Forming device and method for preparing sample for single fiber pull-out test without cutting

Abstract

The invention discloses a forming device and method for preparing a sample for a single fiber pull-out test without cutting, the device comprises a lower clamp assembly, an upper clamp assembly and a sample forming plate, the upper clamp assembly and the lower clamp assembly are both of a detachable half-and-half structure, and a plurality of forming grooves are formed in the sample forming plate; the upper clamp assembly and the lower clamp assembly are used for clamping single fibers, the single fibers correspond to the forming grooves in a one-to-one mode and perpendicularly penetrate through the forming grooves, and guide grooves are formed in the two sides of the lower clamp assembly respectively and used for constraining and guiding the single fibers. According to the forming device, the needed single fiber drawing sample can be obtained only by placing the single fiber and pouring the cement material, the cutting step is directly omitted, the single single fiber drawing sample is formed at a time, time and labor are saved, accuracy is good, and various problems caused by cutting of a large cement matrix sample are avoided; and the whole forming device is simple in structure and easy to manufacture and use.

Description

Technical Field

[0001] The present invention relates to the technical field of single - fiber pull - out specimen preparation, and particularly relates to a forming device and method for preparing specimens for single - fiber pull - out tests without cutting. Background Art

[0002] When studying the toughening mechanism of fibers in cement - based materials, it is crucial to understand the interfacial properties between fibers and the matrix. The single - fiber pull - out test is a common means to explore such interfacial properties. Through this test, key parameters such as the bond strength and slip characteristics between fibers and the matrix can be accurately obtained, thereby deeply revealing the toughening mechanism of fiber - reinforced cement - based materials.

[0003] Currently, there are many deficiencies in the traditional methods for preparing specimens for single - fiber pull - out tests. On the one hand, during the specimen preparation process, it is often necessary to cut the formed specimens to obtain specimens of appropriate sizes containing single fibers. The cutting process is not only cumbersome and complex, requiring professional cutting equipment and operators, but also easily damages the interface between fibers and the matrix, affecting the accuracy of test results. On the other hand, existing specimen forming devices are difficult to precisely control the position and distribution state of fibers in the matrix, resulting in uneven quality of the prepared specimens and poor repeatability and reliability of test results.

[0004] In addition, most existing specimen preparation devices are poured from the contact surface between fibers and cement - based materials, and this method has obvious defects. Errors are inevitably generated during the pouring process, and at the same time, the volume of specimens will change during the curing process. These factors combined make the actual thickness of the final specimens different from the designed thickness, and there are also errors in the thickness of specimens from different batches. This not only affects the accurate measurement of interfacial performance parameters between fibers and cement matrices, but also brings difficulties to the comparative analysis between different test results.

[0005] These problems limit the in - depth study of the interfacial properties between fibers and cement matrices. Therefore, developing a method for preparing specimens for single - fiber pull - out tests without cutting and the corresponding specimen forming device has important practical significance, and can provide a more accurate and reliable experimental basis for the study of the toughening mechanism of fiber - reinforced cement - based materials. Summary of the Invention

[0006] The purpose of the present invention is to address the problems existing in the prior art and provide a forming device and preparation method for specimens for single - fiber pull - out tests, which are simple in structure, quick to load and unload, free from cutting, high in sample preparation precision, stable in specimens, and high in production efficiency.

[0007] To achieve the above - mentioned purpose, the technical solution adopted by the present invention is: A forming device for preparing specimens for single-fiber pull-out tests without cutting, comprising a lower fixture assembly and an upper fixture assembly detachably connected to the lower fixture assembly. Both the upper fixture assembly and the lower fixture assembly are split into two semi-structures. A specimen forming plate is clamped by the semi-structures. The specimen forming plate is provided with a plurality of forming grooves. Between the upper fixture assembly and the lower fixture assembly is used to clamp single fibers. The single fibers are arranged in one-to-one correspondence with the forming grooves and vertically pass through the forming grooves. Guide grooves are respectively arranged on both sides of the lower fixture assembly, and the guide grooves are used to restrain and guide the single fibers.

