Dual elastic bearing configuration hub central piece - arm dual load transfer load sharing method

Abstract

The present application belongs to the field of helicopter rotor system strength design, and particularly relates to a dual-elastic-bearing-configuration hub central piece-arm dual-path load transfer load sharing method. First, the entity model is simplified into a virtual model with physical quantities as elements; then, the equivalent stiffness of each part is solved in combination with the load transfer path characteristics of the entity model and the finite element software; finally, the ratio relationship of the two paths of load is solved according to the quantity relationship of the virtual model. The required computing power of the method is smaller, and the analysis method based on the test results is more accurate. At the same time, the method can be expanded to multi-path load transfer analysis of structural parts, including but not limited to other helicopter arm load transfer analysis, hub metal part load analysis, and elastic bearing load transfer analysis.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of helicopter rotor system strength design, and particularly relates to a double-elastic-bearing-configuration hub central piece-arm double-path load transfer and load distribution method. BACKGROUND

[0002] The main hub central piece-arm structure is one of the core components of the main hub of a helicopter, and bears the main load of the main rotor system, and the strength analysis thereof is related to the design direction and conclusion of the helicopter rotor system. Different from the traditional single-elastic-bearing central piece-arm structure, the double-elastic-bearing-configuration hub can realize double-path load transfer, and through performance design of the centrifugal force elastic bearing / central elastic bearing constituting the double-elastic-bearing, the service life of the elastic bearing can be increased, the replacement frequency can be reduced, and the maintenance cost of the helicopter can be reduced.

[0003] For the new double-elastic-bearing central piece-arm structure, the load transferred from the abutment surface into the hub center is divided into two paths for bearing, and the distribution form of the two-path load affects the strength analysis and life evaluation of the central piece, the arm and the components thereof. Therefore, the present application provides a double-elastic-bearing central piece-arm structure load distribution method, which provides support for the strength analysis of the central piece, the arm and the components thereof. SUMMARY

[0004] The purpose of the present application is to provide a double-elastic-bearing central piece-arm configuration load distribution calculation method, improve the calculation efficiency, and meet the needs of engineering design and application.

[0005] TECHNICAL SCHEME

[0006] The double-elastic-bearing-configuration hub central piece-arm double-path load transfer and load distribution method,

[0007] The following assumptions are made for the model:

[0008] a) The load in six directions transferred into the structure at the abutment surface can be decoupled;

[0009] b) The whole model is small deformation.

[0010] If a spring is used to simulate the stiffness of component i in the direction, the equivalent model can be expressed as Figure 1 As shown in the figure. In the figure, point C is the load bifurcation point, and point D is the load convergence point; K hi , K cfbi , K cbi and K inci respectively represent the stiffness of the central piece, the centrifugal force elastic bearing, the central elastic bearing and the inner connecting piece in the i direction; K 0i is the stiffness of the part of the structure before the load bifurcation on the outer connecting piece in the i direction; and K aiK is the stiffness of the structure in the i direction of the transfer path a after the load on the external connection is bifurcated; bi is the stiffness of the structure in the i direction of the transfer path b after the load on the external connection is bifurcated. cfbi and K cbi It is the bearing performance parameter and can be obtained directly.

[0011] The load transfer process of the structure is as follows:

[0012] a) The load is transferred from the butt joint to the structure through K 0i Then it starts to fork at point C, passes through a and b to converge at point D, and then goes to K hi Transfer to the hub center;

[0013] b) Path a is the centrifugal elastic bearing path, passing through K ai , K inci and K cfbi Arriving at the load confluence point, path b is the central elastic bearing path, passing through K bi and K cbi Arrival at the load confluence point;

[0014] c) A1 is the fitting area between the inner and outer connectors, A2 is the fitting surface between the inner connector and the centrifugal elastic bearing, and B1 is the fitting surface between the outer connector and the central elastic bearing.

[0015] In order to solve the two-way load solution problem of the above model, the present invention provides a solution to load distribution.

[0016] The main idea is: first, simplify the solid model into a virtual model with physical quantities as elements; then, combine the load transfer path characteristics of the solid model with finite element software to solve the equivalent stiffness of each part; finally, according to the quantitative relationship of the virtual model, solve the ratio relationship of the two loads.

[0017] Here are the steps:

[0018] Step 1: Measure K inci .

[0019] In the internal connector model, constrain A2, apply unit displacement u1 at A1, measure the support reaction F1 at A2 in the i direction, and obtain:

[0020]

[0021] Step 2: Solve for K 0i , K ai and K bi .

