A Resin Infiltration Control System and Method for VARI Process of Foam Core Composite Materials

Abstract

The present invention discloses a resin infiltration control system and method for a foam core composite material by the VARI process. The control system includes a mold, a fiber-reinforced preform, a foam core, an auxiliary material layer, a flow guiding layer, a vacuum bag, a resin injection pipeline, a resin outlet pipeline, pipeline control valves, a resin reservoir, a vacuum source, and speed bumps. Among them, a plurality of through holes are provided in the foam core along the thickness direction, and the speed bumps are arranged on both sides of the foam core in the plate-plate area and the upper skin plate-core area of the flow guiding layer. The present invention realizes precise control of the resin infiltration process of the foam core composite material by adjusting the opening position of the foam core, the width of the speed bumps, and the position of the speed bumps. The present invention solves the problems of large differences in resin infiltration effects in various regions of the foam core composite material and difficult control of the infiltration process, and can achieve efficient and high-quality resin infiltration, ensuring the quality stability of the formed parts.

Description

Technical Field

[0001] This invention patent relates to the field of manufacturing by the low-cost liquid molding VARI process in composite material forming technology, and particularly relates to a resin infiltration control system and method for a foam core composite material by the VARI process. Background Art

[0002] With the continuous development of composite material manufacturing technology, composite materials are increasingly widely used in the aerospace field, and their usage has become an important indicator to measure the advancement of aircraft. The low-density foam core composite material structure has excellent structural weight reduction benefits, with the foam core density only being 52 kg / m 3 -110 kg / m 3 , and at the same time has high structural strength and excellent compression creep resistance. In addition, compared with the honeycomb core structure, the foam core structure has lower maintenance costs during use. Therefore, the usage of composite material foam core structures in the aviation field is gradually increasing, and in the future, attempts will be made to apply them to more complex and large-sized structures. Compared with autoclave molding methods, liquid molding technologies represented by VARI (Vacuum Assisted Resin Infusion) show advantages such as high molding quality, low manufacturing cost, high manufacturing efficiency, high dimensional and surface accuracy, etc. during the manufacturing process of foam core composite materials, and have broad application prospects in foam core composite material forming technology.

[0003] The VARI process is to lay preforms such as carbon fiber and glass fiber on a single-sided core block. After laying auxiliary materials, resin inlet and outlet channels are laid. Subsequently, the vacuum bag is encapsulated for leak detection, and under vacuum conditions and pressure, the resin is pressed into the vacuum bag to fully infiltrate the preform. Subsequently, after closing the resin injection and outlet ports, the resin is cured by heating. After cooling, a composite material part is obtained.

[0004] Resin infiltration process control is one of the key technologies determining the molding quality of the VARI process and is also a major difficulty in the manufacturing process. There are differences in the material types, layers, angles, and local structures of the preform in different regions, resulting in different permeability parameters, and there are significant differences in the resin infiltration behavior therein. In regions where infiltration is relatively difficult, phenomena such as the convergence of the resin flow front and air being wrapped by the resin inside the preform are likely to occur, ultimately resulting in defects such as pores inside this region. For the foam core structure, there are significant differences in structure and permeability between the upper skin of the core, the lower skin of the core, and the panel-to-panel area, which are mainly manifested in:

[0005] (1) Differences in resin infiltration behavior between the upper skin of the core and the lower skin of the core

[0006] Such as Figure 2As shown, the flow guiding layer cannot be laid in the area of the lower skin of the foam core. This is because the flow guiding layer is a mesh structure, and under the action of the part weight and the vacuum bag pressure, indentations will be generated on the lower skin, affecting the surface quality of the part. Therefore, the resin infiltration of the lower skin is relatively slower than that of the upper skin. The resin flow front of the upper skin reaches the bleeding tube first, blocking the bleeding pipeline, resulting in a decrease in the vacuum pressure difference at the flow front of the lower skin and insufficient driving force for resin infiltration. An air-wrapped area (15) is formed inside the preform of the lower skin, and thus quality problems such as dry patches or dense pores are likely to occur in this area after curing.