[0008] By improving the structures and cooperation forms of the upper fixture assembly, the lower fixture assembly and the specimen forming plate, this forming device for preparing specimens for single-fiber pull-out tests without cutting only needs to place single fibers and pour cement materials to obtain the required single-fiber pull-out specimens, directly eliminating the cutting step. Single single-fiber pull-out specimens are formed at one time, saving time and effort, with good accuracy, and avoiding various problems caused by cutting large cement matrix specimens. Moreover, the entire forming device has a simple structure, is easy to manufacture and use, has quick loading and unloading, and has a high efficiency in preparing specimens.

[0009] After the specimen forming plate is clamped and fixed by the lower fixture assembly of the forming device, the guide grooves on both sides of the lower fixture assembly can be used to easily restrain and guide single fibers, simplifying the sample preparation process to simply placing single fibers in the specimen forming grooves and then guiding the two ends to the guide grooves on both sides for fixation respectively. Such a design greatly reduces the operation difficulty of single-fiber positioning and fixation, and at the same time ensures that the single fibers can be perpendicular to the cement-based material.

[0010] The advantage of the open structure of the forming grooves is also reflected in the subsequent demolding of the specimens. After the specimens are formed, opening the upper fixture assembly and the lower fixture assembly can easily remove the complete specimens with single fibers, which is beneficial to the subsequent pull-out tests. The specimens prepared by this device have single fibers protruding from both ends, and this design also ensures that when possible errors occur during the experimental operation or curing process and the fibers are damaged, the side with good fiber state can be selected for testing.

[0011] Further, the lower fixture assembly includes a pair of lower clamping blocks. Guide grooves are respectively arranged on the outer sides of the pair of lower clamping blocks. Connection parts are respectively arranged at both ends of the lower clamping blocks, and the connection parts are used to connect an adjacent pair of the lower clamping blocks and the lower clamping blocks to the upper fixture assembly.

[0012] Further, the connection part is an L-shaped connecting arm, and positioning connection holes are respectively arranged in two directions on the connecting arm.

[0013] In some embodiments, a position identifier is provided at the inner-side edge of the upper surface of the lower clamping block. By providing the position identifier, it is beneficial for the alignment of the specimen forming plate to ensure that the single fiber can pass through the exact middle of the forming groove.

[0014] Further, the guiding grooves are triangular grooves arranged at equal intervals, and the depth of the guiding grooves is 0.5 - 1 mm. The gradually changing cross-sectional structure of the triangular grooves from the outside to the inside can be used to clamp the single fiber.

[0015] In some embodiments, an arc-shaped groove is provided at the guiding groove. The diameter of the arc-shaped groove is larger than the width of the notch of the guiding groove. A pluggable fixing rod is provided at the arc-shaped groove, and an elastic ball head is provided at the end of the fixing rod. The diameter of the elastic ball head is not less than the diameter of the arc-shaped groove. This way can better fix the single fiber and keep the single fiber in a straightened state.

[0016] Further, the upper fixture assembly includes a pair of upper clamping plates. Positioning connection holes are provided at both ends of the pair of upper clamping plates, and the positioning connection holes are used to connect with the lower fixture assembly.

[0017] Further, the thickness of the specimen forming plate does not exceed 5 mm. In the clamped state, the upper end surface of the specimen forming plate is flush with the upper end surface of the upper fixture assembly, ensuring that it is not easy to overflow during the subsequent casting of the cement-based material and facilitating scraping.

[0018] Further, the forming grooves are arranged at equal intervals on the specimen forming plate. The depth of the forming groove is greater than the width of the forming groove, and the distance between adjacent forming grooves is not less than the thickness of the specimen forming plate.

