Titanium matrix composite landing gear catapult simulation analysis method

Abstract

The application discloses a titanium matrix composite landing gear ejection simulation analysis method and belongs to the technical field of aviation. The method solves the problem that the titanium matrix composite landing gear is difficult to accurately characterize the mechanical behavior under the ejection working condition due to high actual test cost and limited conditions. The method establishes a landing gear buffer mechanical model and distinguishes the rigid part and the flexible part, constructs a rigid-flexible coupling virtual prototype model of the front landing gear, and performs ejection working condition dynamics simulation to simulate the dynamic response and stress characteristics in the protruding process. The application can accurately simulate the actual test working condition, avoid high cost and risk, and provide an important reference for landing gear structure optimization and performance improvement.

Description

Technical Field

[0001] This invention belongs to the field of aerospace technology, and in particular relates to a simulation analysis method for catapult launch of titanium-based composite landing gear. Background Technology

[0002] As a key structure connecting the aircraft to the ground, the nose landing gear is subjected to complex dynamic loads during catapult launch. These loads include the combined effects of strong impact forces from the catapult system, inertial forces from the structure's own weight, and aerodynamic forces. For landing gear made of titanium-based composite materials, accurately characterizing its mechanical behavior under catapult conditions and optimizing the landing gear structure have become key issues in current aerospace engineering research.

[0003] Currently, the most widely used analytical method in this field is the actual testing method. However, this method exhibits significant limitations in practical applications. First, the actual testing method is extremely expensive, requiring dedicated testing equipment, large testing grounds, and substantial human and material resources. Second, the testing process is severely limited by the capabilities of the testing equipment, site conditions, and safety factors, making it difficult to fully reproduce the complex conditions the landing gear encounters in actual service, especially extreme impact loads and multiphysics coupling environments. These limitations mean that the data obtained through testing may not comprehensively and accurately reflect the dynamic response and internal stress state of the landing gear during ejection extension.

[0004] Due to the limitations of the aforementioned experimental methods, engineering practice lacks an effective analytical tool capable of efficiently and accurately simulating the true mechanical behavior of titanium composite landing gear under catapult conditions. This directly leads to difficulties in fully assessing its cushioning performance, impact load transmission path, and structural reliability during the landing gear design phase, thus affecting the optimization design process and potentially introducing safety risks. In previous attempts to overcome these difficulties, engineers faced the main challenge of constructing a high-fidelity model that could reflect both the elastic deformation of the structure and simulate the dynamic interactions between components, while also incorporating complex factors such as the rigid damping characteristics of the tires and the nonlinear energy absorption characteristics of the buffers into a unified analytical framework. Therefore, there is an urgent need for a simulation analysis method that can overcome the shortcomings of existing experimental methods and accurately analyze the true mechanical behavior of titanium composite nose landing gear during catapult launch. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a simulation analysis method for catapult launch of titanium-based composite landing gear, which can accurately simulate actual test conditions, avoid high costs and risks, and provide an important reference for landing gear structure optimization and performance improvement.

[0006] To achieve the above objectives, this invention provides a simulation analysis method for catapult launch of titanium-based composite landing gear, comprising: Establish a mechanical model of the landing gear buffer, clarify the stress characteristics of the internal structure, and distinguish between the rigid and flexible parts; Based on the aforementioned mechanical model, a rigid-flexible coupling virtual prototype model of the nose landing gear is constructed. The rigid-flexible coupling virtual prototype model was used to perform catapult dynamics simulation to simulate the dynamic response and force characteristics of the nose landing gear during the extension process.

[0007] Optionally, the process of establishing a mechanical model of the landing gear buffer includes: Define the axial load of the buffer, which includes air spring force, hydraulic damping force and structural restraint force; The air spring force is based on the numerical relationship curve between the shock absorber's compression stroke and the force, and is implemented using a spline function. The oil damping force is determined based on the effective oil pressure area, oil hole area, oil density, and flow coefficient of the main oil chamber and the return oil chamber. The structural restraint force is determined based on the buffer's axial stiffness and stroke parameters.

[0008] Optionally, the process of constructing a rigid-flexible coupled virtual prototype model of the nose landing gear includes: Perform geometric modeling and establish geometric models of key components of the front landing gear at a 1:1 scale. The key components include struts, ejection rods, piston rods, rotating sleeves, tires, and upper and lower torque arms. Create a flexible body, use finite element software to model and perform modal analysis on the flexible body components, generate a modal neutral file, and import the modal neutral file into multibody dynamics software to assemble a rigid-flexible hybrid model; Parametric modeling was performed by setting coordinate systems, unit systems, and gravitational acceleration environmental parameters in multibody dynamics software, establishing a tire model, and merging the tire model with the landing gear geometric model into a single computational model.