[0007] (2) Penetration behavior differences between plate-plate and plate-core regions

[0008] The foam core is a porous structure, and the closed pores on the surface will adsorb resin, making it difficult for the preform in the plate-core region to penetrate to a certain extent. The flow rate of the resin front in this part is significantly slower than that in the plate-plate region. When the flow fronts in the plate-plate region are likely to converge near the bleeding port, the bleeding channel is blocked, resulting in the formation of an air wrap (15) near the bleeding port in the upper skin plate-core region of the part, and quality problems such as dry patches or dense pores appear in the cured part (Figure 5(a)).

[0009] A speed bump refers to a strip-shaped process auxiliary material with a significantly lower permeability than the preform of the reinforcing material. The resin has a longer flow time inside the speed bump. Setting the speed bump along the resin flow direction can reduce the resin penetration rate in the local area, adjust the resin penetration front, ensure the uniformity of resin penetration, and avoid resin penetration defects caused by the convergence of the flow fronts.

[0010] The inventor analyzed the influence of the speed bump on the resin penetration behavior through the resin penetration simulation software PAM-RTM. Figure 6 It is the penetration time difference between the upper and lower skins corresponding to different speed bump widths. It can be seen that as the width of the speed bump increases, the upper and lower time differences at the 4 / 4 position gradually decrease. However, when the width of the speed bump is greater than 15 mm, the shortening change of the upper and lower time differences is smaller. When the width of the speed bump is 15 mm and 25 mm, the upper and lower time differences at the 4 / 4 position are basically the same. Figure 7 It is the pressure distribution of the resin in the upper and lower skins after setting the speed bump. It can be seen that after passing through the speed bump, the pressures in the foam core area and the laminate area are basically balanced. After adjustment by the speed bump, the front profiles and pressures of the resin in the upper and lower skins are relatively balanced, reducing the risk of defect generation. Figure 8 It is the simulation result after setting a 15-mm-wide speed bump in the plate-plate region. It can be seen that before the local speed bump, the resin flow rate in the two-sided laminates is higher than that in the plate-core region. When the resin flows through the speed bump, the resin flow front on the side with the local speed bump lags behind the side without the speed bump by 22 mm, and the flow front tends to be consistent with the upper skin. Figure 9The simulation results after setting up the 15-mm-wide plate-core area speed bump are shown. It can be seen that before the resin flows through the speed bump, as shown in Figure 9 the yellow area in [Figure reference], the resin flow in the laminate area on the side with the speed bump is still lagging behind that on the side without the local speed bump; when the resin flows through the through-type speed bump, the resin front profiles in the laminate areas on both sides and the upper skin tend to be consistent. The above simulation results confirm that the speed bump can effectively adjust the uniformity of the resin flow front. Summary of the Invention

[0011] The purpose of the present invention is to solve the existing technical problems and provide a resin infiltration control system and method for the VARI process of foam core sandwich composites. By setting the foam core hole-opening method and resin "speed bumps", the uniform control of the resin flow front in the upper and lower skins, plate-plate area, and plate-core area of the foam core sandwich composite is realized, ensuring good resin infiltration effect and improving the part quality and qualification rate.

[0012] The technical solution of the present invention is as follows: A resin penetration control system for the VARI process of foam core sandwich composites, including a mold, a fiber-reinforced preform, a foam core, an auxiliary material layer, a flow guide layer, a vacuum bag, a glue injection pipeline, a glue outlet pipeline, a pipeline control valve, a resin storage tank, and a vacuum source. The fiber-reinforced preform with a foam core is placed on the mold. A number of through holes are provided in the foam core along the thickness direction. The auxiliary material layer, the flow guide layer, and the vacuum bag are sequentially coated on the outside of the fiber-reinforced preform. Plate-plate area speed bumps and plate-core area speed bumps are provided on the flow guide layer. The glue injection pipeline and the glue outlet pipeline are arranged in the vacuum bag and are respectively connected to the resin storage tank and the vacuum source outside the mold through the pipeline control valves.

[0013] Among the through holes in the foam core, the distance d1 from the holes at the edge of the foam core to the upper edge of the foam core is calculated according to the following equation:

[0014]

[0015] where h is the thickness of the foam core; K1 and K2 are the permeabilities of the upper and lower skin preforms respectively, and θ is the slope angle of the foam core.