[0019] A method for preparing specimens for single fiber pull-out tests without cutting. The preparation method uses the forming device for preparing specimens for single fiber pull-out tests without cutting as described above. The preparation method includes the following steps: Place the specimen forming plate between the split structures of the lower fixture assembly, finely adjust the position of the specimen forming plate, and make the connection line of the guiding grooves on both sides of the lower fixture assembly be in the exact middle of the forming groove of the specimen forming plate. Fix a pair of the lower fixture assemblies through fasteners; Take a number of single fibers, and slowly place each single fiber from the middle of each forming groove one by one. Fix the two ends of the single fiber in the guiding grooves at both ends respectively and ensure that the single fiber is straightened; Place the upper fixture assembly on the lower fixture assembly. The split structure of the upper fixture assembly clamps the forming groove and is fixed on the lower fixture assembly through fasteners; Pour the cement-based material required for the specimen above the forming groove of the specimen forming plate, oscillate and level it. After the cement-based material hardens, remove the upper fixture assembly and the lower fixture assembly, and take out the specimens in the forming groove one by one.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By improving the structures and cooperation forms of the upper fixture assembly, the lower fixture assembly and the specimen forming plate, the forming device for preparing specimens for single fiber pull-out test without cutting can obtain the required single fiber pull-out specimens only by placing single fibers and pouring cement materials, directly eliminating the cutting step. The single fiber pull-out specimens are formed at one time, which is time-saving and labor-saving, with good accuracy, and avoids various problems caused by cutting large cement matrix specimens; 2. The whole forming device has a simple structure, is easy to manufacture and use, and is quick to load and unload. Compared with the existing complex molds for batch forming, it can greatly reduce the preparation time and operation time of specimen preparation, which is beneficial to improving the preparation efficiency of specimens; 3. The guiding grooves can easily restrain and guide single fibers. Such a design greatly reduces the operation difficulty of single fiber positioning and fixing, and at the same time ensures that the single fibers can be perpendicular to the cement-based material; 4. The pouring surface of the specimen is the side surface of the specimen, which effectively ensures the flatness of the contact surface between the single fiber and the cement-based material, and ensures that the volume change of the specimen during the curing process will not affect the specimen thickness and the contact surface between the single fiber and the cement-based material at all. Therefore, the actual thickness of the final specimen is equivalent to the designed thickness, and the error of the specimen thickness in different batches is small, ensuring the accurate measurement of the interfacial performance parameters between the single fiber and the cement matrix, which is beneficial to the comparative analysis between different test results; 5. The specimens prepared by this device have single fibers protruding from both ends. This design also ensures that when possible errors occur during the experimental operation or curing process and cause fiber damage, the side with good fiber state can be selected for testing; 6. Through the setting of the position marks, it is beneficial to the alignment of the specimen forming plate to ensure that the single fiber can pass through the exact middle of the forming groove. In this way, the position and distribution state of the single fiber in the matrix can be precisely controlled, so as to prepare specimens with consistent quality, making the repeatability and reliability of the test results better. Description of the Drawings

[0021] Figure 1 It is an overall schematic diagram of a forming device for preparing specimens for single fiber pull-out test without cutting according to the present invention; Figure 2 It is a structural schematic diagram of the specimen forming plate of the forming device according to the present invention; Figure 3 It is a structural schematic diagram of placing single fibers on the lower fixture assembly according to the present invention; Figure 4 It is a structural schematic diagram after the forming device according to the present invention is closed; Figure 5Schematic structural diagram of another guiding groove of the forming device in Embodiment 2 of the present invention; Figure 6 Schematic structural diagram of a fixing plate used in cooperation with the arc-shaped groove in Embodiment 2 of the present invention; In the figure: 1, lower clamping block; 2, upper clamping plate; 3, specimen forming plate; 4, forming groove; 5, guiding groove; 6, connecting portion; 7, positioning connection hole; 8, fastener; 9, relief groove; 10, single fiber; 11, arc-shaped groove; 12, fixing rod; 13, elastic ball head; 14, fixing plate. Detailed implementation manners

[0022] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0023] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "middle", "upper", "lower", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Embodiment 1

[0024] As Figures 1 to 4 shown, a forming device for preparing specimens for single fiber pull-out tests without cutting includes a lower fixture assembly and an upper fixture assembly detachably connected to the lower fixture assembly. Both the upper fixture assembly and the lower fixture assembly are splitable half structures, and a specimen forming plate 3 is clamped by the half structures. A plurality of forming grooves 4 are provided on the specimen forming plate 3. Between the upper fixture assembly and the lower fixture assembly is used to clamp single fibers 10. The single fibers 10 are arranged in one-to-one correspondence with the forming grooves 4 and vertically pass through the forming grooves 4. Guiding grooves 5 are respectively provided on both sides of the lower fixture assembly, and the guiding grooves 5 are used to restrain and guide the single fibers 10.

