【作者】 韩剑；

【导师】 杨睿；

【作者基本信息】 大连理工大学 ， 机械制造及其自动化， 2025， 博士

【摘要】 现代战争信息化、智能化发展对飞行器结构件提出“轻量化、大承载、强隐身、高可靠”的性能要求,传统介质损耗机制下的结构隐身设计与轻量化设计间矛盾突出,难以实现轻量化约束下承载与隐身的性能集成。同时,现有承载/隐身一体化结构研究中,鲜少考虑结构破坏情况下性能衰减或失效问题,无法满足武器装备的高可靠要求。因此,本文提出一种由点阵芯层、超表面功能层、介质层构成的多层异质层叠结构(超表面增强点阵结构),该结构既可利用超表面电磁调控效应保障隐身性能的精确达成,又可通过点阵芯层的分形多级设计强化结构承载能力、改善结构阻抗对结构破坏的鲁棒性,是实现飞行器结构件性能集成与性能鲁棒性设计的可行方案。超表面增强点阵结构具有性能集成、结构复杂、性能与结构强关联的特点,导致精确设计困难。为此,本文开展多层异质层叠结构电磁特性快速分析的等效传输线模型、基于超表面电磁调控效应的点阵结构隐身性能达成策略、基于分形思想的点阵结构承载性能强化机理与影响规律、轻质承载/低频宽带隐身一体化超表面增强点阵结构设计方法等研究工作,成功设计出具备二次承载和鲁棒性电磁隐身特性的超表面增强分形点阵结构,有效解决了飞行器结构件承载/隐身性能集成和性能鲁棒性设计难题。主要研究内容与结论如下:(1)针对超表面增强点阵结构因跨尺度多层异质特征导致的电磁建模困难问题,从精确分析和快速分析两个层面,开展电磁特性分析方法研究。从性能精确分析角度出发,基于Maxwell方程组,研究适用于超表面增强点阵结构的时域有限差分算法,为电磁特性分析建立计算电磁学求解模型,并通过典型结构验证了模型的计算精度。相较于全波分析商业软件,最大计算误差小于0.5%;从性能快速分析角度,根据超表面增强点阵结构的一般化特征,建立了等效传输线模型,实现了该结构电磁特性的一体化建模,进而利用转移传输矩阵级联,实现了电磁特性的快速求解。其中,基于改进NRW(Nicolson-Ross-Weir)反演算法和等效媒质理论,提出了各向异性点阵结构等效电磁参数建模方法,并分析了方法的适用临界频率,揭示了点阵几何物理参数对等效电磁参数的影响规律。进一步地,建立了基于全连接神经网络的点阵结构等效电磁参数预测模型。(2)面向超表面增强点阵结构隐身性能需求,研究基于超表面电磁调控效应的点阵结构隐身性能达成策略。从等效电路建模角度出发,研究超表面电磁吸收效应、电磁散射效应、电磁吸收-散射混合效应的通用化等效电路表征模型。在此基础上,通过传输线模型描述点阵结构对超表面电磁调控效应的影响,并形成“群智能算法+传输线模型”的点阵结构隐身性能达成策略。分别利用电磁吸收效应、电磁散射效应和电磁吸收-散射混合效应,实现了典型目标频段内的隐身需求,证明了点阵结构隐身性能达成策略的有效性。其中:吸收型超表面增强点阵结构在目标频段(1.5～6GHz)内吸波率达到90%以上;散射型超表面增强点阵结构在目标频段X波段(8～12GHz)内的雷达散射截面(Radar Cross Section,RCS)缩减10d B以上;混合型超表面增强点阵结构在目标频段Ku波段(12～18GHz)内的RCS缩减10d B以上。(3)面向超表面增强点阵结构承载性能增强需求,研究基于分形思想的点阵结构承载性能强化机理与影响规律。受自然界分形树状结构高效的物质与能量传输特性以及优异的力学性能启发,将分形思想运用到点阵结构。通过分形多级点阵结构的力学性能分析,建立了面外压缩性能的理论分析模型和有限元仿真模型,揭示了分形设计对点阵结构二次承载性能和吸能特性达成的作用机理。同时,系统分析了分形点阵结构中杆件截面尺寸、杆件倾斜角度、分形比例等结构参数对承载性能的影响规律。(4)针对飞行器结构件轻质承载和鲁棒性低频宽带隐身的性能集成需求,研究具有承载/隐身性能的超表面增强点阵结构设计方法。从低频宽带隐身性能入手,研究多层阻性超表面级联的吸波带宽拓展机理和磁性材料介质层-超表面协同的低频段电磁强化吸收机制。在此基础上,从性能鲁棒性角度,提出一种含分形点阵芯层、多层阻性超表面功能层和磁性材料介质层的新型结构。同时,利用建立的等效传输线模型,研究该结构的“性能要求-传输线模型参数-结构参数”的反向求解策略,并采用粒子群优化方法,成功设计出具有二次承载和低频宽带隐身特性的超表面增强分形点阵结构。结果表明,结构在L、S、C、X、Ku共5个典型频段(1～18GHz)内吸波率大于90%;并能在点阵芯层一次承载失效压溃的条件下保持吸波率大于90%、二次承载强度为一次承载的1.2倍,实现性能的鲁棒性设计。更多还原

