飞机钣金组件数字化装配误差分析

以飞机数字化制造装配为依托,通过对飞机钣金组件在模拟量协调路线和数字量协调路线下产生误差环节的比较,着重分析了飞机钣金组件在数字化装配过程中产生的系统误差和随机误差的因素和造成误差累积的原因。针对减小在钣金零件制造路线、钣金组件装配路线、温度场变化、振动场变化、应力变化等环节的累积误差提出了改进措施。     

随机激励下非线性振动系统特性的定性分析

求解李雅普诺夫方程,可直接获得平稳随机振动响应协方差矩阵。用等效线性化方法处理非线性系统,通过多次迭代求解李雅普诺夫方程可得到稳定的等效线性系统参数,从而获得一种多自由度非线性系统特性定性分析方法,为实际的非线性动力学系统建模提供了理论依据。对几个实例进行了仿真分析,结果验证了该方法的有效性。     

一种基于随机集的目标跟踪算法研究

针对多传感器多目标跟踪问题,提出了基于随机有限集的概率假设密度（PHD）滤波算法。该算法通过选取与各传感器相关的重要性密度函数,层层更新各传感器的采样粒子,达到多传感器多目标有序PHD跟踪。给出了应用该算法的具体步骤,通过仿真实例证明该算法的有效性。     

飞行器径向连接螺栓振动断裂分析

应用有限元分析结合试验数据,获得随机振动环境下飞行器径向连接螺栓的载荷功率谱密度（PSD）;采用基于弯曲效应的载荷与应力的线性关系,获取螺栓头根部的名义应力功率谱密度;基于Dirlik经验公式,获取应力随机过程的峰值概率密度函数和预期波峰数,联合Miner线性累积损伤模型及经应力集中系数修正的材料S-N曲线,评估径向连接螺栓头根部振动疲劳寿命,获得的结果与试验螺栓头断裂现象符合,并确定螺栓断裂原因为低频共振疲劳。     

Design of face-hobbed spiral bevel gears with reduced maximum tooth contact pressure and transmission errors

The aim of this study is to define optimal tooth modifications, introduced by appropriately chosen head-cutter geometry and machine tool setting, to simultaneously minimize tooth contact pressure and angular displacement error of the driven gear (transmission error) of face-hobbed spiral bevel gears. As a result of these modifications, the gear pair becomes mismatched, and a point contact replaces the theoretical line contact. In the applied loaded tooth contact analysis it is assumed that the point contact under load is spreading over a surface along the whole or part of the ’’potential’’ contact line. A computer program was developed to implement the formulation provided above. By using this program the influence of tooth modifications introduced by the variation in machine tool settings and in head cutter data on load and pressure distributions, transmission errors, and fillet stresses is investigated and discussed. The correlation between the ease-off obtained by pinion tooth modifications and the corresponding tooth contact pressure distribution is investigated and the obtained results are presented.     

基于制导信息的一维波束可控随机脉位脉冲多普勒引信技术研究

针对空空导弹引信的任务特点,综合采用了基于制导信息的起爆控制算法技术、自适应调整天线波束倾角技术、基于频域信号处理的数字信号处理技术设计了总体技术方案.仿真分析和试验表明,系统实现了对作战飞机、导弹等不同类型目标的智能探测,提高了对目标的探测灵敏度和抗干扰能力.     

CubeSail: A low cost CubeSat based solar sail demonstration mission

CubeSail is a nano-solar sail mission based on the 3U CubeSat standard, which is currently being designed and built at the Surrey Space Centre, University of Surrey. CubeSail will have a total mass of around 3 kg and will deploy a 5 × 5 m sail in low Earth orbit. The primary aim of the mission is to demonstrate the concept of solar sailing and end-of-life de-orbiting using the sail membrane as a drag-sail. The spacecraft will have a compact 3-axis stabilised attitude control system, which uses three magnetic torquers aligned with the spacecraft principle axis as well as a novel two-dimensional translation stage separating the spacecraft bus from the sail. CubeSail’s deployment mechanism consists of four novel booms and four-quadrant sail membranes. The proposed booms are made from tape-spring blades and will deploy the sail membrane from a 2U CubeSat standard structure. This paper presents a systems level overview of the CubeSat mission, focusing on the mission orbit and de-orbiting, in addition to the deployment, attitude control and the satellite bus.     

刚度随机失谐叶盘结构概率模态特性分析

基于典型叶盘结构的集中参数模型和Monte Carlo数值计算,分析了刚度随机失谐叶盘结构的概率固有特性.给出了叶盘结构的扇区两自由度集中参数模型,计算并说明了其基本频率结构特性,根据叶盘结构模态振动物理背景,提出了一个定量表征模态振型局部化程度的指标一模态局部化因子,分别计算了不同随机刚度失谐叶盘结构固有频率和模态振型局部化的统计特性,讨论了失谐因素的影响规律等.研究表明,叶片和耦合刚度的失谐影响的频率区间有着明显的不同,并在其影响频段内模态局部化因子会出现"突变"的现象.      

一种AMR磁罗盘的误差建模与校准方法

针对传统磁罗盘硬磁校准时容易受到外界干扰,标定校准为相对值的问题,详细分析了AMR(Anisotropic Magneto Resistance,各向异性磁阻效应)磁罗盘的系统误差并建立其误差模型,提出了标量校准方法用于磁罗盘的硬磁标定校准.与传统方法相比,该方法不需要确切的航向参考值,利用任意多位置下的大量测试数据通过迭代求取校准参数的最优解,通过施加约束避免校准过程中磁干扰的影响,并且校准值为绝对矢量.经过硬磁校准,磁罗盘航向精度提高7倍.实验结果验证了该方法的有效性和实用性.     

PH曲线拟合在数控前瞻中的应用

为解决数控系统进行微小直线段平稳加工的问题,提出了一种拟合方法.综合了误差限制下的微小直线段长度、拐角、直线段相交点单调性等判定条件,将连续的微小直线段分割成若干区域.使用非线性最小二乘法将每一个区域内的点拟合成PH曲线,并通过模拟退火方法调整切矢量来控制拟合误差.根据区域的连接情况,将切矢量分为单向和双向两种调节方法.在模拟退火算法中,将微小直线段的斜率作为切矢量的初始值,利用细分直线的方法逐点计算弓高误差,并将此误差作为目标函数来快速进行切矢量的调整.结果表明,对微小直线段进行区域划分可以提高拟合效率.在控制弓高误差的情况下,此方法可以形成具有良好精度的光滑曲线,可以获得平稳的速度轨迹.