A main rotor bearingless flexible beam strength acquisition method and device

Abstract

The application provides a main rotor bearingless flexible beam strength acquisition method and device, which comprises the following steps: acquiring the stress of a roving winding girder belt of a main rotor bearingless flexible beam; the roving winding girder belt comprises a root connecting area and a blade connecting area; acquiring the stress of a thick plate girder belt of the main rotor bearingless flexible beam; the thick plate girder belt comprises a flapping deformation area; acquiring the stress of a cross-shaped typical layer of the main rotor bearingless flexible beam; the cross-shaped typical layer comprises a torsional deformation area; and acquiring the strength of the main rotor bearingless flexible beam according to the stress of the roving winding girder belt, the thick plate girder belt and the cross-shaped typical layer. The strength and fatigue life calculation results of the bearingless rotor can be obtained through the strength analysis method provided by the application, and the development and use of the aircraft are guaranteed.

Description

Technical Field

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

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

[0003] Among them, the strength design of flexible beams is particularly important as it serves as the foundation for ensuring the safety of flexible beams during flight and as the basis for subsequent maintenance. Advanced and comprehensive flexible beam strength analysis methods can significantly improve the service life of products, increase usage efficiency, and reduce usage costs. Summary of the Invention

[0004] This invention proposes a method and apparatus for obtaining the strength of a bearingless flexible beam of a main rotor, and a method for analyzing the strength of the flexible beam.

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

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

[0007] The stress of the thick plate beam of the main rotor bearingless flexible beam is obtained; the thick plate beam includes the flapping deformation zone;

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

[0009] The strength of the bearingless flexible beam of the main rotor is obtained based on the stress of the roving-wound main beam belt, the thick plate main beam belt, and the cross-shaped typical ply.

[0010] Stress includes: static stress σ s Dynamic stress σ d High-cycle equivalent stress σ ae高周 and low-cycle equivalent stress σ ae低周 ;

[0011] The strength of the main rotor's bearingless flexible beam is obtained based on the stress of the roving-wound main beam belt, the thick plate main beam belt, and the typical cross-shaped layup, including:

[0012] Based on the high-cycle equivalent stress or low-cycle equivalent stress of the roving-wound main beam belt, the thick plate main beam belt, and the cross-shaped typical ply, the safe fatigue life under high-cycle equivalent stress or low-cycle equivalent stress is obtained using the following formula. Based on the safe fatigue life, the strength of the main rotor bearingless flexible beam under high-cycle equivalent stress or low-cycle equivalent stress is obtained.

[0013] ;

[0014] L=N / n ;

[0015] Where N represents the number of fatigue failure cycles, σ f9 The value represents the safe fatigue stress limit, α represents the SN curve parameter with a value of 0.1, n represents the number of fatigue load cycles per hour, and L represents the safe fatigue life in hours.

[0016] Optionally, the static stress σ of the roving wound beam belt s1 The following formula is used to obtain it:

[0017] ;

[0018] Where, σ s1 This represents static stress, with units of MPa and F. xs1 This represents static tensile force, with units of N and S. roving This represents the total area of ​​the beam band in the cross-section, in mm. 2 M ys1 M represents the static bending moment along the y-axis, in Nm. zs1 This represents the static bending moment along the z-axis, in Nm. I y1 This represents the moment of inertia along the y-axis, in mm. 4 ; I z1 The z-axis moment of inertia is expressed in mm. 4 Z0 represents the maximum dimension along the z-axis, Z0 = h / 2, in mm; Y0 represents the maximum dimension along the y-axis, Y0 = (d + (w / 2)) / 2, in mm.

[0019] The y and z axes are the two directions of the flexible beam perpendicular to the spanwise 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-wound beam, d is the distance between the centerlines of the two bushings, and w is the outer diameter of a single roving-wound beam.

[0020] The dynamic stress of the roving wound beam belt is obtained using the following formula:

[0021] ;

[0022] σ d1 M represents dynamic stress, with units of MPa; yd1 M represents the dynamic bending moment along the y-axis, in Nm. zd1 This represents the dynamic bending moment along the z-axis, in Nm.

[0023] The high-cycle equivalent stress of the roving-wound main beam belt is obtained using the following formula:

[0024] ;

[0025] Where, σ ae高周1 σ represents the high-cycle equivalent stress, with units of MPa; s1 σ represents static stress, with units of MPa; d1 R represents dynamic stress, with units of MPa; m K represents the ultimate tensile strength, with units of MPa; t Indicates the stress concentration factor;

[0026] The low-cycle equivalent stress of the roving wound beam belt is obtained using the following formula:

[0027] .

