An aircraft fuselage frame section structure simplified crash dynamics modeling method
By simplifying the modeling of aircraft fuselage frame structures using the principle of large plastic deformation, and simulating large deformation regions as plastic hinges, the problems of long finite element analysis time and non-convergence of calculations are solved, achieving efficient finite element analysis and shortening the design cycle.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA AIRPLANT STRENGTH RES INST
- Filing Date
- 2023-03-30
- Publication Date
- 2026-06-26
AI Technical Summary
Existing finite element analysis methods are time-consuming and prone to non-convergence when calculating the large plastic deformation region of aircraft fuselage frame structures, which affects the aircraft design and optimization process.
The fuselage frame model is established using the principle of large plastic deformation. The large deformation area is simulated as a plastic hinge. The torque and axial force performance parameters of the plastic hinge are determined. The structural response is calculated by combining different gravity fields and initial velocities. The connection relationship is simplified and redundant elements are deleted to establish bending-rotation or axial force-tension-compression type connection relationships.
It improves the computational efficiency of finite element analysis of aircraft fuselage frame crashes, avoids the problem of non-convergence, shortens the design cycle, and improves computational accuracy and efficiency.
Smart Images
Figure CN116756906B_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of aerospace structural impact dynamics technology, and specifically relates to a simplified crash dynamics modeling method for aircraft fuselage frame structures. Background Technology
[0002] The crashworthiness of an aircraft fuselage structure is a crucial indicator of the safety of civil aircraft. During the aircraft design optimization phase, the complexity of the fuselage structure means that numerous factors, such as structural layout and parameter design, affect its crashworthiness. Therefore, it is necessary to select from various fuselage structure layouts and optimize parameters.
[0003] Simulation analysis is a crucial method for evaluating the crashworthiness of civil aircraft. Employing appropriate crashworthiness simulation analysis techniques can not only improve design efficiency and provide a comprehensive understanding of the crashworthiness of civil aircraft, but also significantly reduce research costs. Therefore, research on simulation analysis modeling and model validation of aircraft fuselage segments has always been an important aspect of aircraft structural crashworthiness research. However, conventional finite element analysis methods suffer from long computation times and potential convergence issues when calculating the large plastic deformation regions of aircraft fuselage segments, severely impacting aircraft design and optimization processes. Therefore, a simple and relatively accurate simplified crash dynamics modeling method for aircraft fuselage segments is of great significance. Summary of the Invention
[0004] The purpose of this application is to provide a simplified crash dynamics modeling method for aircraft fuselage frame structures, in order to solve the problems of long calculation time and potential non-convergence of existing finite element analysis methods when calculating the plastic deformation region of aircraft fuselage frame structures.
[0005] The technical solution of this application is: a simplified crash dynamics modeling method for aircraft fuselage frame structures, comprising:
[0006] Establish a fuselage frame model based on the structural features of the corresponding fuselage frame segment, and determine the connection relationship between adjacent components within the fuselage frame model;
[0007] Determine the location and deformation mode of the large deformation area within the fuselage frame model, simulate the large deformation area as a plastic hinge, determine the torque and axial force performance parameters of the corresponding plastic hinge, and determine the energy dissipation distribution principle for each part of the fuselage frame structure.
[0008] By applying different gravitational fields and initial velocities to the fuselage frame segments, the response of the plastic hinges of the fuselage frame segments under different degrees of deformation is calculated.
[0009] Preferably, the process of establishing the fuselage frame model includes:
[0010] The fuselage frame segments are meshed, and corresponding cross-sectional properties are assigned to different cross-sectional locations;
[0011] Based on the connection method between the various parts of the fuselage frame, dynamic constraints are established between the skin and the ribs, and between the ribs and the longitudinal beams;
[0012] The cabin seats are simplified as rigid bodies with mass, and their corresponding reference points are coupled to the cabin floor beams. The mass of a single rigid body includes the mass of the occupants and the mass of the seats.
[0013] Set the contact properties between each component;
[0014] Reference points are set at the plastic hinges and connections on each component, and then coupled to the corresponding nodes;
[0015] Based on the deformation modes of each plastic hinge and connection, establish bending-rotation type connection relationships or axial force-tension-compression type connection relationships between the corresponding reference points, and delete redundant solid elements;
[0016] Assign mechanical property parameters to each connection relationship.
