A preparation mold and method for a carbon fiber composite specimen with a bonded reinforcement sheet

Abstract

The application discloses a preparation mold and a preparation method of a carbon fiber composite sample with a pasted reinforcing sheet, the mold comprises at least four placing plates used for placing the carbon fiber composite sample with the pasted reinforcing sheet; mounting holes are arranged on the placing plates, bolts are penetrated through the mounting holes, the bolts are connected in series with the plurality of placing plates, the length of the screw rod of the bolt is adjustable, the distance between the placing plates can be adjusted by adjusting the screw rod, when the mold is closed, the screw rod of the bolt is in a compressed state, and the placing plates are fastened by a nut, when the mold is opened, the screw rod of the bolt is in an elongated state, the distance between the placing plates is pulled apart, and the carbon fiber composite sample with the pasted reinforcing sheet is convenient to place or take out; the nut is adjusted by a torque wrench with a scale, and then the distance between the placing plates can be adjusted again and the placing plates can be fixed. The application can greatly reduce the time of the carbon fiber composite sample and improve the detection efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon fiber composite material detection, and particularly relates to a preparation mold and a preparation method of a carbon fiber composite material sample with a pasted reinforcing sheet. BACKGROUND

[0002] Carbon fiber is a new material with high strength, high modulus and excellent mechanical properties, and the carbon content is more than 95%. It is a microcrystalline graphite material obtained by carbonization and graphitization of organic fibers. Carbon fiber has many excellent properties. Its specific gravity is less than 1 / 4 of steel, but its strength is higher than that of steel, and it has the characteristics of corrosion resistance, high modulus, no creep, high temperature resistance in non-oxidizing environment, good fatigue resistance and other excellent properties. In addition, it not only has the excellent properties of carbon materials, but also has the softness and processability of textile fibers, and is a new type of reinforcing fiber with wide application prospect.

[0003] Composite material is a material with new properties composed of two or more materials with different properties through physical or chemical methods. The various materials in the composite material take advantage of each other's strengths and produce synergistic effects, so that the comprehensive performance of the composite material is better than that of single material. Resin matrix composite material composed of carbon fiber as reinforcing material and resin matrix is a structural composite material with the most application prospect at present, and has obtained rapid development in recent years and has been widely used in the fields of aviation, aerospace, machinery, electronics and chemical industry.

[0004] At present, the preparation of carbon fiber composite material sample is mostly by manual cutting, sandpaper polishing, four-side glue coating, weight pressing and oven curing. However, the above processes may cause the whole sample to be loose and slippery, so that the uniformity of pressure and the fit degree of the plate cannot be guaranteed, and the test results of the finally prepared composite material sample cannot completely and truly reflect the mechanical properties of high-performance carbon fiber. SUMMARY

[0005] The application aims to provide a preparation mold and a preparation method of a carbon fiber composite material sample with a pasted reinforcing sheet, which can greatly reduce the time of carbon fiber composite material sample, improve the detection efficiency, and provide high-quality and high-efficiency detection data for the carbon fiber production line.

[0006] The technical solution for achieving the object of the present application is: a preparation mold for a carbon fiber composite sample with a reinforcing sheet, characterized in that the mold comprises at least four placement plates for placing the carbon fiber composite sample with the reinforcing sheet; the placement plates are provided with mounting holes, bolts are penetrated through the mounting holes, the bolts are connected in series with the placement plates, the length of the screw rod of the bolt is adjustable, the distance between the placement plates is adjusted by adjusting the screw rod, when the mold is closed, the screw rod of the bolt is in a compressed state, and the placement plates are fastened by a nut, when the mold is opened, the screw rod of the bolt is in an elongated state, the distance between the placement plates is pulled apart, and the carbon fiber composite sample with the reinforcing sheet is conveniently taken out or placed; the nut is adjusted by a torque wrench with a scale, and then the distance between the placement plates is adjusted again and the placement plates are fixed.

