Multi-angle bidirectional single fiber drawing test piece forming device

Abstract

The utility model relates to the technical field of material performance detection, in particular to a multi-angle bidirectional single fiber drawing test piece forming device, which aims to solve the problem that a forming device in the prior art cannot flexibly regulate and control the fiber angle, and comprises at least two forming units, the adjacent forming units are spliced to form a mold cavity, and the mold cavity is used for pouring a concrete test block; a plurality of fiber turning points are arranged on each of the two sides of the mold cavity; the fiber turning point on the left side of the mold cavity is a first turning point, and the fiber turning point on the right side of the mold cavity is a second turning point; one end of the fiber is fixed at the first turning point and penetrates through the test block in the mold cavity, and the other end is fixed at the second turning point. According to the scheme, a special device capable of flexibly regulating and controlling the fiber angle and realizing multi-angle bidirectional single fiber drawing test piece forming is developed.

Description

Technical Field

[0001] This utility model relates to the field of material performance testing technology, and in particular to a multi-angle bidirectional single fiber drawing specimen forming device. Background Technology

[0002] In the research and application of fiber-reinforced cementitious composites, the interfacial bonding performance between the fiber and the matrix is ​​a key factor determining the macroscopic mechanical behavior of the material.

[0003] As a core means of characterizing the properties of this interface, the single fiber pull-out test should simulate the stress state of the fiber in a real component as much as possible.

[0004] In practical engineering, fibers are often at different tilt angles due to load or initial distribution, rather than in an ideal straight alignment.

[0005] Studies have shown that the fiber tilt angle significantly affects its pull-out behavior and interfacial properties, including altering the pull-out force, inducing localized matrix spalling, and generating slip strengthening. Therefore, systematically studying the fiber pull-out mechanism at different tilt angles is of great significance for accurately evaluating the properties of composite materials.

[0006] Several single-fiber pull-out specimen preparation devices have been developed and applied. For example, Chinese Patent CN110702492B discloses a bidirectional single-fiber pull-out cement matrix specimen mold. This mold consists of a bottom layer, a middle layer, and a top layer connected by bolts to form a molding chamber. The two ends of the fiber are fixed to the column and pass through the gaps between the plates, and a diaphragm is used to form the specimen. Compared with traditional methods, this device has the advantages of simple operation and high testing efficiency.

[0007] However, the fiber arrangement direction of this device is relatively simple, and it can only realize the straight fiber embedding. It cannot simulate the fiber pull-out behavior under different tilt angles, resulting in insufficient pull-out data and difficulty in accurately reflecting the multi-angle stress state of the fiber in actual working conditions.

[0008] Although existing research has established several theoretical models for the pull-out behavior of tilted fibers, describing key mechanisms such as the retardation effect and matrix spalling, at the experimental level, there is still a lack of dedicated equipment capable of efficiently and accurately preparing single-fiber pull-out specimens with various preset tilt angles. This technological bottleneck severely restricts the systematic study of fiber-matrix interface properties.

[0009] Therefore, developing a specialized device that can flexibly adjust the fiber angle and achieve multi-angle bidirectional single fiber drawing specimen molding is of urgent need and important value for deeply revealing the influence of fiber tilt angle on interface properties and promoting the optimized design of fiber-reinforced cementitious materials. Utility Model Content

[0010] This invention provides a multi-angle, bidirectional single-fiber drawing specimen forming device to solve the problem that existing forming devices cannot flexibly adjust the fiber angle.

[0011] To alleviate the above-mentioned technical problems, the technical solution provided by this utility model is as follows:

[0012] A multi-angle bidirectional single-fiber drawing specimen forming device includes: at least two forming units;

[0013] Adjacent molding units are spliced ​​together to form a mold cavity, which is used to pour concrete test blocks;

[0014] Multiple fiber turning points are provided on both sides of the mold cavity;

[0015] The fiber turning point on the left side of the mold cavity is taken as the first turning point, and the fiber turning point on the right side of the mold cavity is taken as the second turning point;

[0016] One end of the fiber is fixed at the first turning point, passes through the test block inside the mold cavity, and the other end is fixed at the second turning point.

[0017] Furthermore, the molding unit includes a base layer, an intermediate layer, and a top layer;

[0018] The middle and upper layers are provided with grooves on their edges, and the grooves of the two molding units are joined together to form a mold cavity.