[0009] Optionally, the process of creating a flexible body includes: Finite element software was used to perform mesh generation and modal analysis on the flexible body component, and modal neutral files were output. Import the modal neutral file into the multibody dynamics software and replace the corresponding rigid body component; Adjust the position and orientation of the flexible body, and redefine the kinematic pairs associated with the flexible body.

[0010] Optional, the parametric modeling process includes: Define a tire model in multibody dynamics software and set parameters such as tire mass, moment of inertia, outer radius, width, aspect ratio, vertical stiffness, and vertical damping coefficient. Merge the tire model with the landing gear geometry model and adjust the model to the appropriate position and attitude; Add kinematic pairs and forces to the model, and define the connection methods and relative motion between components.

[0011] Optionally, the process of performing catapult dynamics simulation using a rigid-flexible coupled virtual prototype model includes: Set the takeoff weight, takeoff speed, buffer filling parameters, and buffer strut compression stroke for the catapult launch condition; The fixing and release of the catapult rod to the ground are controlled by a simulation script. First, the catapult rod is fixed to simulate the initial state, and then the catapult rod is released by the failure of the fixed pair to simulate the sudden extension. Run the simulation and output the extension speed time history curve.

[0012] Optionally, controlling the fixing and release process of the launch rod relative to the ground via simulation scripts includes: At the start of the simulation, the launch rod is fixed to the ground for 1 second to simulate the initial stable state. The ejection lever is released by setting the fixed pair to fail, and the subsequent 0.15-second extension process is simulated. The simulation results are processed using the post-processing module to generate the extension velocity time history curve.

[0013] Optionally, the process of setting the takeoff weight, takeoff speed, buffer filling parameters, and buffer strut compression stroke for catapult operation includes: Adjust the equivalent mass parameters of the front landing gear extension according to different equivalent masses; Run multiple simulation cases and output the time history curves of the spur velocity under different equivalent masses; The landing gear structural response, impact load, and cushioning performance were evaluated based on simulation curves.

[0014] Technical advantages of this invention: This invention discloses a simulation analysis method for catapult launch of titanium-based composite landing gear. It can accurately simulate actual test conditions. Combining the working environment and stress characteristics of the nose landing gear, a multibody dynamics model of multiple flexible bodies is constructed using a rigid-flexible coupling modeling method. This model accurately simulates the dynamic response, mechanical behavior, and interactions between components of the nose landing gear during the extension process. It considers not only the elastic deformation of the landing gear structure but also simulates the dynamic characteristics of each component, including tire deformation, the working state of the shock absorbers, and the transmission path of impact loads. The simulation results provide important references for the structural optimization and performance improvement of the nose landing gear, avoiding the high costs and risks of actual catapult tests, and have significant engineering implications for aircraft nose landing gear design. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the structural flow of the landing gear mechanical model in a simulation analysis method for catapult launch of titanium-based composite landing gear according to an embodiment of the present invention; Figure 2 A flowchart for creating MNF in an embodiment of the present invention; Figure 3 This is a virtual prototype rigid body model of the nose landing gear extension in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the import of MNF files into Adams according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a rigid-flexible hybrid virtual prototype model according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the protrusion simulation in an embodiment of the present invention; Figure 7 This is a schematic diagram of the protrusion simulation script file in an embodiment of the present invention; Figure 8 This is a schematic diagram of the extension speed time history curve according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the time history curves of the sudden expansion speed of different equivalent masses in an embodiment of the present invention. Detailed Implementation

[0016] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0017] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0018] This embodiment provides a simulation analysis method for catapult launch of titanium-based composite landing gear, including: establishing a mechanical model of the landing gear buffer, clarifying the stress characteristics of the internal structure and distinguishing between rigid and flexible parts; Based on the aforementioned mechanical model, a rigid-flexible coupling virtual prototype model of the nose landing gear is constructed. The rigid-flexible coupling virtual prototype model was used to perform catapult dynamics simulation to simulate the dynamic response and force characteristics of the nose landing gear during the extension process.

