Airplane flap load spectrum compilation method based on measured data

Abstract

The invention belongs to the field of aircraft fatigue strength, and particularly relates to an aircraft flap load spectrum compilation method based on measured data, which comprises the following steps of: 1, acquiring axial force of each actuating cylinder of a flap by utilizing measured result data of an aircraft load spectrum, and acquiring a corresponding load state; 2, summing the moments of all the actuating cylinders at different deflection angles to obtain the total bending moment of the flap at different deflection angles and the corresponding load state; 3, according to the corresponding flap pressure center positions in different load states, the distances Li from a flap rotating shaft to the pressure center in different load states are calculated; obtaining the flap load Njyi in different load states; 4, according to the total bending moment of the flap in the same load state and the distance Li from a flap rotating shaft to a pressure center, the flap load Njyi in the corresponding load state is calculated; and 5, compiling a flap load spectrum based on the flap load Njyi.

Description

Technical Field

[0001] This application belongs to the field of aircraft fatigue strength, and specifically relates to a method for compiling aircraft flap load spectrum based on measured data. Background Technology

[0002] Load spectra define the various load scenarios an aircraft will encounter throughout its entire life cycle. Load spectra are used not only in aircraft structural design and analysis but also in structural testing. In full-aircraft fatigue testing, load spectra are used to simulate tens of thousands of flight cycles throughout the aircraft's life cycle, ensuring the reliability of the aircraft structure. Through engineering simplification, testing cycles can be shortened, and research and development efficiency improved.

[0003] Compiling a load spectrum that simulates the actual use of an aircraft is the foundation for fatigue analysis, testing, life assessment, and fatigue detail design improvement of aircraft components. It has a significant impact on the success, cost, workload, and time of subsequent analysis and testing work.

[0004] The methods for compiling aircraft flap load spectra and center-of-gravity overload spectra differ significantly, and there is no unified standard in China for compiling flap load spectra. Because the wings and fuselage are strongly correlated with the aircraft's center-of-gravity normal overload, the center-of-gravity normal overload can be used as the primary parameter for selecting loads for the wings and fuselage to ensure consistency with the overall aircraft load spectrum. However, in compiling flap load spectra, a direct relationship cannot be established between flap loads and the aircraft's center-of-gravity normal overload, and flap loads do not correspond one-to-one with flap deflection angles. Therefore, the method for compiling flap load spectra has remained inconclusive.

[0005] Based on the measured flap load of a certain type of aircraft, this paper correlates flight parameters with the measured flap load to determine the flap load values ​​under different flight conditions. Using the rainflow counting method and the damage equivalence principle, a flap load spectrum that can be used for fatigue life analysis and full-aircraft fatigue testing is compiled. Summary of the Invention

[0006] To address the aforementioned issues, a method for compiling aircraft flap load spectra based on measured data is proposed, comprising:

[0007] Step 1: Using the measured data of the aircraft load spectrum, obtain the axial force of each actuator of the flap and obtain the corresponding load state;

[0008] Step 2: Using the 3D digital model or drawings of the aircraft flaps, obtain the active envelope of the flap control surfaces. Based on the flap deflection angle and the extension distance of the actuator, calculate the moment of a single actuator at different deflection angles. Sum the moments of all actuators at different deflection angles to obtain the total bending moment of the flaps at different deflection angles and its corresponding load state.

[0009] Step 3: Based on the corresponding flap center of gravity positions under different load conditions, calculate the distance L from the flap pivot to the center of gravity under different load conditions. i Therefore, the flap load N under different load conditions is obtained. jyi ;

[0010] Step 4: Based on the total bending moment of the flap under the same load condition and the distance L from the flap pivot to the center of pressure. i Calculate the flap load N under the corresponding load conditions. jyi ;

[0011] Step 5: Based on flap load N jyi The flap load spectrum was compiled.

[0012] Preferably, before step 3, the total bending moment of the flaps under different deflection angles is preprocessed, including: effective takeoff and landing judgment: invalid takeoffs and landings during aircraft ground start-up and ground testing are deleted based on center of gravity overload, altitude, and speed parameters, and only effective flight takeoffs and landings are retained; invalid mission segments are eliminated: invalid loads generated during ground control of the flaps after takeoff and landing are deleted based on center of gravity overload, altitude, and speed parameters; abnormal data is eliminated: rainflow counting filtering is performed on the peak and valley values ​​of the flap bending moment, and peak and valley values ​​with small impact on damage are deleted according to the damage equivalence principle.

[0013] Preferably, the load state is defined based on the influence of different parameters such as center of gravity overload, speed, angle of attack, and flap deflection angle on the flap bending moment.

[0014] Preferably, the load state includes, but is not limited to:

[0015] Load condition 1: Speed ​​less than Mach 0.85 and angle of attack less than 10°;

[0016] Load condition 2: Speed ​​less than Mach 0.85 and angle of attack greater than 10°;

[0017] Load condition 3: Speed ​​between Mach 0.85 and Mach 1.25 and angle of attack less than 10°;

[0018] Load condition 4: Speed ​​greater than Mach 1.25 and angle of attack less than 10°.

