基于拓扑优化的叶盘压电阻尼器性能研究

针对压电分支阻尼技术在航空发动机叶盘结构振动抑制问题中的应用,提出了一种拓扑优化方法,可给出限定用量的压电材料在轮盘上的最佳位置,以提升压电分支阻尼的上限。在轮盘上布置压电材料还可防止对叶片通道内流场的影响,避免降低流体效率。首先,论述了该拓扑优化方法的原理,推导了模态机电耦合系数这一核心参数的计算公式及其与最佳阻尼比、模态应变场的关系。其次,建立了基于模态应变场的压电材料分布拓扑优化方法,可用于任意有限元模型。最后,将该优化方法应用于一个航空发动机压气机叶盘结构模型,分别针对单一和多阶模态进行了压电材料在轮盘上分布的拓扑优化,研究这种铺设方式对各典型模态(轮盘主导、叶片主导、耦合振动)的振动抑制效果。结果表明,在仅采用占轮盘质量5%的压电材料的情况下,优化后的压电阻尼器最多可以为轮盘振动主导模态及叶片-轮盘耦合振动模态提供约13%的模态阻尼比,为叶片主导模态提供的模态阻尼比集中在2%～4%。     

叶片弯曲对大折转压气机叶栅内分离结构的影响

通过数值模拟,分析了叶片周向弯曲对大折转角压气机叶栅内分离结构的影响。弯角分别为±10°,±20°,±30°。应用壁面流谱的拓扑法则,详细讨论了不同弯角下的分离形态。结果表明,正弯可以有效遏止角区分离,改变吸力面的分离形态,但不能完全消除吸力面的分离。因此一定范围内的叶片正弯可以改善流动,但当弯角大于20°时,流动重新恶化。反弯则使得叶栅内分离趋势增加,气动性能明显降低。     

拓扑优化在框架式模具结构选形中的应用

对航空复合材料构件制造用框架式模具进行了底部支撑框格的结构拓扑优化;根据对优化结果的分析以及2种底部支撑框格的有限元模拟结果对比,证明了框架式模具底部支撑框格采用桁架式开口具有较高的结构效率。     

Topology optimization of compliant adaptive wing leading edge with composite materials

An approach for designing the compliant adaptive wing leading edge with composite material is proposed based on the topology optimization. Firstly, an equivalent constitutive relationship of laminated glass fiber reinforced epoxy composite plates has been built based on the symmetric laminated plate theory. Then, an optimization objective function of compliant adaptive wing leading edge was used to minimize the least square error（LSE） between deformed curve and desired aerodynamics shape. After that, the topology structures of wing leading edge of different glass fiber ply-orientations were obtained by using the solid isotropic material with penalization（SIMP） model and sensitivity filtering technique. The desired aerodynamics shape of compliant adaptive wing leading edge was obtained based on the proposed approach. The topology structures of wing leading edge depend on the glass fiber ply-orientation. Finally, the corresponding morphing experiment of compliant wing leading edge with composite materials was implemented, which verified the morphing capability of topology structure and illustrated the feasibility for designing compliant wing leading edge. The present paper lays the basis of ply-orientation optimization for compliant adaptive wing leading edge in unmanned aerial vehicle（UAV） field.     

Integrated design of topology and material for composite morphing trailing edge based compliant mechanism

The morphing trailing edge based compliant mechanism is a developing technology which can increase lift-drag ratio for variable flight modes by bending down the trailing edge. Composite material design is integrated into topology optimization for the morphing trailing edge based compliant mechanism in the paper. A two-step optimization strategy is established to solve the integrated design problem. Initially, lamination parameters are introduced and viewed as a bridge between structure stiffness and fiber angles for composite material. Design variables include the lamination parameters and element density. The least-squares between actual and desired displacements at output points along trailing edge is adopted to evaluate the deformed capability of the trailing edge. An integrated optimization model for the composite morphing trailing edge is established with the volume constraints. The optimal topologic shape and lamination parameters are initially obtained. Subsequently, a least-squares optimization between fiber angles and the optimal lamination parameters is implemented to obtain optimal fiber angles. Finally, morphing capability of composites trailing edge based compliant mechanism is investigated by simulation and experiments. The results indicate the composites trailing edge based compliant mechanism can approximately bend down 8 degrees and satisfies the design requirement.     

基于OptiStruct飞机装配型架框架结构的优化设计

建立了飞机装配型架框架优化设计的数学模型;首先对型架框架进行拓扑优化,确定框架的拓扑结构;然后对框架进行截面尺寸优化,确定梁的最终截面尺寸.通过与初始结构的对比,证明了优化设计所取得的效果.     

高负荷压气机叶栅等离子体流动控制数值仿真与拓扑分析

为揭示叶栅等离子体流动控制的影响规律与作用机理,对等离子体气动激励前后高负荷压气机叶栅内部流动和拓扑结构进行了对比研究。结果表明:等离子体气动激励抑制叶栅流动分离的作用效果最明显的区域位于总压损失区域与主流区域的边界上;不同等离子体气动激励布局,对固壁面拓扑结构以及奇点总数的影响规律不同;吸力面流向激励通过增强附面层流体抵抗逆压梯度的能力,可以改善叶栅中间叶高流动特性;端壁横向激励通过抑制横向流动,抑制角区流动分离能力较强,并改变叶片展向的负荷分布;组合激励结合了吸力面流向激励和端壁横向激励的作用优势,因而提高叶栅气动性能、降低流动损失的效果最好。      

复杂电子系统抗核电磁脉冲设计的拓朴图法

本文针对复杂电子系统抗核电磁脉冲设计中所面临的系统结构因素和电路复杂难于进行分析的困难,提出了先将系统划分为若干个简单问题,用现有的理论加以分析,建立传输函数,再利用拓扑图论的点边关联矩阵,将简单问题综合为复杂系统响应的一种便于进行计算机辅助分析,且适用于复杂电子系统抗核电磁脉冲设计的有效方法。     

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...     

轻型空间相机主承力基板结构拓扑优化计

针对目前轻型空间相机主承力基板在结构设计过程中难于同时保证重量轻且刚度高的问题,提出了采用拓扑优化设计思想进行设计的方案.通过建立基于变密度方法的拓扑优化设计数学模型,运用Nastran软件对相机主承力基板进行拓扑优化设计,给出了主承力基板的最优设计方案.经过拓扑优化后相机主承力基板质量从初始的36.8 kg降低到15.4 kg,轻量化程度达58.2%.采用有限元分析方法对拓扑优化的结果进行了模态分析,以验证主承力基板刚度分布是否合理.通过0.5 g扫频振动试验对有限元分析结果进行验证,振动试验结果表明,主承力基板结构一阶自然频率理论分析与试验结果偏差1.86%,充分证明理论分析结果的正确性和准确性.整个优化设计过程证明,采用拓扑优化设计方法大大提高了研制效率,增强了空间相机主承力基板结构的性能,有效降低了基板的重量,满足系统设计要求.