CN102060101B - Skin for morphing wings - Google Patents

Abstract

The invention discloses a skin for morphing wings, belonging to the technical field of design of morphing aircrafts. The skin for the morphing wings is made from fibre reinforced composites, and the cross section of the skin is in an isosceles trapezoid ripple structure. The invention also carries out analysis aiming at the chordwise and spanwise equivalent elastic modulus and flexural modulus of the skin structure with isosceles trapezoid ripples, provides a corresponding mathematical model and can further optimize the skin structure according to the mathematical model. The invention meets the requirements of the skin of the morphing wings of the morphing aircrafts for large deformation aerodynamic load bearing, can realize the design optimization of the skin structure under different load operating conditions according to the mathematical analysis model of the equivalent elastic modulus and the flexural modulus in two different directions of the skin structure, also has structure health monitoring and self-adapting deformation capability and can realize optimal aerodynamic characteristics by controlling the shape and the vibration of the skin.

Description

A kind of covering for morphing

Technical field

The present invention relates to the covering of aircraft, relate in particular to a kind of covering for morphing, belong to the Flight Vehicle Design technical field.

Background technology

Morphing aircraft is a kind of novel aircraft that puts forward in recent years, and morphing is the important research content in the morphing aircraft, it is a kind of novel aircraft wing structure, refer to aircraft wing generation marked change aspect the geometry sizes such as the span, area, chord length, so that flight environment of vehicle on a large scale in (such as cruise, hypervelocity flight, dive fast, the large angle of attack is motor-driven etc.) when changing, can realize the restructuring of wing profile and surface texture, change to adapt to the flying condition that monitors, obtain best pneumatic gentle bullet characteristic.Since the eighties in last century, the country such as American and Britain, moral has carried out the research of intelligent wing, adaptive wing and morphing in succession, present some gordian techniquies of association area flight test of in blimp, having carried out technical identification, be following advanced aircraft the important research direction it

In the continuous variant process of wing, the covering of wing, to have on the one hand enough Rigidity and strengths and bear aerodynamic loading in the aircraft flight process, must have very high elasticity at wing side of a ship length direction on the other hand, large deformation be can realize, stretching or compressive deformation requirement that the wing front and rear edge produces during deflection up and down satisfied; Therefore research can realize that again the stressed-skin construction of large deformation is one of gordian technique in the variant structure research by bearing load; Characteristics for the skin of morphing wing structure, a lot of scholars have proposed multiple solution to this, fish scale lamination stressed-skin construction is a solution, realize large deformation and the carrying of covering by the stressed-skin construction that adopts the fish scale pattern, but can't guarantee continuity and the slickness of skin-surface, cause the aerodynamic characteristic variation of wing; Shape-memory polymer (the cold sturdy pines of Harbin Institute of Technology's development, Lan Xin etc., shape memory polymer composite material and the application in the deployable structure of space thereof, aerospace journal, the 4th phase in 2010) can realize the super large deflection, but load-carrying capacity is limited; The people such as Wang Xiaohong (Wang Xiaohong, marmem drives the design and fabrication of active deformation structure, Harbin Institute of Technology's master thesis, 2006) made the corrugated plating of triangular structure, and with the embedding distortion that has wherein realized driving the elastic wing covering of marmem; The people such as Wu Cunli, Duan Shihui (Wu Cunli, Duan Shihui, Sun Xiasheng. composite material corrugated panel stiffness engineering calculating method and the application in structural analysis [J] aviation journal thereof, 2008, (06)) the corrugated plating elastomeric material that aligns the chordwise structure is studied, and has analyzed composite material corrugated panel stiffness engineering calculating method and the application in structural analysis thereof; People (the Mechanical Properties of Corrugated Composites forCandidate Materials of Flexible Wing Structures such as TomohiroYokozeki and Shin-ichi Takeda, www.elsevier.com/locate/compositesa:Part A 37 (2006) 1578-1586) proposition adds the corrugated plating of riser form with semi arch, study stretching and mechanics of bending performance take carbon fiber as the covering of reinforcing material made by theoretical prediction and analysis of experiments, and proposed the Enhancement Method of this structural elasticity material property.