[0016] The distance d2 between the through holes in the foam core is selected to be 10 mm - 50 mm.

[0017] The width S1 of the plate-core area speed bump is calculated according to the following equation:

[0018]

[0019] where d2 is the distance between the through holes in the foam core; K3 is the permeability of the speed bump.

[0020] The width S2 of the plate-plate area speed bump is calculated according to the following equation:

[0021]

[0022] Among them, d3 is the length of the upper surface of the foam core; K4 is the permeability of the preform in the plate-plate area.

[0023] The auxiliary material layer includes a peelable protective layer, a perforated isolation film, and a resin absorption layer from bottom to top in sequence.

[0024] The width of the speed bump is set to 15 mm.

[0025] A resin infiltration method for a foam sandwich composite material by the VARI process includes the following steps:

[0026] Step 1: Calculate the through-hole positions of the foam core according to the following equation, and fabricate the foam core with through-holes according to the calculation.

[0027]

[0028] Among them, h is the thickness of the foam core; K1 and K2 are the permeabilities of the upper skin and lower skin preforms respectively, and θ is the slope angle of the foam core.

[0029] Step 2: Prepare the foam sandwich preform and lay it above the template.

[0030] Step 3: Lay the auxiliary material layer above the fiber-reinforced preform, and lay the flow guiding layer above the auxiliary material layer.

[0031] Step 4: Set a number of speed bumps above the flow guiding layer, and the widths S1 and S2 of the speed bumps in the plate-core area and the plate-plate area are calculated according to the following equations respectively:

[0032]

[0033]

[0034] Among them, h is the thickness of the foam core; d2 is the spacing of the through-holes of the foam core; d3 is the length of the upper surface of the foam core; K1, K2, K3, and K4 are the permeabilities of the upper skin, lower skin preform, speed bump, and plate-plate area preform respectively; θ is the slope angle of the foam core.

[0035] Step 5: Set the injection pipeline and the resin outlet pipeline above the flow guiding layer. The injection pipeline is connected to the resin storage tank, and the resin outlet pipeline is connected to the vacuum source. The pipelines are adjusted for opening and closing states through control valves.

[0036] Step 6: Cover the outside of the flow guiding layer, injection pipeline, and resin outlet pipeline with a vacuum bag, and fix it on the template.

[0037] Step 7: Close the injection pipeline control valve, connect it to the resin reservoir, close the glue outlet pipeline control valve, and connect it to the vacuum source;

[0038] Step 8: Open the glue outlet pipeline control valve, evacuate the air in the vacuum bag, open the injection pipeline control valve, and start resin infiltration;

[0039] Step 9: After the resin flow front reaches the position of the glue outlet pipeline, close all pipeline control valves to complete resin infiltration.

[0040] The beneficial effects of the present invention are as follows: It realizes the control of the flow front in each area during the resin infiltration process of the VARI molding process for foam sandwich structure composite parts, avoids the problem of air entrapment caused by the convergence of the flow front, reduces the risks of quality problems such as dry spots and pores in the parts, and has higher composite material molding quality and production efficiency compared with the conventional VARI molding process. Description of the Drawings

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0042] Figure 1 It is a schematic structural diagram of the resin penetration control system for the VARI process of foam sandwich structure composite materials provided by the present invention.

[0043] Figure 2 It is a schematic diagram of the convergence of the flow front caused by the penetration difference between the upper and lower cores during the VARI resin infiltration process of the foam sandwich structure.

[0044] Figure 3 It is a schematic diagram of the convergence of the resin flow front in the lower skin area when the "fast flow channel" of the foam core is set unreasonably.

[0045] Figure 4 (a) It is a schematic diagram of the convergence of the resin flow front in the lower skin area when the plate-core area deceleration belt is not set in the VARI process.

[0046] Figure 4 (b) It is a schematic diagram of the alleviation of the convergence of the flow front under the core during the resin infiltration process when the plate-core area deceleration belt is set in the VARI process.