[0028] Optionally, the static stress of the thick plate girder can be obtained using the following formula:

[0029] ;

[0030] The dynamic stress of the thick plate girder is obtained using the following formula:

[0031] ;

[0032] Where, σ s2 σ represents static stress. d2 This represents dynamic stress, with units of MPa.

[0033] F xs2 F represents static tensile force. xd2 This represents dynamic tensile force, measured in N.

[0034] M ys2 M represents the static bending moment along the y-axis. yd2 This represents the dynamic bending moment along the y-axis, in Nm.

[0035] M zs2 M represents the static bending moment along the z-axis. zd2 This represents the dynamic bending moment along the z-axis, in Nm.

[0036] E1 represents the elastic modulus of the main beam band;

[0037] ES represents the tensile stiffness of the cross section;

[0038] EI y EI represents the bending stiffness of the y-axis section. z Indicates the bending stiffness of the z-axis section;

[0039] δ y δ represents the maximum dimension in the y-axis direction. z Indicates the maximum dimension in the z-axis direction;

[0040] The high-cycle equivalent stress of the thick plate girder is obtained using the following formula:

[0041] When R 11 <R0:

[0042]

[0043] When R 11 >R0:

[0044]

[0045] in, R0: The ratio of dynamic to static stress corresponding to the fatigue limit, which is 0.9; σ f9 R represents the material's safe fatigue limit stress, expressed in MPa. m-kq Indicates the safety limit strength, where R is the fiber strength of the composite material at 0 degrees. m-kq =0.7*R m ;R m This indicates the ultimate tensile strength, expressed in MPa.

[0046] The low-cycle equivalent stress of the thick plate girder is obtained using the following formula:

[0047] .

[0048] Optionally, the static and dynamic stresses of a typical cross-shaped ply are obtained using the following formulas:

[0049] The static stress of a typical cruciform ply is obtained using the following formula:

[0050]

[0051] The static and dynamic stresses of a typical cruciform ply are obtained using the following formulas:

[0052] ;

[0053] in, ;

[0054] ;

[0055] σ s3 σ represents static stress. d3 This represents dynamic stress, with units of MPa.

[0056] ε s ε represents static strain. d This represents dynamic strain, with units of MPa.

[0057] E2 represents the elastic modulus of a typical cross-shaped ply;

[0058] F xs3 F represents static tensile force. xd3 Indicates static / dynamic tensile force, unit: N;

[0059] M ys3 M represents the static bending moment along the y-axis. yd3 This represents the dynamic bending moment along the y-axis, in Nm.

[0060] M zs3 M represents the static bending moment along the z-axis. zd3 Represents the dynamic bending moment along the z-axis, in Nm;

[0061] a, b, c, and g represent the load strain coefficients, strain / load, and units με / N and Nm, respectively.

[0062] The high-cycle equivalent stress of a typical cross-shaped ply is obtained using the following formula:

[0063] When R 12 <R0:

[0064] ;

[0065] When R 12 >R0:

[0066] ;

[0067] in, R0: The ratio of dynamic to static stress corresponding to the fatigue limit, which is 0.9; σ f9 R represents the material's safe fatigue limit stress, expressed in MPa. m-kq Indicates the safety limit strength, where R is the fiber strength of the composite material at 0 degrees. m-kq =0.7*R m ;R m This indicates the ultimate tensile strength, expressed in MPa.

[0068] The low-cycle equivalent stress of a typical cross-shaped ply is obtained using the following formula:

[0069] .

[0070] A second aspect of the present invention provides a device for obtaining the strength of a bearingless flexible beam of a main rotor, used to perform the method as described in any one of the first aspects.

[0071] A third aspect of the present invention provides a computer storage medium storing a computer program, which, when executed by a processor, implements the method as described in any one of the first aspects.

[0072] This invention provides a method and apparatus 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 this invention, thus ensuring the development and use of the aircraft. Attached Figure Description

[0073] Figure 1 Schematic diagram of a bearingless rotor flexible beam;

[0074] Figure 2 A cross-sectional diagram of a roving wound onto a main beam;

[0075] Figure 3 This is a schematic diagram of a typical cross-shaped ply cut.

[0076] Figure 4 This is a schematic diagram of a strain gauge patch. Detailed Implementation

[0077] The specific details of the technical solution provided by the present invention will now be described in conjunction with the accompanying drawings.