[0019] Furthermore, the fibers are located between the middle layer and the upper layer.

[0020] Furthermore, it also includes a limiting post that passes through the middle layer and the upper layer, with the fiber fixed to the limiting post.

[0021] Furthermore, it also includes a fixing rod, with the base layer, intermediate layer and upper layer fixed by at least one fixing rod, which is located at the edge of the molding unit.

[0022] Furthermore, the molding unit located at the edge is called the edge molding unit, and the molding unit located in the middle is called the middle molding unit. The edge molding unit has a groove on the side near the middle molding unit, and the middle molding unit has grooves on both sides.

[0023] Furthermore, the edge forming unit includes a side plate, and at least one groove is provided on one side of the side plate;

[0024] The intermediate forming unit includes an intermediate plate, and grooves are provided on both sides of the intermediate plate;

[0025] The grooves on the side plate and the grooves on the middle plate meet to form the mold cavity.

[0026] Furthermore, a slit is provided in the middle of the intermediate forming unit, through which the cutter cuts the fiber.

[0027] Furthermore, a diaphragm is inserted into the mold cavity.

[0028] Furthermore, the two ends of the base layer protrude from the middle and upper layers, and the ends of the fibers are fixed to the protrusions of the base layer.

[0029] The beneficial effects of the multi-angle, bidirectional, single-fiber drawing specimen forming device provided in this solution are analyzed as follows:

[0030] Since the molding device provided in this solution has multiple fiber turning points on both sides of the mold cavity, the fiber angle can be freely selected when fixing the fiber, thus achieving the effect of multi-angle testing. Furthermore, since the fiber in this solution can be tested in both directions, bidirectional testing can be achieved.

[0031] In summary, this solution has developed a specialized device that can flexibly adjust the fiber angle and achieve multi-angle bidirectional single fiber drawing specimen molding. This device is of urgent need and significant value for deeply revealing the influence of fiber tilt angle on interfacial properties and promoting the optimized design of fiber-reinforced cementitious materials. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of this utility model, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 Structural diagram of the multi-angle bidirectional single-fiber drawing specimen forming device provided by this utility model;

[0034] Figure 2 The upper structural diagram of the multi-angle bidirectional single fiber drawing specimen forming device provided by this utility model is omitted.

[0035] Figure 3 A structural diagram of the upper mold in the middle part of the multi-angle bidirectional single fiber drawing specimen forming device provided by this utility model;

[0036] Figure 4 for Figure 1 A magnified view of part A in the image.

[0037] Icons: 100-forming unit; 110-mold cavity; 120-fiber turning point; 121-first turning point; 122-second turning point; 130-limiting support; 140-fixing rod; 150-grooving slit; 160-diaphragm; 101-base layer; 102-intermediate layer; 103-upper layer; 001-edge forming unit; 002-intermediate forming unit; 200-fiber; 300-fixing component. Detailed Implementation

[0038] This embodiment discloses a multi-angle, bidirectional single-fiber drawing specimen forming device; please refer to [other documentation / reference]. Figures 1 to 4 The molding device includes at least two molding units 100; adjacent molding units 100 are spliced ​​to form a mold cavity 110, which is used to pour concrete test blocks; multiple fiber turning points 120 are provided on both sides of the mold cavity 110; the fiber turning point 120 on the left side of the mold cavity 110 is the first turning point 121, and the fiber turning point 120 on the right side of the mold cavity 110 is the second turning point 122; one end of the fiber 200 is fixed to the first turning point 121, passes through the test block inside the mold cavity 110, and the other end is fixed to the second turning point 122.

[0039] When it is necessary to conduct a pull-out force test on fiber 200, first fix one end of fiber 200 to the first turning point 121, then fix the other end of fiber 200 to the second turning point 122, and finally pour concrete into the mold cavity 110. After the concrete solidifies, a concrete test block is formed. After demolding, fix the end of fiber 200 to the testing equipment, and then the subsequent pull-out force test of fiber 200 can be carried out.

[0040] Since the molding device provided in this solution has multiple fiber turning points 120 on both sides of the mold cavity 110, the angle of the fiber 200 can be freely selected when fixing the fiber 200, so the effect of multi-angle testing can be achieved. Furthermore, since the fiber 200 in this solution can be tested in both directions, bidirectional testing can be achieved.

