A fatigue test load debugging method for a main hub central part of an unmanned helicopter

Abstract

The application provides a fatigue test load debugging method for a main hub central part of an unmanned helicopter, comprising the following steps: establishing a mechanical model according to a preset test loading scheme, and calculating theoretical values of a flapping force and a pitching force required to be applied to reach a target load; performing parameter configuration and parameter debugging on each load channel of a coordinated loading control system; performing static load and dynamic load working condition debugging on the main hub central part, so that the static load and the dynamic load meet test requirements; and on the basis of the static load and the dynamic load debugging of the main hub central part, performing low-cycle fatigue test load and high-cycle fatigue test load debugging on the main hub central part, so as to obtain input loads of a flapping force actuator and a pitching force actuator meeting test requirements. The technical scheme of the application solves the problem that the existing fatigue test mode of the main hub central part cannot guarantee that the loads of the hub center and the butt joint surface of the arm of the main hub central part meet test requirements at the same time.

Description

TECHNICAL FIELD

[0001] The present application relates to, but not limited to, the technical field of fatigue test loading of unmanned helicopter main hub central part, and particularly relates to a fatigue test load debugging method of unmanned helicopter main hub central part. BACKGROUND

[0002] The main hub central part is a typical complex moving part in the bearingless rotor hub of the unmanned helicopter, which bears all the loads from the blades through flexible beams, sleeves and other related force transmission components. In actual flight conditions, for the main hub central part, not only high-cycle fatigue caused by high-cycle vibration load needs to be considered, but also low-cycle fatigue mainly caused by air-ground load needs to be considered, and high-low damage superposition is the main means to evaluate the fatigue life.

[0003] At present, for the fatigue test of manned helicopter main hub central part, centrifugal force, flapping force and oscillation force can be applied to synthesize the dynamic bending moment of the hub center to make the load of the hub center meet the test requirements; however, the above control method cannot guarantee that the synthesized bending moment of the arm butt joint surface meets the test and design requirements at the same time. For the fatigue test of unmanned helicopter main hub central part, it is also required that the load of the hub center and the arm butt joint surface meets the test requirements at the same time, and there is still a deficiency in the test loading technology, and a complete fatigue test load loading debugging method for unmanned helicopter main hub central part has not been formed, which makes it difficult to efficiently debug and accurately load the fatigue test load of the unmanned helicopter main hub central part. SUMMARY

[0004] The purpose of the present application is to provide a fatigue test load debugging method for unmanned helicopter main hub central part, to solve the problem that the existing fatigue test method of main hub central part cannot guarantee that the load of the hub center and the arm butt joint surface of the main hub central part meets the test requirements at the same time, whether for manned aircraft or unmanned aircraft.

[0005] The technical solution of the present application is: the present application provides a fatigue test load debugging method for unmanned helicopter main hub central part, the main hub central part is sleeved on the top end of a rotor simulation shaft, a plurality of blade dummy parts are evenly installed at the circumferential position of the main hub central part through arms, the target section of the main hub central part includes a first target section parallel to the rotor simulation shaft and a second target section perpendicular to the first target section; the fatigue test load debugging method comprises:

[0006] Step 1: according to the pre-set test loading scheme, a mechanical model is established, and the flapping force theoretical value and the oscillation force theoretical value required to achieve the target load are calculated;

[0007] Step 2, parameter configuration and parameter debugging are performed on each load channel of the coordinated load control system, so that the output of each load channel corresponding to the actuator cylinder follows the input command; the load channels include a centrifugal force channel, a flapwise force channel, and an edgewise force channel;

[0008] Step 3, static load working condition debugging is performed on the main hub central part, so that the static load meets the test requirements.

[0009] Step 4, dynamic load working condition debugging is performed on the main hub central part, so that the dynamic load meets the test requirements.

