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针对柔性卡箍支承航空发动机管路系统振动问题,研究了柔性卡箍的刚度特性及其对管路系统响应特性的影响。建立了包含管路和柔性卡箍的管路系统流固耦合有限元模型,给出了系统时域响应的Newmark积分方法。采用解析推导和试验测试两种方法对柔性卡箍刚度特性进行了研究,研究结果表明:柔性卡箍的刚度具有明显的分段线性特性。通过对基础简谐激励作用下管路系统时域受迫响应分析,研究了柔性卡箍支承刚度对系统非线性行为的影响。发现柔性卡箍刚度的不对称性较大时,系统的幅频响应特性曲线出现明显的非线性突跳现象;在特定频率范围,响应中存在激励频率的亚谐和超谐分量;随着流体流速和压力的增加,系统固有频率减小。 相似文献
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基于主被动复合驱动的思想提出一种大伸展/收拢比、高载荷/自重比的新型伸缩式伸杆机构,以满足微纳探测器的实际应用需求,用于支撑各类探测载荷远离航天器本体,避免本体剩磁对空间待测信号的干扰,保证探测数据的准确性。首先,探索描述被动驱动源(弹簧铰链)的力矩驱动特性;然后,分析柔性伸杆的弯曲、扭转、压平和卷曲等力学性能。在此基础上,结合建立的柔性伸杆伸展速度、负载动能、弹簧铰链势能及主动驱动(电动机)力矩等参数的能量流约束方程,进行主、被动驱动和柔性伸杆的参数匹配研究;最后,利用有限元软件仿真和样机平台实验验证了参数匹配的合理性。仿真与实验结果表明,针对主被动复合驱动的空间探测柔性伸杆机构,通过合理的参数匹配,可实现柔性伸杆无褶皱地平稳伸展和收拢,为后续的机构设计和控制方案奠定了基础。 相似文献
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基于主被动复合驱动的思想提出一种大伸展/收拢比、高载荷/自重比的新型伸缩式伸杆机构,以满足微纳探测器的实际应用需求,用于支撑各类探测载荷远离航天器本体,避免本体剩磁对空间待测信号的干扰,保证探测数据的准确性。首先,探索描述被动驱动源(弹簧铰链)的力矩驱动特性;然后,分析柔性伸杆的弯曲、扭转、压平和卷曲等力学性能。在此基础上,结合建立的柔性伸杆伸展速度、负载动能、弹簧铰链势能及主动驱动(电动机)力矩等参数的能量流约束方程,进行主、被动驱动和柔性伸杆的参数匹配研究;最后,利用有限元软件仿真和样机平台实验验证了参数匹配的合理性。仿真与实验结果表明,针对主被动复合驱动的空间探测柔性伸杆机构,通过合理的参数匹配,可实现柔性伸杆无褶皱地平稳伸展和收拢,为后续的机构设计和控制方案奠定了基础。 相似文献
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航空发动机、火箭涡轮泵等现代高端涡轮机械对性能有着极致的需求,其轻柔化的支承结构导致转子与柔性基础振动耦合特性明显,必须将其柔性支承结构纳入整体动力学分析之中。然而,柔性基础的高精度建模过程需要耗费大量时间,同时简化的基础模型也难以表达其真实的动力学特性。为此,提出了融合柔性基础传递函数的转子系统动力学建模仿真方法:将实测得到的柔性基础传递函数通过状态子空间法拟合获得低维时域和频域表征的数学模型,通过支承力模型将柔性基础模型耦合到转子有限元模型之中,最终形成基于实物传递函数的混合转子动力学模型。同时,提出了柔性基础从稳态到瞬态的模型转换策略,并采用线性-非线性节点(显-隐)分离的快速瞬态数值积分方法进行求解。基于所提模型和计算方法,开展了柔性基础-转子系统的稳态、瞬态动力学数值仿真,以及稳定转速扫频激励和降速不平衡激励的振动测试试验,结果表明:实测的柔性基础振动特性,能够有效地体现在整机动力学分析之中,且考虑柔性基础特性的转子动力学模型所预测的瞬态动力学响应与试验结果更为吻合。所提方法为含复杂柔性基础的转子系统提供了行之有效的整机建模及瞬态仿真方法。 相似文献
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基于仿章鱼软体机器人空间碎片柔性自适应捕获装置的设想 总被引:1,自引:0,他引:1
《载人航天》2017,(4)
针对空间碎片跨尺度、柔性、自适应捕获的需求,根据任务功能分析及仿生学启示,提出了一种基于仿章鱼充气软体机器人的碎片捕获装置,主要由仿章鱼触手和伸展臂组成,具备远距离可达、末端位姿调整、跨尺度碎片抓捕、目标碎片的测量与识别等能力。捕获装置采用仿章鱼单支链捕获及多支链协同缠绕的方式实现对跨尺度目标的可靠、灵活捕获。捕获触手采用充气软体机器人的机理实现对非结构化碎片的可靠捕获、相容,可实现捕获过程中对碰撞冲击的减缓和能量吸收。伸展臂采用充气驱动的方式展开,具有轻质、大收缩比的特点。触手表面还采用仿壁虎脚趾刚毛实现对碎片的可靠粘附,进一步确保抓取的可靠性。最后通过任务仿真验证了碎片柔性自适应捕获装置的可行性和先进性。 相似文献
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挠性多体航天器姿态动力学建模与分析 总被引:3,自引:0,他引:3
针对带有多个挠性附件以及天线转动机构的卫星等多体航天器.利用伪坐标Lagrange方程建立了系统的姿态动力学模型。通过仿真计算.分析了星体与天线运动的耦合特性.以及挠性附件干扰对卫星姿态的影响.验证了数学模型的正确性。 相似文献
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《中国航空学报》2023,36(5):33-40
A better understanding of the mixing behavior of excited turbulent mixing layers is critical to a number of aerospace applications. Previous studies of excited turbulent mixing layers focused on single frequency excitation or the excitation with fundamental and its second harmonic frequency. There is a lack of detailed studies on applying low and higher frequency excitation. In this study, we have performed large-eddy simulations of periodically excited turbulent mixing layers. The excitation consists of a fundamental frequency and its third harmonic. We have used phase-averaging to identify the vortex structure and strength in the mixing layer, and we have studied the vortex dynamics. Two different vortex paring mechanisms are observed depending on the phase shift between the two excitation frequencies. The influence of these two mechanisms on the mixing of a passive scalar is also studied. It is found that exciting the mixing layer with these low and high frequencies has initially an adverse influence on the mixing process; however, it improves the mixing further downstream of the splitter plate with the excitation using a phase shift of showing the best mixing performance. The present works shed lights on the fundamental vortex dynamics, and has great potential for aeronautical, automotive and combustion engineering applications. 相似文献
