Method and device for acquiring fatigue performance of main rotor bearingless flexible beam

Abstract

The invention provides a method and a device for acquiring fatigue performance of a main rotor bearingless flexible beam. The method comprises the following steps: acquiring stress / strain of a root section test piece of the main rotor bearingless flexible beam; acquiring the stress / strain of the torsional deformation section test piece of the main rotor bearingless flexible beam; and according to the stress / strain of the root section test piece and the torsional deformation section test piece, obtaining the fatigue performance of the root section and the torsional deformation section of the main rotor bearingless flexible beam. The key fatigue performance of the structure can be obtained through the test verification and examination method, the method is used for subsequent flexible beam fatigue life analysis, the structure can be assisted in optimization and weight reduction work, and development and use guarantee of an aircraft is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of aircraft strength, and in particular relates to a method and device for obtaining fatigue performance 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 pitch change operation compared to the ball flexible rotor. Therefore, the flexible beam design is advanced and unique. The structure of the main rotor bearingless flexible beam is as follows: Figure 1 As shown, it includes the root connection area, the flapping deformation area, the torsional deformation area, the blade connection transition area and the blade connection area.

[0003] Among them, the strength design of the flexible beam is particularly important as the basis for ensuring the safety of the flexible beam during flight and the basis for subsequent maintenance.

[0004] The existing technology lacks an advanced and complete flexible beam test verification and assessment plan. Summary of the Invention

[0005] The present invention provides a method and device for obtaining the fatigue performance of a main rotor bearingless flexible beam. In view of the lack of a complete flexible beam test verification and assessment scheme in the existing technology, a flexible beam test verification and assessment scheme is provided, which can fully assess the strength performance of the structure, increase the anti-fatigue design of the structure, improve the service life, reduce production costs, and reduce the weight of the aircraft.

[0006] The present invention provides a method for obtaining fatigue performance of a main rotor bearingless flexible beam, comprising:

[0007] Obtain the stress / strain of the root section test specimen of the main rotor bearingless flexible beam;

[0008] Obtain the stress / strain of the torsional deformation section test specimen of the main rotor bearingless flexible beam;

[0009] According to the stress / strain of the root section test piece and the torsional deformation section test piece, the fatigue performance of the root section and the torsional deformation section of the main rotor bearingless flexible beam is obtained.

[0010] The present invention splits the fatigue performance acquisition of the main rotor bearingless flexible beam into stress / strain acquisition of the root section and the torsional deformation section, which can fully evaluate the strength performance of the structure.

[0011] Optionally, a root section test piece of the main rotor bearingless flexible beam is obtained by cutting out the root connection area and the flapping deformation area;

[0012] The torsional deformation section test piece uses a main rotor bearingless flexible beam sample;

[0013] The root section test piece and the torsional deformation section test piece are both made of glass fiber.

[0014] Optionally, when obtaining the stress / strain of the root section test piece of the main rotor bearingless flexible beam, the clamping plate of the root section test piece includes: an upper plate and a lower plate;

[0015] The upper plate and the lower plate are both provided with grooves for accommodating the swing deformation zone of the root section test piece, and the profile of the grooves matches the swing deformation zone;

[0016] Threaded holes are provided on both sides of the grooves of the upper plate and the lower plate, and the upper plate and the lower plate are fixedly connected by screws passing through the threaded holes;

[0017] The surface of the groove that contacts the swinging deformation zone is coated with adhesive.

[0018] The present invention obtains stress / strain at different parts of the main rotor bearingless flexible beam and designs corresponding samples and splints, which can fully evaluate the strength performance of the structure.

[0019] Optionally, the adhesive thickness is less than 1 cm.

[0020] Optionally, the clamping position of the root section test piece is the center plane of the root bushing of the main rotor bearingless flexible beam; the end of the upper plate and the lower plate away from the root connection area is used to apply centrifugal static load and bending moment force.

[0021] Compared with the traditional test piece modification scheme, it has the advantages of simple installation, shorter clamping plate length and less prone to damage to the clamping area.

[0022] Optionally, the clamping position of the torsional deformation section test piece of the main rotor bearingless flexible beam is the center plane of the root bushing of the main rotor bearingless flexible beam, and the loading position is the center plane of the end bushing of the main rotor bearingless flexible beam.

[0023] Optionally, when obtaining the stress / strain of the torsional deformation section test piece of the main rotor bearingless flexible beam, the strain gauge is set at one end of the torsional deformation zone close to the root of the main rotor bearingless flexible beam.

