部件级多组件结构系统的整体式拓扑布局优化

基于多组件结构系统整体式拓扑布局优化设计方法,研究了同时含有部件布局、组件布局、主结构框架构型和部件结构构型4类设计变量的复杂系统协同优化设计问题,是整体式拓扑布局优化设计面向复杂飞行器结构系统设计的拓展。采用多点约束(MPC)模拟组件、部件及支撑结构之间的刚性连接,采用有限包络圆方法(FCM)解决组件之间、组件与设计域边界之间的几何干涉问题。通过整体式拓扑布局的刚度优化设计,部件和组件均可以获得优化的布局位置,同时主结构框架构型和部件结构构型获得优化的结构样式,充分体现了整体式拓扑布局优化设计方法应用于复杂结构系统设计的能力。     

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.     

Topology Optimization Design for the Layout of theMain Bearing Joint of a Certain Aircraft

为了实现飞机部件的轻量化设计,将拓扑优化和代理模型相结合构建了一个结构布局优化的算法。以某型飞机主承力接头为研究对象,根据结构传力路线和工艺要求,将接头的布局优化转化为耳片的平面拓扑优化与螺栓位置的优化。以接头耳片的厚度和中间排螺栓位置作为布局变量,对每组布局变量下的耳片进行拓扑优化,对布局变量采用基于代理模型的遗传算法进行优化。以质量最小为优化目标,在强度与刚度的多约束条件下,完成了某型飞机主承力接头的布局拓扑优化。结果表明,本方法的优化结果比传统的拓扑优化结果减重约 14.5%,验证了优化算法的可行性与有效性。     

Integrated optimization design of smart morphing wing for accurate shape control

Smart morphing wing, which is equipped with smart materials and able to change structural geometry adaptively, can further improve aerodynamic efficiency of aircraft. This paper presents a new integrated layout and topology optimization design for morphing wing driven by shape memory alloys (SMAs). By simultaneously optimizing the layout of smart actuators and topology of wing substrate, the ultimately determined configuration can achieve smooth, continuous and accurate geometric shape changes. In addition, aerodynamic analysis is carried out to compare smart morphing wing with traditional hinged airfoil. Finally, the optimized smart wing structure is constructed and tested to demonstrate and verify the morphing functionality. Application setbacks are also pointed out for further investigation.     

Integrated batteries layout and structural topology optimization for a solar-powered drone

The purpose of this paper is to demonstrate an integrated optimization scheme for a solar-powered drone structure. Consider a primary beam in the wing of large aspect ratio, where 100 lithium batteries are assembled. In the proposed integrated optimization, the batteries are considered here as parts of the load-carrying structure. The corresponding mechanical behaviors are simulated in the structural design and described with super-elements. The batteries layout and the structural topology are then introduced as mixed design variables and optimized simultaneously to achieve an accordant load-carrying path. Geometrical nonlinearity is considered due to the large deformation. Different periodic structural configurations are tested in the optimization in order to meet the structural manufacturing and assembly convenience. The optimized designs are rebuilt and tested in different load cases. Maintaining the same structural weight, the global mechanical performances are improved greatly compared with the initial design.     

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.     

多组件结构系统布局拓扑优化中处理组件干涉约束的惩罚函数方法

包含大量组件的多组件结构系统布局拓扑优化设计中存在大量的组件干涉约束,研究了包含大量组件的结构系统整体式拓扑布局优化设计问题,基于有限包络圆方法（FCM）提出了处理组件干涉约束的惩罚函数方法,构造了包含结构刚度和组件之间几何干涉函数的内外混合惩罚函数,应用基于梯度的优化算法对包含数十个组件上百个干涉约束的多组件结构系统进行刚度优化设计,得到了清晰的支撑结构构型和无干涉的组件布局位置,充分体现了提出的混合惩罚函数方法在解决多组件结构系统布局拓扑优化设计中组件干涉问题上的有效性和适用性。     

简谐力激励下多组件结构系统的整体优化设计

多组件结构系统整体优化设计通过协同优化支撑结构拓扑构型和组件布局来使结构系统的位移响应最小。本文提出通过模态加速度法（MAM）求解多组件结构系统的位移响应,并以位移响应值最小作为优化目标;引入多点约束（MPC）方法模拟组件与设计域间的铆钉或螺栓连接形式;采用有限包络圆法（FCM）来避免组件之间及组件与设计域边界产生干涉。建立了多组件结构系统整体优化问题的数学模型,并对动响应目标函数关于设计变量的灵敏度进行了推导。最后,通过几个算例验证了整体优化方法在简谐力激励下求解问题的可行性及其在实际问题中的有效性。     

