A method for modeling and analyzing the ground resonance of a tiltrotor aircraft

Abstract

The application provides a swing soft tilting rotor ship surface resonance modeling and analysis method, comprising the following steps: solving a landing gear vertical load static balance equation according to a right half span dynamics model to obtain a wheel vertical load; interpolating a wheel and a bumper compression amount according to data in a first test curve and the wheel vertical load; interpolating a wheel and a bumper stiffness and damping coefficient according to the wheel and the bumper compression amount and data of a second test curve; establishing a full span dynamics model of the aircraft according to the right half span dynamics model and the wheel and the bumper stiffness and damping coefficient; performing trimming analysis on rotor control to obtain a linearized mass, stiffness and damping matrix of the full span dynamics model; and performing eigenvalue analysis on the linearized mass, stiffness and damping matrix to obtain a stability analysis result of the full span dynamics model.

Description

Technical Field

[0001] This application belongs to the field of dynamic analysis technology, and in particular relates to a method for modeling and analyzing the resonance of the deck of a wobbling flexible tiltrotor aircraft. Background Technology

[0002] Tiltrotor aircraft are a new type of aircraft that combines the advantages of helicopters' vertical takeoff and landing (VTOL) with the high-speed cruise and long range of fixed-wing propeller aircraft. The rotor of this type of aircraft is connected to a tilting nacelle on the wing. The nacelle contains a tilting mechanism that allows the rotor and nacelle to synchronously switch from a horizontal to a vertical position. When the nacelle is tilted in the horizontal position, the rotor is equivalent to a traditional fixed-wing propeller, enabling the aircraft to fly at high speeds. When the nacelle is in the vertical position, the aircraft can mimic the vertical takeoff and landing and hovering capabilities of a tandem rotor helicopter.

[0003] Compared to traditional single-rotor helicopters with tail rotors, tiltrotor aircraft have many advantages such as long range and fast cruise, but their special wing / rotor coupling and tilt nacelle characteristics cause more complex aeroelastic stability problems. Summary of the Invention

[0004] Purpose of the invention: This invention proposes a dynamic modeling and analysis method for deck resonance in tiltrotor aircraft with oscillation, in order to avoid and eliminate deck resonance in tiltrotor aircraft.

[0005] This application provides a method for modeling and analyzing deck resonance in a wobbling flexible tiltrotor aircraft. The method includes:

[0006] Step 1: Establish the dynamic model of the right half of the aircraft;

[0007] Step 2: Based on the right half-spread dynamic model, solve the static balance equation of the landing gear vertical load to obtain the wheel vertical load;

[0008] Step 3: Based on the data in the first test curve and the vertical load on the wheel, interpolate to obtain the compression of the wheel and the buffer;

[0009] Step 4: Based on the compression of the wheel and the buffer and the data from the second test curve, interpolate to obtain the stiffness and damping coefficient of the wheel and the buffer;

[0010] Step 5: Based on the right half-span dynamic model and the stiffness and damping coefficients of the wheels and buffers, establish the full-span dynamic model of the aircraft;

[0011] Step 6: Perform a trim analysis on the rotor control to obtain the linearized mass, stiffness, and damping matrix of the full-spread dynamic model;

[0012] Step 7: Perform eigenvalue analysis on the linearized mass, stiffness, and damping matrices to obtain the stability analysis results of the full-extension dynamic model.

[0013] Preferably, step 1 specifically includes:

[0014] Based on the right-hand rule, considering the structural characteristics of the right-hand wing / rotor of the tiltrotor aircraft, a series of coordinate systems are established to describe the spatial positions of the fuselage center of mass, the center of mass of the wing root section, the center of mass of the wing tip section, the center of mass of the tilt nacelle, the center of mass of the rotor hub, the center of mass of the gimbal hinge, and the center of mass of any section of the rotor.

[0015] Based on the aforementioned coordinate system and Hamilton's principle, a dynamic model of the right half of the span is established.

[0016] Preferably, step 2 specifically includes:

[0017] Based on the position coordinates of the engine wheel and the motion equations of the ship's roll, pitch, and heave motions in the right half-extension dynamic model, the static balance equations for the vertical loads of the landing gear are established.

[0018] Solve the static balance equation for the vertical load on the landing gear to obtain the vertical load on the wheels.

[0019] Preferably, the horizontal axis of the first test curve represents the vertical load on the wheel, and the vertical axis represents the compression of the wheel and the buffer.

[0020] Preferably, the horizontal axis of the second test curve represents the compression of the wheel and the buffer, and the vertical axis represents the stiffness and damping coefficient of the wheel and the buffer.

[0021] Preferably, step 5 specifically includes:

[0022] Based on the right half-span dynamic model and the stiffness and damping coefficients of the wheels and buffers, a symmetrical transformation is used to establish the full-span dynamic model of the aircraft.

