A composite aeroengine containment case and engine

Abstract

The application provides an aero-engine composite structure containment case and a manufacturing method thereof. The composite structure containment case is composed of a composite material bearing cylinder and a containment area composite structure; the bearing cylinder is prepared by laying and pasting unidirectional carbon fiber prepreg and hot press tank forming technology; the containment area is prepared by laying high-strength organic fiber integral stitched fabric and RTM forming process; the weight ratio of the warp fibers and the weft fibers of the single-layer woven fabric of the containment area is 6:4-8:2, and the surface density is 100-200 g / m 2 ; the integral stitching is double-sided stitching, the stitching density is 2*2 mm-10*10 mm, the surface density of the integral stitched fabric is 600-900 g / m 2 , and the composite structure containment case has excellent bearing and containment performance, low structure weight and low manufacturing cost.

Description

Technical Field

[0001] This invention belongs to the field of structural and functional integrated composite material technology, and relates to a composite structure housing and engine for aero-engines. Background Technology

[0002] Composite material enclosures for aero-engines are crucial components ensuring engine safety during operation. Early engine enclosures used all-metal fan casings made of steel, aluminum alloy, or titanium alloy, which suffered from high weight and a tendency for broken blades to spring back. To overcome these drawbacks, a combined metal and composite material enclosure ring fan casing was developed. This involves wrapping an aramid epoxy prepreg around the outermost layer of a thin-walled aluminum or titanium alloy structure to reduce structural weight; and adding aluminum or aramid honeycomb core materials to the inner wall of the thin-walled aluminum or titanium alloy structure to mitigate the problem of broken blades springing back. To improve the thrust-to-weight ratio of aero-engines, all-composite material enclosures were further developed. All-composite material enclosures utilize carbon fiber reinforced composite materials for the load-bearing structure, while the enclosure area uses either carbon fiber reinforced composite materials or para-aramid reinforced composite materials.

[0003] Currently, composite material enclosures are manufactured using prepreg fiber automated layup (e.g., patent CN109278372A) or fiber braiding + winding (e.g., patents CN112709612A, CN112855616A), followed by hot pressing or RTM processes. However, prepreg fiber automated layup results in poor interlaminar properties leading to poor enclosure performance, while fiber braiding + winding suffers from low manufacturing efficiency and high equipment investment, resulting in high manufacturing costs for composite material enclosures. Summary of the Invention

[0004] The purpose of this invention is to provide a composite structure enclosure casing for an aero-engine and the engine itself. The composite structure enclosure casing consists of a composite material load-bearing cylinder and an enclosure region. The load-bearing cylinder is made of autoclaved unidirectional carbon fiber reinforced composite material, and the enclosure region is made of RTM-molded organic fiber integrally stitched fabric reinforced composite material. The composite structure enclosure casing not only possesses excellent load-bearing and enclosure performance but also features low structural weight and manufacturing cost.

[0005] The technical solution of the present invention:

[0006] On the one hand, a composite structure enclosure casing is provided, consisting of a load-bearing cylinder and an enclosure area.

[0007] The supporting cylinder is made of unidirectional carbon fiber prepreg and manufactured using autoclave molding technology;

[0008] The containment area is made of a high-strength organic fiber monolithically sewn fabric, prepared by RTM molding process;

[0009] The organic fiber monolithic sewn fabric refers to at least two single-layer woven fabrics sewn together on both sides, with a surface density of 600g to 900g / m². 2 ;

[0010] The weight ratio of warp fibers to weft fibers in a single-layer woven fabric is 6:4 to 8:2, and the areal density is 100 to 200 g / m². 2 Before sewing, it is a single layer of woven fabric; after sewing, it is a single-layer sewn fabric.

[0011] The weight ratio of warp fibers to weft fibers in a single-layer woven fabric is 6:4 to 8:2. The high warp fiber content provides strong circumferential constraint to the containment casing. The double-sided stitching method forms a closed loop structure. When the casing is impacted, the stitching first breaks open, and the breakage of the stitching dissipates a large amount of energy, thus improving the containment capacity of the containment casing.

[0012] The overall stitching is double-sided, with a stitch density of 2*2mm to 10*10mm, a fabric width of 200mm to 800mm, and a length greater than 10m.