[0019] Furthermore, the process of establishing a mechanical model of the landing gear buffer includes: Define the axial load of the buffer, which includes air spring force, hydraulic damping force and structural restraint force; The air spring force is based on the numerical relationship curve between the shock absorber's compression stroke and the force, and is implemented using a spline function. The oil damping force is determined based on the effective oil pressure area, oil hole area, oil density, and flow coefficient of the main oil chamber and the return oil chamber. The structural restraint force is determined based on the buffer's axial stiffness and stroke parameters.

[0020] Furthermore, the process of constructing a rigid-flexible coupled virtual prototype model of the nose landing gear includes: Perform geometric modeling and establish geometric models of key components of the front landing gear at a 1:1 scale. The key components include struts, ejection rods, piston rods, rotating sleeves, tires, and upper and lower torque arms. Create a flexible body, use finite element software to model and perform modal analysis on the flexible body components, generate a modal neutral file, and import the modal neutral file into multibody dynamics software to assemble a rigid-flexible hybrid model; Parametric modeling was performed by setting coordinate systems, unit systems, and gravitational acceleration environmental parameters in multibody dynamics software, establishing a tire model, and merging the tire model with the landing gear geometric model into a single computational model.

[0021] Furthermore, the process of creating a flexible body includes: Finite element software was used to perform mesh generation and modal analysis on the flexible body component, and modal neutral files were output. Import the modal neutral file into the multibody dynamics software and replace the corresponding rigid body component; Adjust the position and orientation of the flexible body, and redefine the kinematic pairs associated with the flexible body.

[0022] Furthermore, the parametric modeling process includes: Define a tire model in multibody dynamics software and set parameters such as tire mass, moment of inertia, outer radius, width, aspect ratio, vertical stiffness, and vertical damping coefficient. Merge the tire model with the landing gear geometry model and adjust the model to the appropriate position and attitude; Add kinematic pairs and forces to the model, and define the connection methods and relative motion between components.

[0023] Furthermore, the process of performing catapult dynamics simulation using a rigid-flexible coupled virtual prototype model includes: Set the takeoff weight, takeoff speed, buffer filling parameters, and buffer strut compression stroke for the catapult launch condition; The fixing and release of the catapult rod to the ground are controlled by a simulation script. First, the catapult rod is fixed to simulate the initial state, and then the catapult rod is released by the failure of the fixed pair to simulate the sudden extension. Run the simulation and output the extension speed time history curve.

[0024] Furthermore, the process of controlling the fixing and release of the launch rod relative to the ground through simulation scripts includes: At the start of the simulation, the launch rod is fixed to the ground for 1 second to simulate the initial stable state. The ejection lever is released by setting the fixed pair to fail, and the subsequent 0.15-second extension process is simulated. The simulation results are processed using the post-processing module to generate the extension velocity time history curve.

[0025] Furthermore, the process of setting the takeoff weight, takeoff speed, buffer filling parameters, and buffer strut compression stroke for catapult launch includes: Adjust the equivalent mass parameters of the front landing gear extension according to different equivalent masses; Run multiple simulation cases and output the time history curves of the spur velocity under different equivalent masses; The landing gear structural response, impact load, and cushioning performance were evaluated based on simulation curves.

[0026] Specifically, the implementation process of this embodiment includes: Step 1: Simplify the landing gear buffer model that needs to be simulated and analyzed, clarify the stress characteristics of the internal structure, and identify the rigid and flexible parts of the landing gear through the mechanical model; Step 2: Analyze the landing gear mechanical model in detail, focusing on the mechanical characteristics of the tires and the shock absorbers. By considering the rigidity and damping characteristics of the tires and the shock absorber's absorption characteristics of impact energy, establish a rigid-flexible coupling virtual prototype model of the landing gear. Step 3: Establish a simulation analysis model for the nose landing gear ejection to simulate the dynamic response and force characteristics of the nose landing gear during the extension process; Step 4: Use the established model to analyze the impact of different equivalent masses on the extension speed, and evaluate the landing gear structural response, impact load and cushioning performance.

[0027] Landing gear buffer mechanical model as follows Figure 1 As shown, in the landing gear buffer mechanical model, the axial load of the buffer can be decomposed and simplified into: air spring force, hydraulic damping force and friction force; while the tire load can be simplified into a combination of linear spring and linear damping.

[0028] Rigid-Flexible Hybrid Virtual Prototype Model Establishment: Model geometry information: The geometric model is established according to a 1:1 scale to create a landing gear model, including key components such as struts, ejection rods, piston rods, rotating sleeves, tires, and upper and lower torque arms.

