CN108104951B - Self-adaptive bump air inlet channel deformation adjustment realization method and profile displacement control system - Google Patents
Self-adaptive bump air inlet channel deformation adjustment realization method and profile displacement control system Download PDFInfo
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- CN108104951B CN108104951B CN201711172914.6A CN201711172914A CN108104951B CN 108104951 B CN108104951 B CN 108104951B CN 201711172914 A CN201711172914 A CN 201711172914A CN 108104951 B CN108104951 B CN 108104951B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
- F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
- F02C7/04—Air intakes for gas-turbine plants or jet-propulsion plants
- F02C7/042—Air intakes for gas-turbine plants or jet-propulsion plants having variable geometry
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
- F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
- F02C7/04—Air intakes for gas-turbine plants or jet-propulsion plants
- F02C7/057—Control or regulation
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Abstract
The invention relates to a method for realizing deformation adjustment of a self-adaptive bulge air inlet, belonging to the field of design of airplane air inlets and comprising the following steps of: 1) selecting a bulge deformation area of the self-adaptive bulge air inlet channel, wherein a flexible composite skin is adopted by the bulge as a surface structure of the bulge deformation area, and the shape of the bulge profile is adjusted by adopting a pressurizing device; 2) analyzing the deformation and the bearing requirement of the self-adaptive bulge, and determining a driving pressurizing pressure value; 3) determining the relation between the deformation shape of the flexible bump profile and the rigidity distribution of the material under uniform pressure, and realizing the control of the bump profile with a complex shape through the material design of the flexible composite skin. The method for realizing the deformation adjustment of the self-adaptive bulge air inlet passage can realize the local adjustable deformation of the bulge molded surface, and the composite flexible skin adopted in the bulge deformation area can realize the rigidity distribution of different bulge molded surfaces through material design, so that a drum with a specific complex shape is formed under the condition of uniform internal pressurization.
Description
Technical Field
The invention belongs to the field of aircraft inlet design in the technology of morphing aircraft, and particularly relates to a method for realizing deformation adjustment of a self-adaptive bulge inlet and a profile displacement control system.
Background
The air inlet of an aircraft is an important airflow adjusting part, which performs primary compression on external incoming flow to provide stable airflow for an engine, and the working efficiency and quality of the air inlet directly influence the performance and safety of the engine. For a high-performance aircraft with supersonic speed and high maneuverability in the future, the air inlet design must solve the contradiction of high-low speed air inlet requirements of an engine, and good forward matching performance is kept in a wide speed range.
At present, some high-performance airplanes adopt an adjustable binary air inlet channel of a rigid deformation mechanism, the air inlet amount of an engine under different flight speeds is controlled by a movable compression inclined plane and an air inlet cone, but the low-speed performance of the airplane is poor due to a sharp lip edge, and the problems of poor stealth performance caused by the increase of the structural weight, the cost and the occupied space are caused by a complex adjusting system, so that the requirements of some high-performance airplanes cannot be met. At present, DSI (direct surface Supersonic inlay) air inlet channels, also called three-dimensional drum type boundary layer-free partition air inlet channels, are increasingly adopted by advanced high-performance airplanes, the problems of stealth design and increase of airplane weight and space are solved by guiding air flow through a simple three-dimensional profile, but the air inlet is not adjustable, and the high performance can be exerted only within the designed flight speed.
Disclosure of Invention
The invention aims to provide a method for realizing deformation adjustment of an adaptive bump air inlet and a profile displacement control system, which are used for solving or reducing any one of the problems.