Summary of the invention

The object of the invention is to solve that skin of morphing wing is tangential requires large deformation and open up to the contradiction that needs load-carrying capacity to exist between strong, a kind of covering for morphing is provided, this covering is very little to rigidity at airfoil chord, can realize large deformation; To then having high rigidity, can bear larger flexural load in the wing exhibition.

The present invention realizes above-mentioned purpose by the following technical solutions:

A kind of covering for morphing is made by fiber reinforced composite, and its cross-sectional plane is the isosceles trapezoid ripple struction.

Adopt the skin of morphing wing of above-mentioned isosceles trapezoid ripple struction, under the power effect of trapezoidal ripple direction, be subject to stretching and compression, this direction rigidity is very little, can produce very large deformation; And in the direction perpendicular to trapezoidal ripple, have the rigidity that is higher than the conventional panels structure, can bear larger flexural load.Skin of morphing wing is tangential to be required large deformation and opens up to the contradiction that needs load-carrying capacity to exist between strong thereby can effectively solve.

In order further to guarantee aerofoil surface smooth degree and air-tightness requirement, can be in the trough of the isosceles trapezoid ripple of its outside face filling elastic material (such as foamed rubber, silica gel etc.), be implemented under the condition of the tangential rigidity of not obvious increase, guarantee the smooth purpose of aerofoil surface.

Further, can in the skin of morphing wing of above-mentioned isosceles trapezoid ripple struction, embed actuator and sensor, thereby realize stressed-skin construction monitoring and control, thereby obtain best aeroperformance.

The present invention is by adopting the isosceles trapezoid ripple struction, solved that skin of morphing wing is tangential to be required large deformation and open up to the contradiction that needs load-carrying capacity to exist between strong, and by embedded sensor and the actuator of covering, realization is to health monitoring and the shape control of stressed-skin construction, obtain best aeroperformance, also by at covering outside face filling elastic material, guaranteed the smooth of aerofoil surface.

Description of drawings

Fig. 1 is the cross sectional representation of one of them ripple of isosceles trapezoid ripple struction of the present invention, wherein schemes the cross sectional representation that a is single ripple, and figure b is 1/4 cross-sectional configuration of single ripple struction;

Fig. 2 is the cross sectional representation of covering described in the specific embodiment, and wherein 1 is quadrature braided glass fibre composite material by multilayer layer and plate, 2 silica gel for filling.

The specific embodiment

Below in conjunction with accompanying drawing technical scheme of the present invention is elaborated:

Covering for morphing of the present invention is made by fiber reinforced composite, and its cross-sectional plane is the isosceles trapezoid ripple struction, is filled with elastomeric material in the trough of the isosceles trapezoid ripple of its outside face, and the cross-sectional plane of one of them ripple is shown in accompanying drawing 1a.

In the design of reality, often need to be optimized according to the structure of design objective to covering, the present invention is directed to the isosceles trapezoid ripple struction analyzes in equivalent elastic modulus and the bending modulus of two different directions, set up corresponding mathematical analysis model, thereby can carry out according to this math modeling the optimization of concrete structure.The structure principle of this math modeling is as follows:

Stressed-skin construction for the isosceles trapezoid corrugated configuration, suppose the ripple direction, the direction that can produce large deformation is horizontal (T), is set as the X-axis of system of axes, the direction that can bear than macrobending load perpendicular to the ripple direction is vertical (L), is set as Y-axis.As shown in Figure 1, wherein scheme the viewgraph of cross-section that a is single ripple struction, figure b is 1/4 cross-sectional configuration of single ripple struction;

The width of supposing single ripple is w _c, highly be h _c, the thickness of trapezoidal wave card is t, for the ease of the calculating of formula, and each parameter l of definition cross-sectional plane ₁, l ₂, l ₃, l ₄, h ₁, h ₂Respectively as shown in Figure 1a.The face in-draw rigidity of supposing the fiber reinforced composite of this covering of formation is A ₁₁, its bending stiffness is D ₁₁, calculate the volume integral of trapezoidal ripple node configuration, just can obtain its vertical equivalent elastic modulus E _LTFor:

