A method of manufacturing a large size composite full annular acoustic liner

Abstract

The application discloses a manufacturing method of a large-size composite material whole-ring sound lining, and belongs to the technical field of composite material sound lining manufacturing. The method splits the structure of the composite material whole-ring sound lining into an inner profile surface panel, a three-dimensional core material and an outer profile surface back plate, and the three parts are manufactured through integrated forming. Meanwhile, an integrated co-curing forming die is designed and manufactured, the inner profile surface panel is manufactured based on the die, the three-dimensional core material is bonded on the inner profile surface panel, the outer profile surface back plate is prepared by laying a prepreg on the three-dimensional core material, and finally, integrated curing is performed to obtain the net-size composite material whole-ring sound lining component after demolding. The composite material whole-ring sound lining structural component prepared by the application has the advantages of light weight, simple structure and good sound insulation function, and the preparation method is reasonable and feasible and has high efficiency.

Description

TECHNICAL FIELD

[0001] The application relates to a manufacturing method of a large-size composite material whole-ring sound baffle, and belongs to the technical field of composite material sound baffles. BACKGROUND

[0002] At present, sound baffles for silencing of aircraft air inlets abroad are divided into split sound baffles and whole-ring sound baffles, the sound baffle is split into less parts, and the sound baffle silencing efficiency is higher; advanced manufacturing technology abroad realizes zero splicing of the air inlet sound baffle components, for example, the A380 whole-ring sound baffle, which can reduce engine noise by about 4 to 5 decibels during the take-off process of an airplane, and can still reduce engine noise by about 2 decibels during the landing process. In China, sound baffles with 8, 6 and 4 splits are all seen, and since the whole-ring sound baffle is difficult to manufacture, no related information about successful development of the whole-ring sound baffle is found in public reports at present. SUMMARY

[0003] The application solves the technical problem that the prior art has shortcomings, and provides a manufacturing method of a large-size composite material whole-ring sound baffle, which realizes high-precision and net-size integral molding of the composite material whole-ring sound baffle through design of a mold, quasi-isotropic layer design of a prepreg and design of sound hole processing of a panel.

[0004] The technical solution of the application is as follows:

[0005] The manufacturing method of the large-size composite material whole-ring sound baffle splits a composite material whole-ring sound baffle structure into an inner shape panel, a three-dimensional core material and an outer shape back plate, and the three parts are manufactured through integral molding, and the specific method comprises the following steps.

[0006] Step one, design and manufacture an assembly co-curing molding mold;

[0007] Step two, lay and cover a prepreg in the assembly co-curing molding mold to prepare the inner shape panel;

[0008] Step three, process sound holes on the inner shape panel;

[0009] Step four, bond the three-dimensional core material to the inner shape panel;

[0010] Step five, lay and cover a prepreg on the three-dimensional core material to prepare the outer shape back plate;

[0011] Step six, perform integral curing, and after curing, demold and take out the prepared sandwich structure, peel off the excess material, and obtain the net-size composite material whole-ring sound baffle component.

[0012] Further, in step one, the designed assembly co-curing molding mold comprises a base plate, an upper cover plate and a side stop plate.

[0013] The substrate is a ring structure, including a column segment and a three-dimensional curved surface segment; the three-dimensional curved surface segment is designed according to the variable curved surface aerodynamic flow channel surface of the inner profile panel, and a profiled concave die is formed;

[0014] The upper cover plate is provided with a circumferential pin positioning hole, and the outer edge of the upper end of the substrate is connected through the pin positioning hole and a bolt to form an integral panel forming die for preparing the inner profile panel in step two;

[0015] The side baffle is located on the inner side of the integral forming die and is used for limiting and supporting the outer profile panel of the integral ring-shaped acoustic liner.

