Transverse tow composite material sample preparation method and mold

Abstract

The present invention discloses a method and a mold for preparing a transverse tow composite material sample. The mold comprises a base plate and two groove plates arranged on the base plate in a mirror-symmetrical manner. The two groove plates are arranged at intervals, and the interval in the middle forms a fiber groove. The groove plate and the base plate are connected by a fixed structure. Clamping mechanisms are arranged at both ends of the fiber groove along the slotting direction. A plurality of parallel grooves are formed on the groove plate, and the grooves are semi-through grooves with one end open. The grooves on the two groove plates are connected to form a casting groove. The sample preparation method comprises two steps: sample preparation and sample demoulding. The mold of the present invention is not easy to deform, has small thermal expansion, high heat transfer efficiency, and improves the sample molding quality; sample damage is avoided during demoulding, and the demoulding success rate is improved; the discreteness of the test results is reduced, and the test accuracy is improved; the sample preparation and demoulding processes are simple to operate, saving time and effort.

Description

Technical Field

[0001] The invention belongs to the field of material testing, and in particular relates to a method for preparing a transverse tow composite material sample and a mould. Background Art

[0002] Fiber reinforced composite materials have been rapidly developed in recent years due to their good mechanical strength and stability, long-term storage and other advantages, especially in the fields of aerospace, navigation, transportation, sports equipment, etc. The interface between the fiber and the matrix in fiber reinforced composite materials is often a relatively weak area in the composite material, so the evaluation of its interface performance is of great significance to the application of composite materials in engineering.

[0003] In recent years, relevant researchers have gradually developed a method for evaluating interfacial bonding strength using transverse fiber bundle composite materials. Among them, Shiqiang Deng disclosed a method for preparing transverse fiber bundle composite material samples and a mold in "Assessment of interfacial bonding between polymer threads and epoxy resin by transverse fibre bundle (TFB) tests". The method uses a rubber mold, in the middle of the resin casting trough, along the direction perpendicular to the length of the casting trough, to cut the side wall of the casting trough with a knife, and the cut crosses the entire mold, and the lower edge of the cut is flush with the bottom of the casting trough. When preparing the sample, the fiber bundle is placed in the cut, and the fiber bundle crosses the casting trough in the middle position. Finally, the resin is poured into the casting trough, and the transverse fiber bundle composite material is obtained by heating and curing.

[0004] However, this method still has the following problems: (1) The rubber mold is prone to bending and deformation during the heating and curing process, which makes the spline bend after curing and does not meet the test requirements; (2) The heat transfer effect of the rubber mold is poor during the heating process, which makes the resin insufficiently heated during the curing process; (3) The rubber mold expands significantly when heated, and the size of the casting trough changes greatly during the heating process, which makes the size of the spline change greatly, and there is a large curing internal stress inside the spline; (4) During the demolding process, since the mold is a whole, the spline has to be pried or broken, which damages the spline and leads to a low demolding success rate; (5) The rubber mold is easily damaged during the sample preparation and demolding process, and the cut seam is easy to relax and widen after long-term use. These factors all lead to a short service life of the mold. Therefore, it is urgent to develop a transverse tow composite material sample preparation method and mold with good molding quality, stable fiber bundle area size, simple operation, high demolding success rate, and mold not easy to damage, so as to provide more accurate data for the interface performance evaluation of fiber reinforced composite materials. Summary of the invention

[0005] The present invention is proposed to solve the problems existing in the prior art in the process of preparing transverse tow composite material samples, such as poor strip forming quality, difficulty in adjusting the fiber volume content in the composite material area, low demoulding success rate, and easy damage to the mold. Its purpose is to provide a method for preparing transverse tow composite material samples and a mold.

[0006] The present invention is achieved through the following technical solutions:

[0007] A mold for preparing a transverse tow composite material sample comprises a base plate and two groove plates arranged on the base plate in mirror symmetry, the two groove plates are arranged at intervals, the interval in the middle forms a fiber groove, and the groove plates and the base plate are connected by a fixed structure; clamping mechanisms are arranged at both ends of the fiber groove; a plurality of grooves are formed on the groove plate, and two symmetrical grooves form a casting groove.

[0008] In the above technical solution, the clamping mechanism is arranged at both ends of the fiber groove along the groove direction.

[0009] In the above technical solution, a plurality of the grooves are arranged in parallel, and the grooves are half-through grooves with one end open.