$E_{\mathrm{LT}}=\frac{{[{(l_1-l_3)}^2+{h_1}^2]}^{1/2}+{[{(l_2-l_4)}^2+{h_2}^2]}^{1/2}+l_3+l_4}{2(l_1+l_2)h_2}{A}_{11}---\left(1\right)$

Suppose that this composite material is the homogeneous material of orthogonal anisotropy, by calculating the moment of inertia of cross-section of semi-circular configuration, the bending stiffness that just can obtain its vertical equivalence is:

$D_{\mathrm{LT}}=(\frac{(l_4-l_2){h_2}^4}{4h_2}+\frac{l_2{h_2}^3}{3}-\frac{(l_3-l_1){h_1}^4}{4h_1}-\frac{l_1{h_1}^3}{3})\frac{A_{11}}{h_2-h_1}---\left(2\right)$

In order to calculate semi-circular ripple struction laterally modulus of elasticity and the bending modulus of equivalence, 1/4 (dotted portion among Fig. 1 b) of getting cross-sectional plane is research object, see it as crooked Bernoulli Jacob-Euler's beam, each parameter of node configuration is shown in Fig. 1 b, wherein h is the height of 1/4 trapezoid cross section, and l is the length of 1/4 trapezoid cross section, and b and a are respectively the upper base of 1/4 trapezoid cross section and the length of waist, α is the angle on trapezoidal waist and base, according to geometrical principle as can be known:

$h=\frac{h_1+h_2}{2},$ $l=\frac{l_1+l_2}{2},$ $b=\frac{l_3+l_4}{2},$ $a=\sqrt{{(l-b)}^2+h^2},$ w _c＝4l，h _c＝2h+t，

α＝arcsin(h/a) (3)

If the end of beam in the horizontal direction independent role has concentrated force P, the horizontal displacement of beam end is δ, according to Castigliano, and the structural strain's energy of beam:

$U=P^2(\frac{a^3{\sin }^2\mathrm{\α}}{6D_{11}}+\frac{a{\cos }^2\mathrm{\α}}{2A_{11}}+\frac{{\mathrm{bh}}^2}{2D_{11}}+\frac{b}{2A_{11}})---\left(4\right)$

Then the horizontal direction displacement δ of beam is:

$\mathrm{\δ}=\frac{\mathrm{dU}}{\mathrm{dP}}=P(\frac{a^3{\sin }^2\mathrm{\α}}{3D_{11}}+\frac{a{\cos }^2\mathrm{\α}}{A_{11}}+\frac{{\mathrm{bh}}^2}{D_{11}}+\frac{b}{A_{11}})---\left(5\right)$

Therefore the horizontal modulus of elasticity of structure is:

$E_T=\frac{w_{c}P}{4\mathrm{\δ}{h}_c}=\frac{4l}{4(2h+t)(\frac{a^3{\sin }^2\mathrm{\α}}{3D_{11}}+\frac{a{\cos }^2\mathrm{\α}}{A_{11}}+\frac{{\mathrm{bh}}^2}{D_{11}}+\frac{b}{A_{11}})}---\left(6\right)$

During the terminal independent role moment M of beam, deformation energy is:

$U=\frac{M_2(a+b)}{2D_{11}}---\left(7\right)$

Corner is:

$\mathrm{\ψ}=\frac{\mathrm{dU}}{\mathrm{dM}}=\frac{M(a+b)}{D_{11}}---\left(8\right)$

Therefore its horizontal equivalent bending modulus is:

$D_T=\frac{\mathrm{lM}}{\mathrm{\ψ}}=\frac{l}{a+b}{D}_{11}---\left(9\right)$

Just can obtain theoretical horizontal equivalent elastic modulus E by formula (1) (2) (6) (9) _T, horizontal equivalent bending modulus D _T, vertical equivalent elastic modulus E _LTWith vertical equivalent bending modulus D _LT