[0007] Preferably, the placement plates are made of iron plates, steel plates, aluminum plates or stainless steel plates.

[0008] Preferably, the placement plates are made of stainless steel plates, which have the best performance of corrosion resistance, dust resistance and rust resistance.

[0009] Preferably, the placement plates are square in shape, with a size of 40cm*40cm*5mm.

[0010] Preferably, smooth centrifugal paper is attached to the opposite surfaces of the placement plates.

[0011] Preferably, the mounting holes are four in number and are uniformly distributed at the four corners of the placement plates.

[0012] Preferably, the height of the bolt is 40cm, the diameter is 10mm, the nut is hexagonal, the height is 5mm, and the maximum width is 12mm.

[0013] Preferably, the reinforcing sheet is made of a carbon plate, a glass fiber plate or an aluminum alloy plate.

[0014] A preparation method of a carbon fiber composite sample with a reinforcing sheet based on the preparation mold, comprising:

[0015] The carbon fiber composite sample is uniformly pasted with the reinforcing sheet by using adhesive WD3010A / B mixed uniformly at a ratio of 100:45;

[0016] The carbon fiber composite sample with the reinforcing sheet is placed on the placement plates of the preparation mold;

[0017] The mold is closed, the nut is fastened by a torque wrench with a scale, and then stress is applied to the placement plates to squeeze out the excess adhesive in the composite sample;

[0018] The whole mold is placed in an oven with an inner cavity size of at least 1M*1M*1M, and curing is performed at the temperature and time set for adhesive forming;

[0019] After the curing is completed, the composite sample is taken out, and is cut by a carving machine to obtain batch samples, and the ambient temperature of the carving machine cutting is 23±2 DEG C, and the humidity is 50±10%.

[0020] Preferably, the torque wrench applies a stress range of 1000-5000 N.

[0021] Compared with the prior art, the application has the beneficial effects that: the application standardizes the carbon fiber composite sample through the preparation mold, adjusts the uniform tension through the movable wrench, extrudes the excess adhesive, and prepares multiple and multiple groups of multiple samples at one time through the multi-layer mold, greatly saves the time cost and space cost, and simultaneously considers the mechanical properties of the carbon fiber composite, thereby improving the product quality of the composite material; the application has simple structure and strong practicability. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Stress-strain diagram for SACMA 1R-94 compression sample.

[0023] Figure 2 Stress-strain diagram for ASTM D6641 compression sample.

[0024] Figure 3 Stress-strain diagram for ASTM D3039 tensile sample.

[0025] Figure 4 Opening state diagram (non-working state) of the forming mold for preparing the adhesive reinforcement piece composite sample of the application.

[0026] Figure 5 Closing state diagram (working state) of the forming mold for preparing the adhesive reinforcement piece composite sample of the application. DETAILED DESCRIPTION

[0027] Combination Figure 4 And Figure 5The present application discloses a molding die for preparing a composite sample with a pasted reinforcing sheet, wherein the reinforcing sheet can be a carbon plate, a glass fiber plate, an aluminum alloy plate or the like. The reinforcing sheet is preferably a glass fiber plate, which has good mechanical properties and a low price, and is suitable for mass purchase. The molding die mainly comprises a plurality of stainless steel plate components and bolt components. The stainless steel plate components are connected in series by the bolt components, and the bolts are fixed by nut components. The tension is adjusted by a torque with a scale. The stainless steel plate component is at least 4 pieces (which can be set according to specific needs), and has a square structure (the shape can also be set according to specific needs). The size of the stainless steel plate is 40 cm*40 cm*5 mm. The bolt is at least 4 pieces, and has a cylindrical structure with a size of 40 cm (height)*10 mm (diameter). The nut component matched with the bolt is at least 4 pieces, and has a hexagonal structure with a size of 5 mm (height)*12 mm (widest part).

