Arresting hook bending fatigue spectrum calculation method and system

Abstract

The present application belongs to the technical field of fatigue design of carrier-based aircraft landing gear, and particularly relates to a method and system for calculating the bending fatigue spectrum of an arresting hook. First, a spring unit is combined with the arresting hook to establish a dynamic model of the arresting hook assembly. Then, dynamic models of the front landing gear and main landing gear and a rigid body model of the arresting hook are established, and the whole aircraft dynamic model is assembled. An arresting force curve is applied to the hook head of the arresting hook and solved. Finally, the arresting hook bending spectrum is formed through the time domain curve of the arresting hook damper. On the basis of the provisions of GJB 67.6A-2008, the arresting hook bending spectrum of the present application is added to the arresting hook fatigue design spectrum, which can truly reflect the stress state of the arresting hook. Combining the arresting hook bending spectrum with the spectrum specified in GJB 67.6A-2008 to design the arresting hook structure or perform fatigue verification can more reasonably determine the life of the arresting hook and ensure aircraft safety.

Description

Technical Field

[0001] The present application belongs to the technical field of fatigue design of carrier-based aircraft landing gear, and in particular relates to a method and system for calculating the bending fatigue spectrum of an arresting hook. Background Art

[0002] During a carrier landing, the arresting hook engages the carrier's arresting cable, absorbing and dissipating the aircraft's directional kinetic energy, forcing the aircraft to a short stop. The resulting arresting load is then transferred through the hook to the rear fuselage reinforcement frame. A buffer dampens the hook's rebound upon contact, allowing it to quickly return to contact with the ship's surface.

[0003] Arresting hook load spectrum calculations are generally performed in accordance with GJB67.6A-2008. The arresting hook load spectrum in GJB67.6A-2008 stipulates that for 90% of arrested landings, the horizontal component of the arresting hook's arresting resistance should be equal to the limit load. For the remaining 10% of arrested landings, the force corresponding to the 90% percentile of the statistical distribution of the arresting gear's arresting resistance at a 90% confidence level, as specified in the relevant standards, should be used. For 90% of arrested landings, the lateral force should be 0.6 times the design weight of the landing ship. For the remaining 10% of arrested landings, the lateral force should be 1.0 times the design weight of the landing ship. The resultant force P on the arresting hook should be applied at a point half the radius of the cable slot from the centerline of the hook handle. The resultant force P should be applied in the following order: 0 → P → 0.5P → P → 0.5P → P → 0.

[0004] The arresting hook typically strikes the deck first and then slides onto the hook cable. After striking the deck or the hook cable, the hook swings upward rapidly, causing the damper load to reach its maximum value. This puts the hook in a state of maximum bending stress.

[0005] GJB67.6A-2008 stipulates the horizontal load of the arresting force after the arresting hook is hooked on the arresting cable, but does not stipulate the bending stress state of the arresting hook.

[0006] Therefore, how to design an arresting hook load spectrum that is more in line with the actual loading scenario of the arresting hook is a problem that needs to be solved. Summary of the Invention

[0007] The purpose of this application is to provide a method and system for calculating the bending fatigue spectrum of an arresting hook, so as to solve the problem that the existing arresting hook load spectrum fails to truly reflect the stress state of the arresting hook.

[0008] The technical solution of this application is: a method for calculating the bending fatigue spectrum of an arresting hook, comprising:

[0009] The initial inflation pressure, compression area, initial inflation volume, piston rod compression stroke, and oil damping coefficient of the spring damper are obtained to establish a spring damper unit. The spring damper unit is then combined with the corresponding spring structural parameters to form a spring unit. The spring unit is then combined with the arresting hook to establish the arresting hook assembly dynamic model.

[0010] The spring damping unit is used to simulate the oil-gas performance of the oil-gas buffer, and the spring unit is used to simulate the tire characteristics, and the dynamic models of the front landing gear and main landing gear are established respectively;

[0011] Define the center of gravity position, the connection position between the landing gear and the fuselage, and the connection position between the arresting hook and the fuselage, and establish a rigid body model of the arresting hook;

[0012] The arresting hook assembly dynamics model, nose and main landing gear dynamics model, and rigid body model are assembled into a full aircraft dynamics model using the actual load-transfer relationship.

[0013] Assume the arresting hook is in the fully extended and lowered state, apply the neutral weight parameter at the center of gravity of the full aircraft dynamics model, apply the initial conditions at the center of gravity, apply the arresting resistance curve at the hook head, and solve to obtain the time domain curve of the arresting hook damper;

[0014] Extract the maximum axial force F of the arresting hook damper through the time domain curve max The angle α' and the arresting force L' at the same moment form the arresting hook bending spectrum.