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Acceleration sensors based modal identification and active vibration control of flexible smart cantilever plate 总被引:1,自引:0,他引:1
Some flexible appendages of spacecrafts, such as solar panels, are cantilever plate structures. Thus, vibration problem is unavoidable when there is slewing maneuver or external disturbance excitation. Vibration of such cantilever plate structures includes coupled bending and torsional motion. Furthermore, the low amplitude vibration near the equilibrium point is very difficult to be quickly suppressed due to nonlinear factors of the hardware in the system, which is harmful to stability and attitude control accuracy. To solve these problems, acceleration sensor-based modal identification and active vibration control methods are presented for the first two bending and the first two torsional modes vibration of the cantilever plate. Optimal placements of three acceleration sensors and PZT patches actuators are performed to decouple the bending and torsional vibration of such cantilever plate for sensing and actuating, and identifications are achieved by experiments. A nonlinear control method is presented to suppress both high and low amplitude vibrations of flexible smart cantilever plate significantly. Experimental comparison researches are conducted by using acceleration proportional feedback and the presented nonlinear control algorithms. The experimental results demonstrate that the presented acceleration sensor-based methods can suppress the vibration of cantilever plate effectively. 相似文献
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考虑了一个带有非线性弹性支承的偏置圆盘Jeffcott转子系统,研究了常数机动载荷对该系统振动特性的影响.通过数值计算发现:常数机动载荷取不同值时,系统的幅频特性曲线可能出现滞后区变窄、消失以及二次跳跃现象;频率比不同值时,系统振幅与常数机动载荷关系曲线差别较大,在特定转速下,先将常数机动载荷缓慢增加至一定值,再缓慢降低至零,可能引起系统由小振幅稳态解跳跃至大振幅稳态解而无法恢复;转子轴心偏移量随着常数机动载荷增加而增大,受系统工作转速影响不大. 相似文献
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We study kinetic excitation mechanisms for high-frequency dispersive Alfvén waves in the solar corona, solar wind, and Earth's
magnetosphere. The ion-cyclotron and Cherenkov kinetic effects are important for these waves which we call the ion-cyclotron
kinetic Alfvén waves (ICKAWs). Ion beams, anisotropic particles distributions and currents provide free energy for the excitation
of ICKAWs in space plasmas. As particular examples we consider ICKAW instabilities in the coronal magnetic reconnection events,
in the fast solar wind, and in the Earth's magnetopause. Energy conversion and transport initiated by ICKAW instabilities
is significant for the whole dynamics of Sun-Earth connection chain, and observations of ICKAW activity could provide a diagnostic/predictive
tool in the space environment research.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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周