[0013] The higher the stitch density, the better the fabric's deformability. However, if there are fewer stitch points, the containment performance will be worse. A stitch density of 2 to 10 is the optimal stitch density. Within this optimal range, the deformability of the stitched fabric can be achieved through winding and shaping, and the containment performance will not be worse.

[0014] The stitching is consistent with the fabric fibers.

[0015] The number of stitching fabric layers in the containment zone is ≥4. The composite containment housing consists of a containment zone on which stitching fabric is laid on top of a cured carbon fiber composite housing support cylinder. The number of stitching fabric layers is determined based on the areal density of the stitching fabric and the required composite material thickness in the containment zone. To ensure integrity, continuous fabric laying is used, and splicing of the stitching fabric is minimized, avoiding unnecessary splicing. After the fabric laying is completed, the stitching fabric is assembled onto a vacuum bag based on the housing support cylinder. Resin is then injected into the stitching fabric, and after curing, a complete composite containment housing is formed.

[0016] The organic fibers are polyimide fibers or heterocyclic aramid fibers.

[0017] The prepreg for the composite material bearing shell is selected according to the different operating temperatures of the enclosure. When the operating temperature is not higher than 120℃, high-toughness epoxy prepreg is used. When the operating temperature is higher than 120℃ but not higher than 200℃, high-toughness bismaleimide prepreg is used.

[0018] High toughness refers to the ability of a material to absorb energy during plastic deformation and fracture under stress. Here, the composite material prepared by high-toughness epoxy / bismaleimide prepreg has a CAI ≥ 300 MPa.

[0019] The enclosed casing requires heat resistance above 150°C. The organic fiber used is high-temperature resistant and high-strength polyimide fiber, while the organic fiber used below 150°C is polyimide fiber or heterocyclic aramid fiber.

[0020] On the other hand, the present invention provides an engine having the aforementioned enclosing casing.

[0021] Advantages of the present invention

[0022] 1. The composite structure housing is lightweight and has good containment performance;

[0023] 2. Compared with using woven preforms, it has higher manufacturing efficiency and lower manufacturing cost;

[0024] 3. It adopts mature manufacturing technology, ensuring stable and reliable performance;

[0025] 4. The manufacturing equipment involved is simple and the investment is low.

[0026] Our research shows that when the containment region uses a multi-layered, integrally stitched fabric of a certain thickness as reinforcement, its containment performance is excellent. Furthermore, the manufacture of the integrally stitched fabric does not require expensive specialized equipment, is highly efficient, and can significantly reduce the manufacturing cost of the containment region reinforcement fabric.

[0027] Excellent containment performance refers to the ability of an engine blade to contain the broken blade within the casing when it breaks and impacts the casing at a distance of 20% from the blade root.

[0028] When using multiple layers of integrally stitched fabric of a certain thickness as reinforcement, the thickness of the reinforcement is smaller compared to when using a single layer of fabric as reinforcement;

[0029] Alternatively, when the reinforcement thickness is uniform, using multiple layers of integrally stitched fabric of a certain thickness can result in a higher blade breakage speed and greater energy containment compared to a single layer of fabric. Attached Figure Description

[0030] Figure 1 A cross-sectional view along the axial direction of the enclosure casing;

[0031] Figure 2 A schematic diagram of the overall stitching fabric laying process;

[0032] Figure 3 This is a structural diagram of a double-layer integrally stitched fabric with a stitch density of 2*2;

[0033] Figure 4This is a structural diagram of a four-layer integrally sewn fabric with a stitch density of 4*4. Detailed Implementation

[0034] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0035] The composite structure enclosure casing of the present invention consists of a composite material load-bearing cylinder and an enclosure region composite structure, and its manufacturing process is as follows:

[0036] 1. The composite material load-bearing cylinder is prepared using prepreg layup autoclave molding technology. First, carbon fiber prepreg is cut according to the design layup requirements, then laid onto a mold to form a vacuum bag assembly structure. Following the curing process specifications of the selected prepreg, it is heated and pressurized in an autoclave to obtain the composite material load-bearing cylinder. The prepreg is selected based on the different operating temperatures of the housing. When the operating temperature is below 120℃, a high-toughness epoxy prepreg is used; when the operating temperature is above 120℃ but below 200℃, a high-toughness bismaleimide prepreg is used.