[0010] Step 5, on the basis of the static load and dynamic load debugging of the main hub central part, low-cycle fatigue test load and high-cycle fatigue test load debugging are performed on the main hub central part, so as to obtain input loads of the flapwise force actuator and the edgewise force actuator that meet the test requirements.

[0011] Optionally, in the fatigue test load debugging method of the unmanned helicopter main hub central part as described above, the mechanical model established in the step 1 is:

[0012] The mechanical model of the flapwise force and the edgewise force loaded on each blade dummy part connected to the main hub central part.

[0013] The preset test loading scheme is to apply centrifugal force, flapwise force and edgewise force to the main hub central part through each blade dummy part, and the target load is the resultant force of the centrifugal force, the flapwise force and the edgewise force applied to each arm.

[0014] Optionally, in the fatigue test load debugging method of the unmanned helicopter main hub central part as described above,

[0015] In the step 2, the load channels include a centrifugal force channel, an edgewise force channel, and a flapwise force channel.

[0016] Optionally, in the fatigue test load debugging method of the unmanned helicopter main hub central part as described above, the step 3 of performing static load working condition debugging on the main hub central part comprises:

[0017] According to the preset test loading scheme, a set centrifugal force load is applied to each arm of the main hub central part at the same time, and a first command load F0 is input through the flapwise force actuator cylinder or the edgewise force actuator cylinder, and according to the measured load of each interpolation profile of each blade dummy part and the rotor simulation shaft, a flapwise static bending moment or an edgewise static bending moment M0 of a second target profile is obtained, so that the static load meets the test requirements.

[0018] Optionally, in the fatigue test load debugging method of the unmanned helicopter main hub central part as described above, the step 4 of performing static load working condition debugging on the main hub central part comprises:

[0019] According to the preset test loading scheme, the preset centrifugal force load is applied to each arm of the main hub central part at the same time, and the second command load F1 is input through the flapping force actuator or the pendulum force actuator, the first target profile hub center dynamic bending moment and the second target profile flapping dynamic bending moment or pendulum dynamic bending moment M1 are obtained according to the measured load of each interpolation profile of the blade dummy part and the rotor simulation shaft, so that the dynamic load meets the test requirements.

[0020] Optionally, in the fatigue test load debugging method of the unmanned helicopter main hub central part, the step 5 comprises:

[0021] While the constant centrifugal force load is applied to each arm of the main hub central part, the flapping force load F2 is applied through the flapping force actuator, and the pendulum force load F3 is applied through the pendulum force actuator, the strain output load of each interpolation profile on the central part simulation shaft and the blade dummy part is collected through the coordinated loading control system, and the strain output load of each interpolation profile is linearly interpolated to obtain the first target profile hub center dynamic bending moment and the second target profile flapping dynamic bending moment and pendulum dynamic bending moment under the combined loading state of the flapping force and the pendulum force.

[0022] Optionally, in the fatigue test load debugging method of the unmanned helicopter main hub central part, the method further comprises:

[0023] Step 6: by repeatedly executing step 5, that is, by repeatedly debugging the loading load F1' of the flapping force actuator and the pendulum force actuator under the action of the constant centrifugal force, the dynamic bending moment of each target profile is continuously close to the test target load, so that the error between the dynamic bending moment of each target profile and the target load is less than the preset error threshold.

[0024] Optionally, in the fatigue test load debugging method of the unmanned helicopter main hub central part, the step 6 comprises:

[0025] The flapping dynamic bending moment and the pendulum dynamic bending moment close to the test target load obtained by the previous debugging are used as the output load of the flapping force actuator and the pendulum force actuator in the fatigue test, and the fatigue test of the main hub central part is carried out, and the measurement load such as the hub center dynamic bending moment and the torque is monitored during the fatigue test, and the flapping force load F2 and the pendulum force load F3 are fine-tuned according to the test situation, so as to ensure that the test load composite design requirement of the key part of the central part is met.

