面向增材制造的拓扑优化技术发展现状与未来

增材制造技术通过材料逐层打印制备结构,为复杂构件制造提供了新的成形方式。拓扑优化因不依赖于初始构型的选择,可设计出传统理念难以获得的创新构型,已成为航空航天和高端装备领域高性能、轻量化结构设计的重要手段。拓扑优化与增材制造有机融合,充分发挥各自优势和潜力,在现代制造业中展现出广阔应用前景。回顾了近年来关于增材制造与拓扑优化技术融合研究的主要内容和应用成果,包括以材料结构一体化为核心的多尺度/多层级结构优化设计、以设计制造一体化为核心的考虑增材制造工艺约束的优化方法等。同时,也分析了未来研究工作中存在的问题与挑战,如点阵结构性能表征及其尺度关联效应、增材制造材料成形各向异性、功能梯度材料与结构、增材制造材料与结构疲劳特性等对设计方法和成形工艺带来的挑战,为未来相关研究工作和航空航天应用提供参考。     

面向增材制造的飞行器结构优化设计关键问题

围绕飞行器复杂结构整体构型研制的高性能、轻量化苛刻需求,着重介绍了面向增材制造的结构优化设计面临的系列关键问题以及相关研究成果。分别从面向增材制造的结构多承载环节整体优化建模与性能分析、整体结构多学科性能与功能综合设计方法、跨尺度结构-微结构性能表征与尺度效应的影响机理,以及增材制造工艺对整体结构件性能的影响机理和制造工艺约束4个方面,阐述如何从结构力学与工艺力学角度科学实现最优性能设计与先进增材制造技术的完美匹配与融合。     

An aerospace bracket designed by thermo-elastic topology optimization and manufactured by additive manufacturing

Combination of topology optimization and additive manufacturing technologies provides an effective approach for the development of light-weight and high-performance structures. A heavy-loaded aerospace bracket is designed by topology optimization and manufactured by additive manufacturing technology in this work. Considering both mechanical forces and temperature loads, a formulation of thermo-elastic topology optimization is firstly proposed and the sensitivity analysis is derived in detail. Then the procedure of numerical optimization design is presented and the final design is additively manufactured using Selective Laser Melting (SLM). The mass of the aerospace bracket is reduced by over 18%, benefiting from topology and size optimization, and the three constraints are satisfied as well in the final design. This work indicates that the integration of thermo-elastic topology optimization and additive manufacturing technologies can be a rather powerful tool kit for the design of structures under thermal-mechanical loading.     

Layout design of thin-walled structures with lattices and stiffeners using multi-material topology optimization

In this paper, the thin-walled structures with lattices and stiffeners manufactured by additive manufacturing are investigated. A design method based on the multi-material topology optimization is proposed for the simultaneous layout optimization of the lattices and stiffeners in thin-walled structures. First, the representative lattice units of the selected lattices are equivalent to the virtual homogeneous materials whose effective elastic matrixes are achieved by the energy-based homogenization method. Meanwhile, the stiffeners are modelled using the solid material. Subsequently, the multi-material topology optimization formulation is established for both the virtual homogeneous materials and solid material to minimize the structural compliance under mass constraint. Thus, the optimal layout of both the lattices and stiffeners could be simultaneously attained by the optimization procedure. Two applications, the aircraft panel structure and the equipment mounting plate, are dealt with to demonstrate the detailed design procedure and reveal the effect of the proposed method. According to numerical comparisons and experimental results, the thin-walled structures with lattices and stiffeners have significant advantages over the traditional stiffened thin-walled structures and lattice sandwich structures in terms of static, dynamic and anti-instability performance.     