[0037] 2. Manufacturing of integrally stitched organic fiber fabric within the containment zone. The integrally stitched fabric uses high-strength organic fibers (polyimide fibers or heterocyclic aramid fibers). Generally, heat resistance requirements exceed 150℃, necessitating the use of high-temperature resistant, high-strength polyimide fibers. Below 150℃, polyimide fibers or heterocyclic aramid fibers can be used. The organic fibers are woven into a fabric using a machine weaving method. The weight ratio of warp fibers to weft fibers is 6:4 to 8:2, and the fabric's areal density is 100 to 200 g / m². 2 Multiple layers of organic fiber fabric are sewn together to form a single fabric. The areal density of the sewn fabric is 600g–900g / m². 2 The suture thread and fabric fibers are consistent, the suture is double-sided, the suture density is 2*2mm~10*10mm, the width of the suture fabric is 200mm~800mm, and the length is greater than 10m.

[0038] 3. Composite Structure Enclosure Manufacturing. Stitching fabric is laid on the enclosure area of ​​the already cured carbon fiber composite housing support cylinder. The number of stitching fabric layers is determined based on the areal density of the stitching fabric and the required composite material thickness for the enclosure area. To ensure integrity, continuous fabric laying is used, and splicing of the stitching fabric is minimized, avoiding unnecessary splicing. After the fabric laying is completed, the stitched fabric is assembled onto a vacuum bag based on the housing support cylinder. Resin is then injected into the stitching fabric, and after curing, a complete composite structure enclosure is formed.

[0039] Figure 1A cross-sectional view of the containment casing along the axial direction is shown, with the carrier cylinder 1 located inside the containment area 2 relative to the inner layer of the casing. Figure 2 A schematic diagram of the integral stitched fabric laid along the supporting cylinder is shown. After multiple layers of integral stitched fabric are wound axially, an enclosing area 2 is formed, where 21, 22, and 23 correspond to the first, second, and third layers of integral stitched fabric, respectively.

[0040] Figure 3 A diagram of an integrally stitched fabric structure with a stitch density of 2*2 is shown in one embodiment, where 21 and 22 correspond to... Figure 2 The first and second integrally sewn fabrics in the middle bearing cylinder 1 are formed by the stitching 221 penetrating the double-layer fabric to form a closed loop structure, with the stitching closure loop spacing being 2mm. Figure 4 A diagram of a four-layer sewn fabric structure with a stitch density of 4*4 is shown in one embodiment, where 21' and 22' correspond to... Figure 2 The first and second layers of integrally sewn fabric in the central bearing cylinder 1 are joined by stitches 221' that penetrate four layers of fabric to form a closed loop structure, with a stitch spacing of 4mm. It should be noted that... Figure 3 , Figure 4 This is merely an illustrative drawing; in any embodiment, the number of fabric layers penetrated by the suture and the spacing of the suture loops can be adjusted arbitrarily.

[0041] When the containment casing is subjected to an impact, the suture closure ring 211 and suture closure ring 211' will first undergo open-loop failure. The breakage of the suture will dissipate a large amount of energy, thereby improving the containment performance of the containment casing.

[0042] To address the influence of the overall stitched fabric layer count and areal density on the containment performance of the containment casing, a composite structure containment casing for aero-engines proposed according to the present invention was prepared using Example 1 and two comparative examples to obtain three types of composite structure containment casings. Table 1 shows the critical containment speeds of the three types of composite structure containment casings for a 1000g broken blade.

[0043] The critical containment speed refers to the maximum speed at which the containment casing will not be broken down by the broken blade. If the speed exceeds this, the broken blade will break down the casing and form a non-containment state.

[0044] Example 1

[0045] Carbon fiber epoxy resin prepreg is laid on the mold in a [±60 / 0] layering pattern with a thickness of 8mm. After laying, it is placed in an autoclave for heating and curing. After demolding, a carbon fiber epoxy resin composite material bearing cylinder is obtained.

[0046] A single-layer fabric of heterocyclic aramid fibers was manufactured using a weaving method. The weight ratio of warp fibers to weft fibers in the single-layer fabric was 6:4, and the fabric areal density was 100 g / m². 2 Six layers of heterocyclic aramid fiber monolayer fabric were sewn together to form a single fabric. The areal density of the sewn fabric was 600 g / m³. 2 The suture thread and fabric fibers are consistent, the suture is double-sided, the suture density is 2*2mm, the width of the suture fabric is 400mm, and the length is 12m.