[0026] The beneficial technical effects of the present application are:

[0027] The application provides a fatigue test load debugging method for a main hub central part of an unmanned helicopter, solves the problems of coordinated loading of test loads of each branch arm of the main hub central part and real simulation of flap bending moment and edgewise bending moment; the flap bending moment in the test process is mainly generated by a flap actuator, the edgewise bending moment is mainly generated by an edgewise actuator, because the loads are coordinated in different phases, in addition, the load applied by the flap actuator and the flap bending moment are not in linear relationship, the load applied by the edgewise actuator and the edgewise bending moment are not in linear relationship, furthermore, because the centrifugal force has uncertainty in unloading action on the flap bending moment and the edgewise bending moment, therefore, the loading shear force of the flap actuator and the edgewise actuator calculated in theory is also not accurate. Therefore, the dynamic load numerical interpolation algorithm is explored in the debugging process, in the fatigue test of the main hub central part of the unmanned helicopter, the flap bending moment and the edgewise bending moment of the butt joint surface of the branch arm and the bending moment of the hub center are debugged, so as to accurately obtain the loading shear force (amplitude and phase) of the flap actuator and the edgewise actuator, the method is scientific and reasonable, and the data is real and accurate.

[0028] By using the fatigue test load debugging method for the main hub central part of the unmanned helicopter provided by the embodiment of the application, the fatigue test load of the central part of the unmanned helicopter is debugged, the boundary conditions of each test load can be accurately simulated, the test state is stable, the test environment is good, the load fluctuation is small, the loading error is small, and the total test error can be controlled within 3%. By using the test data obtained by the method for debugging the test, the performance can be fully verified and the fatigue life of the structure can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings are used to provide further understanding of the technical scheme of the application, and constitute a part of the specification, and are used to explain the technical scheme of the application together with the embodiments of the application, and do not constitute a limitation on the technical scheme of the application.

[0030] Figure 1 The flow chart of the fatigue test load debugging method for the main hub central part of the unmanned helicopter provided by the embodiment of the application is shown in the figure;

[0031] Figure 2 The structural schematic diagram of the main hub central part of the unmanned helicopter in the embodiment of the application is shown in the figure;

[0032] Figure 3 The schematic diagram of the installation structure of the main hub central part of the unmanned helicopter in the fatigue test load debugging test in the embodiment of the application is shown in the figure;

[0033] Figure 4 The schematic diagram of the installation structure of the main hub central part of the unmanned helicopter in the fatigue test load debugging test in the embodiment of the application is shown in the figure; Figure 3 The schematic diagram of the installation structure of the main hub central part of the unmanned helicopter in the fatigue test load debugging test in the embodiment of the application is shown in the figure;

[0034] Figure 5 A schematic diagram of the principle of the loading scheme in the embodiment of the present application;

[0035] Figure 6 A schematic diagram of the principle of the bending moment debugging vector synthesis in the embodiment of the present application;

[0036] Figure 7 A schematic diagram of the mechanical model established based on the test scheme in the embodiment of the present application;

[0037] Figure 8 A schematic diagram of the phase difference of the flapwise bending moment Mb between interpolation profiles on a single blade dummy obtained by the method provided in the embodiment of the present application;

[0038] Figure 9 A schematic diagram of the bending moment calculation principle of the butt joint surface of the arm in the embodiment of the present application;

[0039] Figure 10 A schematic diagram of the bending moment calculation principle of the hub center in the embodiment of the present application. DETAILED DESCRIPTION

[0040] To make the objects, technical solutions and advantages of the present application clearer, the embodiments of the present application will be described in detail below with reference to the drawings. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in any manner without conflict.

[0041] As described in the above background, the fatigue test method of the main hub central part is difficult to ensure that the loads of the hub center and the butt joint surface of the arm of the main hub central part meet the test requirements at the same time, whether for manned or unmanned helicopters. Therefore, for the fatigue test of the main hub central part of the unmanned helicopter, it is difficult to efficiently perform the fatigue test load debugging of the main hub central part and accurately apply the load.

