Civil aircraft strength assessment requirement model construction and verification method based on system engineering

Abstract

The application provides a civil aircraft strength evaluation requirement model construction and verification method based on system engineering, which comprises the following steps: S1, establishing a stakeholder requirement database; S2, constructing a top-level requirement model; S3, establishing an application scenario database based on the top-level requirement model, and establishing a corresponding relationship between the top-level requirement and the scenario; S4, constructing a civil aircraft strength evaluation requirement model based on the corresponding relationship between the top-level requirement and the scenario; S5, verifying the requirement traceability chain in the civil aircraft strength evaluation requirement model, and rectifying the requirement traceability chain that does not meet the requirements. The method can establish a stakeholder requirement-top-level requirement-scenario-architecture-verification requirement traceability chain, so that the source of a verification requirement from a stakeholder requirement can be quickly understood, when a stakeholder requirement is changed, the strength evaluation method that needs to be modified related to the stakeholder requirement can be quickly located, and the related model can be modified, and various scenario requirements can be met.

Description

Technical Field

[0001] This invention relates to the field of civil aircraft demand evaluation, specifically to a method for constructing and verifying a civil aircraft strength assessment demand model based on systems engineering. Background Technology

[0002] Structural strength assessment is a crucial step in the development of civil aircraft. Structural strength verification planning must not only meet airworthiness regulations but also consider the needs of stakeholders such as users and operators, making it a complex systems engineering process.

[0003] Civil aircraft are typical complex systems involving multiple stakeholders. The entire development process involves the integration and verification of numerous products at different levels to demonstrate product conformity to relevant requirements. Requirements-based verification technology has become the best practice for solving verification and integration issues in the development process of complex products. Structural strength assessment of civil aircraft involves verification activities at the material, component, assembly, and overall aircraft levels, making it a complex systems engineering project. A comprehensive structural strength assessment plan for civil aircraft is a crucial prerequisite and fundamental guarantee for achieving full aircraft integrity assessment and verification, and ensuring aircraft operational safety. Clearly, accurate requirements capture is a key step in conducting structural strength assessment of civil aircraft.

[0004] Since structural strength specialists are not responsible for the design of specific systems or products, decomposing the structural strength design and assessment requirements for civil aircraft to systems, subsystems, and products often results in "general requirements that cannot be implemented." Using the MBSE method and SysML modeling language to capture and model the requirements for civil aircraft structural strength assessment not only enables hierarchical management of these requirements and clarifies the hierarchical relationships between them, but also clearly presents the work objects and content of the step-by-step verification of these requirements. However, the specific application of MBSE in the aircraft structural strength design and assessment process still lacks practical experience. Traditional methods suffer from incomplete information collection, non-standardized processes, incomplete analysis, incomplete verification systems, and unsystematic planning.

[0005] In summary, there is an urgent need for a complete and comprehensive model for assessing the strength of civil aircraft and a corresponding evaluation method. Summary of the Invention

[0006] To address the shortcomings of the existing technologies, the present invention aims to provide a system engineering-based method for constructing and verifying a civil aircraft strength assessment requirement model. This method establishes a traceability chain from stakeholder requirements to top-level requirements, scenarios, architecture, and verification requirements, enabling rapid identification of which stakeholder requirement a verification requirement originates from. When a stakeholder requirement changes, the method can quickly locate the relevant model that needs modification and make the necessary changes. The overall method is convenient and efficient, and can meet the needs of various scenarios.

[0007] Specifically, this invention provides a method for constructing and verifying a civil aircraft strength assessment requirement model based on systems engineering, which includes the following steps:

[0008] S1. Establish a stakeholder demand database; the stakeholder demand database includes a static strength demand database, a dynamic strength demand database, a fatigue demand database, and an aeroelasticity demand database.

[0009] S2. Construct the top-level requirements model. The specific construction method is as follows:

[0010] S21. Based on the stakeholder requirements established in step S1, determine whether the requirements need to be analyzed at the top level. If the stakeholder requirements need to be analyzed at the top level, proceed to step S22.

[0011] S22. Use the decomposition module to decompose the needs of stakeholders that require top-level needs analysis, determine the object level corresponding to the needs, and determine the top-level needs corresponding to the needs based on the object level.

[0012] The disassembly conditions for the disassembly module are as follows:

[0013] Where A represents a stakeholder requirement, a represents aircraft-level requirement, b represents component-level requirement, c represents part-component-level requirement, and d represents material-level requirement.

[0014] The disassembly result is: A→A1+A2+A3+A4;

[0015] S23. Construct and output a top-level requirement model using a requirement table or requirement diagram, based on requirement number, requirement name, requirement content, requirement level, and requirement source attribute.

[0016] S3. Establish an application scenario database based on the top-level requirement model, and establish the correspondence between top-level requirements and scenarios;

[0017] S4. Construct a civil aircraft strength assessment requirement model based on the correspondence between top-level requirements and scenarios. The civil aircraft strength assessment requirement model includes a requirement traceability chain.

[0018] S5. Verify the demand traceability chain in the civil aircraft strength assessment demand model, and rectify any non-compliant demand traceability chains. This includes the following sub-steps:

[0019] S51. Traceability chain integrity verification, which includes the following sub-steps:

[0020] S511. Based on the traceability relationship of the civil aircraft strength assessment demand model established in steps S1-S4, a global traceability relationship table is formed in the computer. Based on the global traceability relationship table, the completeness of the traceability chain is first verified to see if there are any scenarios where the needs of stakeholders have not been analyzed or matched. For incomplete traceability chains, steps S1 to S4 need to be repeated. After all are completed, proceed to step S512.

