Method for determining wing damage energy density under high-speed impact kinetic energy unit action

Abstract

The application discloses a kind of wing damage energy density determination methods under the action of high-speed impact kinetic energy unit, belong to structural health monitoring technical field.The existing technology is aimed at solving the problem of insufficient quantitative evaluation index when evaluating the damage effect of high-speed impact kinetic energy unit on aircraft structure. Including computer wing structure bending moment, calculate the limit bending moment of the designated area in the span direction;Establishing a finite element simulation model of wing structure and carrying out bending loading simulation to verify the reliability of the model;Carrying out kinetic energy unit group impact wing structure simulation;Carrying out bending loading simulation to obtain the bending moment drop;Calculate the wing bending moment load under different maneuvering overload conditions as damage threshold;Determine the energy density when the residual bending moment is equal to the damage threshold as the damage criterion;Select the universality of other kinetic energy unit damage element verification criterion.This method can establish the quantitative correlation between kinetic energy unit distribution field parameters and the residual carrying capacity of structure, and provides a quantifiable analysis basis for aircraft load-bearing structure damage evaluation.

Description

Technical Field

[0001] This invention belongs to the field of structural health monitoring technology, specifically relating to a method for determining the energy density of wing damage under the action of a high-speed impact kinetic energy unit. Background Technology

[0002] In the development of modern aviation equipment, aircraft structures may be subjected to various high-speed impact loads during operation. Accurately assessing the degree of damage caused by these impacts to the aircraft structure is of great practical engineering significance.

[0003] In studies on the damage effects of kinetic energy unit clusters on aircraft structures, existing research mostly focuses on the physical damage effects of the kinetic energy unit distribution field, commonly using indicators such as kinetic energy unit penetration probability and structural area elimination percentage as damage criteria for structural components. However, these physical damage indicators are insufficient to comprehensively reflect the degree of degradation in the load-bearing capacity of an aircraft structure after an impact, failing to meet the needs of quantitative assessment of functional damage to aircraft structures. Specifically, when an aircraft wing structure is subjected to a high-speed impact kinetic energy unit, although physical indicators such as penetration probability can determine whether the structure has been penetrated, it is difficult to directly obtain the maximum load bending moment value that the structure can still withstand in subsequent use. Therefore, it is impossible to accurately determine whether the damaged wing structure can still meet the aircraft's maneuverability requirements. This technical problem restricts the accuracy of damage assessment of aircraft load-bearing structures and also brings difficulties to damage resistance design and structural safety margin analysis.

[0004] Based on this, the present invention proposes a method for determining the energy density of wing damage under the action of a high-speed impact kinetic energy unit, in order to solve the problems existing in the prior art. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for determining the energy density of wing damage under the action of a high-speed impact kinetic energy unit, thereby solving the problem of insufficient quantitative evaluation indicators in the existing technology when assessing the damage effect of a high-speed impact kinetic energy unit on aircraft structures.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for determining the energy density of wing damage under high-speed impact kinetic energy unit action, comprising: Step 1: Determine the specified verification conditions based on the target characteristics of the aircraft, and use aerodynamic engineering methods to calculate the aerodynamic load distribution along the span of the wing under these conditions. At the same time, according to the triangle distribution law, the ultimate bending moment of a specified area of ​​the wing on one side is obtained by integrating along the span. Step 2: Establish a complete finite element simulation model of the wing structure, carry out wing bending loading simulation under the same reference conditions as in Step 1, obtain the bending moment simulation results of the wing structure, and compare the simulation results with the theoretical calculation values ​​obtained in Step 1 to verify the reliability of the simulation model. Step 3: After fixing the impact area, use the kinetic energy unit velocity, impact angle, and unit surface density as variables to carry out finite element simulation of the impact of the kinetic energy unit group on the wing structure, simulate different encounter attitudes between the kinetic energy unit and the wing structure; clarify the penetration criterion, the morphology of the hole / aperture and the element deletion criterion, and obtain the wing structure simulation model with kinetic energy unit perforations; Step 4: Using the wing structure simulation model with kinetic energy unit perforation obtained in Step 3 as input, conduct bending loading simulation to the critical state according to the same boundary conditions and failure criteria as in Step 2, obtain the remaining bending bearing capacity of the same specified section as in Step 1, and calculate the reduction in bending moment and damage degree relative to the complete wing. Step 5: Calculate the required bending moment load along the span of the wing under different specified maneuvering overload conditions using theoretical calculation methods, and define the damage judgment overload. The required bending moment at a specified station under the damage judgment overload is determined as the damage threshold. Step 6: Keeping the impact area unchanged, change the impact velocity, angle and unit surface density of the kinetic energy unit, and repeat steps 3 to 4 to obtain the curve of the remaining load-bearing capacity as a function of energy density; first verify the monotonicity of the curve, and then interpolate to solve the critical energy density, which will serve as the damage criterion for the wing structure under the overload condition of the impact area. Step 7: Select other kinetic energy unit damage elements, use the energy density value obtained in Step 6 to calculate the kinetic energy unit density corresponding to the damage element, and repeat Step 3 and Step 4 to calculate the corresponding remaining bearing capacity. Compare it with the damage threshold. If the deviation is within the set tolerance, the energy density criterion is determined to be applicable. If it exceeds the tolerance, a correction parameter is introduced, or the criterion is refined into a function of energy density and damage element type and then recalibrated.