[0024] Optionally, based on the stress of the root section test piece and the torsional deformation section test piece, the fatigue properties of the root section and the torsional deformation section of the main rotor bearingless flexible beam are obtained, including:

[0025] Using the formula Obtain fatigue performance of the root section and torsional deformation section of the main rotor bearingless flexible beam;

[0026] Among them, σ ae Indicates the test stress of the root section and torsional deformation section, in MPa; σ A9 It represents the fatigue performance of the root segment and the torsional deformation segment, and the unit is MPa; N represents the number of failure cycles of the root segment and the torsional deformation segment, and the unit is Mc; the value of α is 0.1.

[0027] Optionally, based on the strains of the root section test piece and the torsional deformation section test piece, fatigue properties of the root section and the torsional deformation section of the main rotor bearingless flexible beam are obtained, including:

[0028] Using the formula Obtain fatigue performance of the root section and torsional deformation section of the main rotor bearingless flexible beam;

[0029] Where N represents the number of failure cycles of the root segment and the torsional deformation segment, and the unit is Mc; the value of α is 0.1; ε ae Represents the test strain of the root segment and the torsional deformation segment, in με; ε A9 It represents the fatigue performance of the root segment and torsional deformation segment, and the unit is με.

[0030] A second aspect of the present invention provides a fatigue performance acquisition device for a main rotor bearingless flexible beam, comprising:

[0031] A first acquisition module is used to acquire stress / strain of a root section test piece of a main rotor bearingless flexible beam;

[0032] The second acquisition module is used to obtain the stress / strain of the torsional deformation section test piece of the main rotor bearingless flexible beam;

[0033] The fatigue performance acquisition module is used to obtain the fatigue performance of the root section and torsional deformation section of the main rotor bearingless flexible beam based on the stress / strain of the root section test piece and the torsional deformation section test piece.

[0034] The present invention provides a method and device for obtaining the fatigue performance of a main rotor bearingless flexible beam, the method comprising: obtaining the stress / strain of a root section test piece of the main rotor bearingless flexible beam; obtaining the stress / strain of a torsional deformation section test piece of the main rotor bearingless flexible beam; obtaining the fatigue performance of the root section and torsional deformation section of the main rotor bearingless flexible beam based on the stress / strain of the root section test piece and the torsional deformation section test piece; the bearingless rotor can obtain the key fatigue performance of the structure through the above test verification and assessment method, which is used for subsequent flexible beam fatigue life analysis, and can assist in structural optimization and weight reduction, thereby ensuring the development and use of the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the flexible beam of the bearingless rotor;

[0036] Figure 2 The root section test piece shape and loading diagram;

[0037] Figure 3 This is a schematic diagram of the root section test piece body;

[0038] Figure 4 Schematic diagram of a single-layer plywood;

[0039] Figure 5 Schematic diagram of loading of the torsional deformation section specimen;

[0040] Figure 6 Schematic diagram of the patch situation and patch position of the test piece;

[0041] Figure 7 This is a schematic diagram of the 355 cross-section patch. DETAILED DESCRIPTION

[0042] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention.

[0043] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed in order to provide a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is in no way limited to any specific arrangement and method proposed below, but rather encompasses any improvements, replacements, and modifications to structures, methods, and devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, well-known structures and techniques are not shown to avoid unnecessary ambiguity in the present invention.

[0044] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0045] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0046] The fatigue performance acquisition method and device of the main rotor bearingless flexible beam provided by the present invention are explained below with reference to the accompanying drawings.

[0047] like Figure 1-7 As shown, the present invention provides a method and device for obtaining fatigue performance of a main rotor bearingless flexible beam, which is a method for verifying and assessing a test scheme for a main rotor bearingless flexible beam. The flexible beam structure schematic diagram is shown in FIG. Figure 1 As shown in the figure, based on the characteristics of the flexible beam structure, stiffness distribution, material properties, stress and strain, a test assessment, test piece modification and fixture design scheme suitable for the flexible beam is designed.

[0048] The present invention provides a method for obtaining fatigue performance of a main rotor bearingless flexible beam, comprising:

[0049] S1. Obtain the stress / strain of the root section test specimen of the main rotor bearingless flexible beam;

[0050] S2. Obtain the stress / strain of the torsional deformation section test piece of the main rotor bearingless flexible beam;

[0051] For example, the root section test piece of the main rotor bearingless flexible beam is obtained by cutting the root connection area and the flapping deformation area; the torsional deformation section test piece uses the main rotor bearingless flexible beam sample; the root section test piece and the torsional deformation section test piece are both made of glass fiber material.