[0025] The forming device for preparing specimens for single-fiber pull-out tests without cutting improves the structures and matching forms of the upper fixture assembly, the lower fixture assembly, and the specimen forming plate. By simply placing single fibers 10 and pouring cement materials, the required single-fiber pull-out specimens can be obtained, directly eliminating the cutting step. The single-fiber pull-out specimens are formed at one time, saving time and effort, with good accuracy, and avoiding various problems caused by cutting large cement matrix specimens. Moreover, the entire forming device has a simple structure, is easy to manufacture and use, has quick loading and unloading, and a high efficiency in preparing specimens.

[0026] Both the upper fixture assembly and the lower fixture assembly are of a split structure, enabling them to be fully opened for taking out the formed specimens. Moreover, this split structure is also easy to assemble and adjust. Cooperating with the specimen forming plate with multiple forming grooves, multiple specimens can be prepared simultaneously. Compared with the existing complex molds for batch forming, it can greatly reduce the preparation time and operation time for specimen preparation, which is beneficial to improving the specimen preparation efficiency.

[0027] After the forming device clamps and fixes the specimen forming plate 3 with the lower fixture assembly, by using the guiding grooves 5 on both sides of the lower fixture assembly, the single fibers 10 can be easily constrained and guided. The sample preparation process is simplified to simply placing the single fibers 10 in the specimen forming grooves and then guiding the two ends to the guiding grooves 5 on both sides for fixation respectively. Such a design greatly reduces the operation difficulty of single-fiber positioning and fixation, and at the same time ensures that the single fibers can be perpendicular to the cement-based material.

[0028] The specimen forming plate 3 is of a plate-shaped structure, and its forming grooves 4 are completely open. It can use the opposite side walls of the upper fixture assembly and the lower fixture assembly as forming surfaces. After clamping and fixing, the upper slot openings of the forming grooves 4 are used as pouring ports for specimen pouring, without the need for additional templates and forming cavities. Moreover, this design enables the poured surface of the specimen to be the side surface of the specimen, which effectively ensures the flatness of the contact surface between the single fibers 10 and the cement-based material, and ensures that the volume change of the specimen during the curing process will not affect the specimen thickness and the contact surface between the single fibers and the cement-based material at all. As a result, the actual thickness of the final specimen is equivalent to the designed thickness, and the error in the specimen thickness of different batches is small, ensuring the accurate measurement of the interfacial performance parameters between the single fibers and the cement matrix, which is beneficial to the comparative analysis between different test results.

[0029] The advantage of the open structure of the forming grooves 4 is also reflected in the subsequent demolding of the specimens. After the specimens are formed, opening the upper fixture assembly and the lower fixture assembly can easily remove the complete specimens with single fibers, which is beneficial to the subsequent pull-out tests. The specimens prepared by this device have single fibers protruding from both ends. This design also ensures that when possible errors occur during the experimental operation or curing process and cause damage to the fibers, the side with good fiber state can be selected for testing.

[0030] Further, the lower fixture assembly includes a pair of lower clamping blocks 1. Guide grooves 5 are respectively arranged on the outer sides of the pair of lower clamping blocks 1. Connecting portions 6 are respectively arranged at both ends of the lower clamping block 1. The connecting portion 6 is used to connect a pair of adjacent lower clamping blocks 1 and the lower clamping block 1 and the upper fixture assembly.

[0031] The upper fixture assembly includes a pair of upper clamping plates 2. Yielding grooves 9 are respectively arranged at both ends of the pair of upper clamping plates 2. Positioning connection holes 7 are arranged at the yielding grooves 9 for connection with the lower fixture assembly. The upper fixture assembly designed in this way has a simple structure and can be conveniently used in cooperation with the lower fixture assembly. The upper clamping plate and the lower clamping block are arranged correspondingly.

[0032] Through the connecting portion 6, a pair of lower clamping blocks 1 can be connected and fixed together, and at the same time, the upper fixture assembly above can also be connected. The bottom surface of the lower clamping block 1 is a flat surface and can be horizontally placed on the operating table to provide a horizontal and stable foundation. Arranging the connecting portion on both sides does not affect the placement of the specimen forming plate.