[0023] Preferably, step 6 specifically includes:

[0024] Under given conditions, aerodynamic load balancing calculations are performed on the rotor to ensure that the rotor thrust coefficient reaches a given value and the roll moment and pitch moment coefficients are both zero, thereby determining the rotor's collective input pitch and cyclic pitch.

[0025] The input collective pitch and periodic pitch are substituted into the full-range dynamic model, and the full-range dynamic model is linearized to obtain the linearized mass, stiffness, and damping matrices of the full-range dynamic model.

[0026] Preferably, the stability analysis results include:

[0027] When the real part of the eigenvalue is positive, the full-scale dynamic model is unstable;

[0028] The full-scale dynamic model is stable when the real part of the eigenvalue is negative.

[0029] The beneficial technical effects of this application are as follows:

[0030] The method for modeling and analyzing deck resonance in a shimmy flexible tiltrotor aircraft provided in this application fully considers the influence of ship motion on the asymmetric loads and deformation of the landing gear, the influence of special tiltrotor mechanisms such as the tilt mechanism and gimbal hinges on the fuselage dynamics model, and the influence of different operating states on rotor control trim. By utilizing the coupling relationships of each degree of freedom within the aeroelastic analysis model of the tiltrotor aircraft under different sea conditions and lift unloading, aeroelastic stability analysis of the shimmy flexible tiltrotor aircraft can be performed under different trim states. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the coordinate system of a full-span tiltrotor aircraft;

[0032] Figure 2 Schematic diagram of vertical forces acting on the landing gear;

[0033] Figure 3 Flowchart of manipulating balancing calculations;

[0034] Figure 4 Flowchart for stability analysis of deck resonance in tiltrotor aircraft. Detailed Implementation

[0035] Complex sea conditions impose stringent requirements on pilot maneuvering and the design of helicopter deck resonance stability. Therefore, it is necessary to fully consider the effects of fuselage rigid body displacement, wing / rotor elastic deformation, and ship motion on the elastic deformation of wheels and buffers, establish a full-spreading dynamic model, conduct in-depth research on deck resonance stability analysis methods for tiltrotor aircraft, and develop a complete set of deck resonance stability analysis techniques to provide design means to avoid and eliminate deck resonance in tiltrotor aircraft.

[0036] This invention provides a dynamic modeling and analysis method for deck resonance of a wobbling flexible tiltrotor aircraft. The tiltrotor aircraft structure consists of a rotor, a tilting nacelle, a wing, and a fuselage-landing gear system.

[0037] Specifically, the steps include the following:

[0038] Step 1: Establish the dynamic model of the right half of the aircraft;

[0039] Step 2: Based on the right half-spread dynamic model, solve the static balance equation of the landing gear vertical load to obtain the wheel vertical load;

[0040] Step 3: Based on the data in the first test curve and the vertical load on the wheel, interpolate to obtain the compression of the wheel and the buffer;

[0041] Step 4: Based on the compression of the wheel and the buffer and the data from the second test curve, interpolate to obtain the stiffness and damping coefficient of the wheel and the buffer;

[0042] Step 5: Based on the right half-span dynamic model and the stiffness and damping coefficients of the wheels and buffers, establish the full-span dynamic model of the aircraft;

[0043] Step 6: Perform a trim analysis on the rotor control to obtain the linearized mass, stiffness, and damping matrix of the full-spread dynamic model;

[0044] Step 7: Perform eigenvalue analysis on the linearized mass, stiffness, and damping matrices to obtain the stability analysis results of the full-extension dynamic model.

[0045] It should be noted that the full-extension dynamics model fully considers the influence of ship motion on the asymmetric load of the landing gear, as well as the left-right symmetrical structural characteristics of the tiltrotor fuselage.

[0046] When a tiltrotor aircraft takes off and lands on a ship's deck, the ship is affected by the sea conditions, resulting in up-and-down motion, rolling motion, and pitching motion. At this time, the ship will exert a vertical force on the landing gear, with the point of application being the landing gear wheels' landing point on the ship's deck.

[0047] Assuming that the inertial load acting on the landing point due to the ship's rolling motion is constant over a short period of time, and that the angle between the ship's deck plane and the sea level remains constant, a static equilibrium equation for the landing gear's vertical load is established based on these assumptions. Solving this equation yields the vertical load on the landing gear wheels. Subsequently, based on the first experimental data, the compression of the landing gear wheels and buffers is interpolated; based on the second experimental data and the compression of the landing gear wheels and buffers, the stiffness and damping coefficients of the landing gear wheels and buffers are interpolated.