[0078] like Figure 1-4 As shown, this invention provides a method and apparatus for obtaining the strength of a bearingless flexible beam for a main rotor. A schematic diagram of the flexible beam structure is shown below. Figure 1 As shown, the main strength analysis areas of this flexible beam are (Ⅰ, Ⅱ, Ⅲ, Ⅴ). The root connection area (Ⅰ) and blade connection area (Ⅴ) are composed of a roving-wound main beam strip; the flapping deformation area (Ⅱ) is composed of a thick plate main beam strip; and the torsional deformation area (Ⅲ) is composed of a typical cross-shaped ply. Based on the structural characteristics, the strength analysis methods for this type of flexible beam include:

[0079] a) Obtain the stress in the roving-wound main beam (regions I and V) of the main rotor bearingless flexible beam;

[0080] b) Obtain the stress in the thick plate beam zone (region II) of the main rotor bearingless flexible beam;

[0081] c) Obtain the stress of a typical cross-shaped ply (region III) of the main rotor's bearingless flexible beam;

[0082] d) Obtain the bearingless flexible beam strength of the main rotor based on the stress of the roving-wound main beam belt, the thick plate main beam belt, and the typical cross-shaped layup.

[0083] For example, the stresses that need to be obtained mainly include the following: static stress Dynamic stress High-cycle equivalent stress σ ae高周 and low-cycle equivalent stress σ ae低周 .

[0084] For example, the stress of the main rotor bearingless flexible beam roving wound with the main beam belt is obtained. A cross-sectional schematic diagram of the roving wound with the main beam belt is shown below. Figure 2 As shown.

[0085] The static stress of the roving-wound beam belt is obtained using the following formula:

[0086]

[0087] Where: σ s Static stress (MPa);

[0088] F xs Static tensile force (N);

[0089] S roving Total area of ​​the cross-section beam band (mm²) 2 );

[0090] M ys y-axis static bending moment (Nm);

[0091] M zs : static bending moment along the z-axis (Nm);

[0092] I y y-axis moment of inertia (mm) 4 );

[0093] I z z-axis moment of inertia (mm) 4 );

[0094] Z0: Maximum dimension along the z-axis, in the diagram Z0 = h / 2 (mm);

[0095] Y0: Maximum dimension of the y-axis, in the figure Y0=(d+(w / 2)) / 2(mm).

[0096] The dynamic stress of the roving wound beam belt is obtained using the following formula:

[0097]

[0098] Where: σ d Dynamic stress (MPa);

[0099] M yd y-axis dynamic bending moment (Nm);

[0100] M zd : Dynamic bending moment along the z-axis (Nm);

[0101] The high-cycle equivalent stress of the roving-wound main beam belt is obtained using the following formula:

[0102]

[0103] Where: σ ae高周 High-cycle equivalent stress (MPa);

[0104] σ s Static stress (MPa);

[0105] σ d Dynamic stress (MPa);

[0106] R m : Ultimate tensile strength (MPa);

[0107] K t Stress concentration factor.

[0108] The low-cycle equivalent stress of the roving wound beam belt is obtained using the following formula:

[0109]

[0110] For example, the stress in the thick plate of the main rotor's bearingless flexible beam is obtained, and the stress is calculated according to the following formula:

[0111] The static and dynamic stresses of the thick plate girder are obtained using the following formulas:

[0112]

[0113] Where: σ s、d Static / dynamic stress (MPa);

[0114] F xs、xd : Static / dynamic tensile force (N);

[0115] M ys、yd : Static / dynamic bending moment along the y-axis (Nm);

[0116] M zs、zd : Z-axis static / dynamic bending moment (Nm);

[0117] E: Elastic modulus of the main beam belt;

[0118] ES: Cross-sectional tensile stiffness;

[0119] EI y EI z : Cross-sectional bending stiffness;

[0120] δ y、z : Maximum dimension in the y / z axis direction.

[0121] The high-cycle equivalent stress of the thick plate girder is obtained using the following formula:

[0122] When R1 < R0:

[0123]

[0124] When R1 > R0:

[0125]

[0126] in: ;

[0127] R0: The ratio of dynamic to static stress corresponding to the fatigue limit, which is 0.9;

[0128] σ f9 Material safety fatigue limit stress (MPa);

[0129] R m-kq : Safety limit strength, where for 0 degrees, composite fiber R m-kq =0.7*R m ;

[0130] The low-cycle equivalent stress of the thick plate girder is obtained using the following formula:

[0131] .