[0007] In a preferred embodiment, the wing loading triangle distribution rule in step 1 is specifically as follows: Along the span of the wing, the load decreases linearly from the wing root to the wingtip, with the maximum load at the wing root and zero load at the wingtip.

[0008] In a preferred embodiment, in step 1, the ultimate bending moment of a specified area on one side of the wing is: ; in, This represents the bending moment experienced by a certain area along the span of the wing; Represents the wingspan of a single wing. b 1Represents the wingspan length of the wing; This represents the spanwise distance from the region in question to the wing root, and its value ranges from 0 to... ; y d represents the spanwise distance from any infinitesimal segment on the wing to the wing root; y It represents an infinitesimal length increment along the span direction; The ultimate load value representing a single wing is calculated as follows: ; in, This represents the proportion of the total load borne by a single wing to the total load of the aircraft. Represents the structural safety factor. m The value represents the aircraft's maximum overload weight, and g represents the acceleration due to gravity. This represents the maximum design overload of the aircraft.

[0009] In a preferred embodiment, step 3, the calculation process of the kinetic energy unit velocity includes: First, calculate the initial velocity of the kinetic energy unit during the transient energy release of the high-energy impact source: ; in, This represents the initial velocity of the kinetic energy unit when the transient energy is released from a high-energy impact source. Represents the empirical coefficient of initial velocity. E Represents the transient energy of the impact source; Represents the mass ratio of energy materials; Secondly, the velocity of the impact kinetic energy unit during its scattering process is calculated to gradually decrease with increasing flight distance due to air resistance, resulting in the following velocity upon reaching the structural surface: ; in, This represents the velocity at which the kinetic energy unit reaches the surface of the structure. Represents air density; This represents the average frontal area of ​​the kinetic energy unit; Represents the mass of the kinetic energy unit; L Represents the flight distance of the kinetic energy unit; e Represents the natural constant; The drag coefficient is represented by the following formula: .

[0010] In a preferred embodiment, in step 3, the impact angle of the kinetic energy unit is... , Let be the angle between the incident velocity direction of the kinetic energy element and the normal direction of the wing structure surface at the impact location. As the incident direction of the kinetic energy element gradually deviates from the normal direction... Increase.

[0011] In a preferred embodiment, step 3, the calculation process of the kinetic energy unit density includes: ; in, ρ Represents the density of kinetic energy units; N This represents the number of kinetic energy units within the effective impact area. A This represents the effective impact area.

[0012] In a preferred embodiment, step 4, the calculation process for the reduction in wing load bending moment, includes: ; in, Represents the reduction in bending moment. This represents the maximum bending moment that a specified area of ​​the wing can withstand when it is in its complete state. This represents the maximum bending moment that the wing can withstand after being impacted by a group of kinetic energy units.

[0013] In a preferred embodiment, step 5, the calculation process of the wing spanwise bending moment load under different maneuvering overload conditions, includes: The bending moment in a spanwise region is calculated based on the triangular distribution law of aircraft wing loads. The calculation process is as follows: ; in, M This represents the bending moment experienced by a certain area along the span of the wing; Represents the wingspan of a single wing. b 1 Represents the wingspan length of the wing; This represents the spanwise distance from the desired region to the wing root; y d represents the spanwise distance from any infinitesimal segment on the wing to the wing root; y It represents an infinitesimal length increment along the span direction; The load values ​​representing the corresponding overload conditions for a single wing: ; in, k This represents the proportion of the total load borne by a single wing to the total load of the aircraft. m Represents the aircraft's maximum overload weight; g Represents gravitational acceleration; n This represents the aircraft's overload value.

[0014] In a preferred embodiment, step 6, the calculation of energy density, includes: ; in, E d Represents energy density; Representing the i The mass of each kinetic energy unit; Representing the i The incident velocity of each kinetic energy unit; A represents the force-bearing area of ​​the impacted structure surface.

