A hydrogen storage cylinder carbon fiber layer defect pre-preparation method

Abstract

The application discloses a hydrogen storage cylinder carbon fiber layer defect prefabrication method, which comprises the following steps: determining a target defect area, designing the shape, size and distribution of a carbon fiber defect mask according to a target defect type; the target defect type comprises macro defects and micro defects; a mask is made at the target defect area position of a carbon fiber prepreg or a carbon fiber cloth, and the shape, size and distribution of the mask determine the shape, size and distribution of the prefabricated defects; a release agent is applied to a designed carbon fiber sample mold, the defect layer with the prepared mask and the sample layer are laid in the mold one by one, the concave mold and the convex mold are pressed to bond the fiber layer, and the carbon fiber sample mold is matched with the size and type of the predetermined defect; the carbon fiber sample with the mask is subjected to heat treatment to realize the predetermined pyrolysis or chemical reaction of the carbon fiber sample, and finally the carbon fiber composite material with the prefabricated defect is formed. The defect prefabrication method has the characteristics of replicability and strong operability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon fiber damage processing, and particularly relates to a hydrogen storage cylinder carbon fiber layer defect prefabrication method. BACKGROUND

[0002] Carbon fiber composite materials have high strength, high modulus, good fatigue resistance and corrosion resistance, and are widely used in the fields of aviation, aerospace, automobile industry and the like. However, due to the instability of carbon fiber composite materials in the manufacturing process and the influence of load and complex environment during service, delamination, porosity, fiber fracture and fiber buckling defects inevitably occur, which will seriously affect the mechanical properties of the carbon fiber composite material laminates.

[0003] However, due to the typical damage of carbon fiber composite materials, such as delamination and porosity, fiber fracture and buckling, the existing carbon fiber composite material preparation process cannot realize accurate defect prefabrication, and the current widely used nondestructive testing technologies such as ultrasonic, CT and thermal imaging have low discrimination degree for actual defect behaviors, which limits the optimization of material properties and the research on defect mechanism.

[0004] Therefore, the above problems need to be solved. SUMMARY

[0005] The present application relates to the technical field of carbon fiber damage processing, and particularly relates to a hydrogen storage cylinder carbon fiber layer defect prefabrication method.

[0006] TECHNICAL SOLUTION: In order to achieve the above object, the present application discloses a hydrogen storage cylinder carbon fiber layer defect prefabrication method, comprising the following steps:

[0007] (1) determining a target defect area, designing the shape, size and distribution of the carbon fiber defect mask according to the target defect type; the target defect type includes macroscopic defects and microscopic defects, wherein the macroscopic defects include delamination and cracks, and the microscopic defects include porosity;

[0008] (2) according to the shape, size and distribution of the preset mask, making a mask at the target defect area position of the carbon fiber prepreg or carbon fiber cloth, the shape and size of the mask determine the shape and size of the prefabricated defect, and the distribution of the mask determines the distribution of the prefabricated defect in the carbon fiber prepreg or carbon fiber cloth; the mask making method includes but is not limited to laser cutting method and mechanical carving method, and the mask position is filled with nondestructive testing filler, the nondestructive testing filler includes but is not limited to aerogel, aerogel felt, polytetrafluoroethylene film or polyimide film, and the mask simulates macroscopic defects or microscopic defects;

[0009] (3) The designed carbon fiber test piece mold is coated with a release agent, and the prepared mask layer and the sample layer are laid in the mold one by one. The concave mold and the convex mold are pressed to make the fiber layer bond. The carbon fiber test piece mold is matched with the size and type of the predetermined defect;

[0010] (4) The carbon fiber test piece with the mask is heat treated to realize the predetermined pyrolysis or chemical reaction of the carbon fiber test piece, and finally form a carbon fiber composite material with a preformed defect.

[0011] In step (2), after determining the corresponding mask position of the layered defect, no mechanical cutting process is required. After coating a layer of epoxy resin glue at the preformed defect position in step (2), the prepared mask is placed. The mask can be selected from polytetrafluoroethylene film wrapped aerogel body, aerogel felt or polytetrafluoroethylene film.

