Design method for lattice microstructure shock-resistant support arm of airplane

Abstract

The invention belongs to the technical field of aircraft design, and relates to a design method of an aircraft dot matrix microstructure impact-resistant support arm. The method comprises the following steps: S1, determining the material selection of the aircraft support arm according to the quantitative relationship between the impact resistance of the structure and each influence factor; s2, quantitatively representing the response to uncertain factors when the aircraft support arm is designed; s3, establishing a mechanical equivalent model of three variables including the load, the elastic modulus and the component thickness, and determining probability distribution information of the variables; s4, constructing a dot matrix unit cell model for forming the aircraft support arm; s5, determining a lattice microstructure with the maximum specific stiffness according to the stress-strain curve of the lattice unit cell model; s6, completing lattice microstructure macroscopic equivalent mechanical performance characterization based on a representative voxel method; and S7, taking maximized rigidity as an optimization target, and performing synchronous optimization on the variables and the dot matrix microstructure to obtain an aircraft support arm optimization design model. The shock resistance of the aircraft support arm is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft design, and in particular relates to a design method for an aircraft lattice microstructure anti-impact support arm. Background Art

[0002] The large impact discrete take-off and landing loads generated by aircraft taking off and landing on mobile platforms increase the difficulty of structural design. At present, the structural design of traditional mobile platform take-off aircraft in China is still mainly based on the land-based aircraft structure to increase the wing area and select area strengthening to complete the adaptability change. This approach that follows the land-based aircraft structural design requires a greater structural weight cost to meet the impact strength requirements, which has an adverse effect on the flight performance of the carrier aircraft. With the continuous research and development of new materials and the rapid development of additive manufacturing technology, the design and manufacture of new lightweight structures have become possible. The development of carrier aircraft structures must break the constraints of traditional material / structural systems and make full use of new lightweight structural design technologies in exchange for weight reduction benefits in order to better support the further improvement of the comprehensive capabilities of the carrier aircraft. Summary of the invention

[0003] In order to solve the above problems, the present application provides a method for designing an aircraft lattice microstructure impact-resistant support arm, which utilizes the characteristics of light weight, high specific strength, and good energy absorption and vibration reduction performance of the additively manufactured lattice microstructure to achieve a lightweight design of the typical structure of the carrier aircraft.

[0004] The present application provides a method for designing an aircraft lattice microstructure anti-impact support arm, which mainly includes: Step S1, determining the material selection of the aircraft support arm according to the quantitative relationship between the structural impact resistance and various influencing factors, wherein the influencing factors include material, surface roughness, and load distribution; Step S2, quantitatively characterizing the response of the aircraft arm to the uncertainty factors during the design; Step S3, establishing a mechanical equivalent model of three variables: load, elastic modulus and component thickness, and determining the probability distribution information of the three variables based on the quantitative relationship obtained in step S2; Step S4, constructing a lattice unit cell model for forming an aircraft support arm; Step S5, determining the lattice microstructure with the maximum specific stiffness according to the stress-strain curve of the lattice unit cell model; Step S6, completing the characterization of the macroscopic equivalent mechanical performance of the lattice microstructure based on the representative voxel method; Step S7, taking maximizing stiffness as the optimization goal, the variables of step S3 and the lattice microstructure of step S5 are optimized synchronously to obtain an optimized design model of the aircraft arm.

[0005] Preferably, in step S1, the structural impact resistance is characterized by structural strain energy.

[0006] Preferably, step S1 further comprises: Step S11, measuring the stress-strain curve of the material at different strain rates; Step S12, obtaining the specific stiffness of the material and the constitutive model of the material according to the stress-strain curve; Step S13, by using constitutive models of different materials to perform simulation analysis to obtain the quantitative relationship between the structural impact resistance and the material, introducing structural defects to simulate and analyze the constitutive model to obtain the quantitative relationship between the structural impact resistance and surface roughness, introducing load defects to simulate and analyze the constitutive model to obtain the quantitative relationship between the structural impact resistance and load distribution.

[0007] Preferably, in step S2, the uncertainty factors include material uncertainty, process uncertainty and load uncertainty.

[0008] Preferably, in step S4, a progressive homogenization method is used to determine the macroscopic equivalent mechanical properties of the lattice unit cell model.

[0009] This application improves the impact resistance of the aircraft support arm, and based on the structural design weight of typical parts in the same part of the carrier aircraft, it can achieve a structural weight reduction of more than 5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a flow chart of a preferred embodiment of the design method of the aircraft lattice microstructure anti-impact support arm of the present application.

[0011] Figure 2 This is a flow chart of the progressive homogenization method. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the implementation of this application will be described in more detail in combination with the drawings in the implementation of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and cannot be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in combination with the drawings.