[0047] Figure 5 (a) It is a schematic diagram of the convergence of the resin flow front in the area near the glue outlet when the plate-plate area deceleration belt is not set in the VARI process.

[0048] Figure 5 (b) is a schematic diagram of the improvement of the resin flow front convergence in the vicinity of the glue outlet area in the case of the VARI process setting the plate-plate area speed bump.

[0049] Figure 6 is the influence of the speed bump width on the time difference between the upper and lower cores

[0050] Figure 7 are the resin pressure simulation results after respectively setting a plate-plate and a plate-core speed bump: (a) upper skin; (b) lower skin

[0051] Figure 8 is the influence of the plate-plate area speed bump on the resin flow front: (a) before flowing through the speed bump; (b) after flowing through the speed bump

[0052] Figure 9 are the influences of respectively setting a plate-plate and a plate-core speed bump on the resin flow front: (a) before flowing through the speed bump; (b) after flowing through the speed bump

[0053] Figure 10 are the simulation and test results of the resin penetration process of the composite material foam sandwich structure under different schemes: (a) resin penetration situation under the core in Test 1; (b) resin penetration situation under the core in the embodiment scheme; (c) resin penetration situation under the core in Test 2; (d) resin penetration situation above the core in Test 2; (e) resin penetration situation under the core in the embodiment; (f) resin penetration situation above the core in the embodiment.

[0054] Figure 11 (a) is the resin penetration process corresponding to Verification Test 2 in the embodiment of the present invention. The abscissa is the resin penetration stage (calculated according to the penetration time), and the ordinate is the resin penetration distance.

[0055] Figure 11 (b) is the resin penetration process corresponding to the embodiment scheme of the present invention. The abscissa is the resin penetration stage (calculated according to the penetration time), and the ordinate is the resin penetration distance.

[0056] The meanings of the marks in the figure are as follows: 1 - template, 2 - fiber-reinforced preform, 3 - foam core, 4 - auxiliary material layer, 5 - flow guiding layer, 6 - vacuum bag, 7 - glue injection pipeline, 8 - glue outlet pipeline, 9 - pipeline control valve, 10 - resin storage, 11 - vacuum source, 12 - through hole of the foam core, 13 - plate-plate area speed bump, 14 - plate-core area speed bump, 15 - resin flow front convergence area. Detailed implementation mode

[0057] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

[0058] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention.

[0059] In the description of the present invention, it should be understood that the terms indicating orientation or positional relationship are based on the orientation or positional relationship 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 should not be construed as a limitation of the present invention.

[0060] In the present invention, unless otherwise clearly specified and defined, if terms such as "installation", "connection", "connection", "fixation", etc. are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] In the present invention, unless otherwise clearly specified and defined, if there is a first feature above or below a second feature, it may include direct contact between the first and second features, or may include the first and second features not being in direct contact but in contact through additional features therebetween. Moreover, the first feature being above, over, and on the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. If there is a first feature below, under, and beneath the second feature, it includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0062] As Figures 1 - 11As shown in the figure, a resin infiltration control system for a foam sandwich composite material using the VARI process includes a mold 1, a fiber-reinforced preform 2, a foam core 3, an auxiliary material layer 4, a flow guiding layer 5, a vacuum bag 6, a glue injection pipeline 7, a glue outlet pipeline 8, a pipeline control valve 9, a resin reservoir 10, and a vacuum source 11. The fiber-reinforced preform 2 with the foam core 3 is placed on the mold 1. A number of through holes 12 are provided in the foam core 3 along the thickness direction. The auxiliary material layer 4, the flow guiding layer 5, and the vacuum bag 6 are sequentially coated on the outside of the fiber-reinforced preform 2. Plate-plate area speed bumps 13 and plate-core area speed bumps 14 are provided on the flow guiding layer 5. The glue injection pipeline 7 and the glue outlet pipeline 8 are arranged in the vacuum bag 6 and are respectively connected to the resin reservoir 11 and the vacuum source 10 outside the mold 1 through the pipeline control valve 9.