[0042] Since the assembly structure and force transmission mode of the main hub central part of the unmanned helicopter are complex, the load forms borne are complex and diverse, and the main hub central part itself is small in structure and light in weight and cannot bear large loads. Therefore, it is crucial to provide an optimized and improved fatigue test load debugging method for truly simulating the size, direction and phase relationship of each load during the fatigue test, so as to accurately apply the load to the key positions of the test part (i.e., the main hub central part), thereby evaluating the true fatigue performance and weak positions of the test part, and providing a basis for evaluating the service life of the main hub central part of the unmanned helicopter.

[0043] In view of the problems existing in the fatigue test method of the main hub central part and based on the characteristics of the main hub central part of the unmanned helicopter, the embodiment of the present application provides a fatigue test load debugging method for the main hub central part of the unmanned helicopter.

[0044] The following specific embodiments of the present application can be combined with each other, and the same or similar concepts or processes can not be described in some embodiments.

[0045] Figure 1 A flowchart of a fatigue test load debugging method of a main hub central part of an unmanned helicopter according to an embodiment of the present application is shown in the figure. Figure 2 A structural schematic diagram of a main hub central part of a helicopter according to an embodiment of the present application is shown in the figure. Figure 3 A schematic diagram of an installation structure of a main hub central part of a helicopter in a fatigue test load debugging test according to an embodiment of the present application is shown in the figure. Figure 4 A schematic diagram of an installation structure of a main hub central part of a helicopter in a fatigue test load debugging test according to an embodiment of the present application is shown in the figure. Figure 3 A schematic diagram of an installation structure of a main hub central part of a helicopter in a fatigue test load debugging test according to an embodiment of the present application is shown in the figure. Figure 5 A principle schematic diagram of a loading scheme according to an embodiment of the present application is shown in the figure.

[0046] Referring to Figure 2 to Figure 5 As shown in the figure, the main hub central part is sleeved on the top end of the rotor simulation shaft, and a plurality of blade dummy parts are uniformly installed at the circumferential positions of the main hub central part through the support arms. The target section of the main hub central part includes a first target section parallel to the rotor simulation shaft and a second target section perpendicular to the first target section. As shown in the figure, each section. Figure 4

[0047] The fatigue test load debugging method of the main hub central part of the unmanned helicopter according to an embodiment of the present application can include the following steps.

[0048] Step 1: According to a preset test loading scheme, a mechanical model is established, and the theoretical values of the flapping force and the edgewise force required to reach the target load are calculated.

[0049] In this step 1, the preset test loading scheme is as shown in the figure, and specifically simulates the actual installation mode of the main hub central part. Figure 3 Figure 4

[0050] Step 2: The parameters of each load channel of the coordinated loading control system are configured and debugged, so that the output of the actuator cylinder corresponding to each load channel follows the input command.

[0051] Each load channel in this step includes a centrifugal force channel, an edgewise force channel, and a flapping force channel.

[0052] Step 3: The main hub central part is subjected to static load condition debugging, so that the static load meets the test requirements.

[0053] Step 4: The main hub central part is subjected to dynamic load condition debugging, so that the dynamic load meets the test requirements.

[0054] ​​​Step 5, on the basis of the static load and dynamic load debugging of the main hub central part, the low cycle fatigue test load and the high cycle fatigue test load of the main hub central part are debugged to obtain the input load of the flapping force actuator and the edgewise force actuator meeting the test requirements.

[0055] In the embodiment of the application, the mechanical model established in step 1 is as follows:

[0056] The mechanical model of the flapping force and the edgewise force loaded on each blade dummy part connected with the main hub central part; the preset test loading scheme is that the centrifugal force, the flapping force and the edgewise force are applied to the main hub central part by each blade dummy part, and the target load is the resultant force of the centrifugal force, the flapping force and the edgewise force applied to each support arm. As shown in Figure 3 and Figure 4 .