[0016] Further, in step one, the special mold steel P20 is used for assembling the co-curing forming die, the mold size is designed according to the size of the integral ring-shaped acoustic liner, and the thermal expansion coefficient compensation is carried out based on the mold expansion amount;

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

[0018] In the formula, Δl is the mold expansion amount, ΔT is the temperature difference during the curing process, α metal is the thermal expansion coefficient of the 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 two, SW110 / epoxy prepreg is used for the surface of the inner profile panel, and carbon fiber fabric prepreg TG800-6k twill / epoxy prepreg is used as the main layer material in the inner part of the panel;

[0020] The body continuous material laid by the automatic material laying machine is laid and covered with the prepreg on the integral panel forming die;

[0021] The composite material is cured and formed by using the integral co-curing process, the temperature rising and falling speed is controlled to be less than or equal to 30 DEG C, the highest curing temperature is controlled to be 180±5 DEG C, and the temperature is kept for at least 4h for curing; the surface single-layer thickness of the inner profile panel after curing is 0.09-0.1mm, and the internal single-layer thickness is 0.2-0.21mm;

[0022] The inner profile panel after curing is demolded and cleaned.

[0023] Further, in step five, the adhesive film is laid on the three-dimensional core material, and the outer profile back plate prepreg is laid and covered, the surface of the outer profile back plate adopts SW110C / epoxy prepreg, and the inner part adopts carbon fiber fabric prepreg TG800-6k twill / epoxy prepreg as the main layer material;

[0024] The whole co-curing process is used for curing forming of the composite material, the temperature rising rate in the curing is not more than 30 DEG C / h, the highest curing temperature is controlled to be 180 DEG C±5 DEG C, the temperature is kept for at least 4 h, and the pressure applied is 0.25±0.02 MPa.

[0025] Further, in step two or step four, when laying up, vacuum pre-compaction is carried out once every 2-3 layers of laying up; the laying up angle is 90 DEG along the axial direction of the mold, and the circumferential laying up angle is 0 DEG; the 0 DEG is a continuous block of one week, the material overlap is 5 mm-10 mm, and the overlap area is evenly distributed along the circumferential direction, and the allowable laying up angle error is ±2 DEG; the laying up environment temperature is controlled to be 23 DEG C±5 DEG C, and the relative humidity is less than or equal to 75%.

[0026] Further, in step three, a metal copper ring is used as a metal inner tube to support the inner profile panel, as many sound holes as possible are designed in the processing area of the sound hole, and the diameter of each sound hole is not less than 1 mm; the sound holes are processed in multiple axes in different quadrants.

[0027] Further, in step four, the adhesive film is first laid on the inner side of the inner profile panel, then the adhesive film is broken by blowing, and then the three-dimensional core material is bonded to the adhesive film on the inner side of the inner profile panel; the bonded structure is cured, and the temperature rising and falling speed is controlled to be not more than 30 DEG C / h, the highest curing temperature is controlled to be 160 DEG C±5 DEG C, and the temperature is kept for at least 2 h.

[0028] Further, the three-dimensional core material adopts AXND-5.5-18 NH aramid paper honeycomb material, is processed and formed according to the flow channel face of the inner profile panel, is bonded to be integrated with the inner profile panel, and supports the outer profile back plate laying.

[0029] Further, before the integral curing in step six, the polytetrafluoroethylene glass cloth is wrapped on the outer side of the back plate, the side baffle is installed, and the auxiliary material is integrally wrapped after compaction.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] (1) The SW110 / epoxy prepreg is used for the forming surface of the panel B and the back plate A in the present application, and the thickness of a single layer of the prepreg after curing is 0.09-0.1 mm; the carbon fiber fabric prepreg TG800-6k twill / epoxy prepreg is used as the main laying material in the inner part of the panel B and the back plate A, and the laying design is (0 / 90) GF [(0 / 90 / 0 / 90 / 0 / 90 / 0) CF] (0 / 90) GF, GF represents the glass fiber fabric prepreg SW110 / epoxy, and CF represents the aramid fiber fabric prepreg TG800-6k twill / epoxy prepreg.

[0032] (2) The pre-preg laying method adopted by the present application can maximize the preservation of fiber continuity when the panel is covered with sound holes, and improve the fatigue resistance of the noise reduction member to noise flow and vibration impact. The pre-preg fabric inside and outside each contains 2 layers of glass fiber fabric pre-preg, and the laminated plate does not cause or reduce the occurrence of phenomena such as fuzzing and splitting around the hole after curing.

