热振环境下异形曲面加筋壳降阶分析及多样性优化方法

Special-shaped stiffened curved shells have been widely used in engine nozzles of fighter planes, hypersonic flight vehicles and flying-wing unmanned air vehicles. This type of special-shaped stiffened curved shells work under high-temperature environment, which could decrease the natural frequency of special-shaped stiffened curved shells and then influence the whole performance of engines. Up to now, there is a lack of effective design methods for special-shaped stiffened curved shells under thermal vibration environment, which results in the overweight of special-shaped stiffened curved shells. Therefore, this project takes the lightweight design of special-shaped stiffened curved shells under thermal vibration environment as the research objective. First, the high-precision curved surface modeling method is established for special-shaped stiffened curved shells based on the mesh deformation method, the mesh smoothing method and the model updating method. Furthermore, efficient assembly and update methods of reduced-order bases are proposed, and then a high-fidelity reduced-order method is established for special-shaped stiffened curved shells under thermal vibration environment. Moreover, based on the discrete material optimization method and the diversity design theory, a diverse optimization approach of stiffener patterns is established for special-shaped stiffened curved shells, which could obtain multiple competitive designs simultaneously at conceptual design stage, and then provide diverse options at detailed design stage. Finally, experiments are carried out to validate the effectiveness of optimal designs. Through the research of this project, we expect to promote the development of the optimization theory for special-shaped thin-walled structures, and obtain several innovative and realizable designs of special-shaped stiffened curved shells used for future aero-engine nozzles.

异形曲面加筋壳广泛应用于战斗机、高超声速飞行器及飞翼布局无人机的发动机尾喷管结构。这类异形曲面加筋壳结构在高温环境下服役，高温导致结构固有振动频率降低，并影响发动机整体性能。目前热振环境下异形曲面加筋壳缺乏有效的设计方法，导致结构超重严重。本项目以热振环境下异形曲面加筋壳轻量化设计为研究目标，首先基于网格变形、网格光顺及模型验证技术建立异形曲面加筋壳高精度曲面建模方法。进而，提出高效的减缩基构建及更新方法，建立热振环境下异形曲面加筋壳高保真度降阶分析方法。在此基础上，基于离散材料优化方法和多样性设计理论，建立异形曲面加筋壳加筋构型多样性优化方法，从而在构型设计阶段获得具有竞争力的多个设计，为后续的精细化设计提供多样性的设计方案，最后完成优化设计的试验验证。希望通过本项目的研究，促进异形曲面薄壁结构优化理论的发展，并获得若干种可用于未来航空发动机尾喷管工程实施的异形曲面加筋壳创新结构方案。

异形曲面加筋壳在航空发动机、飞机、高速飞行器等航空航天装备中广泛应用，其在热振服役环境下的动力学响应对装备结构安全性具有重要影响。本项目以异形曲面加筋壳为研究对象，建立了异形曲面加筋网格变形建模方法、高保真POD降阶分析方法以及基于离散材料设计思想的多样性优化方法，有效提高了复杂曲面建模精度、动力学分析效率及创新构型设计能力。共发表SCI论文32篇、EI论文3篇，授权发明专利5项，申请发明专利8项，获批软件著作权2项。.主要成果包括：.1）建立了异形曲面加筋网格变形建模方法，发展了网格质量检查及拉普拉斯网格光顺方法，从空间降维映射的角度大幅降低了异形曲面加筋壳建模复杂度，可实现异形曲面加筋壳参数化高精度建模；.2）提出了基于POD的侵入式和非侵入式降阶求解框架，并建立了基于序列采样的POD减缩基构建及更新方法，实现了热振环境下异形曲面加筋壳高保真度降阶分析，相比全阶模型分析耗时降低2个数量级以上；.3) 建立了基于离散材料设计思想的异形曲面加筋壳加筋构型多样性优化方法，从而在构型设计阶段获得具有竞争性的多个设计，为后续的精细化设计提供多样性的设计方案，避免设计失败；.4) 加工了典型S弯异形曲面加筋壳试验件，完成了初始方案与优化方案的振动试验，结果表明优化方案相比初始方案减重4.57%、基频提高了20.29%；.5）研究成果应用于我国新一代航空发动机、载人登月着陆器、深空探测器等航空航天装备结构设计，取得了显著的轻量化效果（减重15%~67%），大幅提升了装备设计能力及效率。