[0015] Preferably, in the spring damping unit, the spring force F1 = f(p0, A, V0, s), the damping force

[0016]

[0017] Where: p0 is the initial inflation pressure, A is the compression area, V0 is the initial inflation volume, s is the compression stroke of the piston rod, is the derivative of the compression stroke, and κ is the oil damping coefficient.

[0018] Preferably, the spring force in the tire characteristic is: T1=f(δ); where: δ is the compression amount of the tire.

[0019] Preferably, the time domain curve includes the axial force F, the angle α between the damper and the horizontal plane of the aircraft structure, and the arresting force L.

[0020] Preferably, the weight parameters include weight and inertia; the initial conditions include the shipboard combined speed V E , sinking speed V V 、Aircraft pitch angle θ P .

[0021] Preferably, the arresting resistance L in the arresting resistance curve is f(x), where x is the distance the aircraft glides forward.

[0022] The arresting hook bending fatigue spectrum calculation method and system described in this application supplements the arresting hook fatigue design spectrum specified in GJB 67.6A-2008 with the proposed arresting hook bending spectrum, effectively reflecting the arresting hook's stress state. Combining the arresting hook bending spectrum with the spectrum specified in GJB 67.6A-2008 for arresting hook structural component design or fatigue verification can more accurately determine the arresting hook's lifespan and ensure aircraft safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions provided by this application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of this application.

[0024] Figure 1 Schematic diagram of the dynamic model of the arresting hook assembly in the background technology;

[0025] Figure 2 This is a schematic diagram of the overall process of this application;

[0026] Figure 3 This is a schematic diagram of the dynamic model of the arresting hook assembly in this application;

[0027] Figure 4 This is a schematic diagram of the arresting resistance curve for this application;

[0028] Figure 5 This is a schematic diagram of the arresting hook loading for this application. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] A method for calculating the bending fatigue spectrum of an arresting hook, such as Figure 2 As shown, the following steps are included:

[0031] Step S100: The initial inflation pressure, compressed area, initial inflation volume, piston rod compression stroke, and oil damping coefficient of the spring damper are obtained to establish a spring damper unit. This unit is then combined with the corresponding spring structural parameters to form a spring unit. The spring unit is then combined with the arresting hook to establish the arresting hook assembly dynamic model. The spring structural parameters include tire compression, etc.

[0032] The dynamic model of the arresting hook assembly is as follows Figure 3 As shown, the damper is simulated by a spring damper unit, and the spring damper unit is specifically represented by spring force and resistance force.

[0033] Among them, spring force F1=f(p0,A,V0,s), damping force

[0034] Where: p0 is the initial inflation pressure, A is the compression area, V0 is the initial inflation volume, s is the compression stroke of the piston rod, is the derivative of the compression stroke, and κ is the oil damping coefficient.

[0035] Step S200 , similar to the dynamic models of the nose landing gear and the main landing gear, the oil-gas performance of the oil-gas buffer is simulated by the spring damping unit, and the tire characteristics are simulated by the spring unit, so as to establish the dynamic models of the nose landing gear and the main landing gear respectively.

[0036] Among them, the spring force F2 of the oil-gas buffer is f(p0,A,V0,s), the damping force

[0037] Where: p0 is the initial inflation pressure, A is the compression area, V0 is the initial inflation volume, s is the compression stroke of the piston rod, is the derivative of the compression stroke, and κ is the oil damping coefficient.

[0038] The spring force in the tire characteristics is: T1 = f(δ); where: δ is the amount of tire compression.

[0039] Step S300 , defining the center of gravity position, the connection position between the landing gear and the aircraft body, and the connection position between the arresting hook and the aircraft body, and establishing a rigid aircraft model of the arresting hook.

[0040] The rigid body model can reflect the state in which the arresting hook does not change in shape and size when subjected to external forces. Combined with the dynamic models of the nose landing gear and main landing gear, it can fully reflect the overall state of the arresting hook.

[0041] In step S400, the arresting hook assembly dynamics model, the nose and main landing gear dynamics models, and the rigid body model are assembled into a full aircraft dynamics model using a relationship that can reflect the actual load transfer.

[0042] The actual transmission relationship of energy response is to establish the energy transfer equations between each other, so as to establish the node correspondence of each model, wherein the input and output relationship of the energy of each model can be obtained by collecting existing data.

[0043] Step S500: Assume the arresting hook is in a fully extended and lowered state, apply a neutral weight parameter at the center of gravity of the full aircraft dynamics model, apply initial conditions at the center of gravity, apply an arresting drag curve at the hook head, and solve to obtain time-domain curves of the arresting hook damper axial force F, the angle α between the damper and the horizontal plane of the aircraft structure, and the arresting drag L.

[0044] The arresting hook is in the fully extended and lowered state. The weight parameter (excluding the weight parameters of the landing gear and arresting hook) is applied to the center of gravity of the entire aircraft dynamic model. The weight parameter includes weight and inertia.