[0041] In summary, this solution develops a specialized device that can flexibly adjust the angle of fiber 200 and achieve multi-angle bidirectional single fiber 200 drawing specimen molding. This device is of urgent need and significant value for revealing the influence of fiber 200 tilt angle on interfacial properties and promoting the optimized design of fiber 200 reinforced cementitious materials.

[0042] The shape and structure of the molding device are described in detail below:

[0043] The molding unit 100 includes a base layer 101, an intermediate layer 102, and an upper layer 103;

[0044] The edges of the middle layer 102 and the upper layer 103 are provided with grooves, and the grooves of the two molding units 100 are joined together to form a mold cavity 110.

[0045] The molding unit 100 located at the edge is designated as edge molding unit 001, and the molding unit 100 located in the middle is designated as middle molding unit 002. A groove is provided on the side of the edge molding unit 001 closest to the middle molding unit 002, and grooves are provided on both sides of the middle molding unit 002. When the edge molding unit 001 and the middle molding unit 002 are joined together, their respective grooves surround each other to form a mold cavity 110.

[0046] Preferably, the edge forming unit 001 includes a side plate, and at least one groove is provided on one side of the side plate; the middle forming unit 002 includes a middle plate, and grooves are provided on both sides of the middle plate; the grooves of the side plate and the grooves of the middle plate are joined to form a mold cavity 110. Figure 1 and Figure 2 In the middle plate, four grooves are provided on the side along its length, and four grooves are provided on each of the two side edges along its length. When the side plates and the middle plates are joined, four complete mold cavities 110 are formed. When the middle plates are joined, four complete mold cavities 110 are also formed at the adjacent edges of the two middle plates. Of course, the number of mold cavities 110 can be set to other numbers according to actual needs, such as 3, 5, 6, etc.

[0047] Preferably, the mold cavity 110 is shaped as an irregular hexagon, which is formed by splicing two trapezoids, with the side along the length of the molding unit 100 being longer than the other sides. Of course, the shape of the mold cavity 110 is set according to the inspection standards, and the mold cavity 110 can be set to different shapes and sizes depending on the different inspection standards.

[0048] The specific location of fiber 200 is detailed below:

[0049] To test the pull-out force of fiber 200, it needs to penetrate the concrete. Therefore, fiber 200 is positioned between the upper surface of intermediate layer 102 and the lower surface of upper layer 103. This ensures that after concrete pouring, the thickness of the intermediate layer 102 is equal to the thickness of the upper layer 103, placing fiber 200 precisely in the middle. During the pull-out force test, fiber 200 experiences uniform stress, better reflecting its pull-out resistance. For specific fiber 200 placement details, please refer to [link to relevant documentation]. Figure 2 , Figure 2 This is a top view of the intermediate layer 102, from which you can see the layout and orientation of the fibers 200.

[0050] To fix the fiber 200, the molding device in this embodiment also includes a limiting post 130, which longitudinally passes through the intermediate layer 102 and the upper layer 103. The number of limiting posts 130 can correspond to the number of mold cavities 110. For example, one limiting post 130 may be located on each side of a mold cavity 110, or two limiting posts 130 may be located on each side of a mold cavity 110. Since the fiber 200 is fixed to the limiting post 130, the position of the limiting post 130 is related to the angle of the fiber 200. Therefore, the more limiting posts 130 there are, the more angles the fiber 200 can choose.

[0051] To fix the relative positions of the base layer 101, intermediate layer 102, and upper layer 103, the molding device further includes fixing rods 140, which are preferably located at the edges of the molding unit 100. More preferably, multiple rods are provided at all four edges of the molding device. To fix both the intermediate layer 102 and the upper layer 103 to the base layer 101, the fixing rods 140 should pass through the base layer 101, intermediate layer 102, and upper layer 103 simultaneously. As shown in the figure, six fixing rods 140 are provided on the transverse long side of the molding device. To avoid interference with the limiting support column 130, it is more preferable that multiple fixing rods 140 are provided on the two transverse long sides, while no fixing rods 140 are provided on the longitudinal long side.

[0052] One of the reasons for setting up multiple molding units 100 in this scheme is to mold multiple test blocks at one time. This scheme can mold multiple test blocks at one time in the horizontal direction. However, after the test blocks are demolded, the fibers 200 between multiple test blocks are connected. Therefore, it is necessary to cut the fibers 200 between adjacent test blocks.