[0010] In the above technical solution, the fixing structure includes multiple upper positioning holes and multiple mounting holes formed on the groove plate, and multiple lower positioning holes and multiple screw holes formed on the base plate; the positioning pins are inserted between the upper positioning holes and the lower positioning holes; the bolts pass through the mounting holes and are threadedly connected to the screw holes.

[0011] In the above technical solution, the plurality of lower positioning holes are arranged in one-to-one correspondence with the plurality of upper positioning holes on the two groove plates; and the plurality of screw holes are arranged in one-to-one correspondence with the mounting holes on the two groove plates.

[0012] In the above technical solution, the multiple upper positioning holes are arranged in parallel and dispersed on both sides of each groove, and the upper positioning holes are arranged close to the open end of the groove; the multiple mounting holes are arranged in two rows, one row is arranged on both sides of each groove, and the other row is arranged close to the closed end of the groove.

[0013] In the above technical solution, the side wall of the closed end of the groove is inclined, and the inclination angle is 30°~60°.

[0014] In the above technical solution, the shape of the casting trough is a rectangle, a dumbbell, or a rectangle with two V-shaped notches formed in the middle.

[0015] In the above technical solution, handles are provided on both sides of the bottom plate.

[0016] A method for preparing a transverse tow composite material sample comprises the following steps:

[0017] (I) Sample preparation

[0018] (i) Install a groove plate on the base plate and fix the two together with dowel pins and bolts;

[0019] (ii) placing the fiber in contact with the side wall of the groove plate and the top surface of the bottom plate, and fixing the two ends of the fiber by a clamping mechanism to keep the fiber straight;

[0020] (iii) installing another groove plate on the base plate, fixing the two by means of positioning pins and bolts, pouring resin into the casting trough, heating and curing, and obtaining a test specimen;

[0021] (II) Sample demoulding

[0022] (i) Remove all positioning pins and nuts, loosen the clamping mechanism, and separate the groove plate and the base plate;

[0023] (ii) Place something under the sample to keep the groove plate suspended in the air, and press the groove plate evenly until the sample is separated from the groove plate.

[0024] The beneficial effects of the present invention are:

[0025] The present invention provides a method for preparing a transverse fiber bundle composite material sample and a mold. During the heating and curing process, the mold is not easy to deform, has little thermal expansion, and has high heat transfer efficiency, which greatly improves the molding quality of the sample. During the demolding process, there is no need to pry or bend the sample, especially when the fiber bundle area of ​​the sample is separated from the fiber groove, it is much smoother, thereby avoiding damage to the sample and improving the success rate of demolding. The fiber groove size is determined by the gap between the side walls of two groove plates and is controlled by multiple positioning pins with high precision, thereby reducing the width difference of the fiber bundle area between each sample and helping to reduce the discreteness of the test result. By adjusting the fiber yarn spreading width, the actual fiber width can be ensured to be the same as the depth of the casting groove, thereby ensuring that the fiber width is the same as the sample thickness, and ultimately improving the test accuracy. The metal mold has high firmness, the fiber groove is not easy to be damaged, and the service life of the mold is greatly improved. The sample preparation and demolding process are simple to operate, saving time and effort. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of a mold for preparing a transverse tow composite material sample of the present invention;

[0027] Figure 2 It is a schematic diagram of the exploded structural portion of a mold for preparing a transverse tow composite material sample of the present invention.

[0028] in:

[0029] 1 Base plate 2 Groove plate

[0030] 3 Clamping mechanism 4 Groove

[0031] 5 Upper positioning hole 6 Mounting hole

[0032] 7 Lower positioning hole 8 Screw hole

[0033] 9 Dowel pin 10 Bolt

[0034] 11. Fiber.

[0035] For ordinary technicians in this field, other relevant drawings can be obtained based on the above drawings without any creative work. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0037] Example 1

[0038] like Figure 1 , 2 As shown, a transverse tow composite material sample preparation mold comprises a base plate 1 and two groove plates 2 arranged on the base plate 1 in mirror symmetry, the two groove plates 2 are arranged at intervals, the interval in the middle forms a fiber groove, and the groove plates 2 and the base plate are connected by a fixed structure; clamping mechanisms 3 are arranged at both ends of the fiber groove along the grooving direction; a plurality of parallel grooves 4 are formed on the groove plate 2, the grooves 4 are half-through grooves with one end open, and the grooves 4 on the two groove plates 2 are connected to form a casting groove.