In order to achieve the purpose, the invention adopts the technical scheme that: a method for realizing deformation adjustment of a self-adaptive bulge air inlet comprises the following steps:
1) selecting a bulge deformation area of the self-adaptive bulge air inlet channel, wherein the bulge deformation area is in an oval shape, and establishing a bulge deformation area model;
2) the bulge deformation region adopts a rigid base shell surface as a low-speed bulge molded surface, an outer flexible skin and an inner flexible skin are respectively arranged on the upper surface and the lower surface of the rigid base shell surface, and the outer flexible skin and the inner flexible skin are fixedly connected with the periphery of the elliptic bottom surface of the rigid base shell surface to form an outer closed cavity and an inner closed cavity; the outer flexible skin and the inner flexible skin are connected through a plurality of connecting pieces, the connecting pieces penetrate through the shell surface of the rigid foundation and can slide along with the deformation of the flexible skin, and the height of the bulge profile is adjusted through the pressurizing device to form a profile displacement control system;
3) the outer flexible skin and the inner flexible skin are made of high-elasticity fiber reinforced composite materials based on an elastic matrix, the high-elasticity fibers are composed of independent warp fibers and weft fibers, and the distribution of the warp fibers and the weft fibers can be controlled in density through fiber laying;
4) designing the positions of high and low molded surfaces of the bulges according to the requirement of the airplane on the variable quantity of the throat area of the air inlet channel, and analyzing the strain level on the molded surfaces of the bulges in the process of changing the bulges from the low molded surfaces to the high molded surfaces;
5) determining the pressurizing value of the closed cavity according to the bearing capacity of the bulge molded surface under the condition of different pressurizing values;
6) determining the relation between the deformation shape of the molded surface of the flexible bulge and the material rigidity distribution of the flexible skin under uniform pressure, and establishing a calculation model of the mechanical property of the flexible skin, the material properties of the matrix and the fibers, the fiber volume ratio and the fiber distribution mode;
7) through the grid distribution and optimization of the flexible skin fibers, the rigidity distribution of the flexible skin at each position of the bulge molded surface is different, and the bulge molded surface with a specific complex shape is formed under the action of monotonous uniform pressure.
Further, the maximum variable area of the throat variation in step 4 is Δ a ═ a (h)2)-A(h1) Wherein the area A (h) enclosed by the sectional line and the bottom sectional line of the bulge is:
wherein b is an elliptical semi-axis, h is the maximum deformation height of the bulge, and h is1Bulge height h at the lowest profile position2Bulge high for the highest profile position.
Further, in step 6, since the flexible skin is composed of the elastic matrix and the high-elastic fibers, and the mechanical properties of the flexible skin are related to the material properties of the matrix and the fibers, the fiber volume ratio, and the fiber distribution mode, the mechanical model of the high-elastic fibers of the flexible skin is as follows: defining the warp fiber relative volume content cfxRelative volume content of weft fibers cfyThe two quantities are independent of each other and are a function of x and y, respectively;
basically, when the flexible skin is subjected to uniaxial tension, the strains of the fibers and the matrix in the fiber direction are equal, so that the expression of the macroscopic orthogonal anisotropic elastic constant of the single-layer composite material of the series model is as follows:
in the formula: E. g, ν and c respectively represent the elastic modulus, shear modulus, Poisson's ratio and relative volume content of the material, subscript f represents fiber, m represents matrix;
for the fiber reinforced composite material distributed in the warp and weft directions, each elastic constant of the fiber can be obtained, and a micro element body with the size of dx multiplied by dy multiplied by t is selected and is regarded as the relative volume content of the warp/weft fiber which is respectively cfx、cfyIntroducing a parallel model of the effect on the material properties, and assuming Efx＝Efy＞＞EmThe following can be obtained:
Ex＝Efxcfx+Emcm+(1-C)Em/cm+C(Efycfy+Emcm)
Ey＝Efycfy+Emcm+(1-C)Em/cm+C(Efxcfx+Emcm) (1)
wherein C is the contact coefficient.
Further, in step 7, the relative volume content of the oriented fiber distribution in the flexible skin bulge model is defined as c along the x-axis functionf(x)The relative volume content of the weft fiber distribution as a function of c along the y-axisf(y)The change of the performance of the composite flexible skin material at different positions of the bulge along with the x and y coordinates can be obtained by using the formula 1.