基于拓扑优化和形状优化的桨叶结构设计

直升机旋翼桨叶剖面结构设计是研究旋翼动力学设计的基础。提出一种联合拓扑优化和形状优化的 两级优化设计方法,可用于桨叶剖面结构的设计。第一级优化以变密度法(SIMP)作为拓扑优化的材料插值方 法,以桨叶体积最小化为设计目标,约束桨叶节点位移和应力,建立桨叶的拓扑优化求解模型;第二级优化以重 构的桨叶模型为基础开展形状优化,降低局部应力集中以及找到合理的边界节点位置。对优化后的模型进行 有限元分析,结果表明:通过拓扑优化和形状优化的两级优化,能够得到满足强度和稳定性要求的结构布局,为 桨叶结构设计提供指导方案。     

基于模拟退火遗传算法的平面连续体结构的拓扑优化

采用遗传算法,用染色体基因映射结构离散化后的单元体,通过改变基因代码实现连续结构的拓扑。优化过程中,利用遗传算法进行结构优化,通过有限元技术对结构进行建模和分析。在遗传算法中,引入模拟退火的思想,实时调整结构优化的适应度函数,改善优化分析中个体所处的生存环境,提高优化分析效率,获得较优的结构拓扑效果。算例分析表明所提出的方法是有效的。      

基于Workbench的主起落架车架前轮叉应力分析及结构优化设计

针对某型飞机主起落架车架前轮叉根部多次出现疲劳裂纹,前轮叉作为主起落架车架的关键件,其性能优劣严重影响起落架的安全性。利用ANSYS Workbench仿真软件对其结构进行应力分析,得到其薄弱部位,利用拓扑优化和多参数优化相结合的方法对其结构进行优化和对比分析。分析得到的薄弱部位与实际使用情况相吻合,优化后的结构合理,受力明显改善,质量比优化之前减少了17.3%。     

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。     

中央大翼结构优化设计与分析

随着航空航天事业的发展,航空器的经济性和安全性都有了更高的要求,拓扑优化与结构的优化设计结构减重等的联系日趋紧密。简要论述了拓扑优化技术在航空领域的应用,在不同的工况下,对中央大翼进行静强度分析,论证了结构存在优化的空间。在此结构基础上,分别用 HyperMesh 和 Inspire 软件对中央大翼进行拓扑优化、尺寸优化和稳定性准则优化三级优化,根据优化后的结构并结合实际工程经验和优化需求进行细节建模,对优化后的模型进行强度、位移、屈曲、模态和疲劳分析,结果表明,优化后的中央大翼传力路径合理简单,结构质量较轻,结构合理可行。     

Geometry and size optimization of stiffener layout for three-dimensional box structures with maximization of natural frequencies

Based on the growth mechanism of natural biological branching systems and inspiration from the morphology of plant root tips, a bionic design method called Improved Adaptive Growth Method (IAGM) has been proposed in the authors’ previous research and successfully applied to the reinforcement optimization of three-dimensional box structures with respect to natural frequencies. However, as a kind of ground structure methods, the final layout patterns of stiffeners obtained by using the IAGM are highly subjected to their ground structures, which restricts the optimization effect and freedom to further improve the dynamic performance of structures. To solve this problem, a novel post-processing geometry and size optimization approach is proposed in this article. This method takes the former layout optimization result as start, and iteratively finds the optimal layout angles, locations, and lengths of stiffeners with a few design variables by optimizing the positions of some specific node lines called active node lines. At the same time, thicknesses of stiffeners are also optimized to further improve natural frequencies of three-dimensional box structures. Using this method, stiffeners can be successfully separated from their ground structures and further effectively improve natural frequencies of three-dimensional box structures with less material consumption. Typical numerical examples are illustrated to validate the effectiveness and advantages of the suggested method.     

Shape preserving topology optimization for structural radar cross section control

The purpose of this paper is to present a shape preserving topology optimization method to prevent the adverse effects of the mechanical deformation on the Radar Cross Section(RCS).The optimization will suppress the variation of RCS on the perfect conductor surface by structural design. On the one hand, the physical optics method is utilized to calculate the structural RCS,which is based on the surface displacement field obtained from the finite element analysis of the structure. The correspondi...     