[0048] In the modeling of tiltrotor aircraft deck resonance, a right-side half-span dynamic model of the aircraft is first established based on a right-handed coordinate system. Then, considering the influence of the symmetrical distribution of the fuselage, a left-handed coordinate system is used to convert the right-side half-span dynamic model into a left-side half-span dynamic model. Finally, the two half-span dynamic models are merged into a full-span dynamic model of the aircraft. This modeling process effectively improves the efficiency of tiltrotor aircraft deck resonance modeling.

[0049] Please see Figures 1-4 In other embodiments of this application, the specific implementation steps of the present invention are as follows:

[0050] Step 1: Considering the structural characteristics of the right-side wing / rotor of the tiltrotor aircraft, based on the right-hand rule, establish a series of coordinate systems to describe the spatial positions of the fuselage center of mass, the center of mass of the wing root section, the center of mass of the wing tip section, the center of mass of the tilt nacelle, the rotor hub center, the center of mass of the gimbal hinge, and the center of mass of any section of the rotor. A schematic diagram of the coordinate systems can be found in [link to diagram]. Figure 1 .

[0051] Step 2: On the coordinate system, establish the kinetic and potential energy equations of the right wing / rotor of the tiltrotor, the potential energy equation of the tilt nacelle, and the potential energy equation of the fuselage-landing gear of the tiltrotor. Then, based on Hamilton's principle and the kinetic and potential energy equations, establish the right half-span dynamic model.

[0052] Step 3: Treat the boat's motion as simple harmonic motion, the boat's pitching b jx Horizontal rocking b jy and heave motion b jz The equations of motion.

[0053] b jx =b jxmax cos(ω1t)

[0054] b jy =b jymax cos(ω2t+Δ1)

[0055] b jz =b jzmax cos(ω3t+Δ2)

[0056] Among them, b jx,max b jy,max and b jz,max ω1, ω2, and ω3 are the maximum roll, pitch, and heave displacements, respectively; ω1, ω2, and ω3 are the angular frequencies of roll, pitch, and heave, respectively; Δ1 and Δ2 are the phase differences between roll and pitch and between roll and heave motions, respectively.

[0057] Step 3: Perform a force analysis on the vertical load of the landing gear. The vertical force situation of the landing gear is as follows: Figure 2 As shown in the figure, the landing gear is subjected to a force P from the ship's surface. N , a x a y and a z Let ε be the linear acceleration of the ship's motion. x and ε y Let G be the angular acceleration of the ship, G be the weight of the aircraft, and T be the lift of the aircraft. Based on the position coordinates of the landing gear wheels and the equations of motion for the ship's roll, pitch, and heave in the right-side semi-extension dynamic model, the static balance equation for the vertical load of the landing gear is established.

[0058]

[0059] P ML +P MR =Gcos(b jx cos(b) jy )-T+Ma z -P N

[0060]

[0061] Among them, (X) N ,0,Z N ), (X m ,-Y m Z m ) and (X m ,Y m Z m The coordinates are those of the front starter wheel, the left starter wheel, and the right starter wheel, respectively.

[0062] Step 4: Solve the static balance equation for the vertical load of the landing gear to obtain the vertical load of the wheels.

[0063] Step 5: Based on the first test data and the polynomial interpolation method, perform interpolation calculation with the vertical load of the wheel as the abscissa, and obtain the compression amount of the wheel and the buffer as the ordinate of the interpolation.

[0064] Step 6: Based on the second test data and the polynomial interpolation method, interpolation calculation is performed with the compression of the wheel and the buffer as the abscissa, and the interpolation yields the stiffness and damping coefficient of the wheel and the buffer as the ordinate.

[0065] Step 7: Substitute the stiffness and damping coefficient of the wheel and the buffer into the right half-extension dynamic model to obtain the updated right half-extension dynamic model.

[0066] Step 8: Perform a symmetric transformation on the updated right half-extension dynamic model using a left-handed coordinate system to obtain the left half-extension dynamic model.

[0067] Step 9: Merge the updated right half-span dynamic model and the left half-span dynamic model to obtain the full-span dynamic model of the aircraft. The degrees of freedom of the full-span dynamic model are as follows.

[0068]

[0069] Among them, X f Y f and Z f θ represents the three translational degrees of freedom of the body. fx θ fy and θ fz For the three rotational degrees of freedom of the machine, v R wR and θ R These represent the linear displacement and axial torsion of the wing in the updated right half-span dynamic model, respectively. and It is the flapping angle of the gimbal hinge in the updated right half-extension dynamics model. and Represent the linear displacement and axial torsion of blade i in the three directions, respectively, in the updated right half-span dynamic model. L w L and θ L These represent the linear displacement and axial torsion of the wing in the left half-span dynamic model, respectively. and It is the flapping angle of the gimbal hinge in the left half of the dynamic model. and These represent the linear displacement and axial torsion of blade i in the three directions of the left half-spread dynamic model, respectively.