[0132] For example, the stress of a typical cross-shaped ply of the bearingless flexible beam of the main rotor is obtained. The torsional deformation section of the flexible beam has a cross-shaped cross section, as shown in the schematic diagram below. Figure 3 As shown.

[0133] Select a cross-section in the torsional deformation zone of the flexible beam, and follow... Figure 4 The diagram shows the placement of individual strain gauges, followed by calibration under tensile, bending, and torsional loads. The location and numbering of each strain gauge are shown in the attached diagram. Figure 4 :

[0134] Based on the strain coefficients of each single piece under different loads obtained through multiple calibrations, the surface stress calculation formulas for each region of the cross-shaped profile are finally obtained, as follows:

[0135]

[0136]

[0137] Where: ε s、d : Static / dynamic strain (MPa);

[0138] σ s、d Static / dynamic stress (MPa);

[0139] E: Elastic modulus;

[0140] F xs、xd : Static / dynamic tensile force (N);

[0141] M ys、yd : Static / dynamic bending moment along the y-axis (Nm);

[0142] M zs、zd : Z-axis static / dynamic bending moment (Nm);

[0143] a, b, c, d: Single-piece calibration coefficients (strain / load, με / N, Nm).

[0144] After calculating the static / dynamic stress of a typical cross-shaped section of a flexible beam using the above formula, the high / low cycle equivalent stress can be calculated using the high / low cycle equivalent stress formula in the thick plate beam strip.

[0145] For example, based on the above-mentioned high-cycle / low-cycle equivalent stress, the fatigue life of the flexible beam can be calculated using the following formula:

[0146]

[0147] L=N / n ;

[0148] Where: σ f9 : Safety fatigue stress limit;

[0149] α: SN curve parameter, 0.1 for glass cloth and beam strip, 0.037 for carbon cloth;

[0150] N: Number of fatigue failure cycles;

[0151] n: Number of fatigue load cycles per hour;

[0152] L represents the safe fatigue life, in hours.

Claims

1. A method for obtaining the strength of a bearingless flexible beam for a main rotor, characterized in that, include: The stress of the roving-wound main beam of the bearingless flexible beam of the main rotor is obtained; The roving-wound main beam belt includes the root connection area and the blade connection area; The stress of the thick plate beam of the main rotor bearingless flexible beam is obtained; the thick plate beam includes the flapping deformation zone; The stress of a typical cross-shaped ply of the bearingless flexible beam of the main rotor is obtained; the typical cross-shaped ply includes the torsional deformation zone; The strength of the bearingless flexible beam of the main rotor is obtained based on the stress of the roving-wound main beam belt, the thick plate main beam belt, and the cross-shaped typical ply. Stress includes: static stress σ s Dynamic stress σ d High-cycle equivalent stress σ ae高周 and low-cycle equivalent stress σ ae低周 ; The strength of the main rotor's bearingless flexible beam is obtained based on the stress of the roving-wound main beam belt, the thick plate main beam belt, and the typical cross-shaped ply, including: Based on the high-cycle equivalent stress or low-cycle equivalent stress of the roving-wound main beam belt, the thick plate main beam belt, and the cross-shaped typical ply, the safe fatigue life under high-cycle equivalent stress or low-cycle equivalent stress is obtained using the following formula. Based on the safe fatigue life, the strength of the main rotor bearingless flexible beam under high-cycle equivalent stress or low-cycle equivalent stress is obtained. ； L=N / n ； Where N represents the number of fatigue failure cycles, σ f9 The value represents the safe fatigue stress limit, α represents the SN curve parameter with a value of 0.1, n represents the number of fatigue load cycles per hour, and L represents the safe fatigue life in hours.

