Manufacturing method of large-size composite whole-ring acoustic liner

Abstract

The invention discloses a manufacturing method of a large-size composite material whole-ring acoustic liner, and belongs to the technical field of manufacturing of composite material acoustic liners. According to the method, the composite material whole-ring acoustic liner structure is divided into an inner shape surface panel, a three-dimensional core material and an outer shape surface back plate, and the three parts are integrally formed and manufactured. Meanwhile, a co-curing forming mold is designed, manufactured and assembled, manufacturing of an inner shape face plate is completed based on the mold, then a three-dimensional core material is bonded to the inner shape face plate, then prepreg is laid on the three-dimensional core material to prepare an outer shape face back plate, and finally integral curing and demolding are conducted to obtain the net-size composite whole-ring acoustic liner component. The composite material whole-ring acoustic liner structural member prepared by the invention has the advantages of light weight, simple structure and good silencing function, and the preparation method is reasonable, feasible and high in efficiency.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a large-size composite material full-ring sound liner, belonging to the technical field of composite material sound liner. Background Art

[0002] At present, there are two types of acoustic liners used for silencers in foreign aircraft inlet ducts: petal acoustic liners and full-ring acoustic liners. The fewer petals of the acoustic liners, the higher the silencer efficiency. Foreign advanced manufacturing technology has achieved zero joints in the acoustic liners of the air inlet. For example, the full-ring acoustic liners of the A380 can reduce the engine noise by about 4 to 5 decibels during takeoff and about 2 decibels during landing. Domestic acoustic liners with 8, 6, and 4 petals are available. Due to the difficulty in manufacturing full-ring acoustic liners, there is no news of the successful development of full-ring acoustic liners in public reports. Summary of the invention

[0003] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a method for manufacturing a large-size composite material full-ring sound liner, through mold design, quasi-isotropic layer design of prepreg and panel silencer hole processing design, high-precision, net size one-piece molding of the composite material full-ring sound liner is achieved.

[0004] The technical solution of the present invention is:

[0005] A method for manufacturing a large-size composite full-ring sound liner, wherein the composite full-ring sound liner structure is split into an inner-shaped surface panel, a three-dimensional core material, and an outer-shaped surface back panel, and the above three parts are manufactured by integral molding. The specific method includes:

[0006] Step 1: Design, manufacture and assemble a co-curing molding mold;

[0007] Step 2: Laying prepreg in the assembly co-curing molding mold to prepare the inner surface panel;

[0008] Step 3: Processing silencer holes on the inner surface panel;

[0009] Step 4: Bonding the three-dimensional core material on the inner surface panel;

[0010] Step 5: Laying prepreg on the three-dimensional core material to prepare the outer surface backplane;

[0011] Step six, perform integrated curing, and after the curing is completed, demould and remove the prepared sandwich structure, peel off the excess material, and obtain a net-size composite material full-ring sound lining component.

[0012] Furthermore, in step 1, the designed assembly co-curing molding mold includes a base plate, an upper cover plate and a side baffle plate;

[0013] The base plate is an annular structure, including a column segment and a three-dimensional curved surface segment; the three-dimensional curved surface segment is designed in accordance with the variable curved surface pneumatic flow channel surface of the inner surface panel to form a conformal concave mold;

[0014] The upper cover plate is provided with circumferential pin positioning holes, and the upper outer edge of the base plate is connected through the pin positioning holes and bolts to form an integral panel forming mold for the preparation of the inner surface panel in step 2;

[0015] The side baffle is located on the inner side of the integral forming mold and is used to limit and support the outer surface panel of the entire ring sound lining.

[0016] Furthermore, in step 1, the co-curing molding mold is assembled using special mold steel P20, the mold size is designed according to the size of the whole ring sound liner, and the thermal expansion coefficient is compensated based on the mold expansion;

[0017] Δl=a×ΔT×(α metal -α composite )×l

[0018] Where Δl is the mold expansion, ΔT is the temperature difference during the curing process, and α metal is the thermal expansion coefficient of steel mold, α composite is the thermal expansion coefficient of the composite material, and a is a constant which is an empirical parameter.