[0028] The preparation process of the molding die is as follows:

[0029] In the first step, at least 4 pieces of stainless steel plates with smooth surfaces are placed together in a vertical manner, and centrifugal paper is attached between the stainless steel plates to isolate the A / B glue. After being tensioned, the 4 bolts are fixed by nuts at a tension of 1000-5000 N (which can be set according to specific needs) and a spacing of up to 5 cm between the two stainless steel plates. The running speed of the bolts / nuts is adjusted to adjust the spacing between the stainless steel plates, and the excess adhesive in the composite sample is squeezed out by the two stainless steel plates.

[0030] A method for preparing a carbon fiber composite sample with a pasted reinforcing sheet based on the molding die, comprising:

[0031] A plurality of composite samples with pasted reinforcing sheets are placed on the square sample mold, and the number of layers of the mold is selected according to the number of sample tests. The entire mold is placed in an oven with an inner cavity size of at least 1M*1M*1M, and cured at a temperature and time set for adhesive molding (generally at a temperature of 70°C and a time of 4h). After curing, the composite sample is removed from the mold.

[0032] Second step: the composite sample taken out in the first step is precisely cut by a carving machine to obtain batch samples; this process can still control conditions (precise cutting by a carving machine, control of the temperature and humidity of the external environment, i.e. temperature 23±2℃, humidity 50±10%), to ensure that all batch samples are completed under one condition without human differences, and the conditions of the batch samples prepared are completely consistent;

[0033] Third step: the batch samples cut out in the second step are detected by a powerful machine to obtain final data;

[0034] The forming mold combines the sample placement, reinforcement, glue control and sample forming processes into one under a certain controllable tension adjustment, and the tension can be adjusted and controlled through a movable wrench.

[0035] Example 1

[0036] This example provides a preparation method and effect verification of SACMA 1R-94, specifically including:

[0037] 1. Sample preparation

[0038] First, the carbon fiber composite sample laminated plate is pasted with a reinforcing piece, the adhesive WD3010A / B glue is mixed uniformly at 100:45, and attention should be paid to the thinness of the adhesive. After the reinforcing piece is pasted, the sample is first placed into a forming mold for preparing a composite material sample requiring a reinforcing piece, and then the mold is placed into an oven at 70℃ for 4h, and a carving machine is used to precisely cut into standard compression sample size (at least 6 samples). The geometric size of the sample and the reinforcing piece is shown in Table 1:

[0039] Table 1 Geometric size of SACMA 1R-94 compression sample

[0040]

[0041] 2. Measure the size

[0042] The cut sample is numbered, and the thickness and width of three points on the working section of each test sample are measured and averaged, and then the readings are clearly recorded.

[0043] 3. Test process

[0044] ①Open the test machine program TRAPEZIUM X, click "open method", select the compression performance test method, set the experimental conditions according to SACMA 1R-94, the compression rate is 1 mm / min, and the strength and modulus detection respectively selects different sample: the strength sample needs to paste the reinforcing sheet, and the modulus sample does not need to paste the reinforcing sheet. Set the extensometer to measure the strain of 1000-3000 ust, the limit is 0.01 mm, the gauge length is 5 mm, and the strain gauge selection box is checked. Open the sample size interface and input the sample size in turn, click complete to enter the test operation interface, and calibrate the testing machine in the operation interface.

[0045] ②Symmetrically paste strain gauges (strain gauge silk size ≤3mm) on both sides of the sample. Before pasting, use sandpaper to gently polish the test area until the surface is smooth without concave and convex points, then use a cotton ball soaked in anhydrous ethanol to wipe the test point, then paste the strain gauge with 502 glue, which should be thin and not thick, and gently chase out the air bubbles, then connect the thin lead wire to the strain gauge lead wire, then wrap the thin lead wire on the copper wire and connect it to the strain gauge through the bridge box, and then calibrate and zero the strain gauge.