[0052] S3. Obtain fatigue properties of the root section and torsional deformation section of the main rotor bearingless flexible beam based on the stress / strain of the root section test piece and the torsional deformation section test piece.

[0053] In a specific embodiment, the present invention provides Figure 1 The test plan verification and assessment methods for the flexible beam types shown include:

[0054] a) Design the flexible beam root section test piece and test assessment plan;

[0055] b) Design the flexible beam torsional deformation section test piece and test assessment plan;

[0056] c) Calculate and analyze the fatigue performance of the test piece based on the test methods for the flexible beam root section and the torsional deformation section;

[0057] Optionally, design a flexible beam root section test piece and test assessment plan. The test piece shape and loading diagram are as follows: Figure 2 As shown, the flexible beam is clamped at section 0. In the figure, Fc is the centrifugal static load, and the direction is along the center line of the flexible beam (X axis). Fm is the bending moment force applied to the flexible beam, and the direction is perpendicular to the horizontal plane.

[0058] The design of the test piece in the figure above takes the stress distribution of the flexible beam into consideration. In order to reduce the test stress in the non-test area, an extruded nested plywood design is adopted. The test body and single-layer plywood after the flexible beam test piece is decomposed are as follows: Figure 3 and Figure 4 As shown:

[0059] The clamping plate for the root section test piece includes an upper plate and a lower plate. Each plate is provided with a groove to accommodate the swing deformation zone of the root section test piece, and the groove's profile matches the swing deformation zone. Both plates have threaded holes on either side of the groove, and the upper and lower plates are fixed together using screws passing through the threaded holes. The surface of the groove that contacts the swing deformation zone is coated with adhesive. Optionally, the adhesive is less than 1 cm thick.

[0060] The clamping position of the root section test piece is the center plane of the root bushing of the main rotor bearingless flexible beam; the end of the upper plate and the lower plate away from the root connection area is used to apply centrifugal static load and bending moment force.

[0061] Compared with the traditional test piece modification scheme, this test piece has the advantages of simple installation, shorter clamping plate length and less damage to the clamping area.

[0062] Optionally, the clamping position of the main rotor bearingless flexible beam torsional deformation section test specimen is the center plane of the main rotor bearingless flexible beam's root bushing, and the loading position is the center plane of the main rotor bearingless flexible beam's end bushing. When obtaining the stress / strain of the main rotor bearingless flexible beam torsional deformation section test specimen, a strain gauge is installed at one end of the torsional deformation zone near the root of the main rotor bearingless flexible beam.

[0063] For example, in a specific embodiment, a flexible beam torsional deformation section test piece and a test assessment plan are designed. The shape of the test piece and the loading diagram are as follows: Figure 5 As shown, the flexible beam is clamped at section 0 (left end), and centrifugal force and flapping force are loaded at section 906.

[0064] See the schematic diagram of the flexible beam torsional deformation section bending fatigue test piece patch. Figure 6 , and paste the single piece on the 355 section.

[0065] like Figure 7 As shown, the cross-section of the torsional deformation zone is a cross, with the transverse segment being longer than the vertical segment. The vertical segment comprises two adjacent fiber bundles. Accordingly, there are eight strain gauges, four on the upper and lower surfaces of the two fiber bundles and four on the upper and lower surfaces of the tips of the transverse segment.

[0066] During the test, the data collected from the single piece is used as the maximum strain on the surface of the test piece for subsequent test assessment and analysis; at the same time, the single piece can be used to calibrate the strain-load calibration coefficient under tensile, bending and torsional loads for subsequent strength analysis.

[0067] Optionally, fatigue performance calculation and analysis can be performed based on the test data of the flexible beam root section and the torsional deformation section (stress / strain of the test piece, number of test piece failure cycles). The performance calculation formula is as follows:

[0068] or

[0069] in:

[0070] σ ae : test stress (MPa);

[0071] σ A9 : Fatigue performance of test piece (MPa);

[0072] N: number of cycles to failure of the test piece (Mc);

[0073] α: SN curve parameter, 0.1 for glass cloth and beam belt, 0.037 for carbon cloth;

[0074] ε ae : test strain (με);

[0075] ε A9 : Fatigue performance of test piece (με).

[0076] The fatigue performance of the flexible beam obtained from the test represents the fatigue resistance of the structure. The higher the performance, the better the fatigue resistance. This performance can be used for subsequent flexible beam fatigue life analysis, auxiliary structure optimization and weight reduction, and ensure the development and use of aircraft.

[0077] The above is only a further embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes based on the technical solutions and concepts of the present invention within the scope disclosed by the present invention, which fall within the scope of protection of the present invention.