[0015] In a preferred embodiment, in step 7, the initial velocity of the kinetic energy unit damage element is calculated from step 3.

[0016] Compared with the prior art, the present invention provides a method for determining the energy density of wing damage under the action of a high-speed impact kinetic energy unit, which has the following beneficial effects: This invention presents a novel approach to establishing functional damage criteria for aircraft structures by combining theoretical calculations and simulation methods to develop an energy density damage criterion for wing structures.

[0017] This invention establishes a quantitative correlation between kinetic energy unit distribution field parameters, structural residual load-bearing capacity, and damage level by combining theoretical calculations with finite element simulation, providing a quantifiable analytical basis for damage assessment of aircraft load-bearing structures.

[0018] This invention provides a process for establishing functional damage criteria for wing structures, which can be extended to damage assessment of other types of aerospace structural components and has broad engineering application value.

[0019] This solves the problem of insufficient quantitative evaluation indicators in existing technologies when assessing the damage effect of high-speed impact kinetic energy units on aircraft structures. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the method for determining the energy density of wing damage under the action of a high-speed impact kinetic energy unit according to the present invention.

[0021] Figure 2 This is a graph showing the triangular distribution of wing loads according to the present invention.

[0022] Figure 3 This is a schematic diagram of the finite element simulation model of the wing structure of the present invention.

[0023] Figure 4 This is a schematic diagram of the boundary conditions of the wing structure of the present invention.

[0024] Figure 5 This is a simulation curve of the ultimate bending moment of the wing structure of the present invention.

[0025] Figure 6 This is a schematic diagram of the impact angle of the kinetic energy unit of the present invention.

[0026] Figure 7 This is a schematic diagram of the kinetic energy unit group impact wing structure of the present invention.

[0027] Figure 8 This is a bending moment-displacement curve diagram of the wing structure with linear perforation damage according to the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] As per the instruction manual Figure 1 - Appendix Figure 8 As shown, this invention proposes a method for determining the energy density of wing damage under high-speed impact kinetic energy units. This method establishes a quantitative correlation between kinetic energy unit distribution field parameters, structural residual load-bearing capacity, and damage level through a combination of theoretical calculations and finite element simulations, providing a quantifiable analytical basis for damage assessment of aircraft load-bearing structures. Specific steps include: Step 1: Determine the specified verification conditions based on the target characteristics of the aircraft, and use aerodynamic engineering methods to calculate the aerodynamic load distribution along the span of the wing under these conditions. At the same time, according to the triangle distribution law, the ultimate bending moment of a specified area of ​​the wing on one side is obtained by integrating along the span.

[0030] Based on the target characteristic information of the aircraft, the bending limit load of a single wing is calculated. An appropriate wing load distribution calculation method is selected, and the bending moment of the corresponding region of the single wing is calculated to characterize the bending strength of the wing structure. Specifically, this includes: Step 1.1: Based on the triangular distribution law of aircraft wing loads (the load decreases linearly from the wing root to the wingtip along the spanwise direction, with the maximum load at the wing root and zero load at the wingtip), calculate the ultimate bending moment in region one of the spanwise direction. The calculation process can be expressed as follows: ; in, This represents the bending moment experienced by a certain area along the span of the wing; Represents the wingspan of a single wing. b 1 Represents the wingspan length of the wing; This represents the spanwise distance from the region in question to the wing root, and its value ranges from 0 to... ; yd represents the spanwise distance (i.e., the distance along the wingspan) from any infinitesimal segment on the wing to the wing root; the unit is meters (m). y It represents an infinitesimal length increment along the spanwise direction, that is, a tiny spanwise interval between two adjacent positions on the wing. Its unit is also meter (m), but it is essentially a differential (microelement), representing "a small segment of wingspan length". The ultimate load value representing a single wing can be calculated as follows: ; in, This represents the proportion of the total load borne by a single wing to the total load of the aircraft. represents the structural safety factor, m represents the aircraft's maximum overload weight, and g represents gravitational acceleration. This represents the maximum design overload of the aircraft.

[0031] In this embodiment, the aircraft's maximum overload weight Maximum design overload The acceleration due to gravity is The structural safety factor is 1.5, and the outer wing half-wingspan is... wing root chord length wingtip chord length The length is 0.967m, and the load on the outer section of a single wing accounts for approximately 0.3% of the overall wing load. Therefore, the maximum load on a single wing under maximum takeoff weight can be calculated as follows: ; Substituting the specific values, we can calculate the ultimate load of a single wing at this point. ; By selecting a triangular distribution to calculate the wing load and substituting the specific values, we can obtain: ; Substituting the specific values, the bending moment at the root of one wing is obtained as follows: In the simulation, the impact zone of the kinetic energy unit is approximately 2.5m from the wing root. The calculated bending moment of the outer wing load at this location is: ; Substituting the specific numerical values, the bending moment at the damage point on the outer side of the damaged area is obtained as follows: .