[0057] In the embodiment of the application, the load channels in step 2 include the centrifugal force channel, the edgewise force channel and the flapping force channel.

[0058] In the embodiment of the application, the specific implementation of the static load working condition debugging of the main hub central part in step 3 can include:

[0059] According to the preset test loading scheme, the set centrifugal force load is applied to each support arm of the main hub central part at the same time, and the first command load F0 of the flapping force actuator or the edgewise force actuator is input, that is, the theoretical value of the flapping force or the edgewise force is input, and the flapping static bending moment or the edgewise static bending moment M0 of the second target section is obtained according to the measured load of each interpolation section of each blade dummy part and the rotor simulation shaft, so that the static load meets the test requirements.

[0060] Similarly, in the embodiment of the application, the specific implementation of the static load working condition debugging of the main hub central part in step 4 can include:

[0061] According to the preset test loading scheme, the set centrifugal force load is applied to each support arm of the main hub central part at the same time, and the second command load F1 of the flapping force actuator or the edgewise force actuator is input, that is, the theoretical value of the flapping force or the edgewise force is input, and the hub center dynamic bending moment of the first target section and the flapping dynamic bending moment or the edgewise dynamic bending moment M1 of the second target section are obtained according to the measured load of each interpolation section of each blade dummy part and the rotor simulation shaft, combined with the dynamic load numerical interpolation method, so that the dynamic load meets the test requirements.

[0062] In the embodiment of the application, the implementation of step 5 can include:

[0063] While the constant centrifugal force load is applied to each arm of the main hub central part, the flap force load F2 is applied through the flap force actuator cylinder, and the edgewise force load F3 is applied through the edgewise force actuator cylinder, the strain output load of each interpolation profile on the central part simulation shaft and the blade dummy part is collected by the coordinated loading control system, and the linear interpolation of the strain output load of each interpolation profile is carried out by combining the least square method, so as to obtain the hub center dynamic bending moment of the first target profile and the flap dynamic bending moment and the edgewise dynamic bending moment of the second target profile under the combined loading of the flap force and the edgewise force.

[0064] Further, the method provided by the embodiment of the present application can further include:

[0065] Step 6: The dynamic bending moments of each target profile are continuously close to the test target load by repeatedly performing step 5, that is, by repeatedly adjusting the loading load F1' of the flap force actuator cylinder and the edgewise force actuator cylinder under the action of the constant centrifugal force, so that the error between the dynamic bending moment of each target profile and the target load is less than the preset error threshold, for example, the error between the dynamic bending moment of each target profile and the target load is less than or equal to 3%, that is, the test requirements are met.

[0066] It should be noted that the repeated adjustment method in step 6 of the embodiment of the present application includes:

[0067] The flap dynamic bending moment and the edgewise dynamic bending moment close to the test target load obtained by the previous adjustment are used as the output load of the flap force actuator cylinder and the edgewise force actuator cylinder in the fatigue test, and the fatigue test of the main hub central part is carried out, and the measurement load such as the hub center dynamic bending moment and the torque is monitored during the fatigue test, and the flap force load F2 and the edgewise force load F3 are fine-tuned according to the test situation, so as to ensure that the test load composite design requirements of the key parts of the central part are met.

[0068] The fatigue test load debugging method of the unmanned helicopter main hub central part provided by the embodiment of the application solves the problems of coordinated loading of test loads of each arm of the main hub central part, and real simulation of flap bending moment and edgewise bending moment. The flap bending moment in the test process is mainly generated by the flap actuator, and the edgewise bending moment is mainly generated by the edgewise actuator. Since the loads are coordinated in different phases, in addition, the load applied by the flap actuator is not in linear relationship with the flap bending moment, and the load applied by the edgewise actuator is not in linear relationship with the edgewise bending moment. Furthermore, since the centrifugal force has uncertain unloading effect on the flap bending moment and the edgewise bending moment, the calculated loading shear force of the flap actuator and the edgewise actuator is also inaccurate. Therefore, the dynamic load numerical interpolation algorithm is explored in the debugging process. In the fatigue test of the unmanned helicopter main hub central part, the flap bending moment and the edgewise bending moment of the arm butt joint surface and the hub central bending moment are debugged, so as to accurately obtain the loading shear force (amplitude and phase) of the flap actuator and the edgewise actuator. The method is scientific and reasonable, and the data is real and accurate.