[0017] Preferably, the fuselage frame model includes a crossbeam, skin, bulkhead, counterweights, and ground; the bulkhead is located on the ground, and a skin is provided on the outer side of the bulkhead; the crossbeam is horizontally located inside the bulkhead; multiple sets of counterweights are symmetrically arranged on the upper two sides of the bulkhead; a column is provided between the middle of the crossbeam and the bulkhead, and a column connection is established; a crossbeam-bulb frame connection is established between the ends of the crossbeam and the bulkhead; the crossbeam has multiple segments, and a crossbeam connection is established between adjacent crossbeams; the bulkhead has multiple segments, and a top connection is established between adjacent upper bulkheads, and a bottom connection is established between adjacent lower bulkheads.
[0018] Preferably, when establishing a connection between the partition frame and the crossbeam, or between different segments of the partition frame, redundant units on the corresponding parts are deleted, so that the partition frame is divided into two parts at the plastic hinge. Then, the unit nodes at the two plastic hinges are coupled to their respective reference points to establish a bending-rotation type connection. When establishing a connection between the column, the crossbeam, and the partition frame, redundant units on the corresponding parts are deleted, so that the column and the crossbeam or partition frame are divided into two parts at the plastic hinge. Then, the unit nodes at the two plastic hinges are coupled to their respective reference points to establish an axial force-tension-compression type connection.
[0019] Preferably, the response of the plastic hinge of the fuselage frame structure under different degrees of deformation includes torque, axial force, and yield determination; the calculation formulas for the torque and axial force include:
[0020] F i =D ii ui
[0021] In the formula: F i It is the axial force or torque of the i-th component of the relative motion; D ii u is the stiffness of the i-th component of the relative motion; i For the displacement or rotation of the connection in the i-th direction;
[0022] when When the connection relationship enters the yielding stage, the determination formula includes:
[0023]
[0024] In the formula, P(f) represents the magnitude of the traction force in the connection relationship, and F... 0 The yield force or moment is the force that connects the forces.
[0025] This application presents a simplified crash dynamics modeling method for aircraft fuselage frame structures. It establishes a fuselage frame model based on the structural features of the corresponding frame, determines the location and deformation mode of large deformation regions within the model, simulates these large deformation regions as plastic hinges, and determines the torque and axial force performance parameters of the corresponding plastic hinges. Different gravitational fields and initial velocities are applied to the fuselage frame, and the response of the plastic hinges to different degrees of deformation is calculated. Based on the principle of large plastic deformation, this method fully combines the advantages of simple connection relationship models, high computational efficiency, and high accuracy of the finite element method, improving the computational efficiency of finite element crash analysis of aircraft fuselage frame structures. Furthermore, it avoids potential non-convergence problems when calculating the large plastic deformation regions of aircraft fuselage frame structures, shortening the aircraft structural crashworthiness design cycle and demonstrating significant application potential. Attached Figure Description
[0026] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.
[0027] Figure 1 This is a schematic diagram of the overall process of this application;
[0028] Figure 2 This is a schematic diagram of the fuselage frame model structure of this application;
[0029] Figure 3 A schematic diagram is provided to illustrate the connection relationship at the bottom of the partition frame in this application. Detailed Implementation
[0030] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.
[0031] A simplified crash dynamics modeling method for aircraft fuselage frame structures is proposed. Based on the principle of large plastic deformation, the method reasonably simplifies the fuselage frame by simulating the large plastic deformation region as a plastic hinge, while other regions are represented by normal structural segments. The large plastic deformation region is primarily located at the connection points between various components of the fuselage frame. A plastic hinge is a point in a structural member where the fibers on opposite surfaces yield but do not fail under stress. It can simulate the forces between two components while reducing constraints, thus significantly improving computational efficiency.