[0033] (3) The present application adopts pre-preg integral cutting and continuous laying, which improves the proportion of continuous fibers, and has obvious advantages in improving the stiffness of the shell, reducing the deformation of the shell, and increasing the load bearing efficiency of the shell.

[0034] (4) The present application eliminates the separate inner panel forming mold and outer panel forming mold in the entire manufacturing process of the fan case whole ring sound lining, and the inner panel forming mold is embedded in the assembly and curing mold, realizing a multi-use forming method and saving costs.

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

[0036] (6) The present application applies the combined curing hot press tank forming technology, reasonably splits the inner type panel (panel B) curing, skin core material bonding curing, and the whole curing of the outer type back plate A and the core material, and designs the curing parameters, saves resources, reduces the curing times, and simplifies the integrated and curing cladding process design of the whole ring sound lining.

[0037] (7) The present application adopts the panel forming and sound lining hole processing, and the panel + core material, back plate integrated co-curing forming method, which has high forming efficiency, solves the problems of separate forming, final assembly forming pressure, demolding and other difficulties, and does not need to process the surface aerodynamic surface and end face in the later period, reduces the processing cost, and improves the near net size forming precision of the large size inlet channel of the composite fan case whole ring sound lining. BRIEF DESCRIPTION OF DRAWINGS

[0038] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments and are not intended to limit the scope of the present application. Moreover, the same reference numerals are used throughout the various drawings to designate identical parts. In the drawings:

[0039] Figure 1 is a schematic diagram of a large-size composite whole ring sound lining;

[0040] Figure 2 is a schematic diagram of the base plate structure of the co-curing forming mold of the embodiment of the present application;

[0041] Figure 3 Figure 1 is a schematic diagram of an upper cover plate structure of a co-curing forming mold assembled according to an embodiment of the present application;

[0042] Figure 4 Figure 2 is a schematic diagram of a co-curing forming mold structure assembled according to an embodiment of the present application;

[0043] Figure 5 Figure 3 is a flow chart of a manufacturing method of a fan case whole ring sound liner according to an embodiment of the present application. DETAILED DESCRIPTION

[0044] Exemplary embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood, and the scope of the present disclosure can be accurately conveyed to those skilled in the art.

[0045] The present application proposes a manufacturing method of a large-size composite material whole ring sound liner, which realizes high-precision and net-size integrated molding of the composite material whole ring sound liner, and the prepared composite material whole ring sound liner product has the advantages of light weight, simple structure and good sound attenuation function.

[0046] The diameter of the fan case whole ring sound liner is more than 2 meters, the present application splits the whole ring sound liner into three parts, an inner profile face panel B, a three-dimensional core material C and an outer profile back plate A, as shown in FIG. 1, the inner profile face panel B is provided with upper and lower flanges, and the three parts are integrally molded by composite material. The inner profile face panel B constitutes a pneumatic flow channel face, wherein the B2 part is a cylindrical curved surface, and the B1 part is a three-dimensional asymmetric curved surface in the circumferential and axial directions, which is a large-size pneumatic variable curved surface, and a large number of sound attenuation holes are distributed on the panel. The back plate A has connection requirements, and the back plate has 13 symmetrical grooves, the groove positions are provided with preformed metal hanging points, and the hanging points are connected with the case body. The three-dimensional core material C adopts a honeycomb sandwich material, and is processed into a specific shape according to the flow channel curved surface, and is used to support the inner profile face panel. The manufacturing method of the fan case whole ring sound liner is shown in FIG. 2, and specifically includes the following steps. Figure 1 Figure 5

[0047] First step, mold design and manufacturing

[0048] The forming mold is an important guarantee for ensuring the forming quality and size precision of the sandwich structure part, and therefore the forming mold of the composite material fan case whole ring sound liner needs to be designed to ensure the forming quality of the composite material component panel with a complex multi-curved surface structure, the bonding quality of the sandwich structure, and obtain a component meeting the quality control and assembly size precision requirements.