[0069] By using the fatigue test load debugging method of the unmanned helicopter main hub central part provided by the embodiment of the application, the fatigue test load of the unmanned helicopter central part is debugged, the boundary conditions of each test load can be accurately simulated, the test state is stable, the test environment is good, the load fluctuation is small, the loading error is small, and the total test error can be controlled within 3%. By using the test data obtained by the method for debugging the test, the performance can be fully verified and the fatigue life of the structure can be obtained.

[0070] The fatigue test load debugging method of the unmanned helicopter main hub central part provided by the embodiment of the application is described in detail below through a specific embodiment.

[0071] The fatigue test load debugging method of the unmanned helicopter main hub central part provided by the embodiment of the application solves the technical problem: a fatigue test load debugging method of the unmanned helicopter main hub central part is proposed, which is used for fatigue test of the unmanned helicopter main hub central part. First, the accurate application of each load of the main hub central part is realized, the loading state of the unmanned helicopter main hub central part is simulated, the test boundary conditions are simulated, and the deficiencies of the background technology are overcome. In addition, secondly, by using the method provided by the embodiment of the application, the loading accuracy of the test load can be improved by load debugging correction, the loading balance of each arm of the main hub central part can be ensured, the fatigue performance of the main hub central part can be fully verified, and the problems such as low loading accuracy, large error, and product safety life being conservative due to the fact that the key parts of the main hub central part cannot be fully verified by the traditional debugging method can be effectively overcome.

[0072] In the embodiment, the fatigue test of the main hub central part needs to simulate the loads of centrifugal force F C , torque M Z , lift F Z , flap bending moment M B , flap shear force F b generated by the flap shear force actuator, edgewise bending moment M T , and edgewise shear force F t generated by the edgewise shear force actuator, and each load is loaded in phase coordination. As shown in Figure 6 , it is a schematic diagram of the principle of bending moment debugging vector synthesis in the embodiment.

[0073] The fatigue test load debugging method for the unmanned helicopter main hub central part provided by the embodiment includes the following steps:

[0074] (1) First, design a test loading scheme (as shown in Figure 3 , Figure 4 and Figure 5 ), establish a mechanical model, and calculate the theoretical values of the flap force and the edgewise force required to be applied to achieve the target load, as shown in Figure 7 , it is a schematic diagram of the mechanical model established based on the test scheme in the embodiment. The mechanical model specifically adopts a cantilever beam loading mechanical model.

[0075] (2) Configure and debug the parameters of each load channel of the centrifugal force, the edgewise force, and the flap force, so that the output of each actuator follows the input command.

[0076] (3) Perform static load condition debugging, that is, apply the centrifugal force design load to the four arms of the central part according to the requirements, and input the load F0 (which can refer to the theoretical calculation value) through the flap force or edgewise force actuator. The measured load of the interpolation profile is combined with the least square method to obtain the flap bending moment or edgewise bending moment M0 static load of the target profile, so as to meet the test requirements.

[0077] (4) Perform dynamic load condition debugging, that is, apply the centrifugal force design load to the four arms of the central part according to the requirements, and input the load F1 through the flap force or edgewise force actuator. The measured load of the interpolation profile is combined with the dynamic load value interpolation method (the interpolation calculation formulas are shown in formulas (1) and (2)) to obtain the dynamic flap bending moment or edgewise bending moment M1 of the target profile, so as to meet the test requirements.