[0022] In the outer connecting piece model, the constraint of the interface is applied with a unit displacement u2 at A1 and B1, the support reaction force F2 of the interface in the i direction is measured, and the following is obtained:

[0023]

[0024] In the outer connecting piece model, the constraint of the interface is applied with a unit displacement u3 at A1, the support reaction force F3 of the interface in the i direction is measured, and the following is obtained:

[0025]

[0026] In the outer connecting piece model, the constraint of the interface is applied with a unit displacement u4 at B1, the support reaction force F4 of the interface in the i direction is measured, and the following is obtained:

[0027]

[0028] The simultaneous equations (10)-(12) are solved to obtain K 0i , K ai and K bi are as follows:

[0029]

[0030] wherein,

[0031]

[0032] Step three: the ratio of the two load paths is calculated.

[0033] The stiffness ratio of the load transmission of the a and b paths is as follows:

[0034]

[0035] The load ratio of the load transmission of the a and b paths is as follows:

[0036]

[0037] Further, the parameter K inci of step one is tested by experiments, and then step two is directly entered.

[0038] Further, the method is applicable to the case where the central piece and the support arm are kept on the same central axis in the i direction and no additional bending moment is generated.

[0039] Further, in the method, the master and slave points of the spring unit need to be specified according to the load transmission direction.

[0040] Further, the centrifugal force elastic bearing and the central elastic bearing in the method need to measure the stiffness in the i direction,

[0041] Further, the centrifugal force elastic bearing and the central elastic bearing cannot have a deviation in the direction of the load.

[0042] Further, the central part and the arm structure in the method are made of metal materials.

[0043] Further, the central part-arm structure of the double elastic bearing includes a central part, an arm, a centrifugal force elastic bearing and a central elastic bearing. The central part is connected with the centrifugal force elastic bearing and the central elastic bearing through bolts, and has no direct contact with the arm. The arm is composed of an inner connecting piece and an outer connecting piece, and the inner connecting piece and the outer connecting piece are connected through bolts. The inner connecting piece is connected with the centrifugal force elastic bearing through bolts, and the outer connecting piece is connected with the central elastic bearing through bolts (as shown in the accompanying drawings). Figure 1

[0044] Advantages of the present application:

[0045] A central part-arm load distribution method of a double elastic bearing establishes a mathematical model simulating the load transmission process of the central part-arm structure. The model analyzes the stiffness distribution of the load transmission path in the outer connecting piece through finite element software, and can calculate and give the two-way load transmission ratio of the structure, thereby providing strong support for the strength and fatigue design of the structure, and having important significance for the strength design of the helicopter rotor system. Compared with the existing finite element software simulation method, the present method requires less computing power, and the analysis method based on test results is more accurate. At the same time, the present method can be extended to multi-way load transmission analysis of the structure, including but not limited to load transmission analysis of the arm of other helicopters, load analysis of the hub metal part, and load transmission analysis of the elastic bearing. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 Equivalent model diagram of the central part-arm structure of the double elastic bearing

[0047] Figure 2 Model diagram of the central part-arm elastic bearing

[0048] Wherein: 01 hub center, 02 central part, 03 centrifugal force elastic bearing, 04 central elastic bearing, 05 inner connecting piece, 06 outer connecting piece, 07 arm, 08 butt joint surface. DETAILED DESCRIPTION

[0049] Example 1:

[0050] Step one:

[0051] In the inner connecting piece model, A2 is constrained, and a unit displacement of 100 mm in the x direction is applied at A1. The reaction force of A2 in the x direction is measured to be 10200 N, and the following is obtained:

[0052] ​

[0053] Step two:

[0054] In the outer connector model, the constraint of the interface, the x direction unit displacement 100 mm at A1, B1, the measurement of the interface in the x direction of the support reaction-1672.13 N, get:

[0055]

[0056] In the outer connector model, the constraint of the interface, the x direction unit displacement 100 mm at A1, the measurement of the interface in the x direction of the support reaction-181.818 N, get:

[0057]

[0058] In the outer connector model, the constraint of the interface, the x direction unit displacement 100 mm at B1, the measurement of the interface in the x direction of the support reaction-1666.67 N, get:

[0059]

[0060] Simultaneous equations (18)-(20), the calculation of K 0x , K ax and K bx :

[0061]

[0062] Step three:

[0063] The x direction stiffness of the two elastic bearings is K cfbx =1×10 5 N / mm, K cbx =10 N / mm, the stiffness ratio of the x direction load transmission of a, b two ways is:

[0064]

[0065] Further, the load ratio of the load transmission of a, b two ways is:

[0066]

[0067] Step one:

[0068] In the inner connector model, the constraint of A2, the x direction unit displacement 50 mm at A1, the measurement of A2 in the x direction of the support reaction 5100 N, get:

[0069]

[0070] Step two:

[0071] In the outer connector model, the constraint of the interface, the x-direction unit displacement 100mm is applied at A1, B1, and the reaction force of the interface in the x-direction is measured to be -836.1N, and the following is obtained:

[0072]