[0029] Creating a flexible body: The flexible body component is modeled and modally analyzed using the finite element software Hypermesh; the created flexible body model is imported into ADAMS and assembled into a rigid-flexible hybrid model; the process of creating a modal neutral file using Hypermesh is as follows. Figure 2 As shown.

[0030] Establishment of rigid-flexible coupling model: To facilitate subsequent parameter modifications, this invention employs a parametric modeling method: In ADAMS / view, set a series of modeling environment parameters such as coordinate system, unit system, and gravitational acceleration; Creating a tire model: In Adams, a tire model is built by defining a tire property file and setting parameters including tire mass, moment of inertia, outer radius, width, aspect ratio, vertical stiffness, and vertical damping coefficient. The tire model and the landing gear assembly model built at a 1:1 scale are merged into a single computational model, and the model is adjusted to the appropriate position and attitude.

[0031] Add kinematic pairs and forces to the model to define the connection methods and relative motion between components. Based on the connection relationships between the landing gear components, add constraints to the geometric model.

[0032] Apply axial force to the buffer: Air spring force Oil damping force Friction of the piston rod and structural restraint forces This constitutes the axial load of the buffer, calculated as follows: ; Air spring force : Given the numerical relationship curve between the air spring force Fa and the compression stroke s of the shock absorber, the air spring force can be realized using the spline function AKISPL.

[0033] The oil damping force is : ; in, , These are the effective oil pressure areas of the main and return oil chambers, respectively. The density of the oil; The area of ​​the main oil cavity oil hole; The flow area of ​​the return oil hole; , These are the flow coefficients of the main and return oil holes, respectively.

[0034] friction Friction accounts for a very small proportion of the axial force of the buffer and is not considered in the process of establishing the mechanical model of the buffer.

[0035] Structural restraint force Structural restraint force This reflects the limiting force experienced by the buffer under maximum elongation and compression conditions: ; Where K is the axial stiffness of the buffer; This is the initial stroke of the buffer; This represents the maximum travel of the buffer.

[0036] Titanium-based composite front landing gear catapult launch simulation: Catapult dynamics simulation: Set the takeoff weight and takeoff speed for catapult launch conditions; Set the filling parameters of the buffer strut under catapult conditions; Set the compression stroke of the buffer strut during ejection; After preparations for the extension test were completed, simulation calculations began. First, the launch rod was simulated to be fixed to the ground for 1 second. Then, the launch rod was released by setting a failure of the fixed pair, completing the subsequent 0.15-second extension simulation. The entire process was implemented using a simulation script.

[0037] The simulation results (extendal velocity time history curve) are generated using the PostProcesser module of ADAMS.

[0038] Example of catapult simulation method: A dual-chamber oil-gas buffer was selected, and a virtual prototype rigid body model of the nose landing gear under catapult conditions was established, as follows: Figure 3 As shown; Rigid-Flexible Hybrid Virtual Prototype Model Establishment: In Adams, click "Flexible" on the corresponding rigid body component, and import the MNF file exported from Hypermesh, as shown below. Figure 4 As shown, by adjusting the flexible body and its position and attitude, redefining the relevant kinematic pairs, a rigid-flexible coupling model of the nose landing gear extension virtual prototype is completed. Figure 5 As shown.

[0039] Titanium-based composite front landing gear catapult launch simulation: Catapult dynamics simulation: like Figure 6 After completing the preparations for the extension test, the simulation calculation begins. First, the ejection rod is simulated to be fixed to the ground for 1 second. Then, the ejection rod is released by setting a failure of the fixed joint, completing the subsequent 0.15-second extension simulation. The entire process is implemented using a simulation script, as shown in the simulation script below. Figure 7 As shown.

[0040] The landing gear compression stroke is 530 mm, and the equivalent mass is 6000 kg. The simulation results were obtained using the PostProcessor module of ADAMS. The simulation results are shown in the extension speed-time history curve as follows: Figure 8 As shown.

[0041] Dynamic simulation of stretching tests with different equivalent masses: By varying the equivalent mass of the nose landing gear during extension, a simulation of the nose landing gear model is performed, and the extension curve is output as follows: Figure 9 As shown.

[0042] To accurately simulate actual test conditions, this invention combines the working environment and stress characteristics of the nose landing gear, employing a rigid-flexible coupling modeling method to construct a multibody dynamics model of multiple flexible bodies. This model can accurately simulate the dynamic response, mechanical behavior, and interactions between components of the nose landing gear during the extension process. The flexible body model not only considers the elastic deformation of the landing gear structure but also simulates the dynamic characteristics of each component, including tire deformation, the working state of the shock absorbers, and the transmission path of impact loads. The simulation results provide important references for the structural optimization and performance improvement of the nose landing gear, avoiding the high costs and risks of actual catapult tests, and have significant engineering implications for aircraft nose landing gear design.