[0021] S512. Determine whether all scenarios have completed intensity assessment requirement matching. If there are scenarios that have not completed intensity assessment requirement matching, continue to steps S3 to S4. If all scenarios have completed the matching, proceed to step S52.

[0022] S52. Feasibility verification of the demand traceability chain, calculating the feasibility degree c of the demand traceability chain, specifically including the following sub-steps:

[0023] S521, Calculate the feasibility c1 of the top-level requirement-scenario traceability chain:

[0024] Each top-level requirement-scenario traceability chain includes three dimensions: operational condition completeness, scenario coverage, and historical data conformity of similar aircraft. Each of these three dimensions is scored sequentially (z1, z2, z3 ∈ [0-10]), and weights are assigned to each (a1, a2, a3, where a1 + a2 + a3 = 1). The feasibility c1 is calculated using the following formula:

[0025]

[0026] S522, Calculation scenario - feasibility of the traceability chain for strength assessment requirements c2:

[0027] Each scenario-strength assessment requirement traceability chain includes seven dimensions: integrity of load-bearing components, compliance of static calculation results, compliance of dynamic calculation results, compliance of fatigue calculation results, compliance of aerodynamic calculation results, rationality of verification methods, and compliance of strength assessment methods for similar aircraft. Each of the seven dimensions is scored sequentially as y1, y2, y3, y4, y5, y6, y7 ∈ [0-10], where y1, y2, y3, y4, y5, y6, y7 are the seven dimensions, and weights b1, b2, b3, b4, b5, b6, b7 are assigned to each dimension, satisfying b1+b2+b3+b4+b5+b6+b7=1. The feasibility c2 is calculated using the following formula:

[0028]

[0029] S523. Calculate the feasibility c of the demand traceability chain. The calculation formula is as follows:

[0030] c = min(c1, c2);

[0031] S524. Compare the calculated feasibility c of the demand traceability chain with the set feasibility threshold c0. The feasibility threshold c0∈[0-10]. If c≥c0, the demand traceability chain is determined to meet the requirements. If c<c0, the demand traceability chain is determined to not meet the requirements. Then, modify the top-level requirements corresponding to the scenario and repeat step S5.

[0032] Preferably, in step S4, a traceability matrix is ​​used to express the traceability relationship between the architecture and the scenario, connecting the elements in the architecture model with the related use cases; a traceability matrix is ​​also used to express the traceability relationship between the verification requirements and the architecture, connecting the strength assessment requirements with the related architecture model elements.

[0033] Preferably, step S1 specifically includes the following sub-steps:

[0034] S11. Identify stakeholder needs;

[0035] S12. Construct a stakeholder law requirement database based on the identified stakeholder law requirements. Each database includes a requirement number, requirement name, requirement content, and requirement source.

[0036] Preferably, top-level requirements include airworthiness regulations, standards, and user requirements.

[0037] Preferably, step S3 specifically includes the following sub-steps:

[0038] S31. Determine aircraft scenarios and use cases: For the mission of the model, list the aircraft usage scenarios related to the top-level requirements, and select the top-level measures or solutions to be taken in terms of structure as use cases based on the determined usage scenarios.

[0039] S32. Establish an application scenario database in a one-to-one correspondence manner. The application scenario database includes top-level requirements, usage scenarios, and use cases, and there is a one-to-one correspondence between the top-level requirements, usage scenarios, and use cases.

[0040] Preferably, in step S31, the flight scenario and use case modeling adopts use case diagram modeling. In the use case diagram, the square represents the scenario, the ellipse represents the working condition under this use scenario, the constraint attributes below can describe the state of the aircraft under this scenario, the cube element represents the external participant, and the arrow expresses the information or energy interaction between the external participant and the aircraft under this scenario and working condition.

[0041] Preferably, step S4 specifically includes the following sub-steps:

[0042] S41. Based on top-level requirements and scenarios, determine the specific content of the system's strength assessment requirements, which include strength design requirements and structural strength design schemes.

[0043] S42. When there is a conflict between the same system requirements and the strength assessment requirements, the multiple strength assessment requirements shall be sorted according to their weights, and the strength assessment requirement with the highest weight value shall be selected as the final strength assessment requirement.

[0044] S43. Based on the determined final strength assessment requirements, construct a civil aircraft strength assessment requirement model and output multiple requirement traceability chains. The requirement traceability chain includes top-level requirements, scenarios, use cases, and strength assessment methods.

[0045] Preferably, in step S41, the load is further allocated according to the scenario and working conditions, and a strength bearing scheme for each level is constructed to finally form a strength assessment requirement model.

[0046] The strength assessment requirement model is modeled using a module definition diagram based on the architecture design results. It reflects the load-bearing parts directly related to this scenario and the corresponding strength design schemes of the load-bearing parts under stress.

[0047] Preferably, if the module definition diagram in step S41 is a whole-machine level or component level load-bearing structure, then it continues to be allocated to the component and material level.

