Method and device for acquiring strength of main rotor bearingless flexible beam

Abstract

The invention provides a method and a device for acquiring the strength of a main rotor bearingless flexible beam. The method comprises the following steps: acquiring the stress of a roving winding girder belt of the main rotor bearingless flexible beam; the roving winding girder belt comprises a root connecting area and a paddle connecting area; obtaining the stress of a thick plate girder belt of the main rotor bearingless flexible beam; the thick plate girder belt comprises a waving deformation area; obtaining the stress of a cross-shaped typical laying layer of the main rotor bearingless flexible beam; the cross-shaped typical laying layer comprises a torsional deformation area; and obtaining the main rotor bearingless flexible beam strength according to the stress of the roving winding girder belt, the thick plate girder belt and the cross-shaped typical laying layer. Strength and fatigue life calculation results of the bearingless rotor can be obtained through the strength analysis method provided by the invention, and development and use guarantee of an aircraft is guaranteed.

Description

Technical Field

[0001] The present application belongs to the field of aircraft strength technology, and in particular, relates to a method and device for obtaining the strength of a bearingless flexible beam of a main rotor. Background Art

[0002] As an advanced rotor structure, the bearingless rotor uses a flexible beam as a key component for variable pitch operations compared to the spherical flexible rotor, so the flexible beam design is advanced and unique.

[0003] Among them, the flexible beam strength design is particularly important as the basis for ensuring the safety of the flexible beam during flight and the basis for subsequent maintenance. Advanced and complete flexible beam strength analysis methods can significantly increase the service life of the product, improve its utilization efficiency and reduce its use cost. Summary of the invention

[0004] The present invention provides a main rotor bearingless flexible beam strength acquisition method and device, and provides a flexible beam strength analysis method.

[0005] A first aspect of the present invention provides a method for obtaining the strength of a main rotor bearingless flexible beam, comprising:

[0006] The stress of the roving-wrapped beam belt of the main rotor bearingless flexible beam is obtained; the roving-wrapped beam belt includes a root connection area and a blade connection area;

[0007] Obtaining the stress of the thick plate beam belt of the main rotor bearingless flexible beam; the thick plate beam belt includes a flapping deformation zone;

[0008] Obtain the stress of a typical cross-shaped ply of a main rotor bearingless flexible beam; the typical cross-shaped ply includes a torsional deformation zone;

[0009] The strength of the main rotor bearingless flexible beam is obtained based on the stresses of roving-wrapped beam strips, thick plate beam strips and cross-shaped typical layups.

[0010] Optionally, stresses include: static stress σ s , dynamic stress σ d , high cycle equivalent stress σ ae 高周 and low-frequency equivalent stress σ ae低周 .

[0011] Optionally, the static stress σ of the roving wrapped girder belt s Use the following formula to obtain:

[0012]

[0013] Among them, σ s Indicates static stress in MPa, F xs Indicates static tension, unit is N, Sroving Indicates the total area of ​​the cross-section beam, in mm 2 ;M ys Represents the static bending moment on the y-axis, in Nm; M zs Represents the static bending moment on the z-axis, in Nm; I y Indicates the moment of inertia of the y-axis, in mm 4 ;I z Indicates the moment of inertia of the z-axis, in mm 4 ; Z0 represents the maximum dimension of the z-axis, Z0=h / 2, in mm; Y0 represents the maximum dimension of the y-axis, Y0=(d+(w / 2)) / 2, in mm;

[0014] The y and z axes are two directions of the flexible beam perpendicular to the span centerline, where the y axis is perpendicular to the bushing centerline and the z axis is parallel to the bushing centerline; h is the height of the roving wrapped beam belt, d is the distance between the two bushing centerlines, and w is the outer diameter of a single roving wrapped beam belt;

[0015] The dynamic stress of the roving wrapped beam belt is obtained by the following formula:

[0016]

[0017] σ d Indicates dynamic stress, unit is MPa; M yd Indicates the y-axis dynamic bending moment, in Nm; M zd Indicates the dynamic bending moment along the z-axis, in Nm;

[0018] The high frequency equivalent stress of the roving wrapped beam belt is obtained by the following formula:

[0019]

[0020] Among them, σ ae高周 Represents high-cycle equivalent stress, in MPa; σ s Represents static stress, unit is MPa; σ d Represents dynamic stress, unit is MPa; R m Indicates the ultimate strength, in MPa; K t represents the stress concentration factor;

[0021] The low-frequency equivalent stress of the roving wrapped beam belt is obtained by the following formula:

[0022] σ ae低周 =K t (σ s +σ d ) / 2.