应力和位移约束下连续体结构的拓扑优化

结构拓扑优化设计是结构初始方案设计的重要方法。同时考虑应力和位移约束,采用遗传算法,用染色体基因映射结构离散化后的单元体,对连续体结构进行拓扑优化。为了消除结构中的铰接和棋盘格现象,在拓扑优化分析中引入了结构约束的概念,并在罚函数方法中引入导向因子,改善优化分析结果。该方法可以为工程结构的初始设计提供多种方案,同时为新结构的设计提供了理论基础。算例分析表明所提出的方法是合理、有效的。     

飞机骨架结构方案的优化设计

为了能够有效地降低飞机结构承力件的重量,针对飞机骨架,以加强框和普通框以及翼梁的概念设计为研究内容,通过对“敏度阈值“概念的分析,指出其不足,提出了“改进的敏度阈值“概念,并与“约束补偿“策略结合而形成新的拓扑优化算法,用于上述结构件的材料布局优化设计.多个算例中的拓扑优化结果均显示其结构型式十分新颖,值得深入地探讨.由此可以得出3点结论:(1)采用CAD/CAE和拓扑优化相结合用于飞机结构件的初始方案设计是可行的;(2)作者提出的“改进的敏度阈值“拓扑优化算法是有效的;(3)构建一种具有良好操作性的、有别于经验设计的飞机结构件概念设计新方法.     

Structural topology optimization under stationary random base acceleration excitations

Structural topology optimization subjected to stationary random base acceleration excitations is investigated in this paper. In the random response analysis, the Large Mass Method(LMM) which attributes artificial large mass values at each driven nodal Degree Of Freedom(DOF) to transforming the base acceleration excitations into force excitations is proposed. The Complete Quadratic Combination(CQC) which is commonly used to calculate the random responses in previous optimization has been proven to be computationally expensive especially for large-scale problems. In order to conquer this difficulty, the Pseudo Excitation Method(PEM) and the combined method of PEM and Mode Acceleration Method(MAM) are adopted into the dynamic topology optimization, and random responses are calculated using these two methods to ascertain a high efficiency over the CQC. A density-based topology optimization method minimizing dynamic responses is then formulated based on the integration of LMM and PEM or the combined method of PEM and MAM. Numerical examples are presented to verify the accuracy of the proposed schemes in dynamic response analysis and the quality of the optimized design in improving dynamic performance.     

Multiscale topology optimization using feature-driven method

This paper presents a multiscale design method for simultaneous topology optimization of both macrostructures and microstructures. Geometric features are extended as design primitives at both macro and micro scales and represented by Level Set Functions (LSFs). Parameters related to the locations, sizes, and orientations of macro and micro features are considered as design variables and optimized simultaneously. In the overlapping areas of different macro features, embedded microstructures are optimally figured out as the solution of the corresponding sub-optimization problem. In this study, the eXtended Finite Element Method (XFEM) is implemented for structural and sensitivity analyses with respect to design variables. This method has the advantage of using a fixed grid independent of the topology optimization process. The homogenization procedure is applied to calculate the effective properties of considered microstructures in each macro feature. Numerical examples are presented to illustrate the effectiveness of the proposed method. Results depict that the multiscale design cannot obviously improve structural stiffness compared with a solid-material design under the linear elastic condition.     

考虑气动弹性约束的机翼结构布局优化设计

提出了一种气动弹性约束下的复合材料机翼结构布局优化设计方法.机翼内部翼梁的数目与机翼各部件的尺寸被统一来考虑,拓扑变量和尺寸变量由一个双层循环机制的优化程序来统一处理.第一层,使用蚁群算法来处理拓扑设计变量;第二层,使用NASTRAN的Sol200优化程序来处理尺寸变量,同时考虑强度、刚度、颤振约束,并将第二层的优化结果反馈给第一层以催生出更优的结构布局方案.最后,使用基本的颤振优化(没有调整结构布局)与本文方法对某前掠机翼进行了布局优化设计,并将结果进行了对比.结果表明,综合考虑各种设计约束下,结构布局形式对结构质量有重要影响,应予高度重视,同时证明了本文方法的正确性与可行性.