碳纤维复合材料在发射装置上的应用研究

机载弹射发射装置轻量化设计是现阶段机载武器系统重要的研究课题和难题,碳纤维复合材料应用于制造具有复杂外形的承力结构件,对于航空武器的轻量化设计具有重要意义。选取机载弹射发射装置的典型结构作为研究对象,首先通过结构优化设计和RTM成型工艺获得复合材料结构件;然后,经过各项结构件的试验和整机试验验证,结合应变测量数据,证明其强度满足设计要求,且获得了显著的减重效果。通过对复合材料典型结构件的研究,为其在发射装置领域的应用提供理论指导和依据。     

飞机高能束增材制造结构研究

轻质高效、长寿命、多功能、低成本、快速响应制造是现代飞机结构技术的发展方向,但受限于传统制造技术,一些创新的结构存在"设计得出却造不出"的问题。高能束增材制造技术的发展为新概念结构工程的实现提供了契机。基于高能束增材制造技术,针对现代飞机结构特征需求,提出了大型整体化、梯度复合化和功能结构一体化等发展方向,创建了新概念构型,开展了设计与评定方法研究,提出了基于技术成熟度的工程化验证模式。     

压力载荷下的结构拓扑-形状协同优化

 压力载荷作用下的结构轻量化设计是工程中的常见问题,由于压力加载面的可设计性,现有以固定载荷为基础的拓扑优化技术不能很好地处理这类问题。直接采用CAD参数化样条或B样条曲线描述压力加载面,通过拓扑和形状变量的联合优化满足了工程实际对结构轻量化与边界的功能性与光滑性设计要求。同时,为了避免结构边界形状变化时有限元网格刷新引起的定义拓扑伪密度变量的困难,用所提出的背景网格和密度点技术实现了每一步单元密度设计迭代结果的自动传递,并采用网格变形技术实现了形状设计变量灵敏度分析。采用4个数值算例验证了方法的有效性,其中发动机承力框架的设计结果充分说明该方法在航空结构设计中的重要应用价值。     

Collaborative optimization design of process parameter and structural topology for laser additive manufacturing

High-resolution laser additive manufacturing (LAM) significantly releases design freedom, promoting the development of topology optimization (TO) and advancing structural design methods. In order to fully take advantage of voxelated forming methods and establish the quantitative relationship between the mechanical properties of printing components and multiple process factors (laser- and process- parameters), the concurrent optimization design method based on LAM should cover the process-performance relationship. This study proposes a novel artificial intelligence-facilitated TO method for LAM to concurrently design microscale material property and macroscale structural topology of 3D components by adopting heuristic and gradient-based algorithms. The process–structure–property relationship of selective laser sintering is established by the back propagation neural network, and it is integrated into the TO algorithm for providing a systematic design scheme of structural topology and process parameter. Compared with the classical optimization method, numerical examples show that this method is able to improve the mechanical performance of the macrostructure significantly. In addition, the collaborative design method is able to be widely applied for complex functional part design and optimization, as well as case studies on artificial intelligence-facilitated product evaluation.     

Topology optimization in lightweight design of a 3D-printed flapping-wing micro aerial vehicle

Topology optimization is an effective method to obtain a lightweight structure that meets the requirements of structural strength. Whether the optimization results meet the actual needs mainly depends on the accuracy of the material properties and the boundary conditions, especially for a tiny Flapping-wing Micro Aerial Vehicle (FMAV) transmission system manufactured by 3D printing. In this paper, experimental and numerical computation efforts were undertaken to gain a reliable topology optimization method for the bottom of the transmission system. First, the constitutive behavior of the ultraviolet (UV) curable resin used in fabrication was evaluated. Second, a numerical computation model describing further verified via experiments. Topology optimization modeling considering nonlinear factors, e.g. contact, friction and collision, was presented, and the optimization results were verified by both dynamic simulation and experiments. Finally, detailed discussions on different load cases and constraints were presented to clarify their effect on the optimization. Our methods and results presented in this paper may shed light on the lightweight design of a FMAV.     

惯导系统结构拓扑优化方法研究

针对惯导系统结构拓扑优化问题,提出了一种考虑多工况组合和等效边界处理的优化方法.以惯导系统结构件为研究对象,梳理了不同结构件的载荷工况;以刚度最大为 目标函数,以体积分数、结构频率和最大变形等作为约束条件,研究了变密度拓扑优化方法;以某惯导系统的盖板、惯性台体和外壳体3个结构件为例,进行了优化方法验证.结果表明,与传统设计相比,在满足系统刚度、频率及动态特性的前提下,优化后的3个结构件质量分别减小18.3％、22.6％和18.0％,整体质量减小18.7％,实现了惯导系统结构的轻量化设计.     