[0023] Optionally, the static stress and dynamic stress of the thick plate beam are obtained using the following formula:

[0024]

[0025] Among them, σ s、d Different subscripts are used to represent static / dynamic stress, with the unit being MPa;

[0026] F xs、xd Different subscripts are used to represent static / dynamic tension, in N.

[0027] M ys、yd Different subscripts are used to represent the static / dynamic bending moment of the y-axis, in Nm;

[0028] M zs、zd Different subscripts are used to represent the static / dynamic bending moment of the z-axis, in Nm;

[0029] E represents the elastic modulus of the beam belt;

[0030] ES represents the cross-sectional tensile stiffness;

[0031] EI y , EI z : represent the bending stiffness of the y-axis and z-axis sections respectively;

[0032] δ y、z Different subscripts are used to indicate the maximum size in the y / z axis direction;

[0033] The high-frequency equivalent stress of the thick plate beam is obtained by the following formula:

[0034] When R1<R0:

[0035]

[0036] When R1>R0:

[0037] σ ae高周 =σ d

[0038] in, R0: dynamic and static stress ratio corresponding to fatigue limit, which is 0.9; σ f9 Indicates the material safety fatigue limit stress, in MPa; R m-kq represents the safety limit strength, where for 0 degree composite fiber R m-kq =0.7*R m ;

[0039] The low-frequency equivalent stress of the thick plate beam is obtained by the following formula:

[0040] σae 低周 =(σs+σd) / 2.

[0041] Optionally, the static stress and dynamic stress of a typical cross-shaped ply are obtained using the following formula:

[0042] σ s、d =E×ε s、d ;

[0043] Among them, ε s、d =a×F xs、xd +b×M ys、yd +c×M zs、zd +d×M ts、td ;

[0044] σ s、d Different subscripts are used to represent static / dynamic stress, with the unit being MPa;

[0045] ε s、d Different subscripts are used to represent static / dynamic strain, with the unit being MPa;

[0046] E represents the elastic modulus of a typical cross-shaped ply;

[0047] F xs、xd Different subscripts are used to represent static / dynamic tension, in N.

[0048] M ys、yd Different subscripts are used to represent the static / dynamic bending moment of the y-axis, in Nm;

[0049] M zs、zd Different subscripts are used to represent the static / dynamic bending moment of the z-axis, in Nm;

[0050] a, b, c, d represent load strain factor, strain / load, in units of με / N and Nm, respectively;

[0051] The high-frequency equivalent stress of a typical cross-shaped ply is obtained using the following formula:

[0052] When R1<R0:

[0053]

[0054] When R1>R0:

[0055] σ ae高周 =σ d ;

[0056] in, R0: dynamic and static stress ratio corresponding to fatigue limit, which is 0.9; σ f9 Indicates the material safety fatigue limit stress, in MPa; R m-kq represents the safety limit strength, where for 0 degree composite fiber R m-kq =0.7*R m ;

[0057] The low-frequency equivalent stress of a typical cross-shaped ply is obtained using the following formula:

[0058] σae 低周 =(σs+σd) / 2.

[0059] Optionally, the main rotor bearingless flexible beam strength is obtained based on the stress of the roving wrapped beam tape, the thick plate beam tape and the cross-shaped typical ply, including:

[0060] According to the high-cycle equivalent stress or low-cycle equivalent stress of the roving-wrapped beam belt, the thick plate beam belt and the cross-shaped typical layer, the safe fatigue life under the high-cycle equivalent stress or the low-cycle equivalent stress is obtained by the following formula, and the main rotor bearingless flexible beam strength under the high-cycle equivalent stress or the low-cycle equivalent stress is obtained according to the safe fatigue life;

[0061]

[0062] L = N / n;

[0063] Where N is the number of fatigue failure cycles, σ f9 represents the safety fatigue stress limit, α represents the SN curve parameter, which is 0.1, n represents the number of fatigue load cycles per hour, and L represents the safety fatigue life in hours.

[0064] A second aspect of the present invention provides a main rotor bearingless flexible beam strength acquisition device for executing a method as described in any one of the first aspects.

[0065] A third aspect of the present invention provides a computer storage medium storing a computer program, wherein when the computer program is executed by a processor, the method described in any one of the first aspects is implemented.