[0012] Preferably, in step (2), the shape of the simulated real layered defect of the carbon fiber plate or winding part is circular, and the size is φ3-φ10. The thickness of the mask should not exceed 1mm. To meet the nondestructive testing requirements, the defect size should not exceed 1 / 3 of the size of the carbon fiber test piece.

[0013] Furthermore, in step (4), since the layered defect is a foreign object filling, in order to reduce the resin belt size generated by the filler to achieve the predetermined layered defect effect, a preforming process is first carried out, followed by a heating and curing process.

[0014] Further, in step (2), after determining the defect mask position of the crack defect, a mechanical cutting process is required to simulate the fiber fracture in the actual situation. After cutting the predetermined crack size at the preformed defect position in step (2), the prepared mask is filled. The mask can be selected from polytetrafluoroethylene film wrapped aerogel body, aerogel felt or polytetrafluoroethylene film. The shape is cut on the carbon fiber cloth of the predetermined defect layer, and then the layer is laid.

[0015] Preferably, in step (2), the shape of the simulated real crack defect of the carbon fiber plate or winding part is strip-shaped, and the size is 10-20mm long, 0.8-2mm wide, and 0.3-1.8mm high. To meet the nondestructive testing requirements, the defect size should not exceed 1 / 10 of the size of the carbon fiber test piece, and the crack defect size should be less than 3mm.

[0016] Further, in step (4), after the crack defect is filled, no preforming and heating is required, and only a heating and curing process is required.

[0017] Preferably, in step (2), after determining the location of the defect mask for the pore defect, no mechanical cutting process is required. There are two methods for filling the pore defect mask: the first method is to directly apply epoxy resin and then sprinkle aerogel powder; the second method is to first cure the epoxy resin with aerogel powder on a mold of a predetermined size, and then use the cured block-layer epoxy resin as a mask.

[0018] Furthermore, in step (2), the shape of the simulated real pore defects of carbon fiber plates or winding parts is circular or strip-shaped, and the mask thickness should not exceed 1 mm; the size of the powdered aerogel that acts as pores is determined by the detection requirements, and the size is 10 μm to 300 μm.

[0019] Furthermore, in step (4), after the pore defects are manufactured using the first mask filler method, they need to be cured at room temperature, and then the carbon fibers are stacked and sent to the heating and curing process; after the pore defects are manufactured using the second mask filler method, they need to be pre-formed and then heated and cured.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The defect prefabrication method of the present invention has the characteristics of reproducibility and strong operability, and can prefabricate defects with specific shapes, sizes and distributions in carbon fiber composite materials, thereby realizing the optimization of material properties and the study of defect mechanisms. Attached Figure Description

[0021] Figure 1 This is a flowchart of the carbon fiber defect prefabrication process in this invention;

[0022] Figure 2 This is a schematic diagram of a prefabrication example of cracks and pore defects in a carbon fiber flat plate component according to the present invention;

[0023] Figure 3 This is a schematic diagram of a prefabrication example of delamination and pore defects in a carbon fiber bent component according to the present invention;

[0024] Figure 4 This is a schematic diagram of a prefabrication example of delamination defects in carbon fiber NOL ring specimens in this invention;

[0025] Figure 5 This is a scanning electron microscope image of the surface morphology obtained in Example 3 of the present invention. Detailed Implementation

[0026] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0027] Example 1

[0028] like Figure 1 As shown, the present invention provides a method for prefabricating defects in the carbon fiber layer of a hydrogen storage cylinder, comprising the following steps:

[0029] 100. Determine the target defect area, design the shape, size and distribution of the carbon fiber defect mask according to the target defect type; the target defect type includes macroscopic defects and microscopic defects, wherein the macroscopic defects include delamination and cracks, and the microscopic defects include pores;

[0030] 200. According to the shape, size and distribution of the preset mask, make a mask at the position of the target defect area of the carbon fiber prepreg or carbon fiber cloth, the shape and size of the mask determine the shape and size of the prefabricated defect, and the distribution of the mask determines the distribution of the prefabricated defect in the carbon fiber prepreg or carbon fiber cloth;

[0031] Select appropriate carbon fiber prepreg or carbon fiber cloth as carbon fiber test piece, the prepreg is composed of carbon fiber cloth and resin system, and the resin system can be thermosetting resin or thermoplastic resin;