The invention also provides a self-adaptive bump air inlet channel profile displacement control system, which comprises:
the rigid base shell surface is arranged on the self-adaptive air inlet channel and is elliptical;
the outer flexible skin and the inner flexible skin are arranged on two sides of the shell surface of the rigid foundation, the edges of the outer flexible skin and the inner meat skin are combined with the periphery of the bottom surface of the shell surface of the rigid foundation, an outer closed cavity is formed between the outer skin and the shell surface of the rigid foundation, an inner closed cavity is formed between the inner skin and the shell surface of the rigid foundation, and the outer closed cavity is communicated with the inner closed cavity;
the connecting piece penetrates through the shell surface of the rigid foundation, and two ends of the connecting piece are respectively connected to the outer flexible skin and the inner flexible skin;
the pressurizing device is respectively communicated with the outer closed containing cavity and the inner closed containing cavity, and the adjustment of the air inlet bulge is realized by providing pressure to the outer closed containing cavity or the inner closed containing cavity.
Furthermore, outer flexible skin and interior flexible skin all adopt high carbon-fibre composite based on elasticity to make, high-elastic fiber composite comprises independent warp-wise fibre and latitudinal direction fibre, and wherein but radial fibre and latitudinal direction fibre distribution independent control shop silk density.
Further, the connecting member is a steel cable for providing a pulling force or a supporting force between the outer flexible skin and the inner flexible skin.
Further, the pressurizing medium adopted by the pressurizing device comprises gas or liquid.
The method for realizing the deformation adjustment of the self-adaptive bulge air inlet passage and the profile displacement control system have the following advantages that:
1) the invention can realize the local adjustable deformation of the bulge molded surface in the bulge air inlet channel, thereby realizing the adjustment of the throat area of the air inlet channel and the shape of the inner pipeline;
2) according to the invention, the composite flexible skin adopted in the bulge deformation region can realize different bulge profile rigidity distributions through material design, so that a specific drum with a complex shape is formed under the condition of uniform internal pressurization;
3) the invention has the advantages of gentle load applied in the deformation process of the bulge, moderate strain level of the bulge shell surface, flat and smooth bulge molded surface after deformation and obvious airflow flux change effect.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
FIG. 1 is a front view of an adaptive bulge inlet;
FIG. 2 is a side view of an adaptive bulge inlet;
FIG. 3 is a schematic view of a flexible adjustable bulge
FIG. 4 is a bulge deformation zone model
FIG. 5 is a schematic view of the adjustment of the bulge in the high speed state;
FIG. 6 is a schematic view of the low speed state bump adjustment;
FIG. 7 is a schematic view of a bulge structure based on a composite flexible skin;
FIG. 8 is a schematic view of a cross-sectional dimension of an aircraft bulge inlet
FIG. 9 is a shell surface strain analysis simulation of bulge deformation;
FIG. 10 is a simulation of the ability of the internal plenum to maintain the bulge in deformation;
FIG. 11 is a composite flexible skin material model;
FIG. 12 is the relative volume content cfx＝cfyThe simulation result of bulging deformation under the condition of 0.21 is shown in a diagram;
FIG. 13 is the relative volume content cf(x)A schematic diagram of a simulation result of bulge deformation under linear change conditions;
FIG. 14 is the relative volume content cf(x)A schematic diagram of a bulge deformation simulation result under a symmetrical linear change condition;
FIG. 15 shows the relative volume content cf(x)A diagram of a simulation result of bulge deformation under the symmetrical parabola variation condition;
FIG. 16 is a schematic view of bulge deformation for different weft fiber distributions;
figure 17 is a schematic representation of bulge deformation for different warp fiber distributions.
Detailed Description
In order to make the implementation objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings in the embodiments of the present invention.
The method for realizing the deformation adjustment of the self-adaptive bulge air inlet comprises the following steps:
(1) selecting a bulge deformation area of the self-adaptive bulge air inlet channel and designing an adjustable bulge scheme
(1.1) adaptive bulge inlet as shown in fig. 1 and 2, the air flow entering the engine is adjusted by changing the throat area and the inner pipe shape of the inlet by adjusting the bulge profile. Under a high-speed (flight speed) configuration, the bulge is positioned at the highest position, the air flow is compressed more, and the air inflow is reduced so as to adapt to a high-speed flight state; the bulge is at the lowest position under the low-speed (flight speed) configuration, and the throat area is the largest, thereby meeting the large flow demand of engine air intake.