Can carry out the Parameters Optimal Design of isosceles trapezoid ripple struction according to above-mentioned math modeling, when being optimized, optimization aim and the corresponding constraint condition that can require according to actual design, and adopt existing various optimized algorithm.Design of Structural parameters embodiment is as follows:

Optimization aim: take each parameter of isosceles trapezoidal structure as optimized variable, stressed-skin construction weight W minimum is target, that is: min W (h _c, α, D _T, E _T, D _LT, E _LT)

Constraint condition: in order to make internal drive system be easy to drive, wish the elastic modulus E of covering in structure large deformation direction _tWith bending modulus D _tThe smaller the better, but consider covering at airfoil chord to also will bearing aerodynamic loading, therefore to E _tAnd D _tThe minimum value requirement is also arranged; So the exhibition of wing is very high to E to the Capability Requirement to the covering bending resistance _LTAnd D _LTThe minimum value requirement is arranged; Other parameter A ₁₁, D ₁₁, t, w _cBe chosen to be constant.Therefore constraint condition is formula 10:

D _Tmin＜D _T＜D _Tmax

E _Tmin＜E _T＜E _Tmax

D _LT＞D _LTmin

E _LT＞E _LTmin

(10)

h _c＜h _cmax

α _min＜α＜α _max

According to above-mentioned optimization aim and constraint condition, and according to following math modeling construction parameter is optimized,

$E_{\mathrm{LT}}=\frac{{[{(l_1-l_3)}^2+{h_1}^2]}^{1/2}+{[{(l_2-l_4)}^2+{h_2}^2]}^{1/2}+l_3+l_4}{2(l_1+l_2)h_2}{A}_{11}$

$D_{\mathrm{LT}}=(\frac{(l_4-l_2){h_2}^4}{4h_2}+\frac{l_2{h_2}^3}{3}-\frac{(l_3-l_1){h_1}^4}{4h_1}-\frac{l_1{h_1}^3}{3})\frac{A_{11}}{h_2-h_1}---\left(11\right)$

$E_T=\frac{w_{c}P}{4\mathrm{\δ}{h}_c}=\frac{4l}{4(2h+t)(\frac{a^3{\sin }^2\mathrm{\α}}{3D_{11}}+\frac{a{\cos }^2\mathrm{\α}}{A_{11}}+\frac{{\mathrm{bh}}^2}{D_{11}}+\frac{b}{A_{11}})}$

$D_T=\frac{\mathrm{lM}}{\mathrm{\ψ}}=\frac{l}{a+b}{D}_{11}$

Wherein, E _LTBe vertical equivalent elastic modulus of covering, D _LTBe the vertical equivalent bending modulus of covering, E _TBe the horizontal equivalent elastic modulus of covering, D _TBe the horizontal equivalent bending modulus of covering, A ₁₁And D ₁₁Be respectively face in-draw rigidity and the bending stiffness of the fiber reinforced composite that consist of this covering, t is the thickness of the fiber reinforced composite of this covering of formation, l ₁, l ₂, l ₃, l ₄, h ₁, h ₂Be respectively a plurality of cross section parameters of trapezoidal height and Width, Be the height of 1/4 trapezoid cross section,

Be the length of 1/4 trapezoid cross section,

With Be respectively the upper base of 1/4 trapezoid cross section and the length of waist, α=arcsin (h/a) is the angle on trapezoidal waist and base.

Concrete optimized algorithm can adopt genetic algorithm or Neural network optimization, can obtain so optimum stressed-skin construction parameter.Certainly, also can adopt existing various other optimized algorithm.