[0078]

[0079]

[0080] Wherein, L0, L1 and L2 are the distances of the central piece arm butt joint surface, the 1# strain gauge profile of the flexible beam false piece, the 2# strain gauge profile and the loading center respectively; MB0, MB1 and MB2 are the edgewise bending moments at the butt joint surface, the 1# strain gauge profile and the 2# strain gauge profile respectively; MT0, MT1 and MT2 are the flapwise bending moments at the butt joint surface, the 1# strain gauge profile and the 2# strain gauge profile respectively. For the dynamic load numerical interpolation method, the phase difference of the edgewise bending moments of the strain measurement profiles is considered, so the real-time dynamic bending moment values of the 1# and 2# strain measurement profiles at each time point are collected to interpolate the bending moment values of the butt joint surface at each time point MB0, and then the corresponding bending moment amplitude is converted to be the edgewise bending moment of the butt joint surface.

[0081] (5), on the basis of the debugging results of the steps (3) and (4), further debug the low cycle fatigue test load and the high cycle fatigue test load of the main hub central piece, and obtain the input load F2 of the edgewise or flapwise actuator meeting the test requirements; and the input load F2 is used as the output load of the edgewise and flapwise actuator in the test, and the central piece fatigue test is carried out to monitor the central bending moment M f and the torque M Z and the like, and F2 is fine-tuned according to the test situation to ensure that the test load of the key part of the central piece meets the design requirements. The debugging process is shown in Figure 1 .

[0082] The key technology of the main hub central piece fatigue test debugging of the present application solves the problems of the coordinated loading of the test loads of the arms of the main hub central piece, the real simulation of the edgewise and flapwise bending moments of the butt joint surface of the arms and the central bending moment of the hub, the problem of the large phase difference of the edgewise bending moments between the interpolation profiles of each blade false piece, and the problem of the difficulty in measuring the load of the butt joint surface of the arms, and realizes the joint debugging of the load of the butt joint surface of the arms and the central load of the hub. The test can ensure that the loads of the arms of the central piece are balanced, the connection and assembly of the central piece and the rotor shaft and the flexible beam and the load transmission relationship are simulated, the test bed is stable, the test environment is good, the load fluctuation is small, and the test error can be controlled within 3%.

[0083] As shown in Figure 8 , it is a phase difference diagram of the edgewise bending moments Mb between the interpolation profiles of a single blade false piece obtained by the method provided by the embodiment of the present application, Figure 8 wherein Mb11 and MB12 represent the measured edgewise bending moment loads of the interpolation profile 1 and the interpolation profile 2 of the 1# blade false piece respectively, and ΔФ is the phase difference of the edgewise bending moments between the interpolation profile 1 and the interpolation profile 2; as shown in Figure 9 , it is a schematic diagram of the bending moment calculation principle of the butt joint surface of the arm in the embodiment of the present application; as shown in Figure 10 , it is a schematic diagram of the bending moment calculation principle of the hub center in the embodiment of the present application.

[0084] Although the embodiments of the present application have been disclosed with reference to the above embodiments, the content of the present application is only the embodiments adopted for the purpose of facilitating the understanding of the present application, and is not intended to limit the present application. Any modification and change in the form and details of the embodiments can be made by any person skilled in the art without departing from the spirit and scope of the present application, but the patent protection scope of the present application shall be subject to the scope defined by the appended claims.