[0063] As a preferred solution, the following limitations are imposed on the infiltration system:

[0064] (1) A number of through holes 12 are provided in the foam core 3 along the thickness direction. The distance between the through holes 12 is 10 mm - 50 mm, and the distance d1 from the hole on the outside of the foam core to the upper edge of the foam core is calculated according to the following equation:

[0065]

[0066] where h is the thickness of the foam core; K1 and K2 are the permeabilities of the upper skin and lower skin preforms respectively, and θ is the slope angle of the foam core.

[0067] The purpose of this solution is to solve the problem of the difference in resin infiltration behavior between the upper and lower skin areas of the core. By providing through holes in the thickness direction of the foam core, a "fast flow channel" for resin connecting the upper and lower areas of the core is constructed. After the resin infiltrates into the upper area of the core, it infiltrates the lower skin through the through holes, reducing the difference in resin infiltration behavior between the upper and lower preforms and ensuring the resin infiltration uniformity and part forming quality. As Figure 3 shown in the figure, due to the influence of the upper core flow guiding medium, the infiltration speed of the upper skin is very fast. After the resin flows into the lower skin from the "fast flow channel", reverse flow will occur and converge with the resin flow front at the lower skin, generating an air pocket 15. Therefore, the "fast flow channel" needs to be set at a reasonable position, that is, to ensure that when the resin infiltrates along the two paths of the upper and lower skins, it reaches the "fast flow channel" position at the same time. The derivation process is as follows:

[0068] The time for the resin to reach the "fast flow channel" through the upper skin is equal to the time for it to infiltrate through the lower skin. Since the infiltration time is proportional to the infiltration distance and inversely proportional to the preform permeability, the following equation can be derived and further simplified to obtain the calculation formula for d1.

[0069]

[0070] A number of speed bumps are respectively provided on the flow guiding layer at the plate-plate area on both sides of the foam core and at the upper skin-plate area. The width S1 of the speed bump 14 at the plate-core area is calculated according to the following equation:

[0071]

[0072] The width S2 of the speed bump (13) at the plate-plate area is calculated according to the following equation:

[0073]

[0074] Wherein, d2 is the pitch of the through holes 12 of the foam core; d3 is the length of the upper surface of the foam core; K3 is the permeability of the speed bump; K4 is the permeability of the preform at the plate-plate area.

[0075] The purpose of this solution is to solve the problem of poor resin penetration behavior in the upper core, lower core, plate-plate area and plate-core area. As shown in Figure 4 (a), due to the influence of the flow guiding medium on the upper core, the wetting speed of the upper skin is very fast. After the resin flows into the lower skin from the "fast flow channel", reverse flow will occur, and the resin flow front at the lower skin will converge, generating an air pocket 15. At this time, changing the position of the "fast flow channel" setting cannot affect the penetration rate of the upper core and the lower core. Therefore, the inventor sets a speed bump at the position of the upper skin to slow down the penetration rate of the resin on the upper core, ensuring that between the two "fast flow channels", the resin penetration time on the upper core and the lower core is equivalent. The derivation process is as follows:

[0076] When considering the penetration difference between the upper core and the lower core, between the two "fast flow channels", the resin penetration time on the upper core and the lower core is equal. And the penetration time is proportional to the penetration distance and inversely proportional to the preform permeability. The distance for the resin to penetrate the speed bump is S1, the distance for the resin to penetrate the upper core preform is d2 - S1, and the distance for the resin to penetrate the lower core preform is d2. The following equation can be derived, and further simplified to obtain the calculation method of S1.

[0077]

[0078] When considering the penetration difference between the plate-plate and plate-core, it is necessary to ensure that the resin penetration time along the upper skin is equal to the resin penetration time along the plate-plate area. The penetration time is proportional to the penetration distance and inversely proportional to the preform permeability. The following equation can be derived, and further simplified to obtain the calculation method of S2.

[0079]

[0080] The auxiliary material layer 4, the flow guiding layer 5, and the vacuum bag 6 are successively coated on the outside of the fiber-reinforced preform 2. The glue injection pipeline 7 and the glue outlet pipeline 8 are respectively connected to the resin reservoir 11 and the vacuum source 10 through the pipeline control valve 9. The auxiliary material layer 4 is successively from bottom to top a peelable protective layer, a perforated isolation film, and a glue absorption layer.