[0047] A heterocyclic aramid fiber monolithic fabric was laid in the outer containment area of ​​the carbon fiber epoxy resin composite bearing cylinder. The monolithic fabric consisted of 12 layers, laid continuously with minimal splicing to avoid unnecessary joints. After the fabric was laid, resin was injected and cured at a high temperature to obtain a complete composite structure containing the casing, with a containment area thickness of 9 mm.

[0048] Example 2

[0049] The 12 layers of heterocyclic aramid fiber single-layer fabric are sewn together to form a whole fabric, and the whole sewn fabric has 6 layers.

[0050] Other information is the same as in Example 1.

[0051] Comparative Example 1

[0052] 24 layers of heterocyclic aramid fiber monolayer fabric were sewn together to form a whole fabric. The areal density of the whole fabric after sewing is 2400 g / m². 2 The overall stitched fabric has 3 layers, and the thickness of the containment area is 9mm.

[0053] Other information is the same as in Example 1.

[0054] Table 1 Critical containment speed for different numbers and thicknesses of integrally stitched fabrics

[0055] sample Critical containment speed (r / min) Example 1 8650 Example 2 12440 Comparative Example 1 5460

[0056] To illustrate the effect of different stitch densities on containment performance, a composite structure containment casing for an aero-engine proposed according to the present invention was prepared in accordance with three embodiments and one comparative example to obtain four composite structure containment casings. Table 2 shows the critical containment speeds of composite structure containment casings with different stitch densities for a 1000g broken blade.

[0057] Example 3

[0058] Carbon fiber epoxy resin prepreg is laid on the mold in a [±60 / 0] layering pattern with a thickness of 6mm. After laying, it is placed in an autoclave for heating and curing. After demolding, a carbon fiber epoxy resin composite material bearing cylinder is obtained.

[0059] A heterocyclic aramid fiber monolayer fabric was manufactured using a weaving method. The weight ratio of warp fibers to weft fibers in the monolayer fabric was 8:2, and the fabric areal density was 200 g / m². 2 Four layers of heterocyclic aramid fiber monolayer fabric were sewn together to form a single fabric. The areal density of the sewn fabric is 800 g / m². 2 The suture thread and fabric fibers are consistent, the suture is double-sided, the suture density is 4*4mm, the width of the suture fabric is 400mm, and the length is 12m.

[0060] A heterocyclic aramid fiber monolithic fabric was laid in the outer containment area of ​​the carbon fiber epoxy resin composite bearing cylinder. The monolithic fabric consisted of 10 layers, laid continuously with minimal splicing to avoid unnecessary joints. After the fabric was laid, resin was injected and cured at a high temperature to obtain a complete composite structure containing the casing, with a containment area thickness of 9 mm.

[0061] Example 4

[0062] The suture density is 6*6mm

[0063] Other information is the same as in Example 2.

[0064] Example 5

[0065] The suture density is 10*10mm

[0066] Other information is the same as in Example 2.

[0067] Comparative Example 2

[0068] The suture density is 20*20mm

[0069] Other information is the same as in Example 2.

[0070] Table 2 Critical containment speeds for composite containment casings with different stitch densities

[0071] sample Critical containment speed (r / min) Example 2 12440 Example 3 10530 Example 4 11450 Example 5 12980 Comparative Example 2 6780

[0072] To illustrate the effect of stitching method on containment performance, four composite containment casings were prepared by comparing one example and three comparative examples. Table 3 shows the critical containment speed of composite containment casings with different stitching densities for a 1000g broken blade.

[0073] Example 6

[0074] Carbon fiber epoxy resin prepreg is laid on the mold in a [±60 / 0] layering pattern with a thickness of 6mm. After laying, it is placed in an autoclave for heating and curing. After demolding, a carbon fiber epoxy resin composite material bearing cylinder is obtained.

[0075] Polyimide fiber monolayer fabric is manufactured using a woven method. The weight ratio of warp fibers to weft fibers in the monolayer fabric is 8:2, and the fabric areal density is 200 g / m². 2 Eight layers of heterocyclic aramid fiber monolayer fabric were sewn together to form a single fabric. The areal density of the sewn fabric is 800 g / m³. 2 The suture thread and fabric fibers are consistent, the suture is double-sided, the suture density is 4*4mm, the width of the suture fabric is 400mm, and the length is 12m.