[0033] Specifically, the connecting portion 6 is an L-shaped connecting arm. Positioning connection holes 7 are respectively arranged on the connecting arm in the horizontal and vertical directions. The positioning connection holes on a pair of lower clamping blocks 1 are arranged in one-to-one correspondence, and the two can be fixed by connecting with a fastener 8, such as a bolt. The positioning connection holes on the lower clamping block 1 and the positioning connection holes on the upper clamping plate 2 are also corresponding, and they can also be fixed by connecting with the fastener 8.

[0034] In some embodiments, a position mark (not shown in the drawings) is arranged on the inner edge of the upper surface of the lower clamping block 1. Through the setting of the position mark, it is beneficial to the alignment of the specimen forming plate to ensure that the single fiber can pass through the exact middle of the forming groove, and a drawing specimen with single fibers at both ends in the middle can be obtained. In this way, the position and distribution state of the single fiber in the matrix can be precisely controlled, so as to prepare specimens with consistent quality, making the repeatability and reliability of the test results better.

[0035] Since the forming groove is of an open structure, it is difficult to judge the position of the single fiber in the forming groove whether the single fiber is placed or not; after setting the position mark and matching and echoing the position of the position mark with the guide grooves on both sides, it is very easy to position the clamped specimen forming plate. The center position of the forming groove can be determined by the scale value on the position mark. After making it correspond to the guide groove, the placed single fiber will surely vertically pass through the center of the forming groove. Of course, if single fibers in other position states are needed, they can also be adjusted adaptively.

[0036] By the above method, not only the alignment method of the single fiber and the forming groove is simplified, the alignment difficulty is reduced, the operation convenience is improved, but also it is ensured that each single fiber can be arranged in the forming groove at the preset position.

[0037] In order to further cooperate with the position identification and improve the convenience of positioning and adjusting the specimen forming plate, the specimen forming plate and the lower clamping block can be set to a magnetic attraction structure, so that during the adjustment process, it can be ensured that the specimen forming plate is always closely attached to the side wall of the lower clamping block.

[0038] In the original state, when the specimen forming plate is placed between a pair of the lower clamping blocks, if the pair of lower clamping blocks are not locked, the specimen forming plate is loose. At this time, it is also the time to adjust the specimen forming plate, but the operator needs to hold the specimen forming plate by hand to keep it in a vertical state. After setting the magnetic attraction structure, the magnetic attraction can be used to keep the specimen forming plate in a vertical state automatically, enabling the operator to free up hands for other operations, and there is no need to worry about the inclination of the specimen forming plate. Moreover, this method does not affect the horizontal position adjustment of the specimen forming plate, that is, the alignment adjustment. Only by sliding the specimen forming plate can the position be adjusted to complete the alignment operation.

[0039] The magnetic attraction structure can be a magnet embedded in the specimen forming plate and / or the lower clamping block, or the lower part of the specimen forming plate can be made of a magnetic material and directly adsorbed to the lower clamping block made of a metal material (such as steel or iron).

[0040] Furthermore, the guiding grooves 5 are triangular grooves arranged at equal intervals, and the depth of the guiding grooves 5 is 0.5 - 1 mm. The cross-section of the triangular groove is triangular. When the two ends of the single fiber 10 are placed in the triangular groove, pressing the single fiber 10 can fix the single fiber in the triangular groove. Although this fixing force is not large, it can maintain the state of the single fiber. The most important thing is that the operation is simple and convenient.

[0041] Furthermore, the thickness of the specimen forming plate 3 does not exceed 5 mm. In the clamped state, the upper end surface of the specimen forming plate 3 is flush with the upper end surface of the upper fixture assembly, ensuring that it is not easy to overflow during the subsequent casting of the cement-based material, facilitating scraping, and there is no cement adhesion between adjacent specimens, making it easy to take out individual specimens intact.

[0042] A plurality of forming grooves 4 are provided on the specimen forming plate 3, and the shape, size and thickness of the forming grooves 4 can be designed according to the requirements of the specimen. The specimens formed by casting cement in each forming groove can be directly used.

[0043] Further, the forming grooves 4 are arranged at equal intervals on the specimen forming plate. The depth of the forming groove is greater than the width of the forming groove, and the distance between adjacent forming grooves is not less than the thickness of the specimen forming plate. Example 2

[0044] The difference between this embodiment and Example 1 lies in the improvement of the guiding grooves.