[0048] On the other hand, the present invention also provides a system for constructing and evaluating a civil aircraft strength assessment requirement model based on systems engineering. This system includes a stakeholder requirement database construction module, a top-level requirement model construction module, an application scenario database construction module, a civil aircraft strength assessment requirement model construction module, and a requirement traceability chain verification module, all interconnected. The stakeholder requirement database construction module is used to construct a stakeholder requirement database; the top-level requirement model construction module is used to construct a top-level requirement model; the application scenario database construction module is used to construct an application scenario database; the civil aircraft strength assessment requirement model construction module is used to construct civil aircraft strength assessment requirements; and the requirement traceability chain verification module is used to verify the requirement traceability chain and rectify any non-compliant requirement traceability chains.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] (1) The civil aircraft strength assessment requirement model construction and verification method proposed in this invention based on systems engineering can establish a traceability chain of stakeholder requirements-top-level requirements-scenario-architecture-verification requirements, thereby quickly understanding which stakeholder requirement a certain verification requirement comes from. When a stakeholder requirement changes, the model that needs to be modified can be quickly located and the relevant model can be modified. The overall method is convenient and fast and can meet the requirements of various scenarios.

[0051] (2) By verifying the feasibility of the demand traceability chain, this invention can ensure the integrity and feasibility of the demand traceability chain, and ensure that the relationship between demand, architecture and strength assessment is accurate and unique, thereby enabling the rapid tracing of the strength model related to the demand of the stakeholder method, and thus making modifications. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the method flow for constructing and verifying a civil aircraft strength assessment requirement model based on systems engineering, as described in this invention.

[0053] Figure 2 This is a schematic diagram of the overall process of an embodiment of the present invention;

[0054] Figure 3 This is a schematic block diagram of the system of the present invention;

[0055] Figure 4 This invention provides a model diagram illustrating the application scenarios.

[0056] Figure 5 This is a schematic diagram illustrating the top-level requirements and application scenario tracing relationship of this invention;

[0057] Figure 6 This is a schematic diagram of the strength assessment requirement architecture and traceability relationship model of this invention. Detailed Implementation

[0058] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0059] This invention provides a method for constructing and verifying a civil aircraft strength assessment requirement model based on systems engineering, such as... Figure 1 As shown, it includes the following steps:

[0060] S1. Establish a stakeholder demand database; the stakeholder demand database includes a static strength demand database, a dynamic strength demand database, a fatigue demand database, and an aeroelasticity demand database.

[0061] Step S1 specifically includes the following sub-steps:

[0062] S11. Identify stakeholder needs.

[0063] S12. Construct a stakeholder law requirements database based on the identified stakeholder law requirements. Each database includes a requirement number, requirement name, requirement content, and requirement source. The final stakeholder law requirements database is shown in Table 1. The elements included in the stakeholder law requirements database are serial number, requirement category, and stakeholder requirements.

[0064] Table 1 Stakeholder Needs Database

[0065]

[0066]

[0067]

[0068]

[0069] S2. Construct the top-level requirements model. The specific construction method is as follows:

[0070] S21. Based on the stakeholder requirements established in step S1, determine whether the requirements need to be analyzed at the top level. If the stakeholder requirements need to be analyzed at the top level, proceed to step S22.

[0071] S22. Use the decomposition module to decompose the stakeholder requirements that need to be analyzed at the top level, determine the object level corresponding to the requirement, and determine the top-level requirement corresponding to the requirement based on the object level.

[0072] S23. Construct and output the top-level requirement model in tabular form.

[0073] The disassembly conditions for the disassembly module are as follows:

[0074] Where A represents a stakeholder requirement, a represents aircraft-level requirement, b represents component-level requirement, c represents part-component-level requirement, and d represents material-level requirement.

[0075] The disassembly result is: A→A1+A2+A3+A4;

[0076] For example, based on the description, section (a), (b), (c), and (d) of standard 25.365 "Pressure Chamber Load" are aircraft-level requirements, while sections (e), (f), and (g) are component-level requirements. Therefore, it needs to be broken down into two parts: 25.365(a), (b), (c), and (d) and 25.365(e), (f), and (g). Standard 67.5 is an aircraft-level requirement. Standard 5.631 "Bird Strike Damage" is a component-level requirement. Standard 25.875 "Reinforcement of the Propeller Proxima Cavity" is a component-level requirement. The number of takeoffs and landings requirement for firefighting aircraft is an aircraft-level requirement. The calendar life requirement for firefighting aircraft is an aircraft-level requirement.

[0077] Standard 25.629, "Aeroelastic Stability Requirements," is an aircraft-level requirement.

[0078] S23. Construct and output a top-level requirement model using a requirement table or requirement diagram, based on the requirement number, requirement name, requirement content, requirement level, and requirement source attribute.

[0079] S3. Establish an application scenario database based on the top-level requirement model, and establish the correspondence between top-level requirements and scenarios.

[0080] Step S3 specifically includes the following sub-steps:

[0081] S31. Determine aircraft scenarios and use cases: For the mission of the model, list the aircraft usage scenarios related to the top-level requirements, and select the top-level measures or solutions to be adopted in terms of structure as use cases based on the determined usage scenarios.

[0082] S32. Establish an application scenario database in a one-to-one correspondence manner. The application scenario database includes top-level requirements, usage scenarios, and use cases, with each of these elements corresponding to the others. The final application scenario database is shown in Table 2. The elements of the application scenario database include serial number, scenario level, professional category, application scenario, operating condition, external participants, and load and energy interaction.

[0083] Table 2 Application Scenario Database

[0084]

[0085]

[0086] Flight scenario and use case modeling uses use case diagrams. Boxes represent scenarios, ellipses represent operating conditions within those scenarios, and the constraint attributes below describe the aircraft's state in each scenario, including speed, altitude, etc. Cube elements represent external actors, and arrows represent the information or energy interactions between external actors and the aircraft in those scenarios and operating conditions. The meanings of each model element are shown in Table 3. Each model element includes an element diagram, icon name, and explanation.

[0087] Table 3. Model element definitions in the use case diagram.