[0081] The method for controlling resin penetration using the above control system includes the following steps:

[0082] Step 1: Calculate the position of the through holes 12 of the foam core according to the following equation, and fabricate a foam core with through holes according to the calculation.

[0083]

[0084] Where h is the thickness of the foam core; K1 and K2 are the permeabilities of the upper skin and lower skin preforms respectively, and θ is the slope angle of the foam core.

[0085] Step 2: Prepare the foam sandwich preform 2 and lay it on top of the template 1.

[0086] Step 3: Lay the auxiliary material layer 4 on top of the fiber-reinforced preform 2, and lay the flow guiding layer 5 on top of the auxiliary material layer 4.

[0087] Step 4: Set a number of speed bumps 13 on top of the flow guiding layer 5, where the widths S1 and S2 of the speed bumps 13 in the plate-core area 14 and the plate-plate area are calculated according to the following equations respectively:

[0088]

[0089]

[0090] Where h is the thickness of the foam core; d2 is the spacing of the through holes 12 of the foam core; d3 is the length of the upper surface of the foam core; K1, K2, K3, and K4 are the permeabilities of the upper skin, lower skin preforms, speed bumps, and plate-plate area preforms respectively; θ is the slope angle of the foam core.

[0091] Step 5: Set the glue injection pipeline 7 and the glue outlet pipeline 8 on top of the flow guiding layer 5. The glue injection pipeline 7 is connected to the resin reservoir 11, and the glue outlet pipeline 8 is connected to the vacuum source 1. The pipeline adjusts the opening and closing state through the control valve 9.

[0092] Step 6: Cover the outside of the flow guiding layer 5, the glue injection pipeline 7, and the glue outlet pipeline 8 with the vacuum bag 6 and fix it on the template 1.

[0093] Step 7: Close the control valve 9 of the glue injection pipeline 7 and connect it to the resin reservoir 11. Close the control valve 9 of the glue outlet pipeline 8 and connect it to the vacuum source 10.

[0094] Step 8: Open the control valve 9 of the glue outlet pipeline 8, evacuate the air in the vacuum bag 6, open the control valve 9 of the glue injection pipeline 7, and start the resin infiltration.

[0095] Step 9: After a period of time when the resin flow front reaches the position of the glue outlet pipeline 8, close all the pipeline control valves 9 to complete the resin infiltration.

[0096] In this embodiment:

[0097] The part is a flat foam sandwich structure with a size of 2m x 1.2m. The total number of reinforcing layers is 16, with 8 layers on the upper and lower cores respectively. The laying angle sequence is [0° / 45° / 0° / -45° / 0° / -45° / 90° / 45°]s. The distance from the bottom of the foam core to the edge of the part along the length direction is 15cm, the thickness h of the foam core is 10cm, the opening spacing d2 of the foam core is selected as 25cm, and the slope angle θ of the foam core is 20°. The permeabilities of the upper skin K1, lower skin preform K2, speed bump K3, and plate-plate area preform K4 are 1.32×10 -5 、8.28×10 -6 、8.16×10 -7 、1.46 ×10 -5 The implementation process according to the technical solution of the present invention is as follows:

[0098] Step 1: Calculate the position of the through holes 12 of the foam core according to the following equation. According to the calculation, d1 is 4.98cm, and a foam core with through holes is made according to the calculation result.

[0099] Where h is the thickness of the foam core; K1 and K2 are the permeabilities of the upper skin and lower skin preforms respectively, and θ is the slope angle of the foam core.

[0100]

[0101] Step 2: Prepare the foam sandwich preform 2 and lay it above the template 1.

[0102] Step 3: Lay the auxiliary material layer 4 above the fiber reinforced preform 2, and lay the diversion layer 5 above the auxiliary material layer 4.

[0103] Step 4: Set a number of speed bumps 13 above the diversion layer 5. The widths S1 and S2 of the speed bumps 13 in the plate-core area and plate-plate area are calculated according to the following equations respectively, and S1 and S2 are 28.17cm and 19.18cm respectively.