In this specific embodiment, covering adopts quadrature braided glass fibre composite material by multilayer layer and plate, and is prepared from through hot-press solidifying.Be embedded at covering and be useful on the marmem that large deformation is controlled to stressed-skin construction (SMA) actuator, be used for the sensor of stressed-skin construction monitoring, and be used for piezoelectric actuator that infinitesimal deformation and the vibration of stressed-skin construction part are controlled.Described sensor can adopt one or more in piezoelectric transducer, piezoelectric fabric sensor, the strain sensor, and three kinds of sensors all use in this specific embodiment, respectively static strain and the dynamic vibration response of stressed-skin construction is monitored.In this specific embodiment, piezoelectric actuator does not adopt conventional piezoelectric chip, but adopted the piezoelectric fabric actuator, piezoelectric fabric actuator and body composite structure are realized perfectly merging, both realized the driving to structure, again can be owing to imbedding the intensity that affects structure in the structure; In addition, the driving voltage of piezoelectric fabric actuator can be up to more than 1000 volts, want large many with respect to its power-handling capability of close-up crystal unit, and fiber itself has good elasticity, go for the driving of curved-surface structure.The cross-sectional plane of whole covering as shown in Figure 2, wherein 1 is quadrature braided glass fibre composite material by multilayer layer and plate, 2 are filled in the elastic silica gel in the trough of isosceles trapezoid ripple of covering outside face.

The present invention has satisfied the requirement that the morphing aircraft skin of morphing wing not only requires large deformation but also can bear aerodynamic loading, and can be according to the equivalent elastic modulus of two different directions of stressed-skin construction and the mathematical analysis model of bending modulus, realize the design optimization of stressed-skin construction under the different loads operating mode, also have simultaneously monitoring structural health conditions and self adaptation deformability, can realize best aerodynamic characteristic by shape and the vibration control to covering.

Claims (7)

1. a covering that is used for morphing is made by fiber reinforced composite, it is characterized in that its cross-sectional plane is the isosceles trapezoid ripple struction; The concrete structure parameter of described isosceles trapezoid ripple is optimized according to following math modeling and obtains:

Wherein,

Be vertical equivalent elastic modulus of covering, Be the vertical equivalent bending modulus of covering,

Be the horizontal equivalent elastic modulus of covering,

Be the horizontal equivalent bending modulus of covering,

With

Be respectively face in-draw rigidity and the bending stiffness of the fiber reinforced composite that consist of this covering,

Be the thickness of the fiber reinforced composite that consist of this covering,

Be respectively a plurality of cross section parameters of trapezoidal height and Width, wherein,

Be respectively half of the ripple thickness direction plane of symmetry and ripple ipsilateral joining minor increment;

Be respectively half of the inboard and outside width in ripple top;

Be half of ripple struction thickness;

For half of ripple struction thickness cuts corrugated plating thickness

Be the height of 1/4 trapezoid cross section,

Be the length of 1/4 trapezoid cross section,

With

Be respectively the upper base of 1/4 trapezoid cross section and the length of waist, Angle for trapezoidal waist and base;

Width for single ripple; P, , M,

Be respectively when regarding 1/4 of single ripple struction cross-sectional plane as crooked Bernoulli Jacob-Euler's beam the end of beam concentrated force, the horizontal displacement of beam end, the terminal independent role moment of flexure of beam, corner in the horizontal direction.

2. be used for as claimed in claim 1 the covering of morphing, it is characterized in that, the concrete structure parameter of described trapezoidal ripple adopts genetic algorithm or Neural network optimization to be optimized and obtains.

3. be used for as claimed in claim 1 the covering of morphing, it is characterized in that described fiber reinforced composite are quadrature braided glass fibre composite material.

4. such as claims 1 to 3 covering for morphing as described in each, it is characterized in that, be filled with elastomeric material in the trough of the isosceles trapezoid ripple of its outside face.

5. such as claims 1 to 3 covering for morphing as described in each, it is characterized in that inner embedding of this covering is useful on the marmen that large deformation is controlled to stressed-skin construction.

6. such as claims 1 to 3 covering for morphing as described in each, it is characterized in that inner embedding of this covering is useful on the piezoelectric fabric actuator that infinitesimal deformation and the vibration of stressed-skin construction part are controlled.

7. such as claims 1 to 3 covering for morphing as described in each, it is characterized in that, the inner sensor that is useful on the stressed-skin construction monitoring that embeds of this covering, described sensor comprises one or more in piezoelectric transducer, piezoelectric fabric sensor, the strain sensor.

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