[0088]

[0089] The final modeling output is an application scenario model, such as Figure 4 As shown in the diagram. The top-level requirement-application scenario tracing relationship is illustrated below. Figure 5 As shown.

[0090] S4. Construct a civil aircraft strength assessment requirement model based on the correspondence between top-level requirements and scenarios, which includes the following sub-steps:

[0091] S41. Based on top-level requirements and scenarios, determine the specific content of the system's strength assessment requirements, which include strength design requirements and structural strength design schemes.

[0092] S42. When there is a conflict between the same system requirements and the strength assessment requirements, the multiple strength assessment requirements shall be sorted according to their weights, and the strength assessment requirement with the highest weight value shall be selected as the final strength assessment requirement.

[0093] S43. Based on the determined final strength assessment requirements, construct a civil aircraft strength assessment requirement model and output multiple requirement traceability chains. The requirement traceability chain includes top-level requirements, scenarios, use cases, and strength assessment methods.

[0094] Further load allocation is carried out based on the scenario and working conditions, and a strength bearing scheme for each level is constructed, ultimately forming a strength assessment requirement model as shown in Table 4. The elements of the requirement traceability chain of the strength assessment requirement model include serial number, scenario and working condition, aircraft-level bearing requirements, component-level bearing requirements, part-component-level bearing requirements, material-level bearing requirements, and assessment requirements.

[0095] Table 4 Strength Assessment Demand Model

[0096]

[0097]

[0098]

[0099]

[0100] Strength assessment requirement model construction: Based on the architecture design results, a module definition diagram can be used for modeling. This mainly reflects the load-bearing components directly related to this scenario, which can be the entire machine, parts, components, or materials, as well as the corresponding strength design schemes for these load-bearing components under stress. If the load-bearing scheme is at the whole machine or component level, it can be further allocated to the component and material levels, and then modeling can continue down to the next lower level.

[0101] The meanings of each model element in the module definition diagram are shown in Table 5 below.

[0102] Table 5. Architecture Diagram Element Definitions

[0103]

[0104]

[0105] Subsequently, the strength assessment requirement framework and traceability relationship model were finally formed.

[0106] S5. Verify the demand traceability chain in the civil aircraft strength assessment demand model, and rectify any non-compliant demand traceability chains. This includes the following sub-steps:

[0107] S51. Traceability chain integrity verification, which includes the following sub-steps:

[0108] S511. Based on the traceability relationship of the civil aircraft strength assessment demand model established in steps S1-S4, a global traceability relationship table is formed in the computer. Based on the global traceability relationship table, the integrity of the traceability chain is first verified to see if there are any scenarios where the needs of stakeholders have not been analyzed or matched. For incomplete traceability chains, steps S1 to S4 need to be repeated. After all are completed, proceed to step S512.

[0109] S512. Determine whether all scenarios have completed intensity assessment requirement matching. If there are scenarios that have not completed intensity assessment requirement matching, continue to steps S3 to S4. If all scenarios have completed the matching, proceed to step S52.

[0110] S52. Feasibility verification of the demand traceability chain, calculating the feasibility degree c of the demand traceability chain, specifically including the following sub-steps:

[0111] S521, Calculate the feasibility c1 of the top-level requirement-scenario traceability chain:

[0112] Each top-level requirement-scenario traceability chain includes three dimensions: operational condition completeness, scenario coverage, and consistency with historical data of similar aircraft. Each of these three dimensions is scored sequentially (z1, z2, z3 ∈ ...).

[0113] [0-10]), and assign weights (a1, a2, a3, which must satisfy a1+a2+a3=1); calculate the feasibility c1 using the following formula:

[0114]

[0115] S522, Calculation scenario - feasibility of the traceability chain for strength assessment requirements c2:

[0116] Each scenario-strength assessment requirement traceability chain includes seven dimensions: integrity of load-bearing components, compliance of static calculation results, compliance of dynamic calculation results, compliance of fatigue calculation results, compliance of aerodynamic calculation results, rationality of verification methods, and compliance of strength assessment methods for similar aircraft. Each of the seven dimensions is scored sequentially as y1, y2, y3, y4, y5, y6, y7 ∈ [0-10], where y1, y2, y3, y4, y5, y6, y7 are the seven dimensions, and weights b1, b2, b3, b4, b5, b6, b7 are assigned to each dimension, satisfying b1+b2+b3+b4+b5+b6+b7=1. The feasibility c2 is calculated using the following formula:

[0117]

[0118] S523. Calculate the feasibility c of the demand traceability chain. The calculation formula is as follows:

[0119] c = min(c1, c2).

[0120] S524. Compare the calculated feasibility c of the demand traceability chain with the set feasibility threshold c0. The feasibility threshold c0∈[0-10]. If c≥c0, the demand traceability chain is determined to meet the requirements. If c<c0, the demand traceability chain is determined to not meet the requirements. Then, modify the top-level requirements corresponding to the scenario and repeat step S5.