[0046] ③Sample clamping: The fixture for testing the compression strength of composite materials by combined loading method is complex, and the clamping process of the sample is also complex. It should be clamped according to the requirements of SACMA SRM 1R-94 standard. During the clamping process, it is necessary to ensure that the upper and lower end faces of the sample are parallel, and the sample is perpendicular to the fixture platform, and the bolt is tightened to 0.7-1.0 J, otherwise "top blooming" will occur and the sample will break outside the gauge length section. At the same time, pay attention to fix the connection lead wire of the strain gauge on the fixture with adhesive tape to prevent short circuit caused by contact with the fixture.

[0047] ④Place the combined loading fixture with the clamped sample between the upper and lower compression plates of the testing machine, adjust the crossbeam to make it as close as possible to the combined loading fixture without contacting it. After zeroing the load / stress in the experimental interface, continue to manually adjust the position of the crossbeam to make the compression fixture bear a pre-load of 20-50 N. Click "start experiment" to perform the experiment until the sample breaks.

[0048] ⑤After the experiment is finished, unload the sample, and bundle the broken sample with adhesive tape and mark the number. If the fracture occurs in an unacceptable failure mode and area, it needs to be retested. Whether the composite standard requirements are met is judged according to the fracture mode defined in the standard SACMA SRM 1R-94.

[0049] ⑥After the experiment is finished, save the data, write the sample name, test time and other important information for easy query. Clean the test machine workbench.

[0050] 4. Repeated testing: Based on the data in Tables 2 and 3, the data of the experimental examples and the comparative examples were compared horizontally. It was found that the strength of the SACMA 1R-94 compression sample prepared by the molding mold was generally increased by about 5%, and the stress-strain diagram of the SACMA 1R-94 compression sample is shown in Figure 1

[0051] Table 2: Test data of SACMA 1R-94 compression sample

[0052]

[0053] Table 3: Examples and comparative examples of SACMA 1R-94 compression sample

[0054]

[0055] Example 2

[0056] This example provides the preparation method and effect verification of ASTM D6641, which specifically includes:

[0057] 1. Sample preparation

[0058] First, the carbon fiber composite sample laminated plate is pasted with a reinforcing piece, and the adhesive WD3010A / B is mixed uniformly at a ratio of 100:45. It is noted that the adhesive should be thin and not thick. After the reinforcing piece is pasted, the sample is first placed in a molding mold for preparing a composite material sample with a reinforcing piece, and then the mold is placed in an oven at 70°C for 4 hours. The sample is precisely cut into a standard compression sample size (at least 6 samples) by a carving machine. The geometric size of the sample and the reinforcing piece is shown in Table 4:

[0059] Table 4: Geometric size of ASTM D6641 compression sample

[0060]

[0061] 2. Measure the size

[0062] The cut sample is numbered, and the thickness and width of three points on the gauge section of each test sample are measured and the readings are clearly recorded.

[0063] 3. Test process

[0064] ​①Open the test machine program TRAPEZIUM X, click "open method", select the compression performance test method, set the experimental conditions according to ASTM D 6641 / D 6641M-09, the compression rate is 1.3 mm / min, set the extensometer measurement strain to 20000 ust, the limit is 0.1 mm, the gage length is 5 mm, and check the strain gauge selection box. Open the sample size interface and input the sample size in turn, click complete to enter the test operation interface, and calibrate the testing machine in the operation interface.

[0065] ②Symmetrically paste strain gauges on both sides of the sample. Before pasting, use a cotton ball soaked in anhydrous ethanol to clean the test points, then paste the strain gauges with 502 glue, which should be thin and not thick, and gently remove the air bubbles. Then connect the strain gauges to the strain gauge through the bridge box with the lead wire, and calibrate and zero the strain gauge. Figure 1 .

[0066] ③Sample clamping: The fixture for testing the compression strength of composite materials by combined loading method is complex, and the clamping process of the sample is also complex. It should be clamped according to the requirements of ASTM D 6641 / D 6641M-09 standard. During the clamping process, it is necessary to ensure that the upper and lower end faces of the sample are on the same horizontal plane as the two end faces of the fixture, otherwise "top blooming" will occur and the sample will break outside the gage length section. At the same time, pay attention to fix the connection lead wire of the strain gauge on the fixture with adhesive tape to prevent short circuit caused by contact with the fixture.