[0049] ​​The mold design was optimized based on the composite material ring-shaped acoustic liner. To improve product precision control, the mold used was made of special mold steel P20, with a thermal expansion coefficient generally between 8 and 12 × 10⁻⁶. -6 / ℃, this embodiment uses 10×10 -6 The coefficient of thermal expansion of carbon fiber composites is generally calculated at 1 to 4 × 10⁻⁶ °C. -6 / ℃, this embodiment uses 2×10 -6 The calculation is performed using the temperature / ℃, and the formula is as follows:

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

[0051] In the formula, Δl is the mold expansion, ΔT is the temperature difference experienced during the curing process, and α metal α is the coefficient of thermal expansion of the steel mold. composite α is the coefficient of thermal expansion of the composite material, and α is a constant, an empirical parameter. In this embodiment, ΔT is 70℃, and α... metal It is 12×10⁻⁶ / ℃, α composite With a value of 2×10⁻⁶ / ℃ and a = 1, the mold dimensions are designed to compensate for the coefficient of thermal expansion, thereby eliminating dimensional deviations caused by thermal expansion.

[0052] The co-curing mold assembly includes a substrate 1, a top cover 2, and 12 side baffles 3, such as... Figure 4 As shown, this is used for the final curing and molding of the entire ring acoustic liner of the fan casing. The base plate 1 has a ring structure, and the upper cover plate 2 is connected to the upper outer edge of the base plate 1. These components are combined using positioning pins and bolts to form an integral panel molding mold, which can be used for molding the inner panel B. The side baffle 3 is located inside the integral molding mold and is used to limit and support the outer surface panel of the entire ring acoustic liner. In this invention, the entire manufacturing process of the fan casing ring acoustic liner only requires assembling the co-curing molding mold, eliminating the need for separate inner panel molding molds and outer panel molding molds.

[0053] To ensure the accuracy of the acoustic liner flow channel surface (i.e., the outer curved surface of the inner shaped panel B), the curved surface of substrate 1 is processed separately as column segment 1a and three-dimensional curved surface segment 1b, as follows: Figure 2 As shown, this reduces mold deformation during machining. The upper cover plate 2 and the base plate 1 are connected by circumferential pin positioning holes 2b and bolts, as shown. Figure 3 As shown, this ensures the accuracy of the connection between the two.

[0054] The outer curved surface of the inner panel B serves as the contact surface for the panel forming mold, ensuring the forming accuracy of the large-sized variable-curvature pneumatic flow channel surface throughout the manufacturing process. The panel forming mold is designed as a conformal die, with a surface accuracy of ±0.1mm.

[0055] The overall panel forming die can be used multiple times. The die is designed with a 0.5mm split clearance, and the upper cover plate 2 and base plate 1 working surface are engraved with a side baffle mounting contour line to ensure accurate installation of the side baffle and effective restraint during product curing, thereby fully compacting the product.

[0056] Second step, preparation of the composite material full annular acoustic liner inner surface panel

[0057] The automatic unloader lays the continuous body material of the pre-impregnated material on the layer panel forming die, and the layer angle is uniformly 0° and 90°. Because the panel is covered with micro-porous sound holes, 0° and 90° are beneficial to maximizing the radial and circumferential continuity of the fibers, thereby improving the fatigue resistance of the acoustic liner to noise flow and vibration impact. During layering, the layering is specified to be 90° along the die axis direction, and 0° for circumferential layering. The 0° material is a continuous block of one week, with a 5mm-10mm overlap, and the overlap area is evenly distributed in the circumferential direction, allowing a layering angle error of ±2°. The layering environment temperature is controlled at 23±5℃, and the relative humidity is ≤75%.

[0058] Third step, curing process of the coated auxiliary material

[0059] The overall co-curing process is used to cure and form the composite material, with a temperature rise and fall speed controlled at ≤30℃ / h, a maximum curing temperature controlled at 180±5℃, and a holding time of 4h for sufficient curing. The mold is demolded at room temperature, and the full annular acoustic liner inner surface panel is prepared.

[0060] Fourth step, preparation of the sound holes of the full annular acoustic liner inner surface panel

[0061] During the preparation of the full annular acoustic liner inner surface panel, a 2mm thick copper ring with the same diameter and inner wall is used as a metal inner tire to support the inner surface panel. In the processing area of the sound holes, a three-dimensional software is used to simulate the angle and coordinate information of nearly one hundred thousand holes, with each sound hole having a diameter of not less than 1mm. As many sound holes as possible are designed in the processing area of the sound holes while avoiding spatial interference. The sound holes are processed in multiple quadrants and multiple axes at the same time, thereby improving the manufacturing precision control technology of the sound holes of the full annular acoustic liner of the fan case.