[0019] Further, in step 2, the surface of the inner profile panel is made of SW110 / epoxy prepreg, and the interior of the panel is made of carbon fiber fabric prepreg as the main ply material TG800-6k twill / epoxy prepreg;

[0020] The continuous material of the main body unloaded by the automatic unloading machine is covered with prepreg and then laid on the integral panel forming mold;

[0021] The composite material is cured and formed by using an overall co-curing process, the heating and cooling speed is controlled to be ≤30℃, the maximum curing temperature is controlled to be 180±5℃, and the curing is kept warm for at least 4 hours; after curing, the surface single layer thickness of the inner surface panel is 0.09~0.1mm, and the internal single layer thickness is 0.2~0.21mm;

[0022] De-mould and clean the cured inner surface panel.

[0023] Furthermore, in step five, a film is laid on the three-dimensional core material, and then the outer surface back panel prepreg is laid, the outer surface back panel surface adopts SW110C / epoxy prepreg, and the interior adopts carbon fiber fabric prepreg as the main layer material TG800-6k twill / epoxy prepreg;

[0024] The overall co-curing process is used for composite material curing and molding. The heating rate during curing does not exceed 30°C / h, the maximum curing temperature is controlled at 180±5°C, the temperature is kept at least 4h, and the applied pressure is 0.25±0.02MPa.

[0025] Furthermore, in step 2 or step 4, when laying, vacuum pre-compact once every 2 to 3 layers; the laying is stipulated to be 90° along the axis direction of the mold, and 0° material is used for circumferential laying, 0° is a continuous material block around, the material overlap is 5mm-10mm, the overlapping area is evenly distributed along the circumference, and the laying angle error is allowed to be ±2°; the laying environment temperature is controlled at 23±5℃, and the relative humidity is ≤75%.

[0026] Furthermore, in step three, a metal copper ring is used as a metal inner tube to support the inner surface panel, and as many silencer holes as possible are designed within the processing area set by the silencer holes. The diameter of each silencer hole is not less than 1 mm, and the silencer holes are processed simultaneously in quadrants using multiple axes.

[0027] Furthermore, in step four, a film is first laid on the inner side of the inner surface panel, and then the film is blown, and then the three-dimensional core material is bonded to the film on the inner side of the inner surface panel; the bonded structure is cured, and the heating and cooling speed is controlled not to exceed 30°C / h during curing, the maximum curing temperature is controlled at 160±5°C, and the temperature is kept warm for at least 2h.

[0028] Furthermore, the three-dimensional core material adopts NH aramid paper honeycomb material of AXND-5.5-18, is processed and formed according to the flow channel surface of the inner surface panel, and is bonded to the inner surface panel to support the outer surface back panel layer.

[0029] Furthermore, before the integrated curing in step six, polytetrafluoroethylene glass cloth is coated on the outer side of the back plate, and the side baffle is installed, and after compaction, the auxiliary materials are coated as a whole.

[0030] The advantages of the present invention compared with the prior art are:

[0031] (1) The SW110 / epoxy prepreg is used on the molding surface of the panel B and the back panel A of the present invention, and the single-layer thickness of the prepreg after curing is 0.09-0.1 mm; the carbon fiber fabric prepreg is used as the main ply material TG800-6k twill / epoxy prepreg inside the molding of the panel B and the back panel A, and the ply design is (0 / 90)GF[(0 / 90 / 0 / 90 / 0 / 90 / 0)CF](0 / 90)GF, GF represents glass fiber fabric prepreg SW110 / epoxy, and CF represents aramid fiber fabric prepreg TG800-6k twill / epoxy prepreg.

[0032] (2) The prepreg covering method adopted by the present invention can preserve the fiber continuity to the maximum extent when the panel is full of silencer holes, thereby improving the fatigue resistance of the noise reduction component against noise flow and vibration impact. Two layers of glass fiber fabric prepreg are added to the inner and outer layers of the prepreg fabric, and after curing, the laminate does not cause or reduces the occurrence of peripheral fuzzing, splitting, etc. when punching.

[0033] (3) The present invention adopts integrated slitting and continuous layering of prepreg to increase the proportion of continuous fibers. At the same time, it has obvious advantages in improving shell stiffness, reducing shell deformation, and increasing shell load-bearing efficiency.

