of node A, the position where the second connecting piece (7) is located is the position of node B, the position where the third connecting shaft is located is the position of node C, and the vertical projection position of the central axis of the testing machine on the single-fiber test specimen (10) is the position of node D. According to the angle θ3 required by the test, nodes A, B, and C are respectively rotated. The coordinates at point A are (0, 0). When node A is rotated by an angle θ1, the coordinates of node B are (l2sinθ1, l2cosθ1). When node B is rotated by an angle θ2, the coordinates of node C at this time are obtained as (l2sinθ1 - l3sinθ2, l2cosθ1 + l3cosθ2). When node C is rotated by an angle θ3, the coordinates of node D corresponding to the single-fiber test specimen (10) are (l2sinθ1 - l3sinθ2 - l4sinθ3, l2cosθ1 + l3cosθ2 + l4cosθ3). When ensuring that the single-fiber test specimen (10) is always at the central axis position of the testing machine, the X-direction coordinate of node D should be 0, that is, l2sinθ1 - l3sinθ2 - l4sinθ3 = 0. Since the thickness l4 of the X-Y platform (9) is a fixed value, the relationship satisfied by the lengths of the second adjusting rod (2) and the third adjusting rod (3) is obtained as: l2sinθ1 - l3sinθ2 = l4sinθ3; In the above formula, sinθ3 ≤ 1, so l2sinθ1 - l3sinθ2 ≤ l4; The value range of the rotation angles of node A and node B is both 0° to 180°; The value range of the rotation angle of node C is 0° to 90°; The angle range of a single fiber (10-2) in the matrix (10-1) in the single-fiber test specimen (10) is 0° to 90°; Start the testing machine, ensure that the single-fiber test specimen (10) makes continuous rotational movements at the central axis position of the testing machine, and collect and save in real time the relevant data of the single-fiber test specimen (10) during the rotational movement.

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