[0053] Therefore, the molding device in this embodiment is also provided with a grooving slit 150. The grooving slit 150 is located at the middle position of the intermediate molding unit 002, and its extension direction is the longitudinal direction on the horizontal plane. It is located between two adjacent molding test blocks. After the concrete is poured, the cutter is inserted into the grooving slit 150 to cut the fiber 200, thereby preventing the fibers 200 between adjacent test blocks from connecting together after demolding. For details on the location where the cutter cuts the fiber 200, please refer to [link to relevant documentation]. Figure 2 In actual use, it is not required that the length of the cut fiber 200 be completely consistent; it is only required that the fiber 200 be cut. Therefore, although cutting the fiber 200 at different angles at one time cannot guarantee that all the fiber 200s are of the same length, it still meets the experimental requirements.

[0054] To allow for the molding of more test blocks at once, a diaphragm 160 is inserted into the mold cavity 110. The diaphragm 160 is preferably made of polytetrafluoroethylene (PTFE). Alternatively, a release agent can be applied to the surface of the diaphragm 160 to facilitate the formation of two test blocks after demolding from one mold cavity 110. In this design, a diaphragm 160 passes through all test blocks along the longitudinal direction on the horizontal plane. Figure 2 In the middle, there are a total of 5 groups of test blocks in the longitudinal direction on the horizontal plane, each with a diaphragm 160 inserted. After demolding, the diaphragm 160 is removed. Each longitudinal group can obtain 8 small test blocks, and a total of 40 test blocks can be obtained from the 5 groups.

[0055] To ensure that fiber 200 is within the effective testing area, a single fiber 200 is positioned at the midpoint of its length along the specimen height. The final height of diaphragm 160 should be greater than the cumulative thickness of the intermediate layer 102 and the upper layer 103 to ensure that it can completely separate the cement matrix on both sides of diaphragm 160 after casting, forming an independent test unit.

[0056] It should be further explained that: based on the thickness of the upper layer 103 and the horizontal dimensions of the mold cavity in the horizontal direction of the upper layer 103, preset insertion points are determined on the diaphragm. Subsequently, a needle is used to pierce at these points. Since the diameter of the needle is larger than that of the fiber, the resulting hole provides the fiber with a stress buffer and a margin for adaptive fine-tuning. During the final winding of the fiber around the two points and tightening it, the fiber can complete its final linear positioning within this margin, thereby ensuring that it does not generate harmful lateral stress when passing through the diaphragm. Furthermore, the diaphragm itself possesses a certain degree of flexibility; minor deformation or localized damage does not affect the final demolding of the concrete specimen. In an optional embodiment, the two ends of the base layer 101 protrude from the intermediate layer 102 and the upper layer 103, and the ends of the fiber 200 are fixed to the protrusions of the base layer 101. Please refer to [link to specific details]. Figure 1 and Figure 2 The two free ends of the four fibers 200 protrude from the intermediate layer 102 and are fixed to the upper surface of the base layer 101. The specific fixing method can be, for example, by using a fastener 300, such as adhesive tape, to stick to the surface of the base layer 101.

[0057] The specimen casting process steps are as follows:

[0058] 1) Preparation and positioning of diaphragm 160: According to the mold size and the number of specimens, the polytetrafluoroethylene diaphragm 160 is pre-cut to the specified size with a blade. A line mark is drawn at the middle height position of the concrete specimen corresponding to the diaphragm.

[0059] 2) Insertion and positioning of a single fiber 200: Cut a single fiber 200 of appropriate length and insert it into the eye of the lead needle. Holding the lead needle with the fiber 200 inserted, insert it sequentially through all the marked and positioned polytetrafluoroethylene diaphragms 160.