[0032] Step 2: Establish a complete finite element simulation model of the wing structure, conduct wing bending loading simulation under the same baseline conditions as in Step 1, obtain the bending moment simulation results of the wing structure, and compare the simulation results with the theoretical calculation values ​​obtained in Step 1 to verify the reliability of the simulation model.

[0033] In this embodiment, a finite element simulation model of the wing structure is established. The thickness of each component of the wing is as follows: the thickness of the upper and lower skins of the aircraft is 3mm, the thickness of the ribs is 3mm, the thickness of the spars is 5mm, and the thickness of the front and rear wing wall structures is 3mm. The materials used are JC constitutive descriptions, as shown in Table 1.

[0034] Table 1: Constitutive Parameters of 7075 Aluminum Alloy JC

[0035] The peak value of the curve in the calculation results is taken as the ultimate bending moment load value of the wing structure. For example... Figure 5 As shown in the figure, the support reaction force-displacement curve of the undamaged wing under bending loading is displayed. The horizontal axis represents displacement in mm, and the vertical axis represents support reaction force in N. The curve reaches a peak of approximately 870,000 N at a displacement of about 58-60 mm and then rapidly decreases. By comparing the ultimate bending moment value obtained from the simulation with the bending moment value calculated theoretically in step 1, the reliability of the simulation model can be verified. If the error between the two is within the allowable range, it indicates that the simulation model is accurate and reliable, and can be used for subsequent impact simulation analysis.

[0036] Step 3: Conduct finite element simulation of the wing structure impacted by the impact kinetic energy unit group (fragment impact).

[0037] After fixing the impact area, finite element simulation of the impact of kinetic energy element groups on the wing structure is carried out using kinetic energy element velocity, impact angle, and element surface density as variables to simulate different encounter attitudes between kinetic energy elements and the wing structure; the penetration criterion, the morphology of the breach / aperture, and the element deletion criteria are defined to obtain a simulation model of the wing structure with kinetic energy element perforations. Figure 6 , 7 As shown, this step specifically includes: Step 3.1: Calculate the velocity of the kinetic energy unit. The specific process includes: First, calculate the initial velocity of the kinetic energy unit during the transient energy release of the high-energy impact source: ; in, Represents the initial velocity of the kinetic energy unit (i.e., the velocity at the instant of release) when the transient energy of a high-energy impact source is released, and the unit is usually m / s; Represents the empirical coefficient of initial velocity. E Represents the transient energy of the impact source; The energy material mass ratio, i.e., the ratio of the mass of the energy material to the mass of the metal shell forming the kinetic energy unit (a dimensionless parameter), is the energy material mass ratio. β The range of values ​​is determined based on the characteristics of different types of high-energy impact sources. For different types of high-energy impact sources, its... β The value will vary within a specific range, which directly affects the initial velocity of the kinetic energy unit.

[0038] Secondly, the velocity of the impact kinetic energy element gradually decreases with increasing flight distance due to air resistance during its dispersion process. The velocity at the structural surface is: ; in, This represents the velocity at which the kinetic energy unit reaches the surface of the structure. Represents air density (kg / m³) 3 ); The average frontal area of ​​the kinetic energy unit (m²) 2 ); L represents the mass of the kinetic energy unit; e represents the flight distance of the kinetic energy unit; and e is the natural constant. The drag coefficient depends on the shape of the kinetic energy unit and the flight speed. v f The dispersion velocity of kinetic energy units from high-energy impact sources is generally between 1500 and 2200 m / s, and the drag coefficient is within this range. It can be calculated using the following formula: ; Step 3.2: Calculate the impact angle of the kinetic energy unit. The specific process includes: Impact angle This is the angle between the incident velocity direction of the kinetic energy unit and the normal direction of the wing structure surface at the impact location. The impact angle is determined based on the intersection attitude of the kinetic energy unit relative to the wing structure. When the incident direction of the kinetic energy element is parallel to the normal direction of the wing structure surface, The angle is 0°, and when the incident direction of the kinetic energy unit gradually deviates from the normal direction, Increase.

[0039] Step 3.3: Calculate the kinetic energy unit density. The specific process includes: The kinetic energy element density ρ is the number of kinetic energy elements per unit effective impact area, and its calculation formula is: ; in, ρ Represents the density of kinetic energy units, with units per m³. 2 ; N This represents the number of kinetic energy units within the effective impact area. A Represents the effective impact area, in meters (m²). 2 .