[0121] On the other hand, this invention also provides a system for constructing and evaluating a civil aircraft strength assessment requirement model based on systems engineering, such as... Figure 3 As shown, it includes a stakeholder demand database construction module 1, a top-level demand model construction module 2, an application scenario database construction module 3, a civil aircraft strength assessment demand model construction module 4, and a demand traceability chain verification module 5, all of which are interconnected. The stakeholder demand database construction module 1 is used to construct the stakeholder demand database, the top-level demand model construction module 2 is used to construct the top-level demand model, the application scenario database construction module 3 is used to construct the application scenario database, the civil aircraft strength assessment demand model construction module 4 is used to construct the civil aircraft strength assessment demand, and the demand traceability chain verification module 5 is used to verify the demand traceability chain and rectify any non-compliant demand traceability chains. Specific Implementation

[0123] This embodiment takes a specific civil aircraft as an example to assess its demand and intensity, specifically including the following steps:

[0124] S1. Establish a stakeholder needs database, which includes the following sub-steps:

[0125] Identifying Stakeholder Requirements: First, the stakeholders involved in the strength design of civil aircraft are identified. Stakeholders include organizations and personnel involved in the entire lifecycle of civil aircraft strength design, manufacturing, testing, use, repair, and decommissioning, including airworthiness authorities, airworthiness certification centers, users, operators, and testing personnel. After collecting the requirements, these stakeholder requirements are categorized, interpreted, merged, and tailored. Strength requirements are generally classified into five categories: static strength, dynamic strength, fatigue, aeroelasticity, and composite materials. Then, a stakeholder requirements database is constructed based on the identified stakeholder requirements.

[0126] S2. Construct the top-level requirements model. The specific construction method is as follows:

[0127] S21. Based on the stakeholder requirements established in step S1, determine whether the requirements need to be analyzed at the top level. If the stakeholder requirements need to be analyzed at the top level, proceed to step S22.

[0128] When a stakeholder demand involves multiple levels of an aircraft (including but not limited to aircraft level, component level, part level, and material level), it needs to be broken down and interpreted to determine the corresponding top-level analysis object. Management should then be carried out according to these levels.

[0129] S22. Use the decomposition module to decompose the stakeholder requirements that require top-level requirement analysis, determine the object level corresponding to the requirement, and determine the top-level requirement corresponding to the requirement.

[0130] S23. Construct and output the top-level requirement model in tabular form.

[0131] In this embodiment, the airworthiness clause FAR 25.631, "Bird Strike Damage," is used as an example. The original text of the clause is: "The tail structure must be designed to ensure that the aircraft can continue to be mounted and landed after a collision with a bird weighing 3.6 kg (8 lb), at which point the aircraft's velocity (along its flight path relative to the bird) is equal to Vc at sea level. It is acceptable to meet this requirement by employing statically indeterminate structures and placing control system components in protected locations, or by employing protective devices (such as bulkheads or energy-absorbing materials). It is acceptable to use data from aircraft with similar structural designs where compliance with this requirement is demonstrated by analysis, testing, or a combination of both."

[0132] According to the aforementioned airworthiness requirements, the aircraft's tail structure design must ensure that the aircraft can continue to fly and land safely after colliding with an 8-pound (3.6 kg) bird. The relative velocity between the bird and the aircraft at the time of impact (along the aircraft's flight path) must be equal to V at sea level. c (Design cruise speed).

[0133] The bird strike damage assessment requirements only involve the dynamic strength requirements at the tail fin component level, therefore this stakeholder requirement corresponds to only one top-level requirement. The top-level requirement model is constructed in the form of a requirement table, expressing the stakeholder requirements for the design requirements of the tail fin structure regarding bird strike damage. Designers can summarize and simplify the description of the requirements based on experience.

[0134] S3. Establish an application scenario database based on the top-level requirement model, and establish the correspondence between top-level requirements and scenarios. This includes the following sub-steps:

[0135] S31. Determine aircraft scenarios and use cases: For the mission of the model, list the aircraft usage scenarios related to the top-level requirements, and select the top-level measures or solutions to be adopted in terms of structure as use cases based on the determined usage scenarios.

[0136] S32. Establish an application scenario database in a one-to-one correspondence manner. The application scenario database includes top-level requirements, usage scenarios, and use cases, and there is a one-to-one correspondence between the top-level requirements, usage scenarios, and use cases.

[0137] Flight scenarios are based on stakeholder needs, treating the top-level systems related to those needs as black boxes. They allocate needs to the systems, determining the load scenarios under which the structures of these systems are designed for strength. These scenarios are used to calculate loads, determine typical mission profiles, and clarify the aircraft's operating environment. These scenarios should include typical load conditions, harsh operating environments, and typical mission profiles for the structure. Therefore, the key to scenario analysis is studying the external conditions under which the system bears the loads.

[0138] The specific operation involves listing the aircraft usage scenarios related to the "requirements" for each model's mission: explaining and listing the typical application scenarios of the "strength assessment requirements" obtained from the "stakeholder analysis." The purpose is to help identify the main external loads related to the "requirements."

[0139] Finally, the following content was extracted:

[0140] Scenarios (such as forest fire fighting in mountainous areas, water rescue at sea, airport take-off and landing, high-altitude flight (greater than 7000m), aircraft mooring, etc.).

[0141] Scene characteristics, that is, the state of the object being analyzed in this scene (flight altitude, speed, attitude).

[0142] Load-bearing requirements (explain what external loads it needs to withstand and what strength indicators it needs to meet?).

[0143] Use cases are the top-level structural measures or solutions adopted by the system to meet the strength requirements. Constructing system use cases requires attention to two issues:

[0144] What systems are involved?

[0145] What loads should it bear (or what strength specifications must it meet)?

[0146] Specifically, system use cases are designed to address which structural or system components bear the external loads associated with the "requirement." In other words, by constructing system use cases, the intensity requirement is put into practice.

[0147] (The load-bearing) machine structure or system (which can be the whole machine, component or part, or a system or part of its structure).

[0148] Load-bearing requirements (explain what external loads it needs to withstand and what strength indicators it needs to meet?).

[0149] Analysis hierarchy.