[0104]

[0105]

[0106] Among them, h is the thickness of the foam core; d2 is the distance of the through holes 12) in the foam core; d3 is the length of the upper surface of the foam core; K1, K2, K3, and K4 are the permeabilities of the upper skin, lower skin preform, speed bump, and plate-plate area preform, respectively; θ is the slope angle of the foam core.

[0107] Step Five: Set the glue injection pipeline 7 and the glue outlet pipeline 8 above the diversion layer 5. The glue injection pipeline 7 is connected to the resin reservoir 11, and the glue outlet pipeline 8 is connected to the vacuum source 10. The pipelines are adjusted for the opening and closing states through the control valve 9.

[0108] Step Six: Cover the outside of the diversion layer 5, the glue injection pipeline 7, and the glue outlet pipeline 8 with the vacuum bag 6, and fix and cover it on the template 1.

[0109] Step Seven: Close the control valve 9 of the glue injection pipeline 7, connect it to the resin reservoir 11, close the control valve 9 of the glue outlet pipeline 8, and connect it to the vacuum source 10.

[0110] Step Eight: Open the control valve 9 of the glue outlet pipeline 8, extract the air inside the vacuum bag 6, open the control valve 9 of the glue injection pipeline 7, and start resin infiltration.

[0111] Step Nine: After a period of time when the resin flow front reaches the position of the glue outlet pipeline 8, close all the control valves 9 of the pipelines to complete resin infiltration.

[0112] Step Ten: Cure and demold and trim.

[0113] For the composite material foam sandwich component manufactured according to the above embodiment scheme, during the resin infiltration process, the flow front is uniform, and the internal quality of the product is good after curing and demolding.

[0114] In order to verify the advancement of the technical solution of the present invention, the inventor planned a comparative test, and the specific situation of the comparative test is as follows:

[0115] Test 1: Set the opening position d1 to 10 cm, and do not set a speed bump.

[0116] Test 2: Set the opening position d1 to 4.98 cm, and do not set a speed bump.

[0117] The resin infiltration simulation and test situations corresponding to Test 1, Test 2, and the embodiment scheme are shown in Figure 10 , comparing Test 1 and the scheme of the present invention, it can be seen that when the opening position of the foam core is set to 10 cm ( Figure 10 (a)), dot-shaped resin infiltration spots appear on the lower skin of the core, and after the infiltration spots continue to expand, they converge with the overall flow front. In contrast, after setting the punching position of the foam core according to the calculation result of the scheme of the present invention ( Figure 10(b)), the resin flow front in the lower skin area is relatively more uniform. Comparing Solution 2 and the solution of the present invention, it can be seen that without the speed bump, the resin penetrates faster in the lower core plate area than in the core area, ( Figure 10 (c)), the resin penetrates faster in the upper core area of the core plate than in the lower core area of the core plate ( Figure 10 (c)). After the speed bump is set, the lower core plate area, the core area, and the upper core plate area of the core plate are relatively close, and the resin flow front is more uniform ( Figure 10 (d), (e)). Further, the inventor counted the position differences of the resin flow fronts in the upper skin, lower skin, and plate area during each stage of the resin penetration process of the solution of the present invention and Experiment 2. The results are shown in Figure 11 . In Experiment 2 ( Figure 11 (a)), when the penetration process is within 10%, the resin penetration lengths in the three areas are relatively close. As the penetration time increases, the differences in the resin penetration distances in the three areas gradually increase. The plate area is faster, and the lower skin is the slowest. When the total penetration time reaches 92%, the resin penetration in the plate area is completed, while the lower skin area only penetrates 0.87 m. In the solution of this embodiment ( Figure 11 (b)), the resin penetration distance is relatively uniform in each stage.

[0118] During the implementation of this embodiment, the resin infiltration speed is uniform and consistent, there is no situation of the flow front gathering and air entrapment, the surface quality of the cured part is good, and the non-destructive testing results meet the design requirements.