[0045] Apply initial conditions at the center of gravity, including the combined speed V on the ship E , sinking speed V V 、Aircraft pitch angle θ P .

[0046] The arresting force curve is applied to the hook head of the arresting hook, and the arresting force L = f(x), where x is the distance the aircraft glides forward.

[0047] Step S600: extract the maximum value of the axial force F of the arresting hook damper max The angle α' and the arresting force L' at the same moment form the arresting hook bending spectrum and the real stress state of the arresting hook.

[0048] Through the above design, the arresting hook bending spectrum described in this application is added to the arresting hook fatigue design spectrum specified in GJB 67.6A-2008, effectively reflecting the arresting hook's stress state. Combining the arresting hook bending spectrum with the spectrum specified in GJB 67.6A-2008 for arresting hook structural component design or fatigue verification can more reasonably determine the arresting hook's lifespan and ensure aircraft safety.

[0049] As a specific embodiment, a system for calculating the bending fatigue spectrum of an arresting hook is also included, including:

[0050] The arresting hook model building module obtains the initial inflation pressure, compressed area, initial inflation volume, piston rod compression stroke, and oil damping coefficient of the spring damper to establish a spring damper unit. This unit is then combined with the corresponding spring structural parameters to form a spring unit. The spring unit is then combined with the arresting hook to establish the arresting hook assembly dynamic model.

[0051] The landing gear model building module uses spring-damper units to simulate the oil-gas performance of the oil-gas buffer and spring units to simulate tire characteristics, respectively establishing the dynamic models of the front landing gear and main landing gear;

[0052] The rigid body model building module defines the center of gravity position, the connection position between the landing gear and the body, and the connection position between the arresting hook and the body, and builds the rigid body model of the arresting hook;

[0053] The full aircraft dynamics model building module assembles the arresting hook assembly dynamics model, the nose and main landing gear dynamics models, and the rigid body model into a full aircraft dynamics model using the energy-reflecting actual load-transfer relationship;

[0054] The time domain curve establishment module sets the arresting hook in the fully extended and lowered state, applies the neutral weight parameter at the center of gravity of the full aircraft dynamics model, applies the initial conditions at the center of gravity, and applies the arresting resistance curve at the hook head. The solution is performed to obtain the time domain curve of the arresting hook damper.

[0055] Arresting hook bending spectrum establishment module, extracting the maximum value of the axial force F of the arresting hook damper through the time domain curve max The angle α' and the arresting force L' at the same moment form the arresting hook bending spectrum.

[0056] Preferably, in the spring damping unit, the spring force F1 = f(p0, A, V0, s), the damping force

[0057]

[0058] Where: p0 is the initial inflation pressure, A is the compression area, V0 is the initial inflation volume, s is the compression stroke of the piston rod, is the derivative of the compression stroke, and κ is the oil damping coefficient.

[0059] Preferably, the spring force in the tire characteristic is: T1=f(δ); where: δ is the compression amount of the tire.

[0060] Preferably, the time domain curve includes the axial force F, the angle α between the damper and the horizontal plane of the aircraft structure, and the arresting force L.

[0061] Preferably, the weight parameters include weight and inertia; the initial conditions include the shipboard combined speed V E , sinking speed V V 、Aircraft pitch angle θ P .

[0062] Preferably, the arresting resistance L in the arresting resistance curve is f(x), where x is the distance the aircraft glides forward.

[0063] As a specific implementation method, the following is described with a specific example:

[0064] According to the technical solution in step S500, the bending fatigue spectrum calculation of the arresting hook of a certain type of aircraft is carried out.

[0065] The weight is the maximum landing weight G ZLmax 、V E =190km / h, V V =3.6m / s,θP =3°, the arresting resistance curve is as follows Figure 4 shown.

[0066] By solving the full machine dynamics model, it is found that the damper axial force reaches the maximum value F max When α'=33°, the arresting force along the hook rod axis is L'=47kN. The loading diagram is as follows Figure 5 As shown, the moment around the connection point O between the arresting hook and the fuselage is balanced by the inertial force, which is the same as the actual state, and therefore can better reflect the real state of the arresting hook.

[0067] Finally, it should be noted that the drawings of the embodiments disclosed in the present invention only involve structures related to the embodiments disclosed in the present invention. Other structures can refer to common designs. In the absence of conflicts, the same embodiment and different embodiments of the present invention can be combined with each other.