[0076] Five layers of polyimide fiber monolithic fabric were laid in the outer containment area of ​​the carbon fiber epoxy resin composite bearing cylinder. The fabric was laid continuously with minimal splicing, avoiding unnecessary joints. After the fabric was laid, resin was injected and cured at a high temperature to obtain a complete composite structure containing the casing, with a containment area thickness of 9 mm.

[0077] Comparative Example 3

[0078] Carbon fiber epoxy resin prepreg is laid on the mold in a [±60 / 0] layering pattern with a thickness of 6mm. After laying, it is placed in an autoclave for heating and curing. After demolding, a carbon fiber epoxy resin composite material bearing cylinder is obtained.

[0079] Polyimide fiber monolayer fabric is manufactured using a woven method. The weight ratio of warp fibers to weft fibers in the monolayer fabric is 8:2, and the fabric areal density is 200 g / m². 2 Forty layers of polyimide fiber single-layer fabric are wound around the carrier cylinder. The polyimide fiber is implanted into the adjacent layers from one side using a flocking process. The implantation depth is the thickness of three single-layer fabrics. The three single-layer fabrics are connected in this way. The implantation density is 4*4mm. After flocking is completed, resin injection is performed and the temperature is raised to cure, resulting in a complete composite structure containing the casing with a containment area thickness of 9mm.

[0080] Comparative Example 4

[0081] The single-layer woven fabric is not sewn together, and the number of layers on the supporting cylinder is 40.

[0082] Other information is the same as in Example 6.

[0083] Table 3 Critical containment speeds for containment casings with different stitching methods

[0084] sample Critical containment speed (r / min) Example 6 12460 Comparative Example 3 7670 Comparative Example 4 3550

Claims

1. A composite structure enclosure casing, comprising a supporting cylinder and an enclosure area, characterized in that: The supporting cylinder is made of unidirectional carbon fiber prepreg and manufactured using autoclave molding technology; The containment area is made of a high-strength organic fiber monolithically sewn fabric, prepared by RTM molding process; The organic fiber monolithic sewn fabric refers to at least two single-layer woven fabrics sewn together on both sides, with a surface density of 600g to 900g / m³. 2 The double-sided stitching forms a closed loop structure. When the casing is impacted, the stitching first breaks open, and the breakage of the stitching will dissipate a large amount of energy, thus improving the containment of the casing. The weight ratio of warp fibers to weft fibers in a single-layer woven fabric is 6:4 to 8:2, and the areal density is 100 to 200 g / m². 2 Before sewing, it is a single layer of woven fabric; after sewing, it is a single-layer sewn fabric. The overall stitching is double-sided, with a stitching density of 2*2mm to 10*10mm. The width of the overall stitched fabric is 200mm to 800mm, and the length is greater than 10m. The number of layers of stitched fabric laid in the containment area is ≥4.

2. The enclosure casing according to claim 1, characterized in that: The stitching is consistent with the fabric fibers.

3. The enclosure casing according to claim 1, characterized in that: The organic fibers are polyimide fibers or heterocyclic aramid fibers.

4. The enclosure casing according to claim 1, characterized in that: The prepreg for the composite material bearing shell is selected according to the different operating temperatures of the enclosure. When the operating temperature is not higher than 120℃, high-toughness epoxy prepreg is used. When the operating temperature is higher than 120℃ but not higher than 200℃, high-toughness bismaleimide prepreg is used.

5. The enclosure casing according to claim 4, characterized in that: High toughness refers to the ability of a material to absorb energy during plastic deformation and fracture under stress. Here, the composite material prepared by high-toughness epoxy / bismaleimide prepreg has a CAI ≥ 300 MPa.

6. The enclosure casing according to claim 1, characterized in that: Heat resistance requirements for the housing: Above 150℃, the organic fiber shall be high-temperature resistant and high-strength polyimide fiber; below 150℃, the organic fiber shall be polyimide fiber or heterocyclic aramid fiber.

7. An engine, characterized in that: The enclosure casing as described in claim 1 is used.

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