[0040] In this embodiment, referring to the size parameters of a typical flight vehicle, the assembly radius of the equivalent energy material is 9cm, the assembly height is 40cm, and the density of the equivalent energy material is 1.6g / m³. 3The calculated mass of the energy material is m = 16.28 kg; the mass of a single kinetic energy unit is 7 g, and the number of kinetic energy units is 2400. The calculated mass of the shell is M = 16.8 kg, and the total mass of the high-energy impact source is approximately 33.08 kg.

[0041] The initial velocity of the impact kinetic energy unit is calculated, and the ratio of the mass of the energy material to the mass coefficient of the kinetic energy unit shell is: For the initial empirical characteristic velocity of this type of energy material =2370m / s, and the initial velocity of a single kinetic energy unit can be calculated using the formula. =1914.78 m / s. When the kinetic energy unit's flight distance is 5 m, the velocity of the kinetic energy unit when the high-energy impact source releases transient energy at an altitude of 10,000 meters can be calculated using the formula. =1737.24 m / s, the velocity of the kinetic energy unit during transient energy release at sea level is m / s.

[0042] The reference conditions are set according to the meeting attitude of the aircraft and the high-speed impact kinetic energy unit, as shown in Table 2.

[0043] Table 2: Simulation Operating Condition Planning

[0044] Finite element simulation of the kinetic energy unit group impact wing structure was carried out under the working conditions described in Table 2 above.

[0045] like Figure 6 As shown in the figure, the impact angle of the kinetic energy unit is illustrated, and the geometric definition of the angle between the kinetic energy unit and the reference line normal to the structural surface when the kinetic energy unit impacts the structural surface at high velocity is given. During simulation, different incident angles need to be set to simulate different encounter attitudes between the kinetic energy unit and the wing structure.

[0046] like Figure 7 As shown in the figure, a schematic diagram of the impact of a group of kinetic energy units on an airfoil structure is presented. The impact results of the perforation damage path or the linear kinetic energy unit distribution field are represented by red dashed lines on the green airfoil outline plane. By changing the velocity, angle, and density of the kinetic energy units, simulation models of airfoil structures with different degrees of damage can be obtained.

[0047] After completing the above-mentioned working condition simulation, the simulation model of the wing structure with kinetic energy unit perforation is extracted, and bending loading simulation is carried out to calculate the residual ultimate bending moment of the wing structure with kinetic energy unit perforation.

[0048] Step 4: Using the wing structure simulation model with kinetic energy unit perforations obtained in Step 3 as input, conduct bending loading simulation to the critical state according to the same boundary conditions and failure criteria as in Step 2, obtain the remaining bending bearing capacity of the same specified section as in Step 1, and calculate the reduction in bending moment relative to the intact wing and the degree of damage. Figure 8 As shown.

[0049] The formula for calculating the bending moment reduction of the wing structure is: ; in, Represents the reduction in bending moment. This represents the maximum bending moment that a specified area of ​​the wing can withstand when it is in its complete state. This represents the maximum bending moment that the wing can withstand after being impacted by a group of kinetic energy units.

[0050] In this embodiment, the ultimate bending moment-displacement curve of the wing structure with perforated kinetic energy elements is extracted from the simulation results. When the loaded displacement reaches approximately 24 mm, the bending moment slows down with increasing load, reaching a peak at around 42 mm load, after which the bending moment drops sharply, indicating that the wing structure fails at this point and can no longer withstand the load. The maximum bending moment in the curve is taken as the ultimate bending strength of the wing structure under the damaged state. When the wing damage is a linear kinetic energy element distribution field incident at a vertical angle with a kinetic energy element density of 80 elements / m², the wing structure is considered to have failed. 2 When the damage to the wing is caused by a linear kinetic energy element distribution field with an incident angle of 30° and a kinetic energy element density of 80 elements / m, the ultimate bending moment is 352083 N·m. 2 When the load is generated under the specified conditions, its ultimate bending moment is 346781 N·m.

[0051] When the density of kinetic energy units in the focused impact kinetic energy unit distribution field reaches 81 units / m 2 The density of kinetic energy units in the linear kinetic energy unit distribution field reaches 51 units / m². 2 At this time, the remaining load-bearing capacity of the wing may be lower than the requirements under high overload conditions. According to the energy density calculation formula, we can obtain: ; ; ; ; Under these conditions, the energy density of the focused kinetic energy unit distribution field is: J / m 2 The energy density of the linear kinetic energy unit distribution field is J / m 2When the kinetic energy element density of the focused impact kinetic energy element distribution field reaches 119 elements / m 2 The kinetic energy element density of the linear kinetic energy element distribution field reaches 78 elements / m². 2 At this time, the structural integrity margin may be lower than that required under normal operating conditions. The calculated energy density of the focused kinetic energy unit distribution field under this condition is: J / m 2 The energy density of the linear kinetic energy unit distribution field is: J / m 2 .