[0066] The present invention provides a method and device for obtaining the strength of a bearingless flexible beam of a main rotor. The bearingless rotor can obtain strength and fatigue life calculation results through the strength analysis method provided by the present invention, and the development and use of the aircraft can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 It is a schematic diagram of the bearingless rotor flexible beam;

[0068] Figure 2 It is a cross-sectional schematic diagram of the roving wrapped around the beam belt;

[0069] Figure 3 It is a schematic diagram of a typical cross-shaped ply cut;

[0070] Figure 4 Schematic diagram of strain gauge patch. DETAILED DESCRIPTION

[0071] The specific contents of the technical solution provided by the present invention are introduced below in conjunction with the accompanying drawings.

[0072] like Figure 1-4 As shown, the present invention provides a method and device for obtaining the strength of a main rotor bearingless flexible beam. The schematic diagram of the flexible beam structure is shown in Figure 1 As shown in the figure, the main strength analysis areas of the flexible beam are (Ⅰ, Ⅱ, Ⅲ, Ⅴ), among which the root connection area (Ⅰ) and the blade connection area (Ⅴ) are composed of roving wrapped beam belts, the swing deformation area (Ⅱ) is composed of thick plate beam belts, and the torsional deformation area (Ⅲ) is composed of cross-shaped typical plies. According to the structural characteristics, the strength analysis methods of this type of flexible beam include:

[0073] a) Obtain the stress of the roving-wrapped beam belt (areas I and V) of the main rotor bearingless flexible beam;

[0074] b) Obtain the stress of the thick plate beam belt (area II) of the main rotor bearingless flexible beam;

[0075] c) Obtain the stress of the typical cross-shaped ply (region III) of the main rotor bearingless flexible beam;

[0076] d) The strength of the main rotor bearingless flexible beam is obtained based on the stress of the coarse yarn wrapped beam belt, thick plate beam belt and cross-shaped typical ply.

[0077] For example, the stresses to be obtained mainly include the following: static stress σ s , dynamic stress σd, high cycle equivalent stress σ ae 高周 and low-frequency equivalent stress σ ae 低周 .

[0078] For example, the stress of the main rotor bearingless flexible beam roving wrapped beam belt is obtained, and the cross-sectional schematic diagram of the roving wrapped beam belt is shown in Figure 2 shown.

[0079] The static stress of the roving wrapped beam belt is obtained by the following formula:

[0080]

[0081] Where: s : static stress (MPa);

[0082] F xs : static tension (N);

[0083] S roving :Total area of ​​the cross-section beam (mm 2 );

[0084] M ys: static bending moment on y axis (Nm);

[0085] M zs : static bending moment along z axis (Nm);

[0086] I y : Y-axis moment of inertia (mm 4 );

[0087] I z : z-axis moment of inertia (mm 4 );

[0088] Z0: maximum dimension of z axis, in the figure, Z0=h / 2(mm);

[0089] Y0: maximum dimension of y-axis. In the figure, Y0=(d+(w / 2)) / 2(mm).

[0090] The dynamic stress of the roving wrapped beam belt is obtained by the following formula:

[0091]

[0092] Where: d : dynamic stress (MPa);

[0093] M yd : y-axis dynamic bending moment (Nm);

[0094] M zd : z-axis dynamic bending moment (Nm);

[0095] The high frequency equivalent stress of the roving wrapped beam belt is obtained by the following formula:

[0096]

[0097] Where: ae高周 : High cycle equivalent stress (MPa);

[0098] σ s : static stress (MPa);

[0099] σ d : dynamic stress (MPa);

[0100] R m : Ultimate strength (MPa);

[0101] K t : Stress concentration factor.

[0102] The low-frequency equivalent stress of the roving wrapped beam belt is obtained by the following formula:

[0103] σae 低周 =Kt(σs+σd) / 2

[0104] Exemplarily, the stress of the thick plate beam strip of the main rotor bearingless flexible beam is obtained, and the stress is calculated according to the following formula:

[0105] The static stress and dynamic stress of the thick plate beam are obtained using the following formula:

[0106]

[0107] Where: s、d : Static / dynamic stress (MPa);

[0108] F xs、xd : static / dynamic tension (N);

[0109] M ys、yd : static / dynamic bending moment on y axis (Nm);

[0110] M zs、zd : z-axis static / dynamic bending moment (Nm);

[0111] E: elastic modulus of the beam belt;

[0112] ES: section tensile stiffness;

[0113] EI y , EI z : Section bending stiffness;

[0114] δ y、z : Maximum size in the y / z axis direction.