[0034] (4) The entire manufacturing process of the fan casing full-ring acoustic lining of the present invention eliminates the need for separate inner panel molding molds and outer panel molding molds. The inner panel molding mold is embedded in the assembly curing mold, realizing a one-mold-for-multiple-purpose molding method and saving costs.

[0035] (5) The present invention improves the manufacturing precision control technology of the sound absorbing holes of the whole ring sound liner of the composite material fan casing on the complex curved surface through the selection of mold materials, size design and structure design, and the design of the sound absorbing hole processing method.

[0036] (6) The present invention applies a combined curing autoclave forming technology, rationally splits the curing of the inner surface panel (Panel B), the bonding curing of the skin core material, and the overall curing of the outer surface back panel A and the core material, and tailors the curing parameters to save resources while reducing the number of curing times. The design of the whole-ring sound lining integration and curing coating process is relatively simplified.

[0037] (7) The present invention adopts a molding method in which the panel is formed and the acoustic liner holes are processed, and then the panel + core material and back panel are co-cured and molded as a whole. The molding efficiency is high, and the problems of separate molding, molding pressurization, and demolding in the final assembly are solved. There is no need to process the surface aerodynamic surface and end face in the later stage, which reduces the processing and manufacturing cost and improves the near-net-size molding accuracy of the super-large-size air inlet of the full-ring acoustic liner of the composite fan case. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0039] Figure 1 This is a schematic diagram of a large-scale composite full-ring acoustic liner;

[0040] Figure 2 A schematic diagram of the structure of a substrate for assembling a co-curing molding mold according to an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the structure of an upper cover plate for assembling a co-curing molding mold according to an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of the structure of the co-curing molding mold assembled according to an embodiment of the present invention;

[0043] Figure 5 The present invention is a flow chart of a method for manufacturing a complete ring acoustic liner of a fan casing according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0045] The present invention proposes a method for manufacturing a large-size composite material full-ring sound liner, which achieves high-precision, net-size one-piece molding of the composite material full-ring sound liner. The prepared composite material full-ring sound liner product has the advantages of light weight, simple structure and good sound-absorbing function.

[0046] The diameter of the whole ring sound lining of the fan casing is more than 2 meters. The present invention divides the whole ring sound lining into three parts, the inner surface panel B, the three-dimensional core material C, and the outer surface back panel A. Figure 1 As shown, the inner surface panel B has upper and lower flanges, and the three parts are integrally formed of composite materials. The inner surface panel B constitutes the aerodynamic flow path surface, of which the B2 part is a cylindrical surface, and the B1 part is a circumferential and axial three-dimensional asymmetric surface. It is a large-scale aerodynamic variable surface, and there are more than 100,000 silencer holes distributed on the panel. The back panel A has connection requirements, and there are 13 face-symmetrical grooves on the back panel. Metal hanging points are prefabricated at the groove positions, and the hanging points are connected to the casing body. The three-dimensional core material C adopts honeycomb sandwich material, which is processed into a specific shape according to the flow path surface curve to support the inner surface panel. The method for manufacturing the full-ring acoustic liner of the fan casing is as follows Figure 5 As shown, specifically including:

[0047] The first step is mold design and manufacturing

[0048] The molding mold is an important guarantee for ensuring the molding quality and dimensional accuracy of sandwich structural parts. Therefore, it is necessary to design the molding mold of the full-ring acoustic lining of the composite fan case to ensure the molding quality of the composite component panel with complex multi-curved structures and the bonding quality of the sandwich structure, so as to obtain components that meet the quality control and assembly dimensional accuracy requirements.