[0045] Specifically, as Figure 5 shown, each guiding groove 5 is respectively provided with an arc-shaped groove 11. The diameter of the arc-shaped groove 11 is greater than the notch width of the guiding groove 5. A pluggable fixing rod 12 is provided at the arc-shaped groove 11. An elastic ball head 13 is provided at the end of the fixing rod 12. The diameter of the elastic ball head 13 is not less than the diameter of the arc-shaped groove 11, larger than the opening size of the arc-shaped groove 11, and has a spherical inner cavity, which can allow the elastic ball head 13 to be stuck into the arc-shaped groove 11 to press the single fiber 10.

[0046] In order to further fix the single fiber 10 in the guiding groove 5 and facilitate its straightening, the arc-shaped groove 11 and the fixing rod 12 are provided for supporting use. After the single fiber 10 is placed in the guiding groove 5, the elastic ball head 13 is inserted into the arc-shaped groove 11, and the elastic ball head 13 will press the single fiber 10. At this time, one end of the single fiber 10 is fixed in the guiding groove 5. Pull the other end of the single fiber 10 to make it straight, and the other end can also be fixed through the arc-shaped groove and the fixing rod on the other side of the lower fixture assembly.

[0047] The position of the arc-shaped groove 11 is equivalent to an anchor point position, and the single fiber can be temporarily fixed in the guiding groove 5 by means of the extrusion force of the elastic ball head 13. The fixing rod 12 can be pulled out during subsequent specimen forming. The fixing rod 12 is convenient for plugging and unplugging. The fixing rod 12 can be a single rod body or a structure arranged side by side on the fixing plate 14, as Figure 6 shown, so that the single fibers 10 in a row of guiding grooves 5 can be fixed simultaneously.

[0048] When preparing the drawing specimen, the length of the single fiber protruding from both ends of the specimen can also be set according to the test requirements. The length of a single fiber can be the path length between the arc-shaped grooves in the guiding grooves on both sides of the lower fixture assembly plus the reserved tail length. This path length is the distance from the arc-shaped grooves on both sides to the upper surface of the lower clamping block plus the width of a pair of upper surfaces of the lower clamping blocks and the width of the specimen forming plate. This reserved tail length can be several millimeters to several centimeters, such as leaving about 5 mm, so as to be able to hold the tail end of the single fiber. Example 3

[0049] A method for preparing specimens for single-fiber pull-out tests without cutting. The preparation method uses the forming device for preparing specimens for single-fiber pull-out tests described in Example 1 or Example 2. The preparation method includes the following steps: Place the specimen forming plate between the half structures of the lower fixture assembly, finely adjust the position of the specimen forming plate, so that the connection line of the guiding grooves on both sides of the lower fixture assembly is exactly in the middle of the forming groove of the specimen forming plate, and fix a pair of the lower fixture assemblies through fasteners; Before clamping, a thin layer of lubricant can be evenly applied to the inside of the forming groove and the side walls of the upper and lower fixture assemblies corresponding to the forming groove for subsequent demoulding. The lubricant is vaseline or other oily agents; Take several single fibers, slowly place each single fiber down from the middle of each forming groove one by one, fix the two ends of the single fiber in the guiding grooves at both ends respectively and ensure that the single fiber is straightened; Place the upper fixture assembly on the lower fixture assembly. The half structure of the upper fixture assembly clamps the forming groove and is fixed on the lower fixture assembly through fasteners; Pour the cement-based material required for the specimen above the forming groove of the specimen forming plate, oscillate and level it, wipe off the excess material. After the cement-based material hardens, remove the upper fixture assembly and the lower fixture assembly, and take out each specimen in the forming groove one by one.

[0050] Specifically, place the entire forming device in a curing environment at 20 degrees Celsius and a humidity greater than 95%. After curing for 24 hours or longer, the specimen is completely hardened. At this time, take out the forming device, remove the upper and lower fixture assemblies, take out the specimen forming plate, and gently take out the pull-out specimen with single fibers at both ends.

[0051] The specimens obtained by the above method have good uniformity, do not require a cutting step, have good integrity and no cracking. There is a sufficient length of single-fiber ends left on the upper end surface of the specimen, which can facilitate the single-fiber pull-out test. When specimens of different sizes and thicknesses need to be manufactured, only the specimen forming plate with corresponding sizes and thicknesses needs to be replaced, which is very flexible and convenient.