[0032] Includes the following steps:
[0033] Step S100: Establish the fuselage frame model
[0034] Establish a fuselage frame model based on the structural features of the corresponding fuselage frame segment, and determine the connection relationship between adjacent components within the fuselage frame model;
[0035] like Figure 2 As shown, preferably, the fuselage frame model includes a crossbeam ③, a skin ⑤, a bulkhead ⑥, counterweights ⑧, and a ground ⑨; the bulkhead is located on the ground, with a skin on its outer side, the crossbeam is horizontally located inside the bulkhead, and multiple sets of counterweights are symmetrically located on the upper sides of the bulkhead; there is a column between the middle of the crossbeam and the bulkhead, establishing a column connection relationship ①, and a crossbeam-bulb frame connection relationship ② between the ends of the crossbeam and the bulkhead; the crossbeam has multiple segments, and a crossbeam connection relationship ⑦ is established between adjacent crossbeams, the bulkhead has multiple segments, and a top connection relationship ④ is established between adjacent upper bulkheads, and a lower connection relationship ⑩ is established between adjacent lower bulkheads.
[0036] Preferably, when establishing connections between the partition frame and the crossbeam, or between different segments of the partition frame, redundant units on the corresponding parts are deleted, causing the partition frame to split into two parts at the plastic hinge. Then, the unit nodes at the two plastic hinges are coupled to their respective reference points to establish a bending-rotational connection, such as... Figure 3 When establishing a connection between the column, beam, and partition, delete the redundant units on the corresponding parts, so that the column and beam or partition are divided into two parts at the plastic hinge. Then, couple the unit nodes at the plastic hinge of the two parts to their respective reference points to establish a bending-rotation type connection or an axial force-tension-compression type connection.
[0037] When modeling the fuselage frame, the location of the plastic hinge that appears during the impact should be determined first, and the connection relationship should be established at the location of the plastic hinge.
[0038] Preferably, the process of establishing the fuselage frame model includes:
[0039] 1) Grid the fuselage frame segments and assign corresponding cross-sectional properties to different cross-sectional locations;
[0040] 2) Based on the connection method between the various parts of the fuselage frame, establish dynamic constraints between the skin and the ribs, and between the ribs and the longitudinal beams;
[0041] 3) Simplify the cabin seats as rigid bodies with mass, and then couple their corresponding reference points to the cabin floor beams. The mass of a single rigid body includes the mass of the occupants and the mass of the seats.
[0042] 4) Set the contact properties between each component;
[0043] 5) Set reference points at the plastic hinges and connections on each component, and then couple them to the corresponding nodes;
[0044] 6) Based on the deformation modes of each plastic hinge and connection, establish bending-rotation type connection relationships or axial force-tension-compression type connection relationships between the corresponding reference points, and delete redundant solid elements;
[0045] 7) Assign mechanical property parameters to each connection relationship.
[0046] Through the above steps, the connection relationship between the plastic hinge and adjacent hinges is effectively established. This allows the entire fuselage frame model to be connected as a whole, thus forming the basis for subsequent calculations.
[0047] Step S200: Determine the performance parameters within the fuselage frame model.
[0048] The location and deformation mode of the large deformation region within the fuselage frame model are determined. The large deformation region is simulated as a plastic hinge, and the torque and axial force performance parameters of the corresponding plastic hinge are determined. The energy dissipation distribution principle of each part of the fuselage frame structure is determined. Through this step, the mathematical relationship between each component inside the fuselage frame model is established, which serves as the basis for subsequent calculations.
[0049] Step S300, Response within the computer frame model
[0050] By applying different gravitational fields and initial velocities to the fuselage frame segments, the response of the plastic hinges of the fuselage frame segments under different degrees of deformation is calculated.
[0051] Preferably, the response of the plastic hinge of the fuselage frame structure under different degrees of deformation includes torque, axial force, and yield criterion; the calculation formulas for torque and axial force include:
[0052] F i =D ii u i
[0053] In the formula: F i It is the axial force or torque of the i-th component of the relative motion; D ii u is the stiffness of the i-th component of the relative motion; iFor the displacement or rotation of the connection in the i-th direction;
[0054] when When the connection relationship enters the yielding stage, the determination formula includes:
[0055]
[0056] In the formula, P(f) represents the magnitude of the traction force in the connection relationship, and F... 0 The yield force or moment is the force that connects the forces.