[0049] The mold is optimized and designed according to the composite material whole ring sound lining. In order to improve the precision control of the product, the mold uses special mold steel P20, and the thermal expansion coefficient is generally 8~12×10 -6 / ℃, this example is based on 10×10 -6 / ℃, the thermal expansion coefficient of carbon fiber composite materials is generally 1~4×10 -6 / ℃, this example is based on 2×10 -6 / ℃ is calculated, and the calculation formula is as follows:

[0050] Δl=a×ΔT×(α metal -α composite )×l

[0051] Where Δl is the mold expansion, ΔT is the temperature difference during the curing process, and α metal is the thermal expansion coefficient of steel mold, α composite is the thermal expansion coefficient of the composite material, and a is a constant which is an empirical parameter. In this embodiment, ΔT is 70°C, α metal 12×10-6 / ℃, α composite It is 2×10-6 / ℃, a is 1, and the mold size is designed to compensate for the thermal expansion coefficient and eliminate the dimensional deviation caused by thermal expansion.

[0052] The assembled co-curing molding mold includes a base plate 1, an upper cover plate 2, and 12 side baffles 3, such as Figure 4 As shown, it is used for the final curing molding of the whole ring acoustic liner of the fan casing. Among them, the base plate 1 is a ring structure, and the upper cover plate 2 is connected to the upper outer edge of the base plate 1, and is combined into an integral panel molding mold through positioning pins and bolts, which can be used for the molding of the inner panel B. The side baffle 3 is located on the inner side of the integral molding mold, and is used to limit and support the outer surface panel of the whole ring acoustic liner. In the present invention, the entire manufacturing process of the whole ring acoustic liner of the fan casing only requires the assembly of a co-curing molding mold, eliminating the separate inner panel molding mold and outer panel molding mold.

[0053] In order to ensure the accuracy of the acoustic lining flow channel surface (i.e., the outer curved surface of the inner surface panel B), the curved surface of the base plate 1 is processed separately according to the column segment 1a and the three-dimensional curved surface segment 1b, such as Figure 2 As shown, the deformation of the mold during the machining process is reduced. The upper cover plate 2 and the base plate 1 are connected by circumferential pin positioning holes 2b and bolts, as shown in FIG. Figure 3 As shown, the connection accuracy of the two is guaranteed.

[0054] The outer curved surface of the inner surface panel B is used as the die-attaching surface of the panel forming mold to ensure the forming accuracy of the large-size variable curved pneumatic flow channel surface during the entire manufacturing process. The panel forming mold is designed as a concave mold with a mold surface accuracy of ±0.1mm.

[0055] The integral panel forming mold can be used multiple times. The mold matching petal gap is designed to be 0.5mm, and the side baffle installation contour lines are engraved on the working surfaces of the upper cover plate 2 and the base plate 1 to ensure the accurate installation of the side baffle and effective restraint during product curing to fully compact the product.

[0056] Step 2: Preparation of the inner profile panel of the composite full-ring acoustic lining

[0057] The continuous material of the main body unloaded by the automatic unloading machine is laid on the laminate panel forming mold. The lay-up angle is uniformly 0° and 90°. Because the panel is full of micro-porous silencer holes, 0° and 90° are conducive to maximally preserving the radial and circumferential continuity of the fiber, and improving the fatigue resistance of the sound lining against noise flow and vibration impact. When laying, the lay-up is stipulated to be 90° along the axis of the mold, and 0° material is laid in the circumferential direction. 0° is a continuous material block around the circle, the material overlap is 5mm-10mm, and the overlap area is evenly distributed along the circumference. The lay-up angle error is allowed to be ±2°; the lay-up environment temperature is controlled at 23±5℃, and the relative humidity is ≤75%.

[0058] The third step is to coat the auxiliary materials for curing process

[0059] The composite material is cured and molded by the overall co-curing process, the heating and cooling speed is controlled to be ≤30℃ / h, the maximum curing temperature is controlled to be 180±5℃, and the temperature is kept for 4 hours to fully cure. The demoulding is carried out at room temperature, and the inner surface panel of the whole ring sound lining is prepared.

[0060] Step 4: Preparation of silencer holes in the inner profile panel of the whole ring sound lining

[0061] When preparing the inner profile panel of the full-ring sound liner, a 2mm thick metal copper ring with the same diameter as the inner wall is used as the metal inner tube to support the inner profile panel. Three-dimensional software is used to simulate the angle and coordinate information of nearly 100,000 holes in the processing area set by the silencer holes. The diameter of each silencer hole is not less than 1mm. As many silencer holes as possible are designed in the processing area set by the silencer holes, while avoiding spatial interference. The silencer holes are processed simultaneously in quadrants and multiple axes to improve the manufacturing precision control technology of the silencer holes of the full-ring sound liner of the composite fan case on complex curved surfaces.