【Abstract】 The development of informatization and intelligence in modern warfare puts forward the performance requirements of"lightweight,large load-bearing,strong stealth,and high reliability"for aircraft structural parts.The contradiction between the structural stealth design and the lightweight design under the traditional dielectric loss mechanism is prominent,and it is difficult to realize the performance integration of bearing and stealth under the constraint of lightweight.At the same time,the traditional load-bearing/stealth integrated structure has serious performance attenuation or even failure in the case of structural damage,which cannot meet the reliability requirements of weapons and equipment.Therefore,this paper proposes a multi-layer heterogeneous laminated structure(metasurface-enhanced lattice structure)composed of lattice core layer,metasurface functional layer and dielectric layer,which can not only use the metasurface electromagnetic control effect to ensure the accurate creation of stealth performance,but also enhance the bearing capacity of the structure and improve the robustness of the structural impedance to the structural damage through the fractal multi-stage design of the lattice core layer,which is a feasible scheme to realize the performance integration and performance robustness design of the aircraft structural parts.Metasurface-enhanced lattice structures have the characteristics of integrated performance,complex structure,and strong correlation between performance and structure,which leads to the difficulty of accurate design.This paper carries out research work on the equivalent transmission line model for rapid analysis of the electromagnetic characteristics of multilayer heterogeneous stacked structures,the stealth performance achievement strategy of lattice structures based on the electromagnetic control effect of metasurfaces,the mechanism and influence law of lattice structure bearing performance enhancement based on fractal thinking,and the design method of lightweight loading/low-frequency broadband stealth integrated metasurface enhanced lattice structures.Stealth performance integration and performance robustness design challenges.The main research contents and conclusions are as follows(1)In order to solve the problem of electromagnetic modeling difficulties caused by cross-scale multilayer heterogeneous features of metasurface-enhanced lattice structures,the analysis methods of electromagnetic characteristics has been studied from two levels:accurate analysis and rapid analysis.From the perspective of accurate performance analysis,based on Maxwell’s equations,a finite-difference time-domain algorithm suitable for metasurface-enhanced lattice structures is studied,and a computational electromagnetics solution model is established for the analysis of electromagnetic characteristics,and the calculation accuracy of the model is verified by typical structures.Compared with the commercial software of full-wave analysis,the maximum calculation error is less than 0.5%.From the perspective of rapid performance analysis,the equivalent electromagnetic parameter modeling methods of various heterogeneous lattice structures are proposed.Based on the improved Nicolson-Ross-Weir(NRW)inversion algorithm and the equivalent media theory,a modeling method for the equivalent electromagnetic parameters of anisotropic lattice structures is proposed,and the applicable critical frequencies of the method are analyzed,and the influence of lattice geometric physical parameters on the equivalent electromagnetic parameters is revealed.Furthermore,a lattice structure equivalent electromagnetic parameter prediction model based on fully connected neural network is established.(2)Aiming at the demand of stealth performance of metasurface-enhanced lattice structures,a strategy for achieving the stealth performance of lattice structures based on the electromagnetic control effect of metasurfaces has been studied.From the perspective of equivalent circuit modeling,the generalized equivalent circuit characterization model of metasurface electromagnetic absorption effect,electromagnetic scattering effect and electromagnetic absorption-scattering mixed effect are studied.On this basis,the influence of lattice structure on the electromagnetic control effect of metasurface is described through the transmission line model.The stealth performance achievement strategy of the lattice structure of"swarm intelligence algorithm+transmission line model"is formed.The electromagnetic absorption effect,electromagnetic scattering effect and electromagnetic absorption-scattering mixed effect are used respectively to achieve the stealth requirements in the typical target frequency band,and the effectiveness of the stealth performance achievement strategy of lattice structure is proved.Among them,the absorption rate of the absorption metasurface enhanced lattice structure reaches more than 90%in the target frequency band(1.5～6GHz);The Radar Cross Section(RCS)in the X-band(8～12GHz)of the target band is reduced by more than 10d B.The hybrid metasurface-enhanced lattice structure reduces the RCS by more than 10d B in the target band Ku-band(12～18GHz).(3)The mechanism and influence law of lattice structure load-bearing performance enhancement based on the fractal self-similarity principle has been studied to meet the requirements of the load-bearing performance of metasurface-enhanced lattice structures.Inspired by the efficient material and energy transmission characteristics and excellent mechanical properties of the fractal tree-like structure in nature,the principle of fractal self-similarity is applied to the lattice structure.Through the analysis of the mechanical properties of the fractal multi-level lattice structure,the theoretical analysis model and finite element simulation model of the out-of-plane compression performance are established,and the mechanism of the fractal design on the secondary bearing performance and energy absorption characteristics of the lattice structure is revealed.At the same time,the influence of structural parameters such as member cross-sectional area,member inclination angle and fractal ratio on the bearing performance in the fractal lattice structure is systematically analyzed.(4)In order to meet the performance integration requirements of lightweight bearing and robust low-frequency broadband stealth of aircraft structural parts,a design method of metasurface-enhanced lattice structure with loading/stealth performance has been studied.Starting from the stealth performance of low-frequency broadband multisurface,the absorption bandwidth expansion mechanism of multilayer resistive metasurface cascade and the low-band electromagnetic enhanced absorption mechanism of dielectric layer-metasurface synergy of magnetic materials are studied.On this basis,from the perspective of performance robustness,a new structure consisting of a fractal lattice core layer,a multilayer resistive metasurface functional layer and a magnetic material dielectric layer was proposed.At the same time,using the established equivalent transmission line model,the reverse solution strategy of"performance requirements-transmission line model parameters-structure parameters"of the structure is studied,and the particle swarm optimization method is used to successfully design a metasurface-enhanced fractal lattice structure with the characteristics of secondary bearing and low-frequency broadband stealth.The results show that the absorption rate of the structure in the five typical frequency bands(1～18GHz)of L,S,C,X and Ku is over 90%.In addition,it can maintain the absorption rate over 90%and the secondary bearing strength of 1.2 times that of the primary bearing under the condition of the failure and collapse of the primary bearing layer of the lattice core,so as to achieve the robust design of performance.更多还原