[0119] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. It should be noted that any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A resin penetration control system for a foam sandwich composite material using the VARI process, characterized in that It includes a mold, a fiber-reinforced preform, a foam core, an auxiliary material layer, a flow guiding layer, a vacuum bag, a resin injection pipeline, a resin outlet pipeline, pipeline control valves, a resin reservoir, and a vacuum source. The fiber-reinforced preform with a foam core is placed on the mold. A number of through-holes are provided in the foam core along the thickness direction. The auxiliary material layer, the flow guiding layer, and the vacuum bag are sequentially coated on the outside of the fiber-reinforced preform. Plate-plate area speed bumps and plate-core area speed bumps are provided on the flow guiding layer. The resin injection pipeline and the resin outlet pipeline are arranged inside the vacuum bag and are respectively connected to the resin reservoir and the vacuum source outside the mold through the pipeline control valves. The width S1 of the plate-core area speed bump is calculated according to the following equation: Where, d2 is the distance between through-holes of the foam core; K3 is the permeability of the speed bump, and K1 and K2 are the permeabilities of the upper skin and lower skin preforms respectively; The width S2 of the plate-plate area speed bump is calculated according to the following equation: Where, d3 is the length of the upper surface of the foam core; K4 is the permeability of the plate-plate area preform, h is the thickness of the foam core, and θ is the slope angle of the foam core.

2. The resin penetration control system for a foam sandwich composite material using the VARI process according to claim 1, characterized in that, Among the through-holes of the foam core, the distance d1 from the holes at the edge of the foam core to the upper edge of the foam core is calculated according to the following equation: Where, h is the thickness of the foam core; K1 and K2 are the permeabilities of the upper skin and lower skin preforms respectively, and θ is the slope angle of the foam core.

3. The resin penetration control system for a foam sandwich composite material using the VARI process according to claim 1, characterized in that, The distance d2 between the through-holes of the foam core is selected to be 10 mm - 50 mm.

4. The resin penetration control system for a foam sandwich composite material using the VARI process according to claim 1, characterized in that, The auxiliary material layer is, from bottom to top, a peelable protective layer, a perforated separator film, and a resin absorption layer.

5. The resin penetration control system for a foam sandwich composite material using the VARI process according to claim 1, characterized in that, The width of the speed bump is set to 15 mm.

6. A resin infiltration method for a foam sandwich composite material using the VARI process, characterized in that Using the resin infiltration control system of the VARI process for a foam sandwich composite material described in claim 1 for infiltration, it includes the following steps: Step 1: Calculate the positions of the through-holes of the foam core according to the following equation, and manufacture a foam core with through-holes according to the calculation; Where, h is the thickness of the foam core; K1 and K2 are the permeabilities of the upper skin and lower skin preforms respectively, and θ is the slope angle of the foam core; Step 2: Prepare a foam sandwich preform and lay it above the mold; Step 3: Lay the auxiliary material layer above the fiber-reinforced preform and lay the flow guiding layer above the auxiliary material layer; Step 4: Set a number of speed bumps above the flow guiding layer, and the widths S1 and S2 of the plate-core area speed bump and the plate-plate area speed bump are calculated according to the following equations respectively: Where, h is the thickness of the foam core; d2 is the distance between through-holes of the foam core; d3 is the length of the upper surface of the foam core; K1, K2, K3, and K4 are the permeabilities of the upper skin, lower skin preforms, speed bump, and plate-plate area preform respectively; θ is the slope angle of the foam core; Step 5: Arrange the resin injection pipeline and the resin outlet pipeline above the flow guiding layer. The resin injection pipeline is connected to the resin reservoir, and the resin outlet pipeline is connected to the vacuum source. The pipelines are adjusted for opening and closing states through the control valves; Step 6: Cover the outside of the flow guiding layer, the resin injection pipeline, and the resin outlet pipeline with the vacuum bag and fix it on the mold; Step 7: Close the control valve of the resin injection pipeline and connect it to the resin reservoir, close the control valve of the resin outlet pipeline and connect it to the vacuum source; Step 8: Open the control valve of the resin outlet pipeline, pump out the air in the vacuum bag, open the control valve of the resin injection pipeline, and start resin infiltration; Step Nine: After the resin flow front reaches the position of the glue outlet pipeline, close all pipeline control valves to complete the resin infiltration.

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