[0052] Table 3: The final summary of the damage energy density thresholds for the wing structure is shown in the table below.

[0053] Step 5: Calculate the required bending moment load along the span of the wing under different specified maneuvering overload conditions using theoretical calculation methods, and define the damage judgment overload. The required bending moment at a specified station under the damage judgment overload is determined as the damage threshold. That is, when the wing passes through the impact of the kinetic energy unit group, if its actual bending moment is lower than the bending moment load threshold, the wing structure is judged to be damaged.

[0054] The calculation process for the bending moment of a single-sided aircraft wing under different overload conditions is as follows: Based on the triangular distribution law of wing loads, the bending moment borne by a region along the span is calculated. This calculation process can be expressed as follows: ; in, M This represents the bending moment experienced by a certain area along the span of the wing; Represents the wingspan of a single wing. b 1 Represents the wingspan of the aircraft wing; This represents the spanwise distance from the desired region to the wing root; y d represents the spanwise distance from any infinitesimal segment on the wing to the wing root; y It represents an infinitesimal length increment along the span direction; The load value representing the corresponding overload condition for a single wing can be calculated as follows: ; in, k This represents the proportion of the total load borne by a single wing to the total load of the aircraft. m Represents the aircraft's maximum overload weight; g Represents gravitational acceleration; n This represents the aircraft's overload value.

[0055] Different maneuvering overload conditions include high overload conditions and normal overload conditions. The overload value corresponding to the high overload condition is the design maximum overload, while the overload value corresponding to the normal overload condition is the overload value under normal operating conditions. When the wing experiences impact from a group of kinetic energy units, if its actual bending moment is lower than the bending moment load threshold, the wing structure is considered damaged. By setting different overload values, damage assessment criteria for the wing structure under different operating conditions can be established.

[0056] Step 6: Keeping the impact area unchanged, change the impact velocity, angle, and surface density of the kinetic energy element, and repeat steps 3 to 4 to obtain the curve of the remaining load-bearing capacity as a function of energy density; first verify the monotonicity of the curve, and then interpolate to solve for the critical energy density. E d With critical energy density E d This serves as a damage criterion for the wing structure under overload conditions, applied to the hit area. Energy density E d The calculation method is as follows: ; in, Representing the i The mass of each kinetic energy unit Representing the i The incident velocity of each kinetic energy unit, where A represents the force-bearing area of ​​the impacted structure surface. For a focused high-speed impact kinetic energy unit, the force-bearing area of ​​the impacted structure surface can be represented by the area of ​​the focusing zone.

[0057] Energy density calculations are performed for different types of kinetic energy unit distribution fields, including focused kinetic energy unit distribution fields and linear kinetic energy unit distribution fields. The calculation methods for the impact-bearing surface area differ between these two types of distribution fields: focused distribution fields use the area of ​​the focused zone, while linear distribution fields use the area of ​​the actual kinetic energy unit coverage area. By adjusting the distribution parameters of the kinetic energy units, a series of energy density values ​​and corresponding data points of remaining load-bearing capacity can be obtained. Plotting these data points as curves and performing interpolation calculations yields the critical energy density value corresponding to the sudden change in remaining load-bearing capacity. This critical energy density serves as the damage criterion for the wing structure under specific impact area conditions. When the actual energy density exceeds this critical value, the wing structure is considered to have suffered functional damage.

[0058] Step 7: Select other kinetic energy unit damage elements. The initial velocity of the kinetic energy unit damage elements is calculated using the method described in Step 3. Calculate the kinetic energy unit density corresponding to the damage element using the energy density value obtained in Step 6. After determining the above kinetic energy unit parameters, repeat Steps 3 and 4 to calculate the corresponding remaining load-bearing capacity, i.e., conduct finite element simulation of the wing structure impacted by the new damage element, and obtain the bending moment reduction of the wing structure with the kinetic energy unit perforated structure and compare it with the damage threshold. If the remaining bending moment of the wing structure after the impact of the new damage element is consistent with the set tolerance obtained in Step 5, then the energy density obtained in Step 6 is used as the damage criterion for the wing structure. If there is a large deviation, it is necessary to return to Step 6 to reanalyze the data or refine the criterion into a function of energy density and damage element type and recalibrate until verification is successful.