Claims

1. A method of fatigue test load conditioning for unmanned helicopter main hub central piece, characterized in that, The main hub central part is sleeved on the top end of the rotor simulation shaft, and a plurality of blade dummy parts are uniformly installed at the circumferential positions of the main hub central part through the arms. The target section of the main hub central part includes a first target section parallel to the rotor simulation shaft and a second target section perpendicular to the first target section. The fatigue test load debugging method includes: Step 1: a mechanical model is established according to a preset test loading scheme, and the theoretical values of the flapping force and the edgewise force required to reach the target load are calculated; Step 2: the parameters of each load channel of the coordinated loading control system are configured and debugged, so that the output of each load channel corresponding to the actuator cylinder follows the input command; each load channel includes a centrifugal force channel, an edgewise force channel, and a flapping force channel; Step 3: the main hub central part is subjected to static load condition debugging to make the static load meet the test requirements; Step 4: the main hub central part is subjected to dynamic load condition debugging to make the dynamic load meet the test requirements; Step 5: on the basis of the static load and dynamic load debugging of the main hub central part, the main hub central part is subjected to low-cycle fatigue test load and high-cycle fatigue test load debugging to obtain the input load of the flapping force actuator and the edgewise force actuator that meets the test requirements; In step 3, the static load condition debugging of the main hub central part includes: According to the preset test loading scheme, the set centrifugal force load is applied to each arm of the main hub central part, and the first command load F0 is input through the flapping force actuator cylinder or the edgewise force actuator cylinder, and the flapping static bending moment or the edgewise static bending moment M0 of the second target section is obtained according to the measured load of each interpolation section of the blade dummy part and the rotor simulation shaft, so that the static load meets the test requirements; In step 4, the dynamic load condition debugging of the main hub central part includes: According to the preset test loading scheme, the set centrifugal force load is applied to each arm of the main hub central part, and the second command load F1 is input through the flapping force actuator cylinder or the edgewise force actuator cylinder, and the hub center dynamic bending moment of the first target section and the flapping dynamic bending moment or the edgewise dynamic bending moment M1 of the second target section are obtained according to the measured load of each interpolation section of the blade dummy part and the rotor simulation shaft, so that the dynamic load meets the test requirements.

2. The fatigue test load tuning method for unmanned helicopter main hub center piece according to claim 1, characterized in that, The mechanical model established in step 1 is: The mechanical model of the flapping force and the edgewise force loaded on each blade dummy part connected to the main hub central part; The preset test loading scheme is to apply centrifugal force, flapping force and edgewise force to the main hub central part through each blade dummy part, and the target load is the combined force of the centrifugal force, flapping force and edgewise force applied to each arm.

3. The fatigue test load debugging method for the main hub central part of the unmanned helicopter according to claim 2, wherein In step 2, each load channel includes a centrifugal force channel, an edgewise force channel, and a flapping force channel.

4. The fatigue test load tuning method of claim 3, wherein, Step 5 includes: The constant centrifugal force load is applied to each arm of the main hub central part, the flapping force load F2 is applied through the flapping force actuator, and the edgewise force load F3 is applied through the edgewise force actuator, the strain output load of each interpolation section on the central part simulation shaft and the blade dummy part is collected through the coordinated loading control system, and the strain output load of each interpolation section is linearly interpolated to obtain the hub center dynamic bending moment of the first target section, the flapping dynamic bending moment and the edgewise dynamic bending moment of the second target section under the combined loading state of the flapping force and the edgewise force.

5. The fatigue test load tuning method of claim 4, wherein, Also includes: Step 6, by repeatedly executing step 5, that is, by repeatedly adjusting the loading load F1' of the flapping force actuator and the edgewise force actuator under the action of the constant centrifugal force, the dynamic bending moment of each target section is continuously close to the test target load, so that the error between the dynamic bending moment of each target section and the target load is less than the preset error threshold.

6. The fatigue test load tuning method of claim 5, wherein, The step 6 includes: The flapping dynamic bending moment and the edgewise dynamic bending moment close to the test target load obtained by the previous adjustment are used as the output load of the flapping force actuator and the edgewise force actuator in the fatigue test, the fatigue test of the main hub central part is carried out, the hub center dynamic bending moment and the torque measurement load are monitored during the fatigue test, and the flapping force load F2 and the edgewise force load F3 are fine adjusted according to the test situation, so as to ensure that the test load composite design requirement of the key part of the central part.

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