[0062] Step 5: Bonding the inner profile panel of the whole ring sound lining and the three-dimensional core material

[0063] The three-dimensional core material is NH aramid paper honeycomb of AXND-5.5-18. The bonding process uses adhesive film bonding. During curing, the heating and cooling speed is controlled to be ≤30℃ / h, the maximum curing temperature is controlled to be 160±5℃, and the temperature is kept for 2h to fully cure.

[0064] In view of the fact that the fan case full ring sound lining products have a large number of silencer holes (about 100,000 Φ1mm micropores), which are easily blocked during the bonding and molding process of the sandwich structure, research on the molding process of the micro-perforated plate sandwich structure is carried out. After the film is laid, the film is subjected to "thermal breaking" treatment, that is, a hot air gun is used to blow the film in the honeycomb gaps, so that the film automatically opens holes under the action of the hot air flow, so as to ensure the micro-perforation effect of the sound lining components and achieve excellent porosity.

[0065] Step 6: Before backboard laying, glue is poured on the local core material at the hanging point and embedded with embedded parts, and then the glue film is laid on the core material, and then the backboard of the whole ring sound lining outer surface is laid, and the laying method is the same as step 2. In this step, the backboard forming tooling is eliminated, and a combination of the backboard and the composite material whole ring sound lining is directly formed on the core material.

[0066] In the seventh step, the outer side of the back plate is covered with polytetrafluoroethylene glass cloth, and 12 side baffles 3 are installed. The upper cover plate 2 and the working surface of the base plate 1 are engraved with the side baffle installation contour line to ensure the accurate installation of the side baffle 3 and the effective restraint during the curing of the product to fully compact the product. Align the corresponding engraved lines and grooves on the mold, and after assembly, the auxiliary materials are covered as a whole to complete the integrated curing of the whole ring of the fan casing sound lining.

[0067] Step 8: Demolding of the product

[0068] Remove the side baffles and upper cover in turn, take the entire ring of acoustic lining out of the mold, quickly peel off the excess material, and obtain a net-size component.

[0069] The embodiment is a front acoustic lining product of a certain type of fan casing, and the panel and back panel adopt the design scheme of plying + autoclave curing process. After curing, the micro-cluster holes on the surface of the composite panel are made by precision machining, and the Nomex paper honeycomb core is made by machining, heat setting, trimming and other processes of the honeycomb board; the assembly overlaps the composite micro-cluster hole panel and the aramid paper honeycomb core according to the design requirements, and is fixed with adhesive. The composite back panel on the above-mentioned integral honeycomb surface is formed by plying + autoclave co-curing, and the composite noise reduction integral component is obtained after curing.

[0070] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for manufacturing a large-size composite material full-ring acoustic liner, characterized in that: The composite whole ring sound lining structure is divided into an inner surface panel, a three-dimensional core material, and an outer surface back panel. The above three parts are manufactured by integral molding. The specific method includes: Step 1: Design, manufacture and assemble a co-curing molding mold; Step 2: Laying prepreg in the assembly co-curing molding mold to prepare the inner surface panel; Step 3: Process the silencer hole on the inner surface panel; Step 4: Bonding the three-dimensional core material on the inner surface panel; Step 5: Laying prepreg on the three-dimensional core material to prepare the outer surface backplane; Step six, perform integrated curing, and after the curing is completed, demould and remove the prepared sandwich structure, peel off the excess material, and obtain a net-size composite material full-ring sound lining component.

2. The method for manufacturing a large-size composite full-ring acoustic liner according to claim 1, characterized in that: In step 1, the designed assembly co-curing molding mold includes a base plate, an upper cover plate and a side baffle plate; The base plate is an annular structure, including a column segment and a three-dimensional curved surface segment; the three-dimensional curved surface segment is designed in accordance with the variable curved surface pneumatic flow channel surface of the inner surface panel to form a conformal concave mold; The upper cover plate is provided with circumferential pin positioning holes, and the upper outer edge of the base plate is connected through the pin positioning holes and bolts to form an integral panel forming mold for the preparation of the inner surface panel in step 2; The side baffle is located on the inner side of the integral forming mold and is used to limit and support the outer surface panel of the entire ring sound lining.