[0062] Fifth step, bonding of the full annular acoustic liner inner surface panel and the three-dimensional solid core material

[0063] The three-dimensional solid core material uses AXND-5.5-18 NH aramid paper honeycomb. The bonding process uses adhesive film bonding. During curing, the temperature rise and fall speed is controlled at ≤30℃ / h, the maximum curing temperature is controlled at 160±5℃, and the holding time is 2h for sufficient curing.

[0064] For the fan case whole ring sound lining product with a large number of sound holes (about 100,000 Φ1mm micro holes), it is easy to block in the interlayer structure bonding forming process. The micro-perforated plate interlayer structure forming process is studied. After the adhesive film is laid, the adhesive film is treated by "hot breaking". The adhesive film is blown by the hot air gun to break the adhesive film in the honeycomb gap. The adhesive film is automatically perforated under the action of hot air flow to ensure the micro-perforation effect of the sound lining component and achieve excellent porosity.

[0065] In the sixth step, the local core material at the hanging point position is filled with glue before the back plate is laid, and the embedded part is inlaid, then the adhesive film is laid on the core material, and then the back plate of the whole ring sound lining is laid. The laying method is the same as the second step. This step cancels the back plate forming tooling, and adopts the combination of the core material directly integrated with the back plate and the composite whole ring sound lining.

[0066] In the seventh step, polytetrafluoroethylene glass cloth is wrapped on the outside of the back plate, 12 side baffles 3, an upper cover plate 2 and a base plate 1 are installed, and the working surface of the base plate 1 is engraved with a side baffle installation contour line to ensure the accurate installation of the side baffle 3 and the effective constraint force during the curing of the product, so as to fully compact the product. Align the corresponding engraved lines and grooves on the mold, and after assembly, the whole package of auxiliary materials is completed, and the fan case whole ring sound lining is integrally cured.

[0067] In the eighth step, the product is demolded

[0068] The side baffles, the upper cover plate and the whole ring sound lining are removed from the mold in sequence, and the excess material is quickly peeled off to obtain a net size component.

[0069] The embodiment is a front sound lining product of a certain type of fan case. The face plate and the back plate adopt a laying + autoclave curing process design scheme. After curing, the composite material face plate surface micro group hole is made by using a precision machining process. The Nomex paper honeycomb core is made by machining, heat setting, trimming and other processes. The composite material micro group hole face plate and the aramid paper honeycomb core are combined according to the design requirements, and are fixed by using an adhesive. The above whole honeycomb face is subjected to composite back plate laying + autoclave co-curing forming, and the composite noise reduction whole component is obtained after curing.

[0070] The above-described embodiments are only the preferred specific embodiments of the present application, and the usual changes and replacements made by those skilled in the art within the scope of the technical solutions of the present application should be included in the protection scope of the present application.

Claims

1. A method of manufacturing a large size composite material full annular acoustic liner, characterized in that, The composite whole-ring sound insulation structure is split into an inner profile panel, a three-dimensional core material and an outer profile back plate, and the three parts are manufactured by integral molding. The specific method comprises the following steps: Step 1: design and manufacture an assembly co-curing molding die; Step 2: lay up a prepreg in the assembly co-curing molding die to prepare the inner profile panel; Step 3: process sound insulation holes on the inner profile panel; Step 4: bond the three-dimensional core material to the inner profile panel; Step 5: lay up a prepreg on the three-dimensional core material to prepare the outer profile back plate; Step 6: perform integral curing, and after curing, demold the prepared sandwich structure, peel off the excess material, and obtain the net-size composite whole-ring sound insulation component. In step 1, the designed assembly co-curing molding die comprises a base plate, an upper cover plate and a side stop plate. The base plate is in a ring shape and comprises a column segment and a three-dimensional curved surface segment; the three-dimensional curved surface segment is designed in a shape following the variable curved surface aerodynamic flow channel surface of the inner profile panel to form a shape-following recessed die; The upper cover plate is provided with circumferential pin positioning holes, and the outer edge of the base plate is connected to the upper cover plate through the pin positioning holes and bolts to form an integral panel molding die for preparing the inner profile panel in step 2; The side stop plate is located on the inner side of the integral molding die and is used for limiting and supporting the outer profile panel of the whole-ring sound insulation structure.

