利用配重改善平尾颤振特性方法的研究

针对某型飞机平尾颤振速度偏低的实际问题，详细探讨了利用配重提高颤振速度的方案。分析方法及所得结果将有助于改善平尾的颤振特性，从而提高颤振速度。     

Modal analysis strategy and nonlinear dynamic characteristics of complicated aero-engine dual-rotor system with rub-impact

This paper aims to gain insight into the nonlinear modal characteristics and the possible influence of the modes on the responses for the practical dual-rotor system with rub-impact in aero-engine. The finite solid element method combined with a constraint stiffness model produced by rub-impact is introduced to build the governing equation of the complicated nonlinear dualrotor system. In order to deal with the efficiency and numerical divergence in the process of solving the nonlinear modes of ...     

Dynamic modeling and beating phenomenon analysis of space robots with continuum manipulators

Space robotics has been used extensively in complex space missions. Rigid-manipulator space robots may suffer from rigid-body collisions with targets. This collision is likely to cause damage to the space robot and the target. To overcome such a problem, a novel Continuum-Manipulator Space Robot (CMSR) for performing on-orbit servicing missions is proposed in this paper. Compared with rigid-manipulator space robots, CMSRs are able to perform compliant operations and avoid rigid-body collisions with a target. The CMSR consists of two kinds of flexible components, including solar arrays and continuum manipulators. The elastic vibrations of these flexible components disturb the position and attitude of CMSRs. The beating phenomenon introduced by the energy transfer among these flexible components can cause damage to solar arrays. The complicated dynamic coupling poses enormous challenges in dynamic modeling and vibration analysis. The dynamic model for CMSRs is derived and the mechanism of the beating phenomenon is analyzed in this paper. Simulation results show that an obvious beating phenomenon occurs and the amplitude of the solar arrays increases significantly when the natural frequencies of two kinds of flexible components are close. A method is provided to avoid the beating phenomenon.     

远程火箭校正发动机柔性试车台振动特性分析

为了在地面试验中测量校正发动机的等效力，需要将柔性试车台调整为与火箭弹弹体具有相同的振动特性。根据解析表达式估算试车台系统的固有频率，调整配重、弹性和阻尼元件参数，使得试车台与弹体有相同的固有频率，然后用数值计算方法对试车台的时域响应特性进行分析，最终确定各个参数。采用这种方法可以一次将试车台调整到与火箭弹性具有尽可能一致的运动特性，测得弹性受到的等效力。该方法准确迅速，大大加快了试验进度，也为评估弹体对横向控制力的响应特性提供了一种直接的试验方法。     

Singularity problem of control moment gyro cluster with vibration isolators

As powerful torque amplification actuators, control moment gyros (CMGs) are often used in the attitude control of many state-of-the-art high resolution satellites. However, the distur-bance generated by the CMGs can not only reduce the attitude stability of a satellite but also dete-riorate the performance of optic payloads. Currently, CMG vibration isolators are widely used to target this problem. The isolators can affect the singularity of the CMG system as they are placed between the CMGs and the satellite bus and provide additional freedoms to the CMG system due to their flexibility. The formulation of the output torque of a CMG is studied first considering the dynamic imbalance of its spin rotor and then the deformation angle as a result of the isolator’s flex-ibility is calculated. With the additional freedoms, the influence of isolator on the singularity problem is studied and a new steering logic to escape from the singular states is proposed.     

基于数值预报模式的Ka频段卫星系统降雨衰减短时预测

为精确地实现Ka频段星地链路降雨衰减的短时趋势和强度预测,提出了一种基于数值天气预报的降雨衰减短时预测方法,设计了降雨衰减预测流程,并应用上述方法对某地区发生的降雨过程进行研究,比较分析了降雨衰减的实测值和基于数值预报的降雨衰减预测值。试验结果表明,基于数值预报的降雨衰减和实测值变化趋势符合较好,误差较小,在20GHz频段平均误差约为1.31dB,在30GHz频段平均误差约为2.39dB,在20GHz频段平均误差约为1.31dB,在30GHz频段平均误差约为2.39dB。该方法可实现Ka频段卫星通信系统的短时降雨趋势预测。     

基于有限元--离散元耦合的粒子阻尼减振研究

在侧挂构型发射任务中,中心承力筒与卫星直接连接,其动力学特性对卫星的振动响应有直接影响。首先分析中心承力筒的模态特性,据此完成粒子阻尼器的结构参数设计。随后,使用有限元--离散元耦合仿真方法,确定了阻尼器填充粒子的最佳直径和阻尼器最佳安装位置。仿真结果表明,该方案下星箭界面减振效果可达40%。最后,使用最优粒子阻尼参数开展水平激励实验。实验结果表明,与未安装粒子阻尼器相比,中心承力筒+粒子阻尼器组合体的减振效果可达35%以上,与仿真结果一致。     

一种适宜于航空电子类机载设备的可靠性强化试验方法

目前我国军机机载电子类设备的可靠性试验主要依赖传统的可靠性模拟试验技术,其存在试验周期长、效率低、耗费大以及试验结果易受综合环境应力准确性的影响等缺点.而可靠性强化试验通过外场加严使用环境中的某类或某几类应力来进行试验,可以快速激发设备的设计缺陷和制造工艺等问题.本文提出一种适宜于军机电子类机载设备的可靠性强化试验方法流程,给出试验应力量值、加载时序、运行流程、故障处理要求和回归验证方法等试验实施细则或要求,并在某型号工程研制中进行工程实践.结果表明:试验效果显著,可显著提高设备的可靠性、节约试验经费和时间.     

近地轨道卫星太阳电池阵功率衰减估计

针对LEO(Low Earth Orbit,近地轨道)卫星的太阳电池阵输出功率衰减问题,在分析卫星轨道半长轴、太阳入射角、日地距离等参数变化与影响的基础上,提出按照轨道衰减快慢来区分太阳活动高年与低年,进而通过区分高年与低年,再根据不同季节分别进行太阳电池阵输出功率的衰减估计,而无须做功率归一化。同时,重点关注了夏至前后的最低输出功率的衰减情况,以此作为在轨卫星长期管理中的能源参考,建立平均电流和功率衰减因子估计模型,并结合实际工程数据进行了衰减估计。结果表明,太阳电池阵输出功率的年衰减因子约为-0.012,年衰减率约为1.2%。该结果可应用于在轨卫星长期管理的遥测诊断辅助。     

固体发动机及火箭固有振动特性预估

用有限元方法计算了选用的固体火箭各级发动机壳体，药柱及整机固有频率和振型，并计算了火箭固有振动特性，为发动机冲击试验，今后的模态和振动试验提供了参考数据。这些数据是选择测试设备及量程，激励方式及位置，测点布置及试验夹具设计等测试技术所必需的。