[0150] Finally, based on different scenarios and use cases, the influencing factors of the use cases, namely the external interaction objects of the research object and the information and energy interactions between them, are analyzed. This step also helps strength designers distinguish different use cases.

[0151] Flight scenarios and use case modeling employs use case diagrams. Boxes represent scenarios, ellipses represent operating conditions within those scenarios, and the constraint attributes below describe the aircraft's state in each scenario, including speed, altitude, etc. Cube elements represent external actors, and arrows represent the information or energy interactions between external actors and the aircraft in each scenario and operating condition.

[0152] For example, in the "bird strike" case in Section 1, the analysis results are as follows: One of the flight scenarios corresponding to this requirement is low-altitude flight. In low-altitude flight, the speed range is such that the relative speed between the bird and the aircraft equals the design cruising speed Vc at sea level; the operating condition is "bird strike"; the cube represents the external participant, which in this case is the "bird"; the arrows can represent the information or energy interaction between the external participant and the aircraft in this scenario and operating condition, which in this case is the impact force of the bird on the aircraft of 3.6 kg. The modeling results are shown below. Figure 2 .

[0153] S4. Construct a civil aircraft strength assessment requirement model based on the correspondence between top-level requirements and scenarios, which includes the following sub-steps:

[0154] S41. Based on top-level requirements and scenarios, determine the specific content of the system's strength assessment requirements, which include strength design requirements and structural strength design schemes.

[0155] Based on the top-level load-bearing requirements of the system, the system is treated as a white box, and the requirements are further decomposed and analyzed downwards to obtain load-bearing solutions at lower levels. The granularity of system requirement decomposition should be refined to a level that each discipline can implement in aircraft design. If different stakeholders have different requirements for the strength of the same system, analysis, comprehensive consideration, and trade-offs should be conducted to determine a comprehensive optimal solution.

[0156] The main task of system architecture design is to determine the specific requirements of the system in terms of strength assessment, that is, detailed and specific strength design requirements or detailed structural strength design schemes, which is a further decomposition of system requirements. The granularity of system requirement decomposition should be refined to a level that each discipline can implement in aircraft design.

[0157] Specifically, system architecture design mainly involves breaking down "requirements" into more detailed and specific design requirements for the structural / system structure. In other words, it's about developing a strength plan.

[0158] Detailed and specific strength design requirements or detailed structural strength design schemes represent a further decomposition of system requirements. The granularity of this system requirement decomposition should be refined to a level that each discipline can implement in aircraft design.

[0159] In practice, this step is essential. First, in most cases, after stakeholder analysis, scenario analysis, and system use cases, the resulting aircraft strength assessment requirements are still relatively general and not easily usable by other disciplines (those specifically responsible for the drawings). For example, if only the lifespan index is given for an aircraft, the structural engineering discipline cannot use it; further stress level limits are needed for practical operation. Second, for the verification content corresponding to the strength assessment requirements, whether in static / dynamic strength, fatigue / damage tolerance, or aeroelasticity, there is a coexistence of experimental and analytical methods. Through the system architecture analysis and design step, the strength assessment requirements can be further decomposed and specified, facilitating verification through calculation and analysis.

[0160] More specific and detailed machine structure or system (Note: This can be the whole machine, component or part, or a system or part of its structure).

[0161] Explain what loads the above structures or systems bear (or what strength requirements they should meet).

[0162] Analysis hierarchy.

[0163] Based on the architecture design results, a module definition diagram can be used for modeling. This primarily reflects the load-bearing components directly related to this scenario, which can be the entire machine, parts, components, or materials, as well as the corresponding strength design schemes for these load-bearing components under stress. If the load-bearing scheme is at the machine or component level, it can be further allocated to the component and material levels, and then modeling can continue down to the next lower level.

[0164] Simulation analysis and flight statistics show that the most likely parts of the tail structure to be struck by birds are the leading edges of the horizontal and vertical stabilizers. Typical tail structure damage includes: leading edge skin dents, indentations, skin tears, joint failures, skin and spars penetration, delamination and debonding of composite materials, and even potential frame fracture and stabilizer failure. To ensure the aircraft can continue to fly and land safely after a bird strike, the damaged structure must meet structural integrity requirements in terms of strength, stiffness, damage tolerance, and aeroelastic stability (see requirements of FAR 25.571 and 25.629, etc.), and the aircraft's control system must remain controllable. Furthermore, if fuel tanks are installed on the tail structure (such as the horizontal tail fuel tanks of the Airbus A380 and Boeing 747), it must be ensured that the fuel tanks and related fuel systems will not catch fire due to fuel spillage from a bird strike.

[0165] In this case, the part directly related to the low-altitude flight scenario—the bird strike—is the component-level tail structure. The tail structure does not house fuel tanks. Disassembling it further, its load-bearing components are: horizontal stabilizer and elevator, vertical stabilizer and rudder, and dorsal fin. The load-bearing requirement is: a collision with an 8-pound (3.6 kg) bird (the relative velocity between the bird and the aircraft is equal to V at sea level). c Even so, it can continue to fly and land safely. The strength design requirements for each component are:

[0166] ① The leading edge of the vertical or horizontal tail.

[0167] Penetration of the leading edges of the vertical and horizontal stabilizers is permitted, and the remaining strength of the front beam must meet the requirements of discrete source loads. No equipment, pipelines, control systems, or cables that could affect safe flight after a bird strike must be placed within the leading edges of the vertical and horizontal stabilizers. The aerodynamic impact of penetrating the leading edges of the vertical and horizontal stabilizers must be assessed.

[0168] ② Dorsal fin.