Claims

1. A method for obtaining fatigue performance of a main rotor bearingless flexible beam, characterized in that: include: Obtain the stress / strain of the root section test specimen of the main rotor bearingless flexible beam; Obtain the stress / strain of the torsional deformation section test specimen of the main rotor bearingless flexible beam; According to the stress / strain of the root section test piece and the torsional deformation section test piece, the fatigue performance of the root section and the torsional deformation section of the main rotor bearingless flexible beam is obtained.

2. The fatigue performance acquisition method of the main rotor bearingless flexible beam according to claim 1, characterized in that: The root section test specimen of the main rotor bearingless flexible beam is obtained by cutting the root connection area and the flapping deformation area; The torsional deformation section test piece uses a main rotor bearingless flexible beam sample; The root section test piece and the torsional deformation section test piece are both made of glass fiber.

3. The fatigue performance acquisition method of the main rotor bearingless flexible beam according to claim 2, characterized in that: When obtaining stress / strain of a root section test piece of a main rotor bearingless flexible beam, the clamping plate of the root section test piece includes: an upper plate and a lower plate; The upper plate and the lower plate are both provided with grooves for accommodating the swing deformation zone of the root section test piece, and the profile of the grooves matches the swing deformation zone; Threaded holes are provided on both sides of the grooves of the upper plate and the lower plate, and the upper plate and the lower plate are fixedly connected by screws passing through the threaded holes; The surface of the groove that contacts the swinging deformation zone is coated with adhesive.

4. The fatigue performance acquisition method of the main rotor bearingless flexible beam according to claim 3, characterized in that: The thickness of the adhesive is less than 1 cm.

5. The fatigue performance acquisition method of the main rotor bearingless flexible beam according to claim 3, characterized in that: The clamping position of the root section test piece is the center plane of the root bushing of the main rotor bearingless flexible beam; the end of the upper plate and the lower plate away from the root connection area is used to apply centrifugal static load and bending moment force.

6. The fatigue performance acquisition method of the main rotor bearingless flexible beam according to claim 1, characterized in that: The clamping position of the torsional deformation section test piece of the main rotor bearingless flexible beam is the center plane of the root bushing of the main rotor bearingless flexible beam, and the loading position is the center plane of the end bushing of the main rotor bearingless flexible beam.

7. The fatigue performance acquisition method of the main rotor bearingless flexible beam according to claim 1, characterized in that: When obtaining the stress / strain of the torsional deformation section test piece of the main rotor bearingless flexible beam, the strain gauge is set at one end of the torsional deformation zone close to the root of the main rotor bearingless flexible beam.

8. The fatigue performance acquisition method of the main rotor bearingless flexible beam according to claim 1, characterized in that: Based on the stress of the root section test piece and the torsional deformation section test piece, the fatigue performance of the root section and torsional deformation section of the main rotor bearingless flexible beam is obtained, including: Using the formula Obtain fatigue performance of the root section and torsional deformation section of the main rotor bearingless flexible beam; Among them, σ ae Indicates the test stress of the root section and torsional deformation section, in MPa; σ A9 It represents the fatigue performance of the root segment and the torsional deformation segment, and the unit is MPa; N represents the number of failure cycles of the root segment and the torsional deformation segment, and the unit is Mc; the value of α is 0.

1.

9. The method for obtaining fatigue performance of a main rotor bearingless flexible beam according to claim 1, characterized in that: Based on the strain of the root section test piece and the torsional deformation section test piece, the fatigue performance of the root section and torsional deformation section of the main rotor bearingless flexible beam is obtained, including: Using the formula Obtain fatigue performance of the root section and torsional deformation section of the main rotor bearingless flexible beam; Where N represents the number of failure cycles of the root segment and the torsional deformation segment, and the unit is Mc; the value of α is 0.1; ε ae Represents the test strain of the root segment and the torsional deformation segment, in με; ε A9 It represents the fatigue performance of the root segment and torsional deformation segment, and the unit is με.

10. A fatigue performance acquisition device for a main rotor bearingless flexible beam, characterized in that: include: A first acquisition module is used to acquire stress / strain of a root section test piece of a main rotor bearingless flexible beam; The second acquisition module is used to obtain the stress / strain of the torsional deformation section test piece of the main rotor bearingless flexible beam; The fatigue performance acquisition module is used to obtain the fatigue performance of the root section and torsional deformation section of the main rotor bearingless flexible beam based on the stress / strain of the root section test piece and the torsional deformation section test piece.

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