[0060] 3) Fixing of Fiber 200 and Mold Assembly: Temporarily fix one end of the fiber 200, which has passed through the diaphragm 160, to the corresponding position on the bottom layer using tape. Then, precisely align and overlap the intermediate layer 102 with the bottom layer. Ensure that each PTFE diaphragm 160 is located in the center of the reserved gap of each module unit of the intermediate layer 102. Next, wind the fiber 200 around the positioning post of the intermediate layer 102 along the preset path, tighten it to make it straight, and fix the tail end of the fiber 200 to the bottom layer with tape. After completing this step, the single fiber 200 will be tensioned and positioned on the surface of the intermediate layer 102, and at the same time, each mold cavity 110 is completely divided into two independent parts by the vertical PTFE diaphragm 160;

[0061] 4) Final assembly of the mold and positioning of fiber 200: All mold cavities 110 of the upper layer 103 are precisely aligned with and stacked with the corresponding mold cavities 110 of the middle layer plate. Then, the middle layer 102, upper layer 103, and bottom layer are connected and tightened using fixing rods 140, thus solidifying the entire mold system into a single unit. This assembly process ensures that each fiber 200 is precisely fixed in the cavity formed by the middle layer 102 and the upper layer 103, thereby placing the fiber 200 in the designed central position in the final molded cement specimen.

[0062] 5) Applying the release agent and protecting the fiber 200: Use a cotton swab to evenly apply the release agent to the bottom and sides of the mold groove and the sides of the PTFE membrane 160. During the application process, the application area must be strictly controlled to ensure that the release agent completely avoids the surface of the fiber 200, in order to prevent it from affecting the subsequent fiber 200-matrix interface bonding performance test.

[0063] 6) Casting and compaction of cement-based slurry: Prepare cement-based slurry by mixing according to the mix proportions. Use a small spoon to pour the slurry into each mold cavity 110 separated by the diaphragm 160 in stages. During the casting process, use a fine needle to tamp and vibrate to remove air bubbles. Care must be taken to avoid the fibers 200 during operation to prevent disturbance or damage. After casting, ensure that the top of the slurry is flush with the upper surface of the upper 103 module and that the bottom is in full contact with the bottom surface.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A multi-angle bidirectional single fiber pull-out specimen forming device, characterized by: The application relates to a multi-angle bidirectional single-fiber pull-out test piece forming device. The application comprises: at least two forming units; neighboring forming units are spliced to form a mold cavity for pouring a concrete test piece; a plurality of fiber turning points are arranged on the two sides of the mold cavity; a fiber one end is fixed to a first turning point on the left side of the mold cavity, and the other end is fixed to a second turning point on the right side of the mold cavity.

2. The multi-angle bidirectional single fiber pullout specimen forming device according to claim 1, characterized in that: The forming unit comprises a base layer, an intermediate layer and an upper layer; the edge portions of the intermediate layer and the upper layer are provided with grooves, and the grooves of the two forming units are mutually butted to form the mold cavity.

3. The multi-angle bidirectional single-fiber pull-out test piece forming device according to claim 2, wherein: the fiber is located between the intermediate layer and the upper layer.

4. The multi-angle bidirectional single-fiber pull-out test piece forming device according to claim 3, wherein: a limiting support is further arranged, the limiting support passes through the intermediate layer and the upper layer, and the fiber is fixed to the limiting support.

5. The multi-angle bidirectional single-fiber pull-out test piece forming device according to claim 4, wherein: a fixing plug is further arranged, the base layer, the intermediate layer and the upper layer are fixed by the at least one fixing plug, and the fixing plug is arranged at the edge of the forming unit.

6. The multi-angle bidirectional single-fiber pull-out test piece forming device according to claim 5, wherein: an edge forming unit is arranged at the edge of the forming unit, a middle forming unit is arranged in the middle of the forming unit, a groove is arranged on the side of the edge forming unit close to the middle forming unit, and grooves are arranged on the two sides of the middle forming unit.

7. The multi-angle bidirectional single-fiber pull-out test piece forming device according to claim 6, wherein: the edge forming unit comprises an edge plate, at least one groove is arranged on one side of the edge plate; the middle forming unit comprises a middle plate, and grooves are arranged on the two sides of the middle plate; the grooves of the edge plate and the middle plate are butted to form the mold cavity.

8. The multi-angle bidirectional single-fiber pull test specimen forming device of claim 7, wherein: A cutting groove is arranged in the middle of the middle forming unit, and a cutter cuts the fiber from the cutting groove.

9. The multi-angle bidirectional single-fiber pull test specimen forming device of claim 8, wherein: A diaphragm is arranged in the mold cavity.

10. The multi-angle bidirectional single-fiber pull test specimen forming device of claim 9, wherein: The two ends of the base layer protrude from the intermediate layer and the upper layer, and the end portion of the fiber is fixed to the protruding portion of the base layer.

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