[0073] In the outer connector model, the constraint of the interface, the x-direction unit displacement 100mm is applied at A1, B1, and the reaction force of the interface in the x-direction is measured to be -836.1N, and the following is obtained:

[0074]

[0075] In the outer connector model, the constraint of the interface, the x-direction unit displacement 100mm is applied at A1, B1, and the reaction force of the interface in the x-direction is measured to be -836.1N, and the following is obtained:

[0076]

[0077] Solving equations (25)-(27) simultaneously, the following is obtained: 0x ax bx

[0078]

[0079] Step three:

[0080] Given that the x-direction stiffness of the two elastic bearings is K cfbx = 1 x 10 5 N / mm, K cbx = 10 N / mm, and the stiffness ratio of the x-direction load transmission of a and b is:

[0081]

[0082] Further, the load ratio of the load transmission of a and b is:

[0083]

[0084] ​​​As used herein, unless defined otherwise, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It is also to be understood that terms such as those defined in commonly used dictionaries are to take on ordinary and customary meanings unless otherwise explicitly provided for herein and are to be interpreted as being indicative of the intent of the inventors to invoke a special definition beneficial over conclusions from a more customary, semantic meaning of term, unless otherwise explicitly provided for herein. The summary of the application described above, the detailed description of the application described below, and the drawings illustrate the state of the art, and are not limiting of the present application. It will be readily understood to those skilled in the art that the application is susceptible to broad disposal and use, and that the above described embodiments are only exemplary of the principles of the application and are not to be considered limitation on the scope of the application. Accordingly, the scope of the application is not intended to be limited to the above described embodiments but rather is capable of extending to other embodiments and uses thereof which come within the scope of the following claims and their equivalents.

Claims

1. A dual elastomeric bearing configuration hub central piece - arm dual path load transfer load sharing method, characterized by, First, the entity model is simplified into a virtual model with physical quantities as elements; then, the equivalent stiffness of each part is solved by combining the load transmission path characteristics of the entity model and the finite element software; finally, the ratio relationship of the two loads is obtained according to the quantity relationship of the virtual model; Step one: Measurement ; For the inner connector in the direction of stiffness; direction; Step two: solving , and ; is the stiffness of the part of the structure in the direction before the load is split on the outer connection, is the stiffness of the part of the structure in the direction after the load is split on the outer connection; is the stiffness of the part of the structure in the direction after the load is split on the outer connection; is the stiffness of the part of the structure in the direction after the load is split on the outer connection; Step three: the ratio of the two loads is calculated; , The stiffness ratio of the two load paths is: (7) Then get 、 The load ratio of the two-way load transfer is: (8) and are bearing performance parameters.

2. The method of claim 1, wherein, The steps are as follows: Step one: Measurement ; In the inner connector model, the constraint at point applies unit displacement , measures the reaction force in the direction at point , and obtains: (1) Step two: Solving , and ; In the outer connection model, the constraint is applied to the interface, and , a unit displacement is applied to the interface at two points simultaneously , and the reaction force of the interface in the direction of is measured , and the following is obtained: (2) In the outer connection model, the constraint is applied to the interface, and a unit displacement is applied at , the reaction force of the interface in the direction is measured, and the following is obtained: ​ (3) In the outer connection model, the constraint is applied to the interface, and the unit displacement is applied at , the reaction force of the interface in the direction of is measured, and the following is obtained: ​​ (4) Simultaneous equations (2) - (4) are calculated to obtain , and are: (5) Wherein, (6) 3. The method of claim 2, wherein, Parameters in step one If testing by experimental means, go directly to step two.

4. The method of claim 3, wherein, The method is suitable for the central part and the supporting arm to be in the same central axis in the direction and not to produce additional bending moment. direction remains in the same central axis and does not produce additional bending moment.

5. The method of claim 4, wherein, In this method, the master and slave points of the spring element need to be specified according to the load transmission direction.

6. The method of claim 5, wherein, The centrifugal force elastic bearing and the center elastic bearing in the method need to measure The stiffness in the direction.

7. The method of claim 6, wherein, The centrifugal force elastic bearing and the center elastic bearing cannot have a deviation in the direction of the applied load.

8. The method of claim 7, wherein, The central part and the arm structure are made of metal materials.

9. The method of claim 8, wherein, The central part-arm structure of the double elastic bearing includes four components: a central part, an arm, a centrifugal force elastic bearing, and a center elastic bearing; the central part is connected with the centrifugal force elastic bearing and the center elastic bearing through bolts, and has no direct contact with the arm; the arm is composed of an inner connecting piece and an outer connecting piece, and the inner connecting piece and the outer connecting piece are connected through bolts, wherein the inner connecting piece is connected with the centrifugal force elastic bearing through bolts, and the outer connecting piece is connected with the center elastic bearing through bolts.

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