[0059] The verification process ensures the universality of the damage criterion. By changing parameters such as the initial velocity, incident angle, and distribution density of the kinetic energy elements, the correlation between the energy density threshold and the remaining structural bearing capacity is verified to remain consistent. If different kinetic energy element impact conditions yield consistent remaining bending moment values ​​for the wing structure after calculating the same energy density, it indicates that the energy density value can be used as a universal damage criterion for the wing structure.

[0060] The method described in this invention can accurately assess the damage level of an airfoil structure under the action of high-speed impact kinetic energy units. This method combines theoretical calculations and simulations to propose an energy density damage criterion for airfoil structures, providing a framework for establishing functional damage indicators for aircraft structures. By establishing a quantitative correlation between the kinetic energy unit distribution field parameters and the remaining load-bearing capacity of the structure, the method achieves the transformation from physical damage indicators to functional damage indicators.

[0061] The method of this invention establishes a quantitative correlation between kinetic energy unit distribution field parameters, structural remaining load-bearing capacity, and damage level by combining theoretical calculations with finite element simulation. This provides a quantifiable analytical basis for damage assessment of aircraft load-bearing structures, enabling the damage assessment results to directly reflect the actual load-bearing capacity of the structure in subsequent use.

[0062] The method described in this invention provides a process for establishing functional damage criteria for wing structures. This process can be extended to damage assessment of other types of aerospace structural components, including load-bearing components such as fuselages and tail fins, and has broad engineering application value, providing methodological support for damage assessment of aircraft-wide structures. The damage energy density threshold determined by this invention can accurately assess the degree of damage to the wing structure under high-speed impact kinetic energy. This energy density threshold is directly related to the aircraft's maneuverability requirements, providing an important reference for aircraft damage resistance design and structural safety margin analysis, and helping to determine the remaining service life and airworthiness of the structure after an impact.

[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for determining the energy density of wing damage under high-speed impact kinetic energy unit action, characterized in that, include: Step 1: Determine the specified verification conditions based on the target characteristics of the aircraft, and use aerodynamic engineering methods to calculate the aerodynamic load distribution along the span of the wing under these conditions. At the same time, according to the triangle distribution law, the ultimate bending moment of a specified area of ​​the wing on one side is obtained by integrating along the span. Step 2: Establish a complete finite element simulation model of the wing structure, carry out wing bending loading simulation under the same reference conditions as in Step 1, obtain the bending moment simulation results of the wing structure, and compare the simulation results with the theoretical calculation values ​​obtained in Step 1 to verify the reliability of the simulation model. Step 3: After fixing the impact area, use the velocity of the kinetic energy unit, the impact angle, and the unit surface density as variables to carry out finite element simulation of the impact of the kinetic energy unit group on the wing structure, and simulate different encounter attitudes between the kinetic energy unit and the wing structure. Define the penetration criteria, the morphology of the hole / aperture, and the element deletion criteria to obtain a simulation model of the wing structure with kinetic energy element perforations; Step 4: Using the wing structure simulation model with kinetic energy unit perforation obtained in Step 3 as input, conduct bending loading simulation to the critical state according to the same boundary conditions and failure criteria as in Step 2, obtain the remaining bending bearing capacity of the same specified section as in Step 1, and calculate the reduction in bending moment and damage degree relative to the complete wing. Step 5: Calculate the required bending moment load along the span of the wing under different specified maneuvering overload conditions using theoretical calculation methods, and define the damage judgment overload. The required bending moment at a specified station under the damage judgment overload is determined as the damage threshold. Step 6: Keeping the impact area unchanged, change the impact velocity, angle and unit surface density of the kinetic energy unit, and repeat steps 3 to 4 to obtain the curve of the remaining load-bearing capacity as a function of energy density; first verify the monotonicity of the curve, and then interpolate to solve the critical energy density, which will serve as the damage criterion for the wing structure under the overload condition of the impact area. Step 7: Select other kinetic energy unit damage elements, use the energy density value obtained in Step 6 to calculate the kinetic energy unit density corresponding to the damage element, and repeat Step 3 and Step 4 to calculate the corresponding remaining bearing capacity. Compare it with the damage threshold. If the deviation is within the set tolerance, the energy density criterion is determined to be applicable. If it exceeds the tolerance, a correction parameter is introduced, or the criterion is refined into a function of energy density and damage element type and then recalibrated.

2. The method for determining the energy density of wing damage under high-speed impact kinetic energy unit action as described in claim 1, characterized in that, In step 1, the wing loading triangle distribution rule is specifically as follows: Along the span of the wing, the load decreases linearly from the wing root to the wingtip, with the maximum load at the wing root and zero load at the wingtip.