[0068] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for calculating the bending fatigue spectrum of an arresting hook, characterized in that: include: The initial inflation pressure, compression area, initial inflation volume, piston rod compression stroke, and oil damping coefficient of the spring damper are obtained to establish a spring damper unit. The spring damper unit is then combined with the corresponding spring structural parameters to form a spring unit. The spring unit is then combined with the arresting hook to establish the arresting hook assembly dynamic model. The spring damping unit is used to simulate the oil-gas performance of the oil-gas buffer, and the spring unit is used to simulate the tire characteristics, and the dynamic models of the front landing gear and main landing gear are established respectively; Define the center of gravity position, the connection position between the landing gear and the fuselage, and the connection position between the arresting hook and the fuselage, and establish a rigid body model of the arresting hook; The arresting hook assembly dynamics model, nose and main landing gear dynamics model, and rigid body model are assembled into a full aircraft dynamics model using the actual load-transfer relationship. Assume the arresting hook is in the fully extended and lowered state, apply the neutral weight parameter at the center of gravity of the full aircraft dynamics model, apply the initial conditions at the center of gravity, apply the arresting resistance curve at the hook head, and solve to obtain the time domain curve of the arresting hook damper; Extract the maximum axial force F of the arresting hook damper through the time domain curve max The angle α' and the arresting force L' at the same moment form the arresting hook bending spectrum.

2. The method for calculating the bending fatigue spectrum of an arresting hook according to claim 1, wherein: In the spring damping unit, the spring force F1 = f(p0, A, V0, s), the damping force Where: p0 is the initial inflation pressure, A is the compression area, V0 is the initial inflation volume, s is the compression stroke of the piston rod, is the derivative of the compression stroke, and κ is the oil damping coefficient.

3. The method for calculating the bending fatigue spectrum of an arresting hook according to claim 1, wherein: The spring force in the tire characteristic is: T1 = f(δ); where: δ is the tire compression.

4. The method for calculating the bending fatigue spectrum of an arresting hook according to claim 1, wherein: The time domain curve includes the axial force F, the angle α between the damper and the horizontal plane of the aircraft structure, and the arresting resistance L.

5. The method for calculating the bending fatigue spectrum of an arresting hook according to claim 1, wherein: The weight parameters include weight and inertia; the initial conditions include the shipboard combined speed V E , sinking speed V V 、Aircraft pitch angle θ P .

6. The method for calculating the bending fatigue spectrum of an arresting hook according to claim 1, wherein: The arresting resistance L in the arresting resistance curve is f(x), where x is the distance the aircraft glides forward.

7. A system for calculating bending fatigue spectrum of an arresting hook, using the calculation method according to any one of claims 1 to 6, characterized in that: include: The arresting hook model building module obtains the initial inflation pressure, compressed area, initial inflation volume, piston rod compression stroke, and oil damping coefficient of the spring damper to establish a spring damper unit. This unit is then combined with the corresponding spring structural parameters to form a spring unit. The spring unit is then combined with the arresting hook to establish the arresting hook assembly dynamic model. The landing gear model building module uses spring-damper units to simulate the oil-gas performance of the oil-gas buffer and spring units to simulate tire characteristics, respectively establishing the dynamic models of the front landing gear and main landing gear; The rigid body model building module defines the center of gravity position, the connection position between the landing gear and the body, and the connection position between the arresting hook and the body, and builds the rigid body model of the arresting hook; The full aircraft dynamics model building module assembles the arresting hook assembly dynamics model, the nose and main landing gear dynamics models, and the rigid body model into a full aircraft dynamics model using the energy-reflecting actual load-transfer relationship; The time domain curve establishment module sets the arresting hook in the fully extended and lowered state, applies the neutral weight parameter at the center of gravity of the full aircraft dynamics model, applies the initial conditions at the center of gravity, and applies the arresting resistance curve at the hook head. The solution is performed to obtain the time domain curve of the arresting hook damper. Arresting hook bending spectrum establishment module, extracting the maximum value of the axial force F of the arresting hook damper through the time domain curve max The angle α' and the arresting force L' at the same moment form the arresting hook bending spectrum.

8. The arresting hook bending fatigue spectrum calculation system according to claim 7, characterized in that: In the spring damping unit, the spring force F1 = f(p0, A, V0, s), the damping force Where: p0 is the initial inflation pressure, A is the compression area, V0 is the initial inflation volume, s is the compression stroke of the piston rod, is the derivative of the compression stroke, and κ is the oil damping coefficient.

9. The arresting hook bending fatigue spectrum calculation system according to claim 7, characterized in that: The spring force in the tire characteristic is: T1 = f(δ); where: δ is the tire compression.

10. The arresting hook bending fatigue spectrum calculation system according to claim 7, characterized in that: The time domain curve includes the axial force F, the angle α between the damper and the horizontal plane of the aircraft structure, and the arresting resistance L.

11. The arresting hook bending fatigue spectrum calculation system according to claim 7, characterized in that: The weight parameters include weight and inertia; the initial conditions include the shipboard combined speed V E , sinking speed V V 、Aircraft pitch angle θ P .

12. The arresting hook bending fatigue spectrum calculation system according to claim 7, characterized in that: The arresting resistance L in the arresting resistance curve is f(x), where x is the distance the aircraft glides forward.

Images