The DSI air inlet has good comprehensive efficiency of pneumatics, stealth and structural weight, and from the shape size parameter, the air inlet adopts the quadrangle cross-section more, and the swell is located fuselage lateral inclined wall, and the shape is similar to oval base spherical shell face. Therefore, in the present invention, the shape of the deformation zone of the bulge profile is simulated by using an oval bottom oblate spheroid shell, and a bulge deformation region model is established, as shown in fig. 3 and 4, the geometric shape parameters of the bulge deformation region model include the half axes a and b of the bottom oval, the maximum height h of the shell surface, and the shell thickness t, wherein in this embodiment, the half axis a is 1000mm, and the half axis b is 500 mm.
(1.2) designing a bulge deformation area, wherein a rigid basic shell surface structure is adopted as a low-speed bulge molded surface, flexible skins are respectively arranged on the upper surface and the lower surface of the bulge molded surface, and the edges of the skins are fixedly connected with the elliptical periphery of the bottom surface of the rigid shell surface; the upper surface skin and the lower surface skin are connected through a plurality of rigid cables, and the rigid cables penetrate through the rigid shell surface and can slide along with the deformation of the skins to form a profile displacement control system.
When the air/liquid pressurizing mode is adopted to pressurize the space between the upper surface flexible skin and the rigid shell surface, the upper surface profile gradually bulges until the upper surface profile is just tightly pulled, the lower surface skin is tightly attached to the rigid shell surface structure, and the self-adaptive bulge is at the highest position at the moment, as shown in fig. 5; when the upper pressure is removed and the space between the lower surface skin and the rigid shell surface is pressurized, the lower surface skin bulges downwards to drive the rigid cable to pull the upper skin downwards until the upper skin is attached to the rigid shell surface, and at the moment, the self-adaptive bulge is at the lowest position, as shown in fig. 6. Other shapes belong to the intermediate state and are adjusted by pressurizing at both sides.
(1.3) the flexible skin is made of an elastic fiber reinforced composite material based on an elastic matrix, as shown in fig. 7, the fibers are composed of warp fibers and weft fibers, and the fibers defining the y direction are warp fibers and the x direction is weft fibers. The distribution of the fibers can be controlled by laying the fibers in a density that is independent of the warp and fill directions.
(2) Analyzing the deformation and bearing requirements of the self-adaptive bulge and designing a flexible skin material
(2.1) taking the bulge air inlet channel of a certain airplane as an example, the bulge molded surface is required to be changed up and down at the original bulge height, so that the throat area variation can reach 30%, as shown in FIG. 8, the bulge height h at the lowest molded surface position1Height h of bulge at highest molded surface position2The throat area in the highest profile state is A0The maximum variable area of the throat is Δ A.
Regarding the sectional line of the bulge profile as an arc, the area of the area enclosed by the sectional line of the bulge profile and the sectional line of the bottom surface is:
unit mm2Wherein b is 500 mm. Thus, the areas of the two throats are respectively as follows:
ΔA＝A(h2)-A(h1)、A0＝463000-A(h2) (2)
let Δ A/(Δ A + A)0) 30%, h can be obtained1And h2The range of the solution is approximately h2＝0.7h1+204。
The height of the bulge of the air inlet channel in the original design state is about 230mm, and h is selected in the embodiment1＝80mm，h2260mm as a design solution. The strain level of the flexible skin on the upper surface of the bulge in this case was analyzed by first establishing a model of the base shell surface, with the dimensions of the ellipsoidal shell being 1000mm, b 500mm, h 80mm and t 2mm, and applying uniform pressure inside the shell surface to deform the bulge to a height of 260mm, as shown in fig. 9, it can be seen that the maximum strain level on the shell surface is 15.19%.