3. The method for determining the energy density of wing damage under the action of a high-speed impact kinetic energy unit as described in claim 1, characterized in that, In step 1, the ultimate bending moment of a specified area on one side of the wing is: ； in, This represents the bending moment experienced by a certain area along the span of the wing; Represents the wingspan of a single wing. b 1 Represents the wingspan of the aircraft wing; This represents the spanwise distance from the region in question to the wing root, and its value ranges from 0 to... ; y d represents the spanwise distance from any infinitesimal segment on the wing to the wing root; y It represents an infinitesimal length increment along the span direction; The ultimate load value representing a single wing is calculated as follows: ； in, This represents the proportion of the total load borne by a single wing to the total load of the aircraft. Represents the structural safety factor. m The value represents the aircraft's maximum overload weight, and g represents the acceleration due to gravity. This represents the maximum design overload of the aircraft.

4. The method for determining the energy density of wing damage under high-speed impact kinetic energy unit action as described in claim 1, characterized in that, Step 3, the calculation process for the velocity of the kinetic energy unit includes: First, calculate the initial velocity of the kinetic energy unit during the transient energy release of the high-energy impact source: ； in, This represents the initial velocity of the kinetic energy unit when the transient energy is released from a high-energy impact source. Represents the empirical coefficient of initial velocity. E Represents the transient energy of the impact source; Represents the mass ratio of energy materials; Secondly, the velocity of the impact kinetic energy unit during its scattering process is calculated to gradually decrease with increasing flight distance due to air resistance, resulting in the following velocity upon reaching the structural surface: ； in, This represents the velocity at which the kinetic energy unit reaches the surface of the structure. Represents air density; This represents the average frontal area of ​​the kinetic energy unit; Represents the mass of the kinetic energy unit; L Represents the flight distance of the kinetic energy unit; e Represents the natural constant; The drag coefficient is represented by the following formula: 。 5. The method for determining the energy density of wing damage under the action of a high-speed impact kinetic energy unit as described in claim 1, characterized in that, In step 3, the impact angle of the kinetic energy unit is , Let be the angle between the incident velocity direction of the kinetic energy element and the normal direction of the wing structure surface at the impact location. As the incident direction of the kinetic energy element gradually deviates from the normal direction... Increase.

6. The method for determining the energy density of wing damage under the action of a high-speed impact kinetic energy unit as described in claim 1, characterized in that, Step 3, the calculation process for the kinetic energy unit density includes: ； in, ρ Represents the density of kinetic energy units; N This represents the number of kinetic energy units within the effective impact area. A This represents the effective impact area.

7. The method for determining the energy density of wing damage under high-speed impact kinetic energy unit action as described in claim 1, characterized in that, Step 4, the calculation process for the reduction in wing load-bearing bending moment includes: ； in, Represents the reduction in bending moment. This represents the maximum bending moment that a specified area of ​​the wing can withstand when it is in its complete state. This represents the maximum bending moment that the wing can withstand after being impacted by a group of kinetic energy units.

8. The method for determining the energy density of wing damage under high-speed impact kinetic energy unit action as described in claim 1, characterized in that, Step 5, the calculation process for the wing's spanwise bending moment load under different maneuvering overload conditions includes: The bending moment in a spanwise region is calculated based on the triangular distribution law of aircraft wing loads. The calculation process is as follows: ； in, M This represents the bending moment experienced by a certain area along the span of the wing; Represents the wingspan of a single wing. b 1 Represents the wingspan of the aircraft wing; This represents the spanwise distance from the desired region to the wing root; y d represents the spanwise distance from any infinitesimal segment on the wing to the wing root; y It represents an infinitesimal length increment along the span direction; The load values ​​representing the corresponding overload conditions for a single wing: ； in, k This represents the proportion of the total load borne by a single wing to the total load of the aircraft. m Represents the aircraft's maximum overload weight; g Represents gravitational acceleration; n This represents the aircraft's overload value.

9. The method for determining the energy density of wing damage under the action of a high-speed impact kinetic energy unit as described in claim 1, characterized in that, Step 6, the calculation process for energy density includes: ； in, E d Represents energy density; Representing the i The mass of each kinetic energy unit; Representing the i The incident velocity of each kinetic energy unit; A represents the force-bearing area of ​​the impacted structure surface.

10. The method for determining the energy density of wing damage under the action of a high-speed impact kinetic energy unit as described in claim 1, characterized in that, In step 7, the initial velocity of the kinetic energy unit damage element is calculated from step 3.

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