[0043] The above are merely preferred embodiments 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 scope of the technology 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 simulation analysis method for catapult launch of titanium-based composite landing gear, characterized in that, include: Establish a mechanical model of the landing gear buffer, clarify the stress characteristics of the internal structure, and distinguish between the rigid and flexible parts; Based on the aforementioned mechanical model, a rigid-flexible coupling virtual prototype model of the nose landing gear is constructed. The rigid-flexible coupling virtual prototype model was used to perform catapult dynamics simulation to simulate the dynamic response and force characteristics of the nose landing gear during the extension process.

2. The titanium-based composite landing gear catapult simulation analysis method as described in claim 1, characterized in that, The process of establishing a mechanical model of the landing gear buffer includes: Define the axial load of the buffer, which includes air spring force, hydraulic damping force and structural restraint force; The air spring force is based on the numerical relationship curve between the shock absorber's compression stroke and the force, and is implemented using a spline function. The oil damping force is determined based on the effective oil pressure area, oil hole area, oil density, and flow coefficient of the main oil chamber and the return oil chamber. The structural restraint force is determined based on the buffer's axial stiffness and stroke parameters.

3. The titanium-based composite landing gear catapult simulation analysis method as described in claim 1, characterized in that, The process of constructing a rigid-flexible coupled virtual prototype model of the nose landing gear includes: Perform geometric modeling and establish geometric models of key components of the front landing gear at a 1:1 scale. The key components include struts, ejection rods, piston rods, rotating sleeves, tires, and upper and lower torque arms. Create a flexible body, use finite element software to model and perform modal analysis on the flexible body components, generate a modal neutral file, and import the modal neutral file into multibody dynamics software to assemble a rigid-flexible hybrid model; Parametric modeling was performed by setting coordinate systems, unit systems, and gravitational acceleration environmental parameters in multibody dynamics software, establishing a tire model, and merging the tire model with the landing gear geometric model into a single computational model.

4. The titanium-based composite landing gear catapult simulation analysis method as described in claim 3, characterized in that, The process of creating a flexible body includes: Finite element software was used to perform mesh generation and modal analysis on the flexible body component, and modal neutral files were output. Import the modal neutral file into the multibody dynamics software and replace the corresponding rigid body component; Adjust the position and orientation of the flexible body, and redefine the kinematic pairs associated with the flexible body.

5. The titanium-based composite landing gear catapult simulation analysis method as described in claim 3, characterized in that, The parametric modeling process includes: Define a tire model in multibody dynamics software and set parameters such as tire mass, moment of inertia, outer radius, width, aspect ratio, vertical stiffness, and vertical damping coefficient. Merge the tire model with the landing gear geometry model and adjust the model to the appropriate position and attitude; Add kinematic pairs and forces to the model, and define the connection methods and relative motion between components.

6. The titanium-based composite landing gear catapult simulation analysis method as described in claim 1, characterized in that, The process of performing catapult dynamics simulation using a rigid-flexible coupled virtual prototype model includes: Set the takeoff weight, takeoff speed, buffer filling parameters, and buffer strut compression stroke for the catapult launch condition; The fixing and release of the catapult rod to the ground are controlled by a simulation script. First, the catapult rod is fixed to simulate the initial state, and then the catapult rod is released by the failure of the fixed pair to simulate the sudden extension. Run the simulation and output the extension speed time history curve.

7. The titanium-based composite landing gear catapult simulation analysis method as described in claim 6, characterized in that, The process of controlling the fixing and release of the launch rod from the ground through simulation scripts includes: At the start of the simulation, the launch rod is fixed to the ground for 1 second to simulate the initial stable state. The ejection lever is released by setting the fixed pair to fail, and the subsequent 0.15-second extension process is simulated. The simulation results are processed using the post-processing module to generate the extension velocity time history curve.

8. The titanium-based composite landing gear catapult simulation analysis method as described in claim 6, characterized in that, The process of setting the takeoff weight, takeoff speed, buffer filling parameters, and buffer strut compression stroke for catapult launch includes: Adjust the equivalent mass parameters of the front landing gear extension according to different equivalent masses; Run multiple simulation cases and output the time history curves of the spur velocity under different equivalent masses; The landing gear structural response, impact load, and cushioning performance were evaluated based on simulation curves.

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