[0032] The mask making method includes but is not limited to laser cutting method and mechanical carving method, fill in the nondestructive testing filler at the mask position, the nondestructive testing filler includes but is not limited to aerogel, aerogel felt, polytetrafluoroethylene film or polyimide film, and the mask simulates macroscopic defects or microscopic defects;

[0033] After determining the corresponding mask position of the delamination defect, no mechanical cutting process is needed, a layer of epoxy resin adhesive is applied at the prefabricated defect position in step 200, and then the prepared mask is placed, the mask can be selected as the aerogel body wrapped with polytetrafluoroethylene film, and aerogel felt or polytetrafluoroethylene film can also be used in the case of low air gap requirement; The shape of the simulated real delamination defect of the carbon fiber plate or winding piece is circular, and the size is φ3-φ10, the thickness of the mask should not exceed 1mm, and the defect size should not exceed 1 / 3 of the size of the carbon fiber test piece to meet the nondestructive testing requirement;

[0034] After determining the defect mask position of the crack defect, a mechanical cutting process is needed to simulate the fiber fracture in the actual situation, a predetermined crack size is cut at the prefabricated defect position in step 200, and then the prepared mask is filled, the mask can be selected as the aerogel body wrapped with polytetrafluoroethylene film, and aerogel felt or polytetrafluoroethylene film can also be used in the case of low air gap requirement; The shape is cut on the carbon fiber cloth of the predetermined defect layer, and then the layer is laid; The shape of the simulated real crack defect of the carbon fiber plate or winding piece is strip-shaped, and the size is 10-20mm long, 0.8-2mm wide and 0.3-1.8mm high (one to nine layers of 0.3mm carbon fiber cloth thickness); In order to meet the nondestructive testing requirement, the defect size should not exceed 1 / 10 of the size of the carbon fiber test piece, and the crack defect size is less than 3mm;

[0035] The mask filler method is divided into two types: the first mask filler method is to directly smear epoxy resin glue and then sprinkle aerogel powder; the second mask filler method is to first solidify the epoxy resin glue with aerogel powder on a predetermined size mold, and then use the solidified block-shaped epoxy resin as a mask; the shape of the simulated carbon fiber plate or winding part real porosity defect is circular or strip-shaped, and the mask thickness should not exceed 1 mm (thick coating of epoxy resin under the condition of smearing); the size of the powder-shaped aerogel serving as the porosity is determined by the detection requirement, and is generally 10-300 μm;

[0036] 300. A release agent is applied to the completely designed carbon fiber test piece mold, and the defect layer with the prepared mask and the test layer are laid in the mold one by one. The concave mold and the convex mold are pressed to bond the fiber layer. The carbon fiber test piece mold should be adapted to the size and type of the predetermined defect;

[0037] 400. The carbon fiber test piece with the mask is subjected to heat treatment to achieve the predetermined pyrolysis or chemical reaction of the carbon fiber test piece;

[0038] The shape and position of the pre-prepared defect are maintained during the curing process, and the resin flow caused by the subsequent heat treatment process is prevented. The carbon fiber prepreg with the mask is subjected to heat treatment. The purpose of the heat treatment is to cause the carbon fiber in the mask area to undergo a predetermined degree of pyrolysis or chemical reaction, thereby forming a pre-prepared defect in the area. The temperature and time of the heat treatment need to be accurately controlled to ensure that the formation of the pre-prepared defect meets the predetermined requirements;

[0039] The heat treatment curing can be autoclave curing, automatic pressure curing, vacuum bag negative pressure curing or other appropriate curing methods. During the curing process, the shape and size of the pre-prepared defect are maintained, and finally a carbon fiber composite material with a pre-prepared defect is formed;

[0040] The carbon fiber in the mask area undergoes a predetermined degree of heat treatment curing reaction during the heat treatment process. The curing treatment methods include but are not limited to vacuum bag oven molding, autoclave AC molding, hand lay-up hot pressing molding, and filament winding molding;

[0041] Since the layered defect is filled with foreign matter, in order to reduce the resin band size caused by the filler to achieve the predetermined layered defect effect, a preforming process is required. The preforming pressure is selected to be 0.1-0.3 MPa, preferably 0.3 MPa, and the preforming temperature is selected to be 80-100℃, and heated for 30 min. The curing pressure is selected to be 0.3 MPa, and the curing temperature is selected to be 130℃, and heated for 90 min;