增材制造阵风锁支座的装机应用研究

根据3D 打印技术的装机推进要求，在完成材料及工艺的验证后，即开始进行试片级增材制造材料许用值试验以及增材制造零件级试验。增材制造的零件由于其工艺特点，通常X-Y 方向与Z 方向力学性能有差异，与传统金属零件设计时各向同性的特点有差异，因此有必要在接近真实飞行状态下测试其力学性能。以增材制造阵风锁支座为例，计算飞机运营过程中最大载荷状态，选取最典型的载荷方向进行工装试验方案设计；在试验开始前，进行工程计算和软件仿真，预测失效模式和失效载荷。结果表明：软件仿真和工程计算的结果准确有效，增材制造钛合金阵风锁支座的力学性能稳定，能够承受极端工况的考验，满足装机要求。     

微小型航空燃气轮机离心叶轮拓扑优化设计

离心叶轮是微小型航空燃气轮机中的关键部件,要求其在满足气动性能的前提下,尽量减轻结构重量,传统设计制造技术已基本发挥到极致,但增材制造技术及拓扑优化设计方法的发展为其进一步优化设计拓展了新的空间。针对某型航空微型燃气轮机离心叶轮减重设计问题,依托增材制造和拓扑优化设计技术,在现有设计的基础上,首先对离心叶轮进行静强度分...     

激光增材制造高强高韧TC11钛合金力学性能及航空主承力结构应用分析

随着损伤容限设计理念发展和轻量化要求提高,高强高韧钛合金逐渐成为航空装备关键主承力构件主要结构材料。激光增材制造制备钛合金大型主承力构件具有数字化、短周期、低成本等技术优势,特别是激光增材制造过程超常固态相变动力学条件为制备高强高韧钛合金提供了新的机会。本文根据航空主承力结构选材性能要求,对激光增材制造TC11钛合金静强度、疲劳和损伤容限特性进行测试与分析,在此基础上对其在航空主承力结构的应用前景进行分析。结果表明,激光增材制造TC11钛合金力学性能具有显著的高强高韧和低屈强比特征,其疲劳缺口敏感性和裂纹扩展速率低,性能分散性小,综合性能满足航空主承力结构选材要求。与目前航空主承力结构广泛应用的TC4-DT损伤容限型钛合金相比,激光增材制造TC11高强高韧钛合金损伤容限特性相当、疲劳性能有所改善、许用应力提高23%,结构具有进一步减重优势。激光增材制造TC11钛合金优异的强韧性匹配在提高结构许用应力的同时可避免大厚度结构发生脆性断裂,其低疲劳缺口敏感性和优异的疲劳裂纹扩展特性对于结构服役安全具有重要意义。     

考虑阻尼性能的复合结构多尺度拓扑优化设计

最优阻尼复合结构应该是阻尼材料自身的材料性能和阻尼材料在板壳结构上的分布形态均是最优的。针对板壳阻尼复合结构的多尺度设计问题,建立了基于非比例阻尼模型的复合结构多尺度拓扑优化方法,实现了阻尼材料在宏微观两尺度上的协同设计,同时获得最优的阻尼材料宏观分布形态和微观构型。以结构模态阻尼比为目标,分别研究了复合结构的单目标和多目标多尺度设计问题。结果表明,在单目标设计中,当最大化结构的某一阶模态阻尼比时,优化后结构的该阶模态阻尼比最大,同时结构在该阶处的频率响应最小;在多目标设计中,以结构前3阶模态阻尼比之和为目标,虽然在每一阶处的性能劣于单目标设计结果,但是结构前3阶模态阻尼比的总体性能更优。同时,从微结构的构型可得,最优的微结构构型中低刚度高阻尼材料的分布相互连接,其损失模量（微结构复弹性矩阵的虚部）和阻尼因子（微结构复弹性矩阵的虚部与实部之比）都相对较高,且呈现负泊松比现象。优化后复合结构的动力学性能显著提高。     

Multi-scale design and optimization for solid-lattice hybrid structures and their application to aerospace vehicle components