[0070] Step 10: Under the given conditions, perform control and trim calculations on the rotor to ensure that the rotor thrust T reaches the given value and the roll torque M reaches the given value. x And pitching moment M y All values ​​are zero, thus determining the rotor's collective input pitch θ. 75 and periodic pitch θ 1c and θ 1s The flowchart for manipulating the balancing calculation is shown below. Figure 3 In the figure, Δθ represents the difference between the total input distance and the difference between the periodic variable distances calculated in the two iteration steps.

[0071] Step 11: Substitute the input collective pitch and periodic pitch into the full-range dynamic model, and linearize the full-range dynamic model to obtain the linearized mass, stiffness, and damping matrices of the full-range dynamic model (too many expressions to list separately).

[0072] Step 12: Perform eigenvalue analysis on the linearized mass, stiffness, and damping matrices to obtain the stability analysis results of the full-extension dynamic model.

[0073] When the real part of the eigenvalue is positive, the full-scale dynamic model is unstable;

[0074] The full-scale dynamic model is stable when the real part of the eigenvalue is negative.

[0075] The calculation and analysis process is as follows: Figure 4 As shown.

[0076] This application provides a method for modeling and analyzing deck resonance in a shimmy flexible tiltrotor aircraft. The aircraft model comprises four parts: fuselage-landing gear system, wing, rotor, and tilting nacelle. Considering the rigid body displacement of the fuselage, the elastic deformation of the wing / rotor, and the influence of ship motion on the elastic deformation of the landing gear, a full-span dynamic model of the aircraft is established. Aeroelastic stability analysis of the shimmy flexible tiltrotor aircraft can be performed under different trim conditions, sea states, and lift unloading.

Claims

1. A method for modeling and analyzing deck resonance in a wobbling flexible tiltrotor aircraft, characterized in that, The method includes: Step 1: Establish the dynamic model of the right half of the aircraft; Step 2: Based on the right half-spread dynamic model, solve the static balance equation of the landing gear vertical load to obtain the wheel vertical load; Step 3: Based on the data in the first test curve and the vertical load on the wheel, interpolate to obtain the compression of the wheel and the buffer; Step 4: Based on the compression of the wheel and the buffer and the data from the second test curve, interpolate to obtain the stiffness and damping coefficient of the wheel and the buffer; Step 5: Based on the right half-span dynamic model and the stiffness and damping coefficients of the wheels and buffers, establish the full-span dynamic model of the aircraft; Step 6: Perform a trim analysis on the rotor control to obtain the linearized mass, stiffness, and damping matrix of the full-spread dynamic model; Step 7: Perform eigenvalue analysis on the linearized mass, stiffness, and damping matrices to obtain the stability analysis results of the full-extension dynamic model; In the first test curve, the horizontal axis represents the vertical load on the wheel, and the vertical axis represents the compression of the wheel and the buffer; in the second test curve, the horizontal axis represents the compression of the wheel and the buffer, and the vertical axis represents the stiffness and damping coefficient of the wheel and the buffer.

2. The method according to claim 1, characterized in that, Step 1 specifically includes: Based on the right-hand rule, considering the structural characteristics of the right-hand wing / rotor of the tiltrotor aircraft, a series of coordinate systems are established to describe the spatial positions of the fuselage center of mass, the center of mass of the wing root section, the center of mass of the wing tip section, the center of mass of the tilt nacelle, the center of mass of the rotor hub, the center of mass of the gimbal hinge, and the center of mass of any section of the rotor. Based on the aforementioned coordinate system and Hamilton's principle, a dynamic model of the right half of the span is established.

3. The method according to claim 2, characterized in that, Step 2 specifically includes: Based on the position coordinates of the engine wheel and the motion equations of the ship's roll, pitch, and heave motions in the right half-extension dynamic model, the static balance equations for the vertical loads of the landing gear are established. Solve the static balance equation for the vertical load on the landing gear to obtain the vertical load on the wheels.

4. The method according to claim 3, characterized in that, Step 5 specifically includes: Based on the right half-span dynamic model and the stiffness and damping coefficients of the wheels and buffers, a symmetrical transformation is used to establish the full-span dynamic model of the aircraft.

5. The method according to claim 4, characterized in that, Step 6 specifically includes: Under given conditions, aerodynamic load balancing calculations are performed on the rotor to ensure that the rotor thrust coefficient reaches a given value and the roll moment and pitch moment coefficients are both zero, thereby determining the rotor's collective input pitch and cyclic pitch. The input collective pitch and periodic pitch are substituted into the full-range dynamic model, and the full-range dynamic model is linearized to obtain the linearized mass, stiffness, and damping matrices of the full-range dynamic model.

6. The method according to claim 5, characterized in that, The stability analysis results include: When the real part of the eigenvalue is positive, the full-scale dynamic model is unstable; The full-scale dynamic model is stable when the real part of the eigenvalue is negative.

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