基于在轨温度测量数据的整星结构尺寸稳定性分析

针对高精度测绘卫星结构尺寸稳定性这一关键性问题,基于在轨温度测量数据,利用热分析模型和在轨温度变化规律,提出了卫星结构在轨温度场的反演方法.基于卫星结构在轨温度场反演数据,提出了针对载荷安装面法向夹角的拟合计算方法和夹角稳定性短期、长期指标的预示方法.根据该方法,给出了高分七号卫星在轨初期1个月内的结构稳定短期指标和长...     

组合层板在横向载荷作用下的变形特性

用Hellinger-Reissner变分泛涵,对由多层薄板组合而成的组合层板在横向载荷作用下变形的受力特性进行了研究。组合层板的层数是任意的,各层的材料可以相同也可以不同,每层的厚度是均匀的。假设各层间互相接触,且满足滑移条件,用杂交元建立了组合层板的受力模型。根据假设条件导出了位移函数和应力函数多项式。用杂交元对组合层板进行了分析计算,并用实验进行了验证,说明计算理论的正确性。从计算结果看出,在绐定的薄板厚度很薄的情况下,多层板基本上是绕每层板的中性平面弯曲的。在工程应用时,可以按单层板进行计算,不会带来很大的误差。     

浮球平台刚性的计算与实验研究

本文从浮球平台的结构特点出发,找到了适合于该复杂结构的三维有限元网格的分法,并编制了相应的单元及节点信息生成程序。使用ADINA程序计算了该结构的位移值,分析了其刚度,并与实验值作了比较,证明了本文方法的可靠性。     

不同的力-时间函数及初始冲击压力对叶片响应的影响

本文以矩形悬臂板模拟真实叶片,以冲击载荷模拟鸟撞击载荷,采用有限元法计算悬臂板在冲击载荷下的非线性瞬态响应。通过分组比较,分析了不同的力—时间函数及初始冲击压力对叶片响应的影响。本文得出的结论可供建立鸟撞击载荷模型时参考。     

支撑元件对平板结构热变形的影响

外热流环境的变化会引起空间飞行器表面温度的剧烈变动，使裸露在外空间的结构组件产生较大的热变形，从而影响结构及相关敏感器的指向精度。本文以平板结构为对象，研究了两类不同安装固定方式对结构热变形的影响。分析表明，与位移完全约束的固定支撑元件相比，位移部分释放的轴承支撑元件可以释放结构的热应力，抑制结构的翘曲变形，有利于保持平板结构的平直度。     

复合材料层合板的非同步固化翘曲变形分析

复合材料层合板在实际固化过程中因板内温度梯度的存在,各铺层内树脂的固化反应并非同步进行。这种非同步过程导致层合板内固化后残余应务的分布不同于经典分析方法的计算结果,使按对称铺层设计的层合板亦存在固化后翘变形。针对实际固化过程的非同步特征,文中给出一种基于弹性子叠层块的非同步固化过程描述模型,用此模型对非同步固化过程引起的对称层合板翘曲变形进行计算机模拟,分析树脂固化收缩率,固化过程中板内温度梯度,     

宽体客机高速风洞试验数据修正方法

宽体客机航程远、巡航马赫数高,其气动设计对风洞试验数据精准度要求很高。通过完善中国空气动力研究与发展中心FL-26风洞试验数据修正技术和设备,对宽体客机高速风洞测力试验数据进行支撑/洞壁干扰、模型变形及流场畸变等系统修正,获取干净、可靠的风洞试验基准数据,为开展雷诺数、静气动弹性和动力影响等相关性修正奠定基础。研究表明：支撑干扰试验时,尾腔压力分布测量位置和假支杆长度伸入模型尾腔50 mm即可获得可靠的支撑干扰试验结果;在试验包线范围内,洞壁干扰对宽体客机模型升力、阻力和俯仰力矩系数影响较小;试验模型变形对宽体客机气动特性影响较为明显,马赫数0.85时模型变形后的升力线斜率减小0.005左右,焦点前移0.021 b_A,需进行相关修正。     

Nonlinear thermomechanical deformation behaviour of P-FGM shallow spherical shell panel

In the present article, the linear and the nonlinear deformation behaviour of functionally graded (FG) spherical shell panel are examined under thermomechanical load. The temperature-dependent effective material properties of FG shell panel are evaluated using Voigt’s micro-mechanical rule in conjunction with power-law distribution. The nonlinear mathematical model of the FG shell panel is developed based on higher-order shear deformation theory and Green-Lagrange type geometrical nonlinearity. The desired nonlinear governing equation of the FG shell panel is computed using the variational principle. The model is discretised through suitable nonlinear finite element steps and solved using direct iterative method. The convergence and the val-idation behaviour of the present numerical model are performed to show the efficacy of the model. The effect of different parameters on the nonlinear deformation behaviour of FG spherical shell panel is highlighted by solving numerous examples.     

An investigation on adaptively machining the leading and tailing edges of an SPF/DB titanium hollow blade using free-form deformation

Titanium hollow blades are characterized with lightweight and high structural strength, which are widely used in advanced aircraft engines nowadays. Superplastic forming/diffusion bonding (SPF/DB) combined with numerical control (NC) milling is a major solution for manufacturing titanium hollow blades. Due to the shape deviation caused by multiple heat and pressure cycles in the SPF/DB process, it is hard to manufacture the leading and tailing edges by the milling process. This paper presents a new adaptive machining approach using free-form deformation to solve this problem. The actual SPF/DB shape of a hollow blade was firstly inspected by an on-machine measurement method. The measured point data were matched to the nominal SPF/DB shape with an improved ICP algorithm afterwards, by which the point-pairs between the measurement points and their corresponding points on the nominal SPF/DB shape were established, and the maximum modification amount of the final nominal shape was constrained. Based on the displacements between the point-pairs, an accurate FFD volume was iteratively calculated. By embedding the final nominal shape in the deformation space, a new final shape of the hollow blade was built. Finally, a series of measurement and machining tests was performed, the results of which validated the feasibility of the proposed adaptive machining approach.     

非对称偏馈环形网状天线索网预张力设计方法

提出一种考虑桁架柔性变形对索网平衡态影响的非对称偏馈环形网状天线索网预张力设计方法。该方法将天线整体结构分为内部索网与外部桁架两部分,通过内部索网预张力与外部桁架变形间的不断迭代,寻找满足索网形状及张力要求的天线平衡态,以实现网状天线索网预张力优化配置的目的。相比于常规基于刚性桁架假设的预张力设计,该方法可充分计及环形桁架与柔性索网协调变形,获得高精度反射面,且该方法适用于非对称偏馈天线,可有效避免后期张力调试,节约人力物力。算例分析验证了在进行预张力设计时计及桁架柔性的必要性及方法的正确性和有效性。