[0042] After the crack defect is filled, preforming heating is not required. The curing pressure is selected to be 0.3 MPa, the curing temperature is selected to be 130℃, and heating is performed for 120 min;

[0043] The first mask filler method for manufacturing the void defect needs to be cured at room temperature for 24 hours, and then the carbon fiber is stacked and sent to the heating and curing process. The second mask filler method for manufacturing the void defect needs to go through the preforming process, the preforming pressure is selected from 0.1 to 0.3 MPa, preferably 0.3 MPa, the preforming temperature is selected from 80 to 100 DEG C, and heated for 30 minutes; the curing pressure is selected from 0.3 MPa, the curing temperature is selected from 130 DEG C, and heated for 120 minutes;

[0044] 500. demolding, finally forming a carbon fiber composite material with a preformed defect.

[0045] Example 2

[0046] As shown in Figure 2 , the process flow of one of the hydrogen storage cylinder carbon fiber layer defect preforming methods in Example 1 is used, the carbon fiber flat part defect preforming is arranged in the target position center 10*25mm rectangular area Two layers of carbon fiber thickness mask are used to simulate crack and void defects, and the hand lay-up hot pressing forming method is used, wherein three layers of preformed masks and ten layers of complete unidirectional carbon fiber prepreg cloth 0 / 90 orthogonal superposition are placed in the flat part mold coated with release agent, 0.3MPa of gravity pressure is applied, and the hot oven is sent to 130 DEG C heat treatment for 120 minutes, and finally demolding is completed to preform the defect.

[0047] Example 3

[0048] As shown in Figure 3 , the process flow of one of the hydrogen storage cylinder carbon fiber layer defect preforming methods in Example 1 is used, the carbon fiber curved part defect preforming is arranged in the target position center circular φ25, φ30 or φ50 area Two layers of carbon fiber thickness mask are used to simulate delamination and void defects, and the vacuum bag oven forming method is used, wherein three layers of preformed masks and five layers of complete unidirectional carbon fiber prepreg cloth 0 / 90 orthogonal superposition are placed in the curved part mold coated with release agent, 0.1MPa of vacuum bag negative pressure is applied, and the hot oven is sent to 100 DEG C preforming for 30 minutes, and then heated at 130 DEG C for 90 minutes, and finally demolding is completed to preform the defect, as shown in Figure 5 , the surface morphology diagram observed by scanning electron microscope obtained in Example 3 is shown.

[0049] Example 4

[0050] As shown in Figure 4As shown, using the process flow of the carbon fiber layer defect preforming method of one hydrogen storage cylinder in Example 1, the carbon fiber NOL ring defect preforming is suspended during winding to the predetermined defect carbon fiber layer (preferably using wet winding), a circular φ4 area 1.2mm thick (about four layers of carbon fiber winding layer) mask is arranged at the target position to simulate the delamination defect, the winding process is continued, the filament winding forming method is used, the complete test block is sent into the high temperature curing furnace, the NOL ring test piece is machined and cut, and finally the defect preforming is completed.

Claims

1. A method for pre-preparing defects of carbon fiber layer of hydrogen storage cylinder, characterized in that, The method comprises the following steps: (1) determining a target defect area, and designing the shape, size and distribution of a carbon fiber defect mask according to a target defect type; the target defect type comprises macro defects and micro defects, wherein the macro defects comprise delamination and cracks, and the micro defects comprise pores; (2) making a mask at the target defect area position of a carbon fiber prepreg or carbon fiber cloth according to the shape, size and distribution of the preset mask; the shape and size of the mask determine the shape and size of the prefabricated defect, and the distribution of the mask determines the distribution of the prefabricated defect in the carbon fiber prepreg or carbon fiber cloth; the mask making method comprises, but is not limited to, a laser cutting method and a mechanical carving method; a filler for nondestructive testing is filled in the mask position; the filler for nondestructive testing comprises, but is not limited to, aerogel, aerogel felt, polytetrafluoroethylene film or polyimide film; the mask simulates macro defects or micro defects; (3) applying a release agent to a designed carbon fiber test piece mold, laying the defect layer with the made mask and the test piece layer into the mold one by one, and pressing the concave mold and the convex mold to make the fiber layer bond; the carbon fiber test piece mold is matched with the size and type of the predetermined defect; (4) performing heat treatment on the carbon fiber test piece with the mask to realize the predetermined pyrolysis or chemical reaction of the carbon fiber test piece, and finally forming a carbon fiber composite material with a prefabricated defect.