[0115] The high-frequency equivalent stress of the thick plate beam is obtained by the following formula:

[0116] When R1<R0:

[0117]

[0118] When R1>R0:

[0119] σ ae高周 =σ d

[0120] in:

[0121] R0: dynamic and static stress ratio corresponding to fatigue limit, which is 0.9;

[0122] σ f9 : Material safety fatigue limit stress (MPa);

[0123] R m-kq : Safety ultimate strength, where for 0 degree composite fiber R m-kq =0.7*R m ;

[0124] The low-frequency equivalent stress of the thick plate beam is obtained by the following formula:

[0125] σae 低周 =(σs+σd) / 2.

[0126] For example, the stress of a typical cross-shaped ply of a main rotor bearingless flexible beam is obtained. The torsional deformation section of the flexible beam is a cross-shaped section. The cross-section diagram is as follows: Figure 3 shown.

[0127] Select a section in the torsional deformation zone of the flexible beam and follow the Figure 4 As shown in the figure, a single strain gauge is attached and calibration is performed under tensile, bending and torsion loads. The position and number of the single patch are shown in the figure below:

[0128] The load strain coefficients of each single piece under different loads are obtained through multiple calibrations, and finally the surface stress calculation formula of each area of ​​the cross section is obtained as follows:

[0129] ε s、d =a×F xs、xd +b×M ys、yd +c×M zs、zd +d×M ts、td

[0130] σ s、d =E×ε s、d

[0131] Where: s、d : static / dynamic strain (MPa);

[0132] σ s、d : Static / dynamic stress (MPa);

[0133] E: elastic modulus;

[0134] F xs、xd : static / dynamic tension (N);

[0135] M ys、yd : static / dynamic bending moment on y axis (Nm);

[0136] M zs、zd : z-axis static / dynamic bending moment (Nm);

[0137] a, b, c, d: single piece calibration coefficients (strain / load, με / N, Nm).

[0138] After calculating the static / dynamic stress of the typical cross-shaped section of the flexible beam according to the above formula, the high / low cycle equivalent stress can be calculated according to the high / low cycle equivalent stress formula in the thick plate beam strip.

[0139] For example, the flexible beam strength analysis is performed based on the above-mentioned high-cycle / low-cycle equivalent stress, and the fatigue life of the flexible beam can be calculated according to the following formula:

[0140]

[0141] L = N / n;

[0142] Where: f9 : Safe fatigue stress limit;

[0143] α: SN curve parameter, 0.1 for glass cloth and beam belt, 0.037 for carbon cloth;

[0144] N: number of fatigue failure cycles;

[0145] n: number of fatigue load cycles per hour;

[0146] L represents the safe fatigue life, hours.

Claims

1. A method for obtaining the strength of a main rotor bearingless flexible beam, characterized in that: include: Obtaining the stress of the roving-wrapped beam belt of the main rotor bearingless flexible beam; The roving-wrapped girder belt includes a root connection area and a blade connection area; Obtaining the stress of the thick plate beam belt of the main rotor bearingless flexible beam; the thick plate beam belt includes a flapping deformation zone; Obtain the stress of a typical cross-shaped ply of a main rotor bearingless flexible beam; the typical cross-shaped ply includes a torsional deformation zone; The strength of the main rotor bearingless flexible beam is obtained based on the stresses of roving-wrapped beam strips, thick plate beam strips and cross-shaped typical layups.

2. The main rotor bearingless flexible beam strength acquisition method according to claim 1 is characterized in that the stress include: Static stress σ s , dynamic stress σ d , high cycle equivalent stress σ ae 高周 and low-frequency equivalent stress σ ae 低周 .