[0039] The fixing structure includes a plurality of upper positioning holes 5 and a plurality of mounting holes 6 formed on the groove plate 2, and a plurality of lower positioning holes 7 and a plurality of screw holes 8 formed on the base plate 1; the plurality of lower positioning holes 7 are arranged in one-to-one correspondence with the plurality of upper positioning holes 5 on the two groove plates 2; the plurality of screw holes 8 are arranged in one-to-one correspondence with the mounting holes 6 on the two groove plates 2; the positioning pin 9 is inserted between the upper positioning hole 5 and the lower positioning hole 7; the bolt 10 passes through the mounting hole 6 and is threadedly connected with the screw hole 8.

[0040] The plurality of upper positioning holes 5 are arranged in parallel and dispersed on both sides of each groove 4, and the upper positioning hole 5 is arranged near the open end of the groove 4.

[0041] The plurality of mounting holes 6 are arranged in two rows, one row is arranged at both sides of each groove 4 , and the other row is arranged near the closed end of the groove 4 .

[0042] The side wall of the closed end of the groove 4 is inclined at an angle of 30° to 60°. That is, the casting groove formed by the two grooves 4 is a structure that is wide at the top and narrow at the bottom. The actual function of this structure is: when pouring resin into the casting groove during sample preparation, it is convenient to observe whether the resin liquid level on both sides is flush with the upper edge of the casting groove, which helps to improve the quality of resin molding; when demolding, the inclined setting helps to separate the sample from the mold.

[0043] The number of the casting troughs is 2 to 8.

[0044] The shape of the casting trough includes but is not limited to a rectangle, a dumbbell-shaped strip, and a rectangle with two V-shaped notches in the middle.

[0045] Handles are installed on both sides of the bottom plate 1.

[0046] The width of the fiber groove is 0.1-1.0 mm.

[0047] The clamping mechanism 3 has the function of adjusting the fiber yarn width, and the applicable initial fiber width range is 4.0~10.0mm, and the adjustable range is -2.0~+2.0mm on this basis. The specific structure of the clamping mechanism 3 can be but not limited to the following structure: the clamping mechanism 3 includes two clamping plates and a clamping rod arranged opposite to each other, the end of the fiber bundle is placed between the two clamping plates, and the two clamping plates are connected by means of a top screw, a spring clip, etc., so as to clamp the fiber bundle; one end of the clamping rod is connected to the bottom plate 1, and the other end is connected to the clamping plate, and the distance between the clamping plate and the bottom plate is adjusted by a screw structure, so as to adjust the tension and relaxation of the fiber bundle.

[0048] The clamping mechanism 3 can apply tension to the fiber, the range of which is 1-100N.

[0049] The metal material of the mold includes but is not limited to steel, aluminum, and aluminum alloy.

[0050] The fibers to which the present invention is applied include but are not limited to glass fibers, carbon fibers, aramid fibers, quartz fibers, nylon fibers, and the like.

[0051] Example 2

[0052] Based on Example 1, a method for preparing a transverse tow composite material sample comprises the following steps:

[0053] (I) Sample preparation

[0054] (i) Install a groove plate 2 on the base plate 1 and fix the two together by means of positioning pins 9 and bolts 10;

[0055] (ii) placing the fiber 11 against the side wall of the groove plate 2 and the top surface of the bottom plate 1, with both ends fixed by a clamping mechanism 3 to keep the fiber straight;

[0056] (iii) another groove plate 2 is mounted on the base plate 1, the two are fixed by means of positioning pins 9 and bolts 10, resin is poured into the casting trough, and heated and cured to obtain a sample;

[0057] (II) Sample demoulding

[0058] (i) Remove all positioning pins and nuts, loosen the clamping mechanism 3, and separate the groove plate 2 and the base plate 1;

[0059] (ii) Place an object under the sample to keep the groove plate 2 suspended in the air, and press the groove plate 2 evenly until the sample is separated from the groove plate 2.

[0060] Example 3

[0061] Based on Example 1, in this example, the width of the fiber slot 12 is set to 0.1 mm, the casting slot 12 is in the shape of a dumbbell-shaped strip, and the number is 2. The mold is made of 45# steel, and the fiber used is glass fiber.

[0062] Example 4

[0063] Based on Example 1, in this example, the width of the fiber slot 12 is set to 0.5 mm, the casting slot 12 is rectangular in shape, and the number is 6. The mold is made of aluminum alloy, and the fiber used is aramid.

[0064] Example 5

[0065] Based on Example 1, in this example, the width of the fiber slot 12 is set to 1.0 mm, and the shape of the casting slot 12 is a rectangle with two V-shaped notches in the middle, and the number is 8. The mold is made of aluminum, and the fiber used is carbon fiber.