And (2.2) the flexible skin is used as a surface structure of the self-adaptive bulge, so that the surface deformation capacity is met, the pneumatic load can be borne when the bulge is in various states, the shape stability of the bulge is kept, and excessive deformation is avoided. The surface pressure distribution of a DSI bump air inlet channel under the conditions of the height of 16km and the speed of 1.6Ma is as follows: the bulge profile has a pressure in the region along the major axis (-a, -0.5a) of 0.0186MPa, in the region (-0.5a, -0.28a) of 0.0238MPa, and in the region (-a, -0.5a) of 0.0269 MPa. The bearing capacity of the self-adaptive air inlet bulge molded surface based on the flexible skin under the conditions of different charging values is simulated by taking the external load as the external load.
Firstly, uniformly distributed pressure load P is applied to a basic shell surface model0Simulating the internal pressurizing value of the flexible skin bulge to be P0The case (1). And correspondingly adjusting the modulus of the bulge material to enable the bulge after deformation to reach the height required by the design.Then, the external load is applied on the basis, and the bulge deforms inwards by delta u under the action of external pressure, as shown in fig. 10. The results show that as the inflation pressure increases, the resistance of the bulge profile to external loads increases, but the stiffness requirements for the flexible skin correspondingly increase. The two factors are combined, and the charging value of the invention is initially determined to be 1MPa after the design is compromised.
(3) The relation between the deformation shape of the profile of the flexible bulge and the rigidity distribution of the material under uniform pressure is researched, and the requirement of the specific bulge profile is met through the design of the bulge material
And (3.1) as the flexible skin consists of an elastic matrix and high-elastic fibers, the mechanical property of the flexible skin is related to the material properties of the matrix and the fibers, the volume ratio of the fibers and the fiber distribution mode.
A mechanical model for establishing the high-elasticity fiber reinforced flexible skin is shown in FIG. 11, and the relative volume content c of the warp fibers is definedfxRelative volume content of weft fibers cfyThe two quantities are independent of each other and are a function of x and y, respectively.
According to the mesomechanics theory of the composite material, a material mechanics analysis method is adopted, the strain of the fiber and the strain of the matrix in the fiber direction are equal when the unidirectional stretching is basically assumed, and therefore the expression of the macroscopic orthotropic elastic constant of the single-layer composite material of the series model is given:
wherein E, G, v and c respectively represent the elastic modulus, the shear modulus, the Poisson's ratio and the relative volume content of the material, the subscript f represents the fiber, and m represents the matrix.
For the fiber reinforced composite material with fiber distributed in warp and weft, various elastic constants can be deduced. Selecting the microelement with the size of dx multiplied by dy multiplied by t, which can be approximately regarded as the relative volume content of warp/weft fiber respectively being cfx、cfyIntroducing a parallel model of the effect on the material properties, and assuming Efx＝Efy＞＞EmIt can be deduced that:
Ex＝Efxcfx+Emcm+(1-C)Em/cm+C(Efycfy+Emcm)
Ey＝Efycfy+Emcm+(1-C)Em/cm+C(Efxcfx+Emcm) (4)
wherein C is the contact coefficient.
And (3.2) controlling the flow field of the air inlet in different flight states by the self-adaptive bulge air inlet through a specific bulge surface, wherein the load for driving deformation is internal uniform pressurization. Through the grid distribution and optimization of the fibers, the rigidity distribution of the composite flexible skin at each position of the bulge molded surface is different, the specific bulge molded surface with the complex shape is formed under the action of monotonous uniform pressure, and the flow field of the air inlet channel is better improved.
Defining a composite flexible skin bulge model, wherein the relative volume content of the distribution of the warp fibers is c along the function of the x axisf(x) The relative volume content of the weft fiber distribution as a function of c along the y-axisf(y), the change of the performance of the composite flexible skin material at different positions of the bulge along with the x and y coordinates can be obtained by using a formula 4, and the gradient material is assigned to the model shell unit for simulation calculation through a Umat subprogram in ABAQUS.
