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341.
为解决共形相控阵雷达中组件与共形天线平台不匹配以及线缆插拔带来的系统不稳定等问题,对基于LCP基板的柔性T/R组件封装技术开展研究。分析了基板层压质量控制及有源芯片埋置方法,通过ANSYS软件仿真了基板不同弯曲角度下的应力分布。结果显示叠加层压辅材后的优化层压过程可以有效去除层间气泡,MMIC埋置的气密性可达7.4×10-7 Pa·m3/s。仿真结果表明在-55~80 ℃的温度循环下,当基板弯曲角度大于10°时,弯曲应力随着弯曲角度的增加迅速增长。当基板弯曲角度小于10°时,T/R共形组件保持优良性能。 相似文献
342.
《中国航空学报》2022,35(11):209-218
The kinematic characteristics of flexible membrane wing have vital influences on its aerodynamic characteristics. To deeply explore the regularities between them, time-resolved aerodynamic forces and deformations at different aeroelastic parameters and angles of attack (α) were measured synchronously by wind tunnel experiments. The membrane motion can be mainly divided into two states at α > 0° with various lift-enhancement regularities: Deformed-Steady State (DSS) at pre-stall, and Dynamic Balance State (DBS) at around stall and post-stall. Besides, the mean camber, maximum vibration amplitude, and lift coefficient almost reach their maxima simultaneously within the DBS region. By introducing momentum coefficient Cμ of membrane vibration, positive correlation among amplitude, momentum and lift is successfully established, and the lift-enhancement mechanism of membrane vibration is revealed. Moreover, it is newly and surprisingly found that at different vibration modes, the maximum vibration amplitude and root mean square of vibration velocity present positive and linear correlation with different slopes, and their chordwise locations are basically consistent. Therefore, novel ideas for active control of flexible wing are proposed: by controlling the vibration amplitude, frequency, and mode, while selecting the specific chordwise locations for intensive excitation, Cμ can be efficiently increased. Ultimately, the aerodynamic performance will be improved. 相似文献
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《中国航空学报》2023,36(4):409-422
The flight-structural dynamics of a high-aspect-ratio wing challenge the flight control design. This paper develops a reduced model of coupled dynamics with stability consideration. The structural dynamics are formulated with dihedrals, and the central loads drive the deformation. The control-oriented model with essential coupled dynamics is formulated. Modal sensitivity analysis and input–output pairing are performed to identify the control structure. Besides, an example of flight control design is provided to discuss the necessity of considering structural dynamics in controller design. Analytical coupled flight dynamics provide a system-theoretic approach for stability and facilitate model-based control techniques. Simulation results reveal the characteristics of flight-structural coupled dynamics and demonstrate that the influence of flexible modes should be considered in control design, especially in lateral dynamics. 相似文献
347.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(5):2095-2127
The present work theoretically demonstrates the dynamic analysis of a planar multi-link manipulator considering flexible links and joints mounted on a moving base. A nonlinear model of a multi-manipulator (N-links) has been developed accounting for an equivalent bi-directional mobile base. The nonlinear Euler-Bernoulli beam and spring-inertia/mass system have been introduced to demonstrate the flexibilities of links and joints, respectively. Modal analysis followed by trajectory analysis has been performed to investigate the behaviors of manipulator taking into account of accurate boundary conditions. Further, vibration characteristics, steady-state responses, and their stability at resonant situations due to joint motions and inertial coupling have been studied. Results of exploiting geometric and inertial coupling due to flexible arms on stability analysis of steady-state responses have been investigated and have been subsequently verified with the findings by directly solving the governing equations. Steady-state response characteristics to explore the dynamics of the multi-link manipulators under resonant states have been studied with the varying actuator mass, the flexibility of links, lifted payload, and joint parameters. The results thus obtained, deliver a useful insight into the position analysis and long-term behavior of multi-link flexible manipulators under harmonic hub-joint motions that shall further enable its proper vibration attenuation and control. 相似文献
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随着空间碎片数量的增加,其对近地轨道中的在轨卫星产生越来越严重的威胁,空间多碎片的高效清理在近年来也成为了学界关注的热点问题。针对柔性绳网在一次任务中同时对多个碎片进行捕获清理的问题,建立了柔性绳网的动力学模型和与碎片接触动力学模型,并对捕获过程中柔性绳网与碎片的运动进行了仿真模拟。针对绳网的最大拉伸力、质量块位移速度等变量,深入分析捕获过程中绳网与碎片的运动特性。数值仿真结果表明,在一次任务中,柔性绳网可以对多个旋转空间碎片进行捕获,并实现稳定的包裹缠绕,展示了柔性绳网良好的捕获能力。 相似文献