[0067] ④Place the clamped sample combined loading fixture between the upper and lower compression plates of the testing machine, adjust the crossbeam to make it as close as possible to the combined loading fixture without contacting it. After adjusting the load / stress to zero on the experimental interface, continue to manually adjust the position of the crossbeam to make the compression fixture bear a pre-load of 20-50 N. Click "start experiment" to perform the experiment until the sample breaks.

[0068] ⑤After the experiment is finished, unload the sample, and bundle the broken sample with adhesive tape and mark the number. If the breaking mode and area are unacceptable, the sample needs to be retested. Refer to the breaking mode defined in the standard ASTM D 6641 / D 6641M-09 to determine whether the composite standard requirements are met.

[0069] ⑥After the experiment is finished, save the data, write down the sample name, test time and other important information for easy query. Clean the test machine workbench.

[0070] 4. Repeated detection: According to the data of the experimental examples and the comparative examples in Tables 5 and 6, the compression samples prepared by the forming mold have a strength generally increased by about 8%, and a modulus generally increased by about 10%. The stress-strain diagram of the ASTM D6641 compression sample is shown in Figure 2 .

[0071] Table 5 Test data table for ASTM D6641 compression samples

[0072]

[0073]

[0074] Table 6 Examples and comparative examples of ASTM D6641 compression samples

[0075]

[0076] Example 3

[0077] This example provides the preparation method and effect verification of ASTM D3039, specifically including:

[0078] 1. Sample preparation

[0079] First, the carbon fiber composite sample laminated plate is pasted with a reinforcing piece, and the adhesive WD3010A / B is mixed uniformly at 100:45. Note that the adhesive should be thin and not thick. After the reinforcing piece is pasted, the sample is first placed in a molding mold that requires the reinforcing piece to be pasted to prepare the composite material sample, and then the mold is placed in an oven at 70°C for 4 hours. The sample is precisely cut into a standard compression sample size (at least 6 samples) using an engraving machine. The geometric dimensions of the sample and the reinforcing piece are shown in the table:

[0080] Table 7 Geometric dimensions of ASTM D3039 tensile samples

[0081]

[0082] 2. Measure the size

[0083] The cut sample is numbered, and the thickness and width are measured at three points within 5mm of each end of the middle distance gauge, and the readings are clearly recorded.

[0084] 3. Test process

[0085] ① Open the TRAPEZIUM X program of the testing machine, click "open method", select the tensile property test method, and set the experimental conditions according to ASTM D 3039 / D3039M. The tensile rate is 2mm / min, the extension gauge full scale is set to 2.5mm, the limit is 0.2mm, and the gauge length is 50mm. Open the sample size interface and input the sample size in sequence, click complete to enter the test operation interface, and zero and calibrate the testing machine and extension gauge in the operation interface.

[0086] 2. Install the specimen on the wedge grips of the Instron machine and apply the initial load of 250 N. After the pre-load is stable, gently clamp the extensometer in the middle of the specimen and fix the extensometer with the clamped contact part of the specimen with rubber bands to prevent the extensometer from slipping during the test. Gently remove the extensometer positioning pin.

[0087] 3. After adjusting the extensometer strain to zero at the experimental interface, click "Start Experiment" when the limit set by the extensometer is reached. Pause the experiment, remove the extensometer and insert the positioning pin, and then continue the experiment until the specimen is destroyed.

[0088] 4. After the experiment is finished, unload the specimen and bundle the broken specimen with tape and record the number. If the fracture occurs inside the reinforcement or the clamped end, it needs to be retested. Refer to the standard ASTM D 3039 / D3039M to determine whether the fracture mode meets the standard requirements.

[0089] 5. After the experiment is finished, save the data, write the sample name, test time and other important information for easy query. Clean the test machine work platform.