3. The main rotor bearingless flexible beam strength acquisition method according to claim 2 is characterized in that: Static stress σ of roving wrapped beam belt s Use the following formula to obtain: Among them, σ s Indicates static stress in MPa, F xs Indicates static tension, unit is N, S roving Indicates the total area of ​​the cross-section beam, in mm 2 ;M ys Represents the static bending moment on the y-axis, in Nm; M zs Represents the static bending moment on the z-axis, in Nm; I y Indicates the moment of inertia of the y-axis, in mm 4 ;I z Indicates the moment of inertia of the z-axis, in mm 4 ; Z0 represents the maximum dimension of the z-axis, Z0=h / 2, in mm; Y0 represents the maximum dimension of the y-axis, Y0=(d+(w / 2)) / 2, in mm; The y and z axes are two directions of the flexible beam perpendicular to the span centerline, where the y axis is perpendicular to the bushing centerline and the z axis is parallel to the bushing centerline; h is the height of the roving wrapped beam belt, d is the distance between the two bushing centerlines, and w is the outer diameter of a single roving wrapped beam belt; The dynamic stress of the roving wrapped beam belt is obtained by the following formula: σ d Indicates dynamic stress, unit is MPa; M yd Indicates the y-axis dynamic bending moment, in Nm; M zd Indicates the dynamic bending moment along the z-axis, in Nm; The high frequency equivalent stress of the roving wrapped beam belt is obtained by the following formula: Among them, σ ae高周 Represents high-cycle equivalent stress, in MPa; σ s Represents static stress, unit is MPa; σ d Represents dynamic stress, unit is MPa; R m Indicates the ultimate strength, in MPa; K t represents the stress concentration factor; The low-frequency equivalent stress of the roving wrapped beam belt is obtained by the following formula: s ae低周 =K t (s s +s d ) / 2。 4. The main rotor bearingless flexible beam strength acquisition method according to claim 2, characterized in that: The static stress and dynamic stress of the thick plate beam are obtained using the following formula: Among them, σ s、d Different subscripts are used to represent static / dynamic stress, with the unit being MPa; F xs、xd Different subscripts are used to represent static / dynamic tension, in N. M ys、yd Different subscripts are used to represent the static / dynamic bending moment of the y-axis, in Nm; M zs、zd Different subscripts are used to represent the static / dynamic bending moment of the z-axis, in Nm; E represents the elastic modulus of the beam belt; ES represents the cross-sectional tensile stiffness; EI y , EI z : represent the bending stiffness of the y-axis and z-axis sections respectively; δ y、z Different subscripts are used to indicate the maximum size in the y / z axis direction; The high-frequency equivalent stress of the thick plate beam is obtained by the following formula: When R1<R0: When R1>R0: s ae高周 =s d in, R0: dynamic and static stress ratio corresponding to fatigue limit, which is 0.9; σ f9 Indicates the material safety fatigue limit stress, in MPa; R m-kq represents the safety limit strength, where for 0 degree composite fiber R m-kq =0.7*R m ; The low-frequency equivalent stress of the thick plate beam is obtained by the following formula: σae 低周 =(σs+σd) / 2。 5. The main rotor bearingless flexible beam strength acquisition method according to claim 2, characterized in that: The static stress and dynamic stress of a typical cross-shaped ply are obtained using the following formula: s s、d =E×e s、d ; Among them, ε s、d =a×F xs、xd +b×M ys、yd +c×M zs、zd +d×M ts、td ; σ s、d Different subscripts are used to represent static / dynamic stress, with the unit being MPa; ε s、d Different subscripts are used to represent static / dynamic strain, with the unit being MPa; E represents the elastic modulus of a typical cross-shaped ply; F xs、xd Different subscripts are used to represent static / dynamic tension, in N. M ys、yd Different subscripts are used to represent the static / dynamic bending moment of the y-axis, in Nm; M zs、zd Different subscripts are used to represent the static / dynamic bending moment of the z-axis, in Nm; a, b, c, d represent load strain factor, strain / load, in units of με / N and Nm, respectively; The high-frequency equivalent stress of a typical cross-shaped ply is obtained using the following formula: When R1<R0: When R1>R0: s ae高周 =s d ; in, R0: dynamic and static stress ratio corresponding to fatigue limit, which is 0.9; σ f9 Indicates the material safety fatigue limit stress, in MPa; R m-kq represents the safety limit strength, where for 0 degree composite fiber R m-kq =0.7*R m ; The low-frequency equivalent stress of a typical cross-shaped ply is obtained using the following formula: σae 低周 =(σs+σd) / 2。 6. The main rotor bearingless flexible beam strength acquisition method according to claim 2, characterized in that: The main rotor bearingless flexible beam strength is obtained based on the stress of roving-wound beam tape, thick plate beam tape and cross-shaped typical plies, including: According to the high-cycle equivalent stress or low-cycle equivalent stress of the roving-wrapped beam belt, the thick plate beam belt and the cross-shaped typical layer, the safe fatigue life under the high-cycle equivalent stress or the low-cycle equivalent stress is obtained by the following formula, and the main rotor bearingless flexible beam strength under the high-cycle equivalent stress or the low-cycle equivalent stress is obtained according to the safe fatigue life; L = N / n; Where N is the number of fatigue failure cycles, σ f9 represents the safety fatigue stress limit, α represents the SN curve parameter, which is 0.1, n represents the number of fatigue load cycles per hour, and L represents the safety fatigue life in hours.

7. A main rotor bearingless flexible beam strength acquisition device, characterized in that: Used to perform the method according to any one of claims 1 to 6.

8. A computer storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

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