3. The method for manufacturing a large-size composite material full-ring acoustic liner according to claim 2, characterized in that: In step 1, the co-curing molding mold is assembled, the mold size is designed according to the size of the whole ring sound liner, and the thermal expansion coefficient is compensated based on the mold expansion amount; Δl=a×ΔT×(a metal -a composite )×l Where Δl is the mold expansion, ΔT is the temperature difference during the curing process, and α metal is the thermal expansion coefficient of steel mold, α composite is the thermal expansion coefficient of the composite material, and a is a constant which is an empirical parameter.

4. The method for manufacturing a large-size composite full-ring acoustic liner according to claim 2, characterized in that: In step 2, the surface of the inner profile panel is made of SW110 / epoxy prepreg, and the interior of the panel is made of carbon fiber fabric prepreg as the main ply material TG800-6k twill / epoxy prepreg; The continuous material of the main body unloaded by the automatic unloading machine is covered with prepreg and then laid on the integral panel forming mold; The composite material is cured and formed by using an overall co-curing process, the heating and cooling speed is controlled to be ≤30℃, the maximum curing temperature is controlled to be 180±5℃, and the curing is kept warm for at least 4 hours; after curing, the surface single layer thickness of the inner surface panel is 0.09~0.1mm, and the internal single layer thickness is 0.2~0.21mm; De-mould and clean the cured inner surface panel.

5. The method for manufacturing a large-size composite full-ring acoustic liner according to claim 1, characterized in that: In step 5, a film is laid on the three-dimensional core material, and then the outer surface back panel prepreg is laid. The outer surface back panel surface adopts SW110C / epoxy prepreg, and the inner part adopts carbon fiber fabric prepreg as the main layer material TG800-6k twill / epoxy prepreg; The overall co-curing process is used for composite material curing and molding. The heating rate during curing does not exceed 30°C / h, the maximum curing temperature is controlled at 180±5°C, the temperature is kept at least 4h, and the applied pressure is 0.25±0.02MPa.

6. The method for manufacturing a large-size composite full-ring acoustic liner according to claim 4 or 5, characterized in that: In step 2 or step 4, when laying, vacuum pre-compact once every 2 to 3 layers; the laying is stipulated to be 90° along the axis of the mold, and 0° material is used for circumferential laying, 0° is a continuous material block around, the material overlap is 5mm-10mm, and the overlapping area is evenly distributed along the circumference, and the laying angle error is allowed to be ±2°; the laying environment temperature is controlled at 23±5℃, and the relative humidity is ≤75%.

7. The method for manufacturing a large-size composite full-ring acoustic liner according to claim 1, characterized in that: In step three, a metal copper ring is used as a metal inner tube to support the inner surface panel, and enough silencer holes are designed as much as possible within the processing area set by the silencer holes. The diameter of each silencer hole is not less than 1mm, and the silencer holes are processed simultaneously by quadrant multi-axis.

8. The method for manufacturing a large-size composite full-ring acoustic liner according to claim 1, characterized in that: In step 4, first lay a film on the inner side of the inner surface panel, then blow the film, and then bond the three-dimensional core material to the film on the inner side of the inner surface panel; cure the bonded structure, control the heating and cooling speed to no more than 30°C / h during curing, control the maximum curing temperature to 160±5°C, and keep it warm for at least 2h.

9. The method for manufacturing a large-size composite full-ring acoustic liner according to claim 8, characterized in that: The three-dimensional core material adopts AXND-5.5-18 NH aramid paper honeycomb material, which is processed and formed according to the flow channel surface of the inner surface panel, and is bonded to the inner surface panel to support the outer surface back panel layer.

10. The method for manufacturing a large-size composite material full-ring acoustic liner according to claim 2, characterized in that: Before the integrated curing in step six, polytetrafluoroethylene glass cloth is coated on the outside of the back plate, and the side baffle is installed, and after compaction, the auxiliary materials are coated as a whole.

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