[0019] Preferably, the formula for calculating the flap load is:

[0020] N Jyi =L i / M;

[0021] Where, N Jyi Let M be the flap load, M be the total flap bending moment, and L be the total flap bending moment. i denoted as , where is the distance from the flap pivot to the pressure center, and i represents the corresponding load state.

[0022] Preferably, when there are four moving cylinders, the total bending moment M 襟翼 The calculation formula is:

[0023] M 襟翼 =M 襟翼1 +M 襟翼2 +M 襟翼3 +M 襟翼4 ;

[0024] Among them, M 襟翼1 M 襟翼2 M 襟翼3 With M 襟翼4 These are the bending moments generated by the four actuators on the flaps.

[0025] The advantages of this application include:

[0026] 1) It can obtain the actual load history that reflects the usage status of the aircraft flaps;

[0027] 2) It can provide more accurate loads for flap fatigue life analysis and flap testing, improving calculation and testing accuracy;

[0028] 3) The flap load spectrum compiled using this method can reduce the number of test cycles, shorten the test time, and save costs. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the lever arm of the flap at different deflection angles according to a preferred embodiment of this application;

[0030] Figure 2 This is a schematic diagram of the original load history of the actual measured flap bending moment.

[0031] Figure 3 It is the flap bending moment data, rainflow count, and load history.

[0032] Figure 4 This is a schematic diagram showing the flap pressure center position under different load conditions.

[0033] Figure 5 This is a schematic diagram of the load spectrum of a certain landing flap. Detailed Implementation

[0034] To make the technical solution and advantages of this application clearer, the technical solution of this application will be described in a clearer and more complete manner below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of this application, and are only used to explain this application, not to limit this application. It should be noted that, for ease of description, only the parts related to this application are shown in the accompanying drawings. Other related parts can be referred to the general design. In the absence of conflict, the embodiments and technical features in the embodiments of this application can be combined with each other to obtain new embodiments.

[0035] Given that current flap load spectra are insufficient to accurately reflect the various load scenarios encountered by flaps throughout the entire lifespan of field aircraft, this invention proposes a method for compiling flap load spectra, such as... Figures 1-5 As shown:

[0036] The main steps include:

[0037] Step 1: Using the measured data of the aircraft load spectrum, obtain the axial force of each flap actuator. At the same time, obtain the main aircraft parameters corresponding to the axial force of each flap actuator, including: center of gravity overload, altitude, speed, angle of attack, flap deflection angle, etc.

[0038] Table 1 Measured data of load spectrum

[0039] Serial Number Parameter name Parameter symbol 1 Axial force of flap actuator 1 <![CDATA[P 作动筒 1]]> 2 axial force of flap actuator 2 <![CDATA[P 作动筒 2]]> 3 3-axis force of flap actuator <![CDATA[P 作动筒 3]]> 4 4-axis force flap actuator <![CDATA[P 作动筒 4]]> 5 flap deflection angle δjy 6 high H 7 speed M 8 Angle of attack α

[0040] Step 2: Using the 3D digital model or drawings of the aircraft flaps, obtain the active envelope of the flap control surfaces. Using the flap deflection angle and the actuator extension distance AA', calculate the distance 0A from the pivot to the actuator corresponding to different deflection angles of the flaps, thereby obtaining the torque of the flaps at different deflection angles.

[0041] M 襟翼i =P 作动筒i ×OA i (1)

[0042] in:

[0043] M 襟翼 The torque generated by an actuator;

[0044] P 作动筒 The axial force of an actuator cylinder;

[0045] OA i The distance from an actuator cylinder to the rotating shaft;

[0046] Using the bending moment calculation formula above, the bending moments corresponding to the four arms can be obtained. Finally, the bending moments corresponding to the four arms are summed to obtain the total bending moment M of the flap. 襟翼 .

[0047] M 襟翼 =M 襟翼1 +M 襟翼2 +M 襟翼3 +M 襟翼4 ;

[0048] Step 3: Preprocess the measured flap moment data obtained from the calculation: (1) Judge effective takeoffs and landings. According to parameters such as center-of-gravity overload, altitude, and speed, delete invalid takeoffs and landings such as aircraft engine start-up on the ground and ground debugging, and only retain effective flight takeoffs and landings; (2) Eliminate invalid mission segments. According to parameters such as center-of-gravity overload, altitude, and speed, only retain the data during the flight process, and delete the invalid loads generated during the ground control of the flap during takeoff and after landing; (3) Eliminate abnormal data. Perform rain-flow counting filtering on the remaining peak and valley values of the flap moment. According to the damage equivalence principle, delete the peak and valley values of the moment that have less impact on the damage. The peak and valley values are deleted in pairs.