Using the bulge model with equal density distribution of fiber as reference, and the whole shell surface cfx＝0.21，cfy＝0.21，Ef＝8GPa，EmThe bulge basic profile model of the present solution was established at 3MPa and C0.1, and the deformation of the bulge under the condition of internal pressurization of 1MPa was obtained by simulation, as shown in fig. 12. It can be seen that the bulge deformation is the same as the shell surface of the isotropic material, and is symmetrical along the x and y axes, and the root part of the skin connected with the fuselage structure along the airflow direction protrudes seriously, possibly resulting in unsmooth and continuous connection.
Changing c in the Umat subroutinef(x)、cfAnd (y) the expression is used for analyzing the influence of different fiber distribution modes on the deformation shape of the bulge under uniform pressurization.
When in use
And meanwhile, the shell surface deformation result is shown in fig. 13, the rigidity of the x-axis negative direction is small, the highest point of bulge deformation deviates to the left, and the effect is obvious.
Comparison of
And
as a result of the shell surface deformation in both cases, the bulge in the middle area of the bulge is more pronounced due to the greater stiffness at both ends along the x-axis than in the middle. Comparing fig. 14 and 15, it can be seen that the parabolic fiber distribution variation can form a smoother continuous bulge deformation.
Fig. 16 and 17 summarize the deformation effect of the bulges with different distribution functions, and the corresponding fiber distribution forms can be selected or combined according to the design bulge shape.
The invention discloses a method for realizing deformation adjustment of a self-adaptive bulge air inlet passage and a profile displacement control system, which combine the advantages of a DSI air inlet passage and the requirements of a high-performance machine on the adjustable air inlet passage, and provides a method for realizing the self-adaptive bulge air inlet passage adaptive to different flight states.
The above description is only for the best mode of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (4)
1. A method for realizing deformation adjustment of a self-adaptive bulge air inlet passage is characterized by comprising the following steps:
1) selecting a bulge deformation area of the self-adaptive bulge air inlet channel, wherein the bulge deformation area is in an oval shape, and establishing a bulge deformation area model;
2) the bulge deformation region adopts a rigid base shell surface as a low-speed bulge molded surface, an outer flexible skin and an inner flexible skin are respectively arranged on the upper surface and the lower surface of the rigid base shell surface, and the outer flexible skin and the inner flexible skin are fixedly connected with the periphery of the elliptic bottom surface of the rigid base shell surface to form an outer closed cavity and an inner closed cavity; the outer flexible skin and the inner flexible skin are connected through a plurality of connecting pieces, the connecting pieces penetrate through the shell surface of the rigid foundation and can slide along with the deformation of the flexible skin, and the height of the bulge profile is adjusted through the pressurizing device to form a profile displacement control system;
3) the outer flexible skin and the inner flexible skin are made of high-elasticity fiber reinforced composite materials based on an elastic matrix, the high-elasticity fibers are composed of independent warp fibers and weft fibers, and the distribution of the warp fibers and the weft fibers can be controlled in density through fiber laying;
4) designing the positions of high and low molded surfaces of the bulges according to the requirement of the airplane on the variable quantity of the throat area of the air inlet, analyzing the strain level on the molded surface of the bulges in the process of changing the bulges from the low molded surface to the high molded surface, wherein the maximum variable area of the throat area variable quantity is delta A (h)2)-A(h1) Wherein the area A (h) enclosed by the sectional line and the bottom sectional line of the bulge is:
in the formula, b is an elliptical semi-axis, h is the maximum deformation height of the bulge, and h is1Bulge height h at the lowest profile position2The highest molded surface position is bulged to be high;
5) determining the pressurizing value of the closed cavity according to the bearing capacity of the bulge molded surface under the condition of different pressurizing values;