By integrating topology optimization and lattice-based optimization, a novel multi-scale design method is proposed to create solid-lattice hybrid structures and thus to improve the mechanical performance as well as reduce the structural weight. To achieve this purpose, a two-step procedure is developed to design and optimize the innovative structures. Initially, the classical topology optimization is utilized to find the optimal material layout and primary load carrying paths. Afterwards, the solid-lattice hybrid structures are reconstructed using the finite element mesh based modeling method. And lattice-based optimization is performed to obtain the optimal cross-section area of the lattice structures. Finally, two typical aerospace structures are optimized to demonstrate the effectiveness of the proposed optimization framework. The numerical results are quite encouraging since the solid-lattice hybrid structures obtained by the presented approach show remarkably improved performance when compared with traditional designs.     

轻质材料与结构的一体化设计

针对多孔材料微结构构型的可设计性,基于材料多尺度均匀化计算理论,提出以宏观结构最大刚度为目标,材料微结构构型为变量的材料与结构一体化设计新方法,实现了材料宏观布局设计与材料微结构精细设计的统一。采用凸规划对偶优化求解技术与二次型周长约束格式相结合的途径,实现了快速求解与材料分布棋盘格效应的控制。数值计算结果表明,在材料用量一定的情况下,本方法能有效地实现蜂窝结构及夹层结构的拓扑优化设计,为满足极端环境下航空航天结构的设计需求提供了新的设计思想。     

等强度三维空心叶片的内部拓扑结构

以ANSYS软件为平台,基于双向渐进结构优化法对所提出的等强度风扇叶片的内部结构形式进行探索性研究,在对叶片内部结构进行拓扑优化的过程中提出了中面应力基准法,简化了优化模型,同时有针对性的解决了双向渐进结构优化法在应用中的一些技术问题,实现了等强度风扇叶片内部结构的优化,获得了内部结构的拓扑形式.所得结果可为发动机轻量化设计提供参考.      

直升机结构设计的三维虚拟装配技术应用分析

虚拟现实技术通常被认为是三维计算机图形学在先进的输入和输出设备支持下的一种自然延生和增强。这项技术最近已发展成熟足以可保证应用于实际工程中。这项新技术和工程、设计及制造的软件系统的集成将对计算机辅助工程领域起着新的推动作用。深受虚拟现实技术影响的设计和制造领域中的一个重要方面就是装配设计。本文着重介绍此项技术概念以及如何运用到直升机结构装配设计中,及如何产生一个虚拟装配设计环境。     

激光选区熔化技术在航空航天领域的发展现状及典型应用

增材制造技术(AM)是一种基于离散-堆积原理,以计算机模型数据来加工组件的新型制造技术。激光选区熔化(SLM)作为增材制造领域的一项重要技术,以其一体化制造特点和在复杂结构零部件制造领域的显著优势,成为航空航天制造领域的重点发展技术和前沿方向。本文综述了SLM技术的材料体系和应用领域,主要对SLM技术的最新工艺研究和航空航天领域的典型应用进行细致分析。重点阐述SLM铁基合金、镍基合金、钛合金和铝合金等材料体系的研究进展及成果。SLM技术在各领域广泛应用的同时,也存在成形材料内部缺陷多、高性能材料的裂纹及变形、标准体系的欠缺和粉末材料兼容性低等诸多问题和不足之处,使其发展受到一定制约,需要在这些方面做更深入的工作。     

点阵夹芯主动冷却结构发展现状与展望

点阵结构呈周期性规则形状,具有比强度高、比刚度高、轻质及换热效率高的特点,是当前国际上公认的具有广泛应用前景的结构。将点阵结构应用于主动冷却技术,形成点阵夹芯主动冷却结构是解决超燃冲压发动机热防护问题的有效手段。点阵结构的发展离不开制备工艺的进步,本文对传统机械加工工艺与增材制造技术用于点阵结构制备的原理与现状进行了综述,通过文献调研归纳总结点阵结构单元、设计尺寸以及与其他强化换热结构的协同作用对换热性能的影响;在此基础上分析点阵夹芯主动冷却结构在超燃冲压发动机中的潜在应用价值,针对其工程应用提出下一步的发展建议。