[0169] The dorsal fin may be penetrated; however, no equipment, piping, control systems, or cables may be placed inside the dorsal fin that would impair safe flight after a bird strike; the aerodynamic impact of dorsal fin damage must be assessed.

[0170] ③Rudder and elevator.

[0171] Rudder and elevator are permissible to be damaged; assess the impact of rudder and elevator damage on aerodynamic and handling stability.

[0172] Architectural models such as Figure 5 As shown, "oval boxes" represent bird strike cases, and "square boxes" represent components or sub-components that bear the load under this condition, as well as the structural strength design requirements or load-bearing schemes for these load-bearing structures.

[0173] Summary of strength assessment requirements.

[0174] The work of capturing aircraft strength assessment requirements should be summarized, using concise and clear language to summarize, organize, and itemize the requirements, and compile a list of strength assessment requirements. In this list, each requirement should also include corresponding verification projects and required resources based on the actual verification technologies and their maturity levels. A summary can be provided in Table 6 below:

[0175] Table 6 Summary of Strength Assessment Requirements

[0176]

[0177] For example, in the case of a bird strike, the final assessment requirements are shown in Table 7 below:

[0178] Table 7 Results of Intensity Assessment Requirements for Bird Strike Cases

[0179]

[0180]

[0181] S42. When there is a conflict between the same system requirements and the strength assessment requirements, the multiple strength assessment requirements shall be sorted according to their weights, and the strength assessment requirement with the highest weight value shall be selected as the final strength assessment requirement.

[0182] S43. Based on the determined final strength assessment requirements, construct a civil aircraft strength assessment requirement model and output multiple requirement traceability chains. The requirement traceability chain includes top-level requirements, scenarios, use cases, and strength assessment methods.

[0183] S5. Verify the demand traceability chain in the civil aircraft strength assessment demand model, and rectify any non-compliant demand traceability chains.

[0184] S51. Traceability chain integrity verification: There is no integrity issue in this embodiment, so proceed directly to step S52.

[0185] S52. Feasibility verification of the demand traceability chain: Calculate the feasibility degree c of the demand traceability chain. In this embodiment, the feasibility degree c of the demand traceability chain is calculated to be 8.52 using the above method, which meets the requirements and can be directly traced in subsequent applications.

[0186] Set c0 = 8.

[0187] Top-level requirements - Feasibility calculation of the scenario traceability chain:

[0188] Scoring items Operating condition integrity Scene coverage Compliance with historical data of similar aircraft <![CDATA[Expert scoring (z i )]]> 8 9 10 <![CDATA[Weight distribution (a i )]]> 0.25 0.25 0.5

[0189]

[0190] Scenario - Feasibility calculation of the traceability chain for intensity assessment requirements:

[0191]

[0192]

[0193]

[0194] c = min(c1, c2) = 8.52

[0195] We can conclude that c > c0, which meets the requirements.

[0196] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for constructing and verifying a civil aircraft strength assessment requirement model based on systems engineering, characterized in that: It includes the following steps: S1. Establish a stakeholder demand database; the stakeholder demand database includes a static strength demand database, a dynamic strength demand database, a fatigue demand database, and an aeroelasticity demand database. S2. Construct the top-level requirements model. The specific construction method is as follows: S21. Based on the stakeholder requirements established in step S1, determine whether the requirements need to be analyzed at the top level. If the stakeholder requirements need to be analyzed at the top level, proceed to step S22. S22. Use the decomposition module to decompose the needs of stakeholders that require top-level needs analysis, determine the object level corresponding to the needs, and determine the top-level needs corresponding to the needs based on the object level. The disassembly conditions for the disassembly module are as follows: Where A represents a stakeholder requirement, a represents aircraft-level requirement, b represents component-level requirement, c represents part-component-level requirement, and d represents material-level requirement. The disassembly results are as follows: S23. Construct and output a top-level requirement model using a requirement table or requirement diagram, based on requirement number, requirement name, requirement content, requirement level, and requirement source attribute. S3. Establish an application scenario database based on the top-level requirement model, and establish the correspondence between top-level requirements and scenarios; S4. Construct a civil aircraft strength assessment requirement model based on the correspondence between top-level requirements and scenarios. The civil aircraft strength assessment requirement model includes a requirement traceability chain. S5. Verify the demand traceability chain in the civil aircraft strength assessment demand model, and rectify any non-compliant demand traceability chains. This includes the following steps: S51. Traceability chain integrity verification, which includes the following sub-steps: S511. Based on the traceability relationship of the civil aircraft strength assessment demand model established in steps S1-S4, a global traceability relationship table is formed in the computer. Based on the global traceability relationship table, the completeness of the traceability chain is first verified to see if there are any scenarios where the needs of stakeholders have not been analyzed or matched. For incomplete traceability chains, steps S1 to S4 need to be repeated. After all are completed, proceed to step S512. S512. Determine whether all scenarios have completed intensity assessment requirement matching. If there are scenarios that have not completed intensity assessment requirement matching, continue to steps S3 to S4. If all scenarios have completed the matching, proceed to step S52. S52. Feasibility verification of the demand traceability chain, calculating the feasibility degree c of the demand traceability chain, specifically including the following sub-steps: S521, Calculate the feasibility c1 of the top-level requirement-scenario traceability chain: Each top-level requirement-scenario traceability chain includes three dimensions: operational condition completeness, scenario coverage, and historical data conformity of similar aircraft. Each of these three dimensions is scored sequentially, where z1, z2, z3 ∈ [0-10]. Each of z1, z2, z3 represents one of the three dimensions and is assigned a weight a1, a2, a3, respectively, satisfying a1 + a2 + a3 = 1. The feasibility c1 is calculated using the following formula: S522, Calculation scenario - feasibility of the traceability chain for strength assessment requirements c2: Each scenario-strength assessment requirement traceability chain includes seven dimensions: integrity of load-bearing components, compliance of static calculation results, compliance of dynamic calculation results, compliance of fatigue calculation results, compliance of aerodynamic calculation results, rationality of verification methods, and compliance of strength assessment methods for similar aircraft. Each of the seven dimensions is scored sequentially as y1, y2, y3, y4, y5, y6, y7 ∈ [0-10], where y1, y2, y3, y4, y5, y6, y7 are the seven dimensions, and weights b1, b2, b3, b4, b5, b6, b7 are assigned to each dimension, satisfying b1+b2+b3+b4+b5+b6+b7=1. The feasibility c2 is calculated using the following formula: S523. Calculate the feasibility c of the demand traceability chain. The calculation formula is as follows: c = min(c1, c2); S524. Compare the calculated feasibility c of the demand traceability chain with the set feasibility threshold c0. The feasibility threshold c0∈[0-10]. If c≥c0, the demand traceability chain is determined to meet the requirements. If c<c0, the demand traceability chain is determined to not meet the requirements. Then, modify the top-level requirements corresponding to the scenario and repeat step S5.