2. The method for obtaining the strength of the bearingless flexible beam of the main rotor according to claim 1, characterized in that, Static stress σ of roving wound on beam belt s1 The following formula is used to obtain it: ； Where, σ s1 This represents static stress, with units of MPa and F. xs1 This represents static tensile force, with units of N and S. roving This represents the total area of ​​the beam band in the cross-section, in mm. 2 M ys1 M represents the static bending moment along the y-axis, in Nm. zs1 This represents the static bending moment along the z-axis, in Nm. I y1 This represents the moment of inertia along the y-axis, in mm. 4 ; I z1 The z-axis moment of inertia is expressed in mm. 4 Z0 represents the maximum dimension along the z-axis, Z0 = h / 2, in mm; Y0 represents the maximum dimension along the y-axis, Y0 = (d + (w / 2)) / 2, in mm. The y and z axes are the two directions of the flexible beam perpendicular to the spanwise 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-wound beam, d is the distance between the centerlines of the two bushings, and w is the outer diameter of a single roving-wound beam. The dynamic stress of the roving wound beam belt is obtained using the following formula: ； σ d1 M represents dynamic stress, with units of MPa; yd1 M represents the dynamic bending moment along the y-axis, in Nm. zd1 This represents the dynamic bending moment along the z-axis, in Nm. The high-cycle equivalent stress of the roving-wound main beam belt is obtained using the following formula: ； Where, σ ae高周1 σ represents the high-cycle equivalent stress, with units of MPa; s1 σ represents static stress, with units of MPa; d1 R represents dynamic stress, with units of MPa; m K represents the ultimate tensile strength, with units of MPa; t Indicates the stress concentration factor; The low-cycle equivalent stress of the roving wound beam belt is obtained using the following formula: 。 3. The method for obtaining the strength of the bearingless flexible beam of the main rotor according to claim 1, characterized in that, The static stress of the thick plate girder is obtained using the following formula: ； The dynamic stress of the thick plate girder is obtained using the following formula: ； Where, σ s2 σ represents static stress. d2 This represents dynamic stress, with units of MPa. F xs2 F represents static tensile force. xd2 This represents dynamic tensile force, expressed in N (N). M ys2 M represents the static bending moment along the y-axis. yd2 This represents the dynamic bending moment along the y-axis, in Nm. M zs2 M represents the static bending moment along the z-axis. zd2 This represents the dynamic bending moment along the z-axis, in Nm. E1 represents the elastic modulus of the main beam band; ES represents the tensile stiffness of the cross section; EI y EI represents the bending stiffness of the y-axis section. z Indicates the bending stiffness of the z-axis section; δ y δ represents the maximum dimension in the y-axis direction. z Indicates the maximum dimension in the z-axis direction; The high-cycle equivalent stress of the thick plate girder is obtained using the following formula: When R 11 <R0: When R 11 >R0: in, R0: The ratio of dynamic to static stress corresponding to the fatigue limit, which is 0.9; σ f9 R represents the material's safe fatigue limit stress, expressed in MPa. m-kq Indicates the safety limit strength, where R is the fiber strength of the composite material at 0 degrees. m-kq =0.7*R m ;R m This indicates the ultimate tensile strength, expressed in MPa. The low-cycle equivalent stress of the thick plate girder is obtained using the following formula: 。 4. The method for obtaining the strength of the bearingless flexible beam of the main rotor according to claim 1, characterized in that, The static and dynamic stresses of a typical cruciform ply are obtained using the following formulas: The static stress of a typical cruciform ply is obtained using the following formula: The static and dynamic stresses of a typical cruciform ply are obtained using the following formulas: ； in, ; ； σ s3 σ represents static stress. d3 This represents dynamic stress, with units of MPa. ε s ε represents static strain. d This represents dynamic strain, with units of MPa. E2 represents the elastic modulus of a typical cross-shaped ply; F xs3 F represents static tensile force. xd3 This indicates static / dynamic tensile force, in N (unit: N). M ys3 M represents the static bending moment along the y-axis. yd3 This represents the dynamic bending moment along the y-axis, in Nm. M zs3 M represents the static bending moment along the z-axis. zd3 Represents the dynamic bending moment along the z-axis, in Nm; a, b, c, and g represent the load strain coefficients, strain / load, and units με / N and Nm, respectively. The high-cycle equivalent stress of a typical cross-shaped ply is obtained using the following formula: When R 12 <R0: ； When R 12 >R0: ； in, R0: The ratio of dynamic to static stress corresponding to the fatigue limit, which is 0.9; σ f9 R represents the material's safe fatigue limit stress, expressed in MPa. m-kq Indicates the safety limit strength, where R is the fiber strength of the composite material at 0 degrees. m-kq =0.7*R m ;R m This indicates the ultimate tensile strength, expressed in MPa. The low-cycle equivalent stress of a typical cross-shaped ply is obtained using the following formula: 。 5. A device for obtaining the strength of a bearingless flexible beam of a main rotor, characterized in that, Used to perform the method as described in any one of claims 1-4.

6. A computer storage medium, characterized in that, The device contains a computer program that, when executed by a processor, implements the method as described in any one of claims 1-4.

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