2. The method for pre-preparing defects of carbon fiber layer of hydrogen storage cylinder according to claim 1, characterized in that: After the delamination defect position in the step (2) is determined, a mechanical cutting process is not required; after a layer of epoxy resin glue is applied to the prefabricated defect position in the step (2), the made mask is placed; the mask can be selected from an aerogel body wrapped with a polytetrafluoroethylene film, aerogel felt or a polytetrafluoroethylene film.

3. The method of claim 2, wherein the method further comprises: In the step (2), the shape of the simulated real delamination defect of the carbon fiber plate or winding part is circular, and the size is φ3-φ10; the thickness of the mask should not exceed 1mm; to meet the nondestructive testing requirement, the defect size should not exceed 1 / 3 of the size of the carbon fiber test piece. ​ 4. The method for pre-preparing defects of carbon fiber layer of hydrogen storage cylinder according to claim 3, characterized in that: In the step (4), since the delamination defect is a foreign object, to reduce the resin band size generated by the filler and achieve the predetermined delamination defect effect, a preforming process is performed first, and then a heating and curing process is performed.

5. The method of claim 1, wherein the method further comprises: After the crack defect position in the step (2) is determined, a mechanical cutting process is required to simulate the fiber fracture in the actual situation; after the predetermined crack size is cut in the prefabricated defect position in the step (2), the made mask is filled; the mask can be selected from an aerogel body wrapped with a polytetrafluoroethylene film, aerogel felt or a polytetrafluoroethylene film; the carbon fiber cloth on the predetermined defect layer is cut into a shape and then laid. ​ 6. The method of claim 5, wherein the method further comprises: In the step (2), the shape of the simulated real crack defect of the carbon fiber plate or winding part is strip-shaped, and the size is 10-20mm in length, 0.8-2mm in width and 0.3-1.8mm in height; to meet the nondestructive testing requirement, the defect size should not exceed 1 / 10 of the size of the carbon fiber test piece, and the crack defect size is less than 3mm. ​ 7. The method of claim 6, wherein the method further comprises: applying a layer of carbon fiber to the surface of the hydrogen storage cylinder; and applying a layer of resin to the layer of carbon fiber. In the step (4), after the crack defect is filled, no preforming and heating is required, and only a heating and curing process is performed.

8. The method of claim 1, wherein the method further comprises: 5 applying a carbon fiber layer to the surface of the hydrogen storage cylinder; and applying a resin layer to the carbon fiber layer. The step (2) does not need to carry out mechanical cutting process after determining the position of the defect mask of the pore defect, and the mask filling method of the pore defect is divided into two kinds: the first mask filling method is to directly smear epoxy resin glue and then sprinkle aerogel powder; the second mask filling method is to first solidify the epoxy resin glue with aerogel powder on a predetermined size mold, and the solidified block layer epoxy resin is used as a mask.

9. The method of claim 8, wherein the method further comprises: 5 applying a carbon fiber layer to the surface of the hydrogen storage cylinder; and applying a resin layer to the carbon fiber layer. In the step (2), the shape of the real pore defect of the simulated carbon fiber plate or winding part is circular or strip-shaped, and the mask thickness should not exceed 1 mm; the size of the powder-shaped aerogel serving as the pore is determined by the detection requirement, and the size is 10 μm to 300 μm.

10. The method of claim 9, wherein the method further comprises: 5 applying a carbon fiber layer to the surface of the hydrogen storage cylinder; and applying a resin layer to the carbon fiber layer. In the step (4), after the pore defect is manufactured according to the first mask filling method, normal temperature solidification is needed, and then the carbon fiber is sent into the heating and solidification process; after the pore defect is manufactured according to the second mask filling method, a preforming process is needed, and then the heating and solidification process is carried out.

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