[0013] This application provides a method for designing an aircraft lattice microstructure anti-impact support arm, such as Figure 1 As shown, it mainly includes: Step S1, determining the material selection of the aircraft support arm according to the quantitative relationship between the structural impact resistance and various influencing factors, wherein the influencing factors include material, surface roughness, and load distribution; Step S2, quantitatively characterizing the response of the aircraft arm to the uncertainty factors during the design; Step S3, establishing a mechanical equivalent model of three variables: load, elastic modulus and component thickness, and determining the probability distribution information of the three variables based on the quantitative relationship obtained in step S2; Step S4, constructing a lattice unit cell model for forming an aircraft support arm; Step S5, determining the lattice microstructure with the maximum specific stiffness according to the stress-strain curve of the lattice unit cell model; Step S6, completing the characterization of the macroscopic equivalent mechanical performance of the lattice microstructure based on the representative voxel method; Step S7, taking maximizing stiffness as the optimization goal, the variables of step S3 and the lattice microstructure of step S5 are optimized synchronously to obtain an optimized design model of the aircraft arm.

[0014] The following details are explained in detail.

[0015] Step S1 is mainly to clarify the material selection scheme of the aircraft support arm. In some optional embodiments, in step S1, the structural impact resistance is characterized by structural strain energy. In some optional embodiments, step S1 further includes: step S11, measuring the stress-strain curve of the material at different strain rates; step S12, obtaining the specific stiffness of the material and the constitutive model of the material according to the stress-strain curve; step S13, obtaining the quantitative relationship between the structural impact resistance and the material by using the constitutive models of different materials for simulation analysis, introducing structural defects to simulate the constitutive model to obtain the quantitative relationship between the structural impact resistance and the surface roughness, and introducing load defects to simulate the constitutive model to obtain the quantitative relationship between the structural impact resistance and the load distribution.

[0016] Specifically, we conducted data analysis on the impact resistance of typical metal materials for aircraft carriers. Taking 7000 series aluminum alloy, TA15 titanium alloy and A100 steel as examples, we processed standard test pieces, measured the stress-strain curves of the materials at different strain rates, obtained their specific stiffness and the constitutive model of the materials, and used the specific stiffness to measure the impact resistance of the materials. Based on the constitutive models of different materials, we introduced structural defects and load defects to simulate and analyze the typical structure, compared the simulation results under different materials and defects, summarized the factors affecting the impact resistance of the typical structure, and obtained the displacement response and stress and strain distribution of the typical structure under the action of corresponding parameters. The factors that mainly affect the fatigue / impact resistance of typical aircraft structures; the influence of materials on impact resistance is characterized by using constitutive models of different materials for simulation analysis; the influence of processing technology on impact resistance is characterized by introducing structural defects; the influence of load on structural impact resistance is characterized by introducing load defects, and the performance impact analysis is completed mainly with theoretical analysis methods supplemented by finite element simulation. A relationship model between structural impact resistance and dispersion influencing factors is established. The specific relationship model can be quantitatively characterized, such as the relationship between different materials and structural strain energy, the relationship between different surface roughness and structural strain energy, and the relationship between different load distribution conditions and structural strain energy.

[0017] After the material is selected, step S2 mainly quantitatively characterizes the response of the system to the uncertainty factors. In some optional implementations, in step S2, the uncertainty factors include material uncertainty, process uncertainty and load uncertainty.

[0018] Specifically, the influence of existing materials, processes and loads on aircraft structural performance is analyzed. Based on non-probability theory and the minimum volume method, the parameter sampling of three random variables, load, elastic modulus and component thickness, is completed, and the dimension reduction minimum volume method is proposed to achieve accurate envelope and uncertainty modeling of test samples. Subsequently, based on the probability conservation principle of standard normal space and physical space and the monotonicity of structural performance to random variables, the random parameters are converted into deterministic parameters to complete the interval variable conversion. Based on the deterministic parameters obtained by the conversion, the transformation from the reliability optimization model to the deterministic optimization model is completed, and the macroscopic mechanical properties of the periodic microstructure of the aircraft arm structure impact resistance are collectively characterized.

[0019] In step S3, structural reliability analysis is to consider various uncertain factors on the basis of deterministic structural analysis and measure the probability of the engineering structure completing the predetermined function under specified conditions. First, the three random variables of load, elastic modulus and component thickness are sampled using the exponential convex model, and an appropriate mechanical equivalent model is established to complete uncertainty modeling. Then, based on the random variable probability distribution information obtained by uncertainty quantification, the first-order reliability method is used to perform reliability analysis on the typical structural model, and the failure probability of the arm component based on the impact load is obtained, and the most likely failure point location is determined.

[0020] Steps S4 to S6 are to model and select the lattice unit cells constituting the aircraft support arm. In some optional implementations, in step S4, a progressive homogenization method is used to determine the macroscopic equivalent mechanical performance of the lattice unit cell model.

[0021] like Figure 2 As shown, the asymptotic homogenization method is used to calculate the strain energy of the unit cell, completing the collective characterization of the macroscopic equivalent mechanical properties of the unit cell. Furthermore, a sophisticated numerical simulation model can be used to verify the effectiveness of the asymptotic homogenization method.