[0049] Step 4: Analyze the influence of different parameter changes of center-of-gravity overload, speed, angle of attack, and flap deflection angle on the flap moment. For example:

[0050] Load state 1: M0 < 0.85, α < 10°; Flap center of pressure: X1, Y2.

[0051] Load state 2: M0 < 0.85, α > 10°, Flap center of pressure: X2, Y2.

[0052] Load state 3: 0.85 < M0 < 1.25, α < 10°, Flap center of pressure: X3, Y3.

[0053] Load state 4: M0 > 1.25, α < 10°, Flap center of pressure: X4, Y4.

[0054] According to the flap center-of-pressure positions corresponding to different load states, calculate the distance L from the flap rotation axis to the center of pressure for different load states i , where M0 is the flight Mach number.

[0055] Thus, obtain the flap loads N for different load states jyi , and the flap load calculation formula is:

[0056] N Jyi = L i / M;

[0057] Among them, N Jyi is the flap load, M is the total flap moment, L i is the distance from the flap rotation axis to the center of pressure, and i is the corresponding load state.

[0058] Table 2 Flap load calculation for different load states

[0059] Serial Number Load condition Core position flap lever arm flap loading 1 Load condition 1 X1,Y1 L1 <![CDATA[N jy 1=M / L1]]> 2 Load condition 2 X2,Y2 L2 <![CDATA[N jy 2=M / L2]]> 3 Load condition 3 X3,Y3 L3 <![CDATA[N jy 3=M / L3]]> 4 Load condition 4 X4,Y4 L4 <![CDATA[N jy 4=M / L4]]>

[0060] Step 5: Perform rain-flow counting on the flap load N jyi and then, according to the damage equivalence principle, perform load transfer-in and transfer-out to finally form the flap load spectrum.

[0061] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for compiling aircraft flap load spectra based on measured data, characterized in that, include: Step 1: Using the measured data of the aircraft load spectrum, obtain the axial force of each actuator of the flap and obtain the corresponding load state; Step 2: Using the 3D digital model or drawings of the aircraft flaps, obtain the active envelope of the flap control surfaces. Based on the flap deflection angle and the extension distance of the actuator, calculate the moment of a single actuator at different deflection angles. Sum the moments of all actuators at different deflection angles to obtain the total bending moment of the flaps at different deflection angles and its corresponding load state. Step 3: Based on the corresponding flap center of gravity positions under different load conditions, calculate the distance L from the flap pivot to the center of gravity under different load conditions. i Therefore, the flap load N under different load conditions is obtained. jyi ; Step 4: Based on the total bending moment of the flap under the same load condition and the distance L from the flap pivot to the center of pressure. i Calculate the flap load N under the corresponding load conditions. jyi ; Step 5: Based on flap load N jyi The flap load spectrum was compiled.

2. The method for compiling aircraft flap load spectra based on measured data as described in claim 1, characterized in that, Before step 3, the total bending moment of the flaps under different deflection angles is preprocessed, including: effective takeoff and landing judgment: invalid takeoffs and landings during aircraft ground start-up and ground testing are deleted based on center of gravity overload, altitude, and speed parameters, and only effective flight takeoffs and landings are retained; invalid mission segments are eliminated: invalid loads generated during ground control of the flaps after takeoff and landing are deleted based on center of gravity overload, altitude, and speed parameters; abnormal data is eliminated: rainflow counting filtering is performed on the peak and valley values ​​of the flap bending moment, and peak and valley values ​​with small impact on damage are deleted according to the damage equivalence principle.

3. The method for compiling aircraft flap load spectra based on measured data as described in claim 1, characterized in that, The load state is defined based on the influence of different parameters such as center of gravity overload, speed, angle of attack, and flap deflection angle on the flap bending moment.

4. The method for compiling aircraft flap load spectra based on measured data as described in claim 1, characterized in that, The load state includes, but is not limited to: Load condition 1: Speed ​​less than Mach 0.85 and angle of attack less than 10°; Load condition 2: Speed ​​less than Mach 0.85 and angle of attack greater than 10°; Load condition 3: Speed ​​between Mach 0.85 and Mach 1.25 and angle of attack less than 10°; Load condition 4: Speed ​​greater than Mach 1.25 and angle of attack less than 10°.

5. The method for compiling aircraft flap load spectra based on measured data as described in claim 1, characterized in that, The formula for calculating flap load is: N Jyi =L i / M; Where, N Jyi Let M be the flap load, M be the total flap bending moment, and L be the total flap bending moment. i denoted as , where is the distance from the flap pivot to the pressure center, and i represents the corresponding load state.

6. The method for compiling aircraft flap load spectra based on measured data as described in claim 1, characterized in that, When there are four moving cylinders, the total bending moment M 襟翼 The calculation formula is: M 襟翼 =M 襟翼1 +M 襟翼2 +M 襟翼3 +M 襟翼4 ; Among them, M 襟翼1 M 襟翼2 M 襟翼3 With M 襟翼4 These are the bending moments generated by the four actuators on the flaps.

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