[0052] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A forming device for preparing specimens for single fiber pull-out tests without cutting, characterized in that, It includes a lower clamp assembly and an upper clamp assembly detachably connected to the lower clamp assembly, the upper clamp assembly and the lower clamp assembly are both detachable half structures, a sample forming plate is clamped by the half structures, and a plurality of forming grooves are provided on the sample forming plate; the upper clamp assembly and the lower clamp assembly are used to clamp single fibers, the single fibers are arranged in one-to-one correspondence with the forming grooves and vertically pass through the forming grooves, and guide grooves are respectively provided on both sides of the lower clamp assembly, and the guide grooves are used to restrain and guide the single fibers.

2. The forming device for preparing specimens for single fiber pull-out test without cutting according to claim 1, characterized in that, The lower clamp assembly includes a pair of lower clamp blocks, the outer sides of the pair of lower clamp blocks are respectively provided with the guide grooves, and the two ends of the lower clamp blocks are respectively provided with connecting parts, and the connecting parts are used to connect the adjacent pair of lower clamp blocks and the lower clamp blocks and the upper clamp assembly.

3. The forming device for preparing a specimen for a single fiber pull-out test without cutting according to claim 2, wherein The connecting portion is an L-shaped connecting arm, and the connecting arm is provided with positioning connecting holes in two directions respectively.

4. The forming device for preparing a specimen for a single fiber pull-out test without cutting according to claim 2, characterized in that, A position mark is provided on the inner edge of the upper surface of the lower clamping block.

5. The forming device for preparing specimens for single fiber pull-out test without cutting according to claim 1, characterized in that, The guide grooves are triangular grooves arranged at equal intervals, and the depth of the guide grooves is 0.5-1 mm.

6. The forming device for preparing a specimen for a single fiber pull-out test without cutting according to claim 1, characterized in that, An arc-shaped groove is provided at the guide groove, the diameter of which is larger than the slot width of the guide groove, a pluggable fixing rod is provided at the arc-shaped groove, an elastic ball head is provided at the end of the fixing rod, and the diameter of the elastic ball head is not smaller than the diameter of the arc-shaped groove.

7. The forming device for preparing a specimen for a single fiber pull-out test without cutting according to claim 1, wherein, The upper clamp assembly comprises a pair of upper clamp plates, both ends of the pair of upper clamp plates are respectively provided with clearance grooves, and the clearance grooves are provided with positioning connection holes for connecting with the lower clamp assembly.

8. The forming device for preparing specimens for single fiber pull-out test without cutting according to claim 1, characterized in that, The thickness of the sample forming plate does not exceed 5 mm, and in the clamped state, the upper end surface of the sample forming plate is flush with the upper end surface of the upper clamp assembly.

9. The forming device for preparing a specimen for a single fiber pull-out test without cutting according to claim 1, characterized in that, The molding grooves are arranged at equal intervals on the sample molding plate, the depth of the molding grooves is greater than the width of the molding grooves, and the spacing between adjacent molding grooves is not less than the thickness of the sample molding plate.

10. A method for preparing a specimen for a single fiber pull-out test without cutting, characterized in that, The preparation method uses the molding device for preparing a single fiber pullout test specimen without cutting as claimed in any one of claims 1 to 9, and the preparation method comprises the following steps: Place the sample forming plate between the half structures of the lower fixture assembly, fine-tune the position of the sample forming plate so that the connecting line of the guide grooves on both sides of the lower fixture assembly is in the middle of the forming groove of the sample forming plate, and fix the pair of lower fixture assemblies by fasteners; Take a number of single fibers, and slowly put them down from the middle of each of the forming grooves one by one, fix the two ends of the single fibers in the guide grooves at the two ends respectively, and ensure that the single fibers are straightened; Placing the upper clamp assembly on the lower clamp assembly, the half structure of the upper clamp assembly clamps the forming groove and is fixed to the lower clamp assembly by fasteners; Pour the cement-based material required for the sample onto the molding groove of the sample molding plate, shake and smooth it, and after the cement-based material hardens, remove the upper clamp assembly and the lower clamp assembly, and take out the samples in the molding groove one by one.

Images