2. The method for constructing and verifying a civil aircraft strength assessment requirement model based on systems engineering as described in claim 1, characterized in that: In step S4, a traceability matrix is ​​used to express the traceability relationship between the architecture and the scenario, connecting the elements in the architecture model with the related use cases; a traceability matrix is ​​also used to express the traceability relationship between the verification requirements and the architecture, connecting the strength assessment requirements with the related architecture model elements.

3. The method for constructing and verifying a civil aircraft strength assessment requirement model based on systems engineering as described in claim 1, characterized in that: Step S1 specifically includes the following sub-steps: S11. Identify stakeholder needs; S12. Construct a stakeholder law requirement database based on the identified stakeholder law requirements. Each database includes a requirement number, requirement name, requirement content, and requirement source.

4. The method for constructing and verifying a civil aircraft strength assessment requirement model based on systems engineering as described in claim 1, characterized in that: Top-level requirements include airworthiness regulations, standards, and user requirements.

5. The method for constructing and verifying a civil aircraft strength assessment requirement model based on systems engineering as described in claim 1, characterized in that: Step S3 specifically includes the following sub-steps: S31. Determine aircraft scenarios and use cases: For the mission of the model, list the aircraft usage scenarios related to the top-level requirements, and select the top-level measures or solutions to be taken in terms of structure as use cases based on the determined usage scenarios. S32. Establish an application scenario database in a one-to-one correspondence manner. The application scenario database includes top-level requirements, usage scenarios, and use cases, and there is a one-to-one correspondence between the top-level requirements, usage scenarios, and use cases.

6. The method for constructing and verifying a civil aircraft strength assessment requirement model based on systems engineering as described in claim 1, characterized in that: In step S31, flight scenario and use case modeling adopts use case diagram modeling. In the use case diagram, the square represents the scenario, the ellipse represents the working condition under this use scenario, the constraint attributes below can describe the state of the aircraft under this scenario, the cube element represents the external participant, and the arrow expresses the information or energy interaction between the external participant and the aircraft under this scenario and working condition.

7. The method for constructing and verifying a civil aircraft strength assessment requirement model based on systems engineering as described in claim 1, characterized in that: Step S4 specifically includes the following sub-steps: S41. Based on top-level requirements and scenarios, determine the specific content of the system's strength assessment requirements, which include strength design requirements and structural strength design schemes. S42. When there is a conflict between the same system requirements and the strength assessment requirements, the multiple strength assessment requirements shall be sorted according to their weights, and the strength assessment requirement with the highest weight value shall be selected as the final strength assessment requirement. S43. Based on the determined final strength assessment requirements, construct a civil aircraft strength assessment requirement model and output multiple requirement traceability chains. The requirement traceability chain includes top-level requirements, scenarios, use cases, and strength assessment methods.

8. The method for constructing and verifying a civil aircraft strength assessment requirement model based on systems engineering as described in claim 1, characterized in that: In step S41, the load is further allocated according to the scenario and working conditions, and the strength bearing scheme of each level is constructed to finally form a strength assessment requirement model. The strength assessment requirement model is modeled using a module definition diagram based on the architecture design results. It reflects the load-bearing parts directly related to this scenario and the corresponding strength design schemes of the load-bearing parts under stress.

9. The method for constructing and verifying a civil aircraft strength assessment requirement model based on systems engineering as described in claim 1, characterized in that: If the module definition diagram in step S41 is a whole-machine level or component level load, then continue to allocate to the component and material level.

10. A system for constructing and evaluating a civil aircraft strength assessment requirement model based on systems engineering, used in the method for constructing and verifying a civil aircraft strength assessment requirement model based on systems engineering as described in claim 1, characterized in that: It includes a stakeholder demand database construction module, a top-level demand model construction module, an application scenario database construction module, a civil aircraft strength assessment demand model construction module, and a demand traceability chain verification module, all of which are interconnected. The stakeholder demand database construction module is used to construct the stakeholder demand database, the top-level demand model construction module is used to construct the top-level demand model, the application scenario database construction module is used to construct the application scenario database, the civil aircraft strength assessment demand model construction module is used to construct the civil aircraft strength assessment requirements, and the demand traceability chain verification module is used to verify the demand traceability chain and rectify any non-compliant demand traceability chains.

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