[0057] This application establishes a fuselage frame model based on the structural features of the corresponding fuselage frame segment, determines the location and deformation mode of the large deformation region within the fuselage frame model, simulates the large deformation region as a plastic hinge, and determines the torque and axial force performance parameters of the corresponding plastic hinge. Different gravitational fields and initial velocities are applied to the fuselage frame segment, and the response of the plastic hinge of the fuselage frame structure under different deformation degrees is calculated. Based on the principle of large plastic deformation, it fully combines the advantages of simple connection relationship model, fast computational efficiency, and high computational accuracy of the finite element method, improving the computational efficiency of finite element analysis of aircraft fuselage frame segments in crash tests. It also avoids potential non-convergence problems when calculating the large plastic deformation region of the aircraft fuselage frame structure, shortening the aircraft structural crashworthiness design cycle, and has significant application prospects. Compared with using solid and shell elements in the large deformation region, the calculation is easier to converge and has lower requirements for mesh quality.
[0058] The above are merely specific 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 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 simplified crash dynamics modeling method for aircraft fuselage frame structures, characterized in that, include: Establish a fuselage frame model based on the structural features of the corresponding fuselage frame segment, and determine the connection relationship between adjacent components within the fuselage frame model; Determine the location and deformation mode of the large deformation area within the fuselage frame model, simulate the large deformation area as a plastic hinge, determine the torque and axial force performance parameters of the corresponding plastic hinge, and determine the energy dissipation distribution principle for each part of the fuselage frame structure. By applying different gravitational fields and initial velocities to the fuselage frame segments, the response of the plastic hinges of the fuselage frame segments under different degrees of deformation is calculated. The fuselage frame model includes crossbeams, skin, bulkheads, counterweights, and a ground surface. The bulkheads are positioned on the ground, with skin covering their outer sides. The crossbeams are horizontally positioned inside the bulkheads. Multiple sets of counterweights are symmetrically arranged on the upper sides of the bulkheads. A column connects the middle of the crossbeam to the bulkhead, and a crossbeam-bulb connection is established between the ends of the crossbeams and the bulkheads. The crossbeams have multiple segments, and adjacent crossbeams are connected. The bulkheads have multiple segments, and adjacent upper bulkheads are connected at their top, while adjacent lower bulkheads are connected at their bottom. When establishing connections between the partition frame and the crossbeam, or between different segments of the partition frame, redundant units on the corresponding parts are deleted, causing the partition frame to split into two parts at the plastic hinge. Then, the unit nodes at the two plastic hinges are coupled to their respective reference points to establish a bending-rotation type connection. When establishing connections between the column, the crossbeam, and the partition frame, redundant units on the corresponding parts are deleted, causing the column and the crossbeam or partition frame to split into two parts at the plastic hinge. Then, the unit nodes at the two plastic hinges are coupled to their respective reference points to establish an axial force-tension-compression type connection.
2. The simplified crash dynamics modeling method for aircraft fuselage frame structures as described in claim 1, characterized in that, The process of creating the fuselage frame model includes: The fuselage frame segments are meshed, and corresponding cross-sectional properties are assigned to different cross-sectional locations; Based on the connection method between the various parts of the fuselage frame, dynamic constraints are established between the skin and the ribs, and between the ribs and the longitudinal beams; The cabin seats are simplified as rigid bodies with mass, and their corresponding reference points are coupled to the cabin floor beams. The mass of a single rigid body includes the mass of the occupants and the mass of the seats. Set the contact properties between each component; Reference points are set at the plastic hinges and connections on each component, and then coupled to the corresponding nodes; Based on the deformation modes of each plastic hinge and connection, establish bending-rotation type connection relationships or axial force-tension-compression type connection relationships between the corresponding reference points, and delete redundant solid elements; Assign mechanical property parameters to each connection relationship.
3. The simplified crash dynamics modeling method for aircraft fuselage frame structures as described in claim 1, characterized in that, The response of the plastic hinge of the fuselage frame structure under different degrees of deformation includes torque, axial force, and yield determination; The formulas for calculating the torque and axial force include: ； In the formula: It is the axial force or torque of the i-th component of the relative motion; Let be the stiffness of the i-th component of the relative motion; For the displacement or rotation of the connection in the i-th direction; when When the connection relationship enters the yielding stage, the determination formula includes: ； In the formula, The magnitude of the traction force is related to the connection relationship. The yield force or moment is the force that connects the forces.