2. The method of manufacturing a large size composite full annular acoustic liner according to claim 1, wherein, In step 1, the assembly co-curing molding die is designed according to the size of the whole-ring sound insulation structure, and the thermal expansion coefficient is compensated based on the expansion amount of the die. Δl = a x ΔT x (α metal -α composite ) x l where Δl is the mold expansion, ΔT is the temperature difference experienced during curing, α metal is the thermal expansion coefficient of the steel mold, α composite is the thermal expansion coefficient of the composite, and a is a constant that is an empirical parameter.

3. The method of manufacturing a large size composite full annular acoustic liner of claim 1, wherein, In step 2, SW110 / epoxy prepreg is used on the surface of the inner profile panel, and carbon fiber fabric prepreg TG800-6k twill / epoxy prepreg is used as the main layer material in the inner part of the panel. The body continuous material laid by the automatic material laying machine is laid on the integral panel molding die. The composite material is cured and formed by integral co-curing process, the temperature rising speed is controlled to be less than or equal to 30℃, the highest curing temperature is controlled to be 180±5℃, and the curing is preserved for at least 4h; after curing, the single-layer thickness of the surface of the inner profile panel is 0.09-0.1mm, and the single-layer thickness of the inner part is 0.2-0.21mm. The inner profile panel after curing is demolded and cleaned.

4. The method of manufacturing a large size composite full annular acoustic liner of claim 1, wherein, In step 5, the three-dimensional core material is laid with adhesive film, and then the outer profile back plate prepreg is laid; SW110C / epoxy prepreg is used on the surface of the outer profile back plate, and carbon fiber fabric prepreg TG800-6k twill / epoxy prepreg is used as the main layer material in the inner part. The composite material is cured and formed by integral co-curing process, the temperature rising speed is controlled to be less than or equal to 30℃ / h, the highest curing temperature is controlled to be 180±5℃, and the curing is preserved for at least 4h, and the applied pressure is 0.25±0.02MPa.

5. The method of manufacturing a large-size composite full annular acoustic liner according to claim 3 or 4, characterized in that, In step 2 or step 4, when laying up, vacuum pre-compaction is performed once every 2-3 layers; the laying direction is 90° along the axis of the die, and the circumferential laying direction is 0°, and the 0° is a continuous material block per week, the material overlap is 5mm-10mm, and the overlap area is evenly distributed along the circumferential direction, and the allowable laying angle error is ±2°; the laying environment temperature is controlled to be 23±5℃, and the relative humidity is less than or equal to 75%.

6. The method of manufacturing a large scale composite full annular acoustic liner of claim 1, wherein, In step three, a metal copper ring is used as a metal inner tube to support the inner profile panel, and as many sound holes as possible are designed in the processing area of the sound hole setting, each sound hole has a diameter of not less than 1mm, and the sound holes are processed simultaneously in multiple axes in different quadrants.

7. The method of manufacturing a large scale composite full annular acoustic liner of claim 1, wherein, In step four, the inner profile panel is first pasted with a rubber film on the inner side, then the rubber film is blown and broken, and then a three-dimensional core material is bonded to the rubber film on the inner side of the inner profile panel; the bonded structure is cured, the temperature rising and falling speed is controlled to be not more than 30℃ / h, the highest curing temperature is controlled to be 160±5℃, and the temperature is kept for at least 2h.

8. The method of manufacturing a large size composite full annular acoustic liner of claim 7, wherein, The three-dimensional core material is AXND-5.5-18 NH aramid paper honeycomb material, which is processed and shaped according to the flow surface of the inner profile panel, and is bonded with the inner profile panel to support the outer profile back panel layer.

9. The method of manufacturing a large scale composite full annular acoustic liner of claim 1, wherein, Before the integral curing in step six, polytetrafluoroethylene glass cloth is wrapped on the outer side of the back panel, the side baffle is installed, and the auxiliary material is wrapped after compaction.

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