6) determining the relation between the deformation shape of the profile of the flexible bulge and the material rigidity distribution of the flexible skin under uniform pressure, and establishing the mechanical properties of the flexible skin and the materials of the matrix and the fibersThe mechanical properties of the flexible skin are related to the material properties of the matrix and the fibers, the fiber volume ratio and the fiber distribution mode, so that the mechanical model of the flexible skin high-elasticity fibers is as follows: defining the warp fiber relative volume content cfxRelative volume content of weft fibers cfyThe two quantities are independent of each other and are a function of x and y, respectively;
basically, when the flexible skin is subjected to uniaxial tension, the strains of the fibers and the matrix in the fiber direction are equal, so that the expression of the macroscopic orthogonal anisotropic elastic constant of the single-layer composite material of the series model is as follows:
E1＝Efcf+Emcm，
ν12＝cfνf+cmνm，
in the formula: E. g, ν and c respectively represent the elastic modulus, shear modulus, Poisson's ratio and relative volume content of the material, subscript f represents fiber, m represents matrix;
for the fiber reinforced composite material distributed in the warp and weft directions, each elastic constant of the fiber can be obtained, and a micro element body with the size of dx multiplied by dy multiplied by t is selected and is regarded as the relative volume content of the warp/weft fiber which is respectively cfx、cfyIntroducing a parallel model of the effect on the material properties, and assuming Efx＝Efy＞＞EmThe following can be obtained:
Ex＝Efxcfx+Emcm+(1-C)Em/cm+C(Efycfy+Emcm)
Ey＝Efycfy+Emcm+(1-C)Em/cm+C(Efxcfx+Emcm)
wherein C is the contact coefficient;
7) defining the relative volume content of the oriented fiber distribution in the flexible skin bulge model as c along the x-axis functionf(x)The relative volume content of the weft fiber distribution as a function of c along the y-axisf(y)The change of the performance of the composite flexible skin material at different positions of the bulge along with x and y coordinates can be obtained by the formula, and the rigidity distribution of the flexible skin at each position of the bulge molded surface is different by the grid distribution and optimization of the flexible skin fiber, so that the bulge molded surface with a specific complex shape is obtained under the action of monotonous uniform pressure.
2. The utility model provides an adaptive bulge intake duct profile displacement control system which characterized in that, adaptive bulge intake duct profile displacement control system includes:
the rigid base shell surface is arranged on the self-adaptive air inlet channel and is elliptical;
an outer flexible skin and an inner flexible skin, the outer flexible skin and the inner flexible skin are arranged on two sides of the shell surface of the rigid foundation, the edges of the outer flexible skin and the inner meat skin are combined with the periphery of the bottom surface of the shell surface of the rigid foundation, an outer closed cavity is formed between the outer skin and the shell surface of the rigid foundation, an inner closed cavity is formed between the inner skin and the shell surface of the rigid foundation, the outer closed cavity is communicated with the inner closed cavity, wherein the outer flexible skin and the inner flexible skin are both made of high carbon fiber composite materials based on elasticity, the high-elasticity fiber composite material is composed of independent warp fibers and weft fibers, the distribution of the warp fibers and the weft fibers can independently control the filament laying density, the outer flexible skin and the inner flexible skin meet a calculation model of the mechanical property of the flexible skin, which is related to the material properties, the fiber volume ratio and the fiber distribution mode of the matrix and the fibers in claim 1;
the connecting piece penetrates through the shell surface of the rigid foundation, and two ends of the connecting piece are respectively connected to the outer flexible skin and the inner flexible skin;
the pressurizing device is respectively communicated with the outer closed containing cavity and the inner closed containing cavity, and the adjustment of the air inlet bulge is realized by providing pressure to the outer closed containing cavity or the inner closed containing cavity.
3. The adaptive bump inlet profile displacement control system of claim 2, wherein the connector is a wire rope for providing tension or support between the outer flexible skin and the inner flexible skin.
4. The adaptive bump inlet profile displacement control system of claim 2, wherein the pressurizing medium used by the pressurizing device comprises a gas or a liquid.
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| CN111648865B (en) * | 2020-04-30 | 2022-02-08 | 南京航空航天大学 | Multi-air-chamber bulge central body structure of variable particle separator and design method thereof |
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