[0022] Through the method of structural parameterized finite element simulation, multiple groups of macroscopic mechanical performance parameters of multi-cell structures with different unit cell types and sizes are obtained. The equivalent stiffness properties of the lattice unit cell are solved by the asymptotic homogenization method and the representative volume element method, and an equivalent model based on the homogenization method is established. The corresponding finite element fine model is established, and the quasi-static compression simulation calculation is performed, which is compared with the equivalent model to verify the effectiveness of the equivalent model.

[0023] In step S5, the collective characterization of the macroscopic equivalent mechanical performance of the multiphase unit cell of the periodic microstructure under complex uncertainty is analyzed, and the maximum displacement and the fine model error are calculated using the equivalent model. The force displacement curve of the lattice unit cell is calculated to find the lattice microstructure with the maximum specific stiffness.

[0024] Finally, in step S6, the macrostructure and microstructure are optimized synchronously, which mainly includes three aspects: (1) The strength / stiffness design constraints of the aircraft arm structure under fatigue / impact loads in the use environment are analyzed to determine the impact excitation function between the maximum impact response and the natural frequency of the system, namely the impact spectrum. The impact load is converted into a static load with the same action point and direction, and the force transmission path is optimized by topology optimization to obtain the configuration of the aircraft arm. Then, considering the effect of the impact load, the size of the aircraft arm is designed through parameter optimization. Therefore, the response analysis and optimization design problem of the aircraft arm structure under dynamic load can be converted into the response and optimization problem under static load.

[0025] (2) For responses that require cross-scale calculations for sensitivity analysis, the sensitivity of the two scales is linked by the chain rule to establish a sensitivity set. For the robust design of the aircraft arm structure, the analysis problem of multiple main failure mode coupling is simplified to the analysis problem of multiple single failure modes, and the sensitivity analysis of the robust optimization problem is carried out. Taking the initial unit cell configuration as the object, the optimization target is perturbed and expanded, the geometric dimensions of the periodic microstructure are refined, the robust design of vibration reduction and energy absorption is carried out, and a high-performance periodic microstructure model is constructed to achieve the robust design of the aircraft arm structure.

[0026] (3) Establish a robust design framework based on structural topology optimization and a macro / micro collaborative optimization method based on sensitivity set parameterized lattice to simultaneously optimize the macro material distribution and lattice configuration changes. First, based on the cross-level sensitivity uncertainty study, optimize the macro structure and micro material specific stiffness performance, and extend this method to three-dimensional structures to make the structural design and material design independent of each other. For the aircraft arm structure, carry out topology optimization design with the goal of minimum compliance / maximum stiffness to obtain the innovative topological configuration of the aircraft arm. Extract features based on the topology optimization results of the integrated model, reconstruct the model and perform parameter optimization. Use an efficient adaptive proxy model optimization method to design the structural parameters of impact-resistant parts, and complete the aircraft arm structure design for dynamic response.

[0027] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A design method for an aircraft lattice microstructure anti-impact support arm, characterized in that: include: Step S1, determining the material selection of the aircraft support arm according to the quantitative relationship between the structural impact resistance and various influencing factors, wherein the influencing factors include material, surface roughness, and load distribution; Step S2, quantitatively characterizing the response of the aircraft arm to the uncertainty factors during the design; Step S3, establishing a mechanical equivalent model of three variables: load, elastic modulus and component thickness, and determining the probability distribution information of the three variables based on the quantitative relationship obtained in step S2; Step S4, constructing a lattice unit cell model for forming an aircraft support arm; Step S5, determining the lattice microstructure with the maximum specific stiffness according to the stress-strain curve of the lattice unit cell model; Step S6, completing the characterization of the macroscopic equivalent mechanical performance of the lattice microstructure based on the representative voxel method; Step S7, taking maximizing stiffness as the optimization goal, the variables of step S3 and the lattice microstructure of step S5 are optimized synchronously to obtain an optimized design model of the aircraft arm.

2. The method for designing an aircraft lattice microstructure anti-impact support arm according to claim 1, characterized in that: In step S1, the structural impact resistance is characterized by structural strain energy.

3. The design method of the aircraft lattice microstructure anti-impact support arm according to claim 2, characterized in that: Step S1 further comprises: Step S11, measuring the stress-strain curve of the material at different strain rates; Step S12, obtaining the specific stiffness of the material and the constitutive model of the material according to the stress-strain curve; Step S13, by using constitutive models of different materials to perform simulation analysis to obtain the quantitative relationship between the structural impact resistance and the material, introducing structural defects to simulate and analyze the constitutive model to obtain the quantitative relationship between the structural impact resistance and surface roughness, introducing load defects to simulate and analyze the constitutive model to obtain the quantitative relationship between the structural impact resistance and load distribution.

4. The method for designing an aircraft lattice microstructure anti-impact support arm according to claim 1, characterized in that: In step S2, the uncertainty factors include material uncertainty, process uncertainty and load uncertainty.

5. The method for designing an aircraft lattice microstructure anti-impact support arm according to claim 1, characterized in that: In step S4, the macroscopic equivalent mechanical performance of the lattice unit cell model is determined by using a progressive homogenization method.

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