太阳帆航天器的轨道动力学和轨道控制研究

研究了太阳帆轨道动力学和利用太阳帆推进实现非开普勒轨道的太阳帆控制问题 ,推导了Gauss形式的太阳帆探测器密切轨道六要素微分方程,分析了太阳帆的轨道控制设 计方法,描述了适合太阳帆姿态控制的执行机构。在此理论基础上以SPORT计划作为设计实 例,并进行了设计与仿真,实现了任务要求的目标轨道。     

星载大型天线反射器桁架展开动力学建模仿真

以星载大型可展开天线为对象,研究了索网绷紧前天线反射器桁架在轨展开动力学过程。对大型天线展开机构特点和展开原理进行分析,建立了反射器桁架驱动和传动机构动力学模型。为避免初始时刻天线反射器切断铰约束方程雅克比矩阵奇异,以及小展开角情况下动力学方程左端系数矩阵数值性态差问题,提出了基于几何的替代约束求解方案。对星载大型天线在轨展开动力学过程进行了数值仿真,仿真结果表明,提出的方法能够有效解决初始时刻天线反射器切断铰约束方程雅克比矩阵奇异问题。     

On the dynamics of the heliosphere on intermediate and long time-scales

A time-dependent, three-dimensional model of the dynamics of the heliosphere as a result of solar activity and a time-varying local interstellar medium is presented. The model is based on a recent version of the well known ZEUS code and employs parallel processing. It includes the solar and interstellar plasma components as well as neutral atoms, and contains the heliospheric magnetic field in a kinematic fashion. We study the dynamics of the heliosphere due to solar activity on periods of months to years up to the so-called Schwabe (11-year) cycle as well as due to time variations of the local interstellar medium, all of which have drawn increasing attention during recent years, as the significance of their direct or indirect effect on the Earth and its environment is under lively debate.     

Ion dynamics associated with Alfven wave in the near-Earth magnetotail: Two-dimensional global hybrid simulation

Ion dynamics in the near-Earth magnetotail region is examined during periods of fast Earthward flow with a two-dimensional (2-D) global-scale hybrid simulation. The simulation shows that shear Alfven waves are generated at x ∼ −10R_E, where the strong earthward flow is arrested by the dipole field, and propagate along field lines from the equator to both southern and northern polar ionosphere. Non-gyrotropic ion velocity distributions occur where the large-amplitude Alfven waves are dominant. The simulation indicates that the Alfven waves are generated by interaction of the fast earthward flow with the stationary near-Earth plasma. Beam ions are found to be pitch-angle scattered and trapped in the wave field, leading to the non-gyrotropic ion distributions in the high-latitude plasma sheet boundary. In addition, significant particle heating and acceleration are found to occur behind the dipolarization front due to the effect of wave turbulence.     

表面贴有压电片的桁架结构系统静力可靠性分析(英文)

对表面贴有压电片的主动杆单元组成的桁架结构系统,在考虑电荷载和机械荷载联合作用的机电耦合效应时,利用力学原理,建立了静力分析的有限元模型。同时研究了压电杆元的破坏机理,给出压电杆单元破坏的判断准则。以材料的断裂强度、损伤电场强度、杆元的截面积和外荷载等为随机变量,建立了压电桁架结构单元的安全余量的表达式。并在此基础上,引入随机有限元法和结构系统可靠性理论,对该桁架结构系统进行可靠性分析。最后由算例说明本文方法的有效性。     

航天器推进剂晃动与控制系统之间耦合效应的混合型估算方法(英文)

基于等效力学模型理论与计算流体力学技术,提出了一种用于估算航天器中推进剂晃动的力学影响的方法.以计算流体力学技术为依托,建立了晃动的等效力学模型并将其整合为晃动模块,以便在航天器导航控制回路的仿真分析中应用.该模块体现了航天器运动特征参数与推进剂晃动动力响应之间的映射关系,使其在用于分析晃动与控制系统之间的耦合效应时,比直接应用计算流体力学分析软件更为方便.该方法的正确性与优势通过检验算例得到了验证.通过在实例中应用,证明了该方法可方便地用于确定晃动的影响和检验数种防晃设计的有效性.     

空气动力对薄膜结构动力特性的影响规律

薄膜结构刚度小、自重轻、自振频率低,对外力作用非常敏感,因此在分析其动力特性时应考虑到空气与结构的耦合作用。本文利用附加空气质量、辐射阻尼和气承刚度这一简化气动力模型来考虑空气与振动薄膜结构之间的相互作用。分别推导了附加空气质量、辐射阻尼和气承刚度的计算方法及其相应的变化规律。并进一步采用算例分析对结构在空气中的自由振动和受迫简谐振动进行了系统分析,同时探讨了气动力对薄膜结构动力特性的影响规律。     

Thermal–structure coupling analysis and multi-objective optimization of motor rotor in MSPMSM

With the high speed, the rotor of magnetically suspended permanent magnet synchronous motor(MSPMSM) suffers great thermal stress and mechanical stress resulting from the temperature rise problem caused by rotor losses, which leads to instability and inefficiency.In this paper, the mechanical–temperature field coupling analysis is conducted to analyze the relationship between the temperature field and structure, and multi-objective optimization of a rotor is performed to improve the design reliability and efficiency. Firstly, the temperature field is calculated by the 2 D finite element model of MSPMSM and the method of applying the 2 D temperature result to the 3 D finite element model of the motor rotor equivalently is proposed. Then the thermal–structure coupling analysis is processed through mathematic method and finite element method(FEM),in which the 3 D finite element model is established precisely in a way and approaches the practical operation state further. Moreover, the impact produced by the temperature and structure on the mechanical strength is analyzed in detail. Finally, the optimization mathematical model of the motor rotor is established with Sequential Quadratic Programming-NLPQL selected in the optimization scheme. Through optimization, the strength of the components in the motor rotor increases obviously and satisfies the design requirement, which to a great extend enhances the service life of the MSPMSM rotor.     

二维流场、热、结构一体化数值模拟

流场、热、结构问题,在传统的计算中,通常是先算流场、再算热响应和热结构问题,这显然是人为地分割了本身统一的、连续的过程,使得计算结果存在较多不足。本文给出一种把流场、热、结构耦合起来进行一体化数值模拟的方法。算例证明,本方法较好地模拟了动态的物理过程。     

特型涡轮转子耦合系统振动特性分析

本文分析研究了特型涡轮转子多重耦合振动系统的固有特性。对分析计算中所用的单晶合金的弹性矩阵作了分析推导。全面研究了此涡轮转子耦合振动的特性。在后处理中表述了多重耦合的模态特征。所引出的结论可供类似结构的耦合振动分析参考,有一定的工程实用价值。