[0090] 4. Repeated detection: According to Tables 8 and 9, the data of the experimental examples and the comparative examples can be compared horizontally. The strength of the ASTM D3039 tensile specimen prepared by the forming mold is generally increased by about 10%, and the modulus is generally increased by about 3%. The stress-strain diagram of the ASTM D3039 tensile specimen is shown in Figure 3 .

[0091] Table 8 Detection data table of ASTM D3039 tensile specimen

[0092]

[0093]

[0094] Table 9 ASTM D6641 compression specimen of the examples and the comparative examples

[0095]

[0096] The SACMA 1R-94, ASTM D6641 and ASTM D3039 in the examples 1-3 can be placed in different layers at the same time, and the composite specimen can be prepared at the same time.

Claims

1. A mold for preparing a carbon fiber composite sample with bonded reinforcing sheets, characterized in that, The device includes at least four placement plates for holding carbon fiber composite samples with bonded reinforcing sheets. Each placement plate has mounting holes through which bolts pass, connecting multiple placement plates in series. The bolt lengths are adjustable, allowing for adjustment of the distance between the placement plates. When the mold is closed, the bolts are compressed and secured to the placement plates with nuts. When the mold is open, the bolts are extended, widening the distance between the placement plates to facilitate placement or removal of the carbon fiber composite samples with bonded reinforcing sheets. The nuts are adjusted using a graduated torque wrench, which further adjusts the distance between the placement plates and secures them.

2. The mold for preparing the carbon fiber composite sample with adhesive reinforcing sheet according to claim 1, characterized in that, The placement plate is made of iron plate, steel plate, aluminum plate or stainless steel plate.

3. The mold for preparing the carbon fiber composite sample with adhesive reinforcing sheet according to claim 2, characterized in that, The placement plate is made of stainless steel.

4. The mold for preparing the carbon fiber composite sample with adhesive reinforcing sheet according to any one of claims 1 to 3, characterized in that, The placement plate is square, with dimensions of 40cm*40cm*5mm.

5. The mold for preparing the carbon fiber composite sample with adhesive reinforcing sheet according to claim 4, characterized in that, Smooth centrifugal paper is attached to the opposing surfaces between the placement plates.

6. The mold for preparing the carbon fiber composite sample with adhesive reinforcing sheet according to claim 4, characterized in that, There are four mounting holes, evenly distributed at the four corners of the placement plate.

7. The mold for preparing the carbon fiber composite sample with adhesive reinforcing sheet according to claim 5, characterized in that, The bolt is 40cm high and 10mm in diameter, and the nut is hexagonal, 5mm high, and 12mm wide at its widest point.

8. The mold for preparing the carbon fiber composite sample with adhesive reinforcing sheet according to claim 1, characterized in that, The reinforcing sheet is made of carbon fiber plate, fiberglass plate or aluminum alloy plate.

9. A method for preparing a carbon fiber composite sample with adhesive reinforcing sheet based on the preparation mold described in claim 1, characterized in that, include: The carbon fiber composite sample was evenly bonded to the reinforcing sheet using adhesive. The adhesive used was WD3010A / B glue, which was mixed evenly at a ratio of 100:

45. The carbon fiber composite sample with the adhesive reinforcing sheet is placed on the placement plate of the preparation mold; Close the mold and tighten the nut with a graduated torque wrench to apply stress to the placement plate and squeeze out excess adhesive from the composite sample. Place the mold entirely into an oven with an inner cavity size of at least 1M*1M*1M, and cure it according to the temperature and time set for the adhesive molding process; After curing, the composite sample was removed and cut by an engraving machine to obtain batch samples. The ambient temperature for engraving was 23±2℃ and the humidity was 50±10%.

10. The method for preparing a carbon fiber composite sample with bonded reinforcing sheet according to claim 9, characterized in that, The torque wrench applies stress ranging from 1000 to 5000 N.

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