[0066] The present invention provides a method for preparing a transverse fiber bundle composite material sample and a mold. During the heating and curing process, the mold is not easy to deform, has little thermal expansion, and has high heat transfer efficiency, which greatly improves the molding quality of the sample. During the demolding process, there is no need to pry or bend the sample, especially when the fiber bundle area of ​​the sample is separated from the fiber groove, it is much smoother, thereby avoiding damage to the sample and improving the success rate of demolding. The fiber groove size is determined by the gap between the side walls of two groove plates and is controlled by multiple positioning pins with high precision, thereby reducing the width difference of the fiber bundle area between each sample and helping to reduce the discreteness of the test result. By adjusting the fiber yarn spreading width, the actual fiber width can be ensured to be the same as the depth of the casting groove, thereby ensuring that the fiber width is the same as the sample thickness, and ultimately improving the test accuracy. The metal mold has high firmness, the fiber groove is not easy to be damaged, and the service life of the mold is greatly improved. The sample preparation and demolding process are simple to operate, saving time and effort.

[0067] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0068] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are 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 limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0069] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0070] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A transverse tow composite material sample preparation die, characterized in that: It comprises a base plate (1) and two groove plates (2) arranged on the base plate (1) in a mirror-symmetrical manner, the two groove plates (2) being arranged at an interval, the interval between them forming a fiber groove, the groove plates (2) and the base plate being connected via a fixed structure; clamping mechanisms (3) are arranged at both ends of the fiber groove; a plurality of grooves (4) are formed on the groove plate (2), and two symmetrical grooves (4) form a casting groove; The clamping mechanism (3) is arranged at both ends of the fiber slot along the slotting direction; A plurality of the grooves (4) are arranged in parallel, and the grooves (4) are half-through grooves with one end open; The fixing structure comprises a plurality of upper positioning holes (5) and a plurality of mounting holes (6) formed on the groove plate (2), and a plurality of lower positioning holes (7) and a plurality of screw holes (8) formed on the bottom plate (1); the positioning pins (9) are inserted between the upper positioning holes (5) and the lower positioning holes (7); and the bolts (10) pass through the mounting holes (6) and are threadedly connected to the screw holes (8).

2. The transverse tow composite material sample preparation mold according to claim 1, characterized in that: The plurality of lower positioning holes (7) are arranged in one-to-one correspondence with the plurality of upper positioning holes (5) on the two groove plates (2); and the plurality of screw holes (8) are arranged in one-to-one correspondence with the mounting holes (6) on the two groove plates (2).

3. The transverse tow composite material sample preparation mold according to claim 1, characterized in that: The plurality of upper positioning holes (5) are arranged in parallel and dispersed on both sides of each groove (4), and the upper positioning holes (5) are arranged close to the open end of the groove (4); the plurality of mounting holes (6) are arranged in two rows, one row is arranged on both sides of each groove (4), and the other row is arranged close to the closed end of the groove (4).

4. The transverse tow composite material sample preparation mold according to claim 1, characterized in that: The side wall of the closed end of the groove (4) is inclined, and the inclination angle is 30° to 60°.

5. The transverse tow composite material sample preparation mold according to claim 1, characterized in that: The shape of the casting trough is a rectangle, a dumbbell, or a rectangle with two V-shaped notches formed in the middle.

6. The transverse tow composite material sample preparation mold according to claim 1, characterized in that: Handles are provided on both sides of the bottom plate (1).

7. A method for preparing a sample using the transverse tow composite material sample preparation mold according to claim 1, characterized in that: The following steps are involved: (I) Sample preparation (i) installing a groove plate (2) on the base plate (1) and fixing the two by means of positioning pins (9) and bolts (10); (ii) placing the fiber (11) in contact with the side wall of the groove plate (2) and the top surface of the bottom plate (1), and fixing the two ends of the fiber by a clamping mechanism (3) to keep the fiber straight; (iii) installing another groove plate (2) on the base plate (1), fixing the two by means of positioning pins (9) and bolts (10), pouring resin into the casting trough, heating and curing, and obtaining a sample; (II) Sample demoulding (i) Remove all positioning pins and nuts, loosen the clamping mechanism (3), and separate the groove plate (2) and the base plate (1); (ii) Place an object under the sample to keep the groove plate (2) suspended in the air, and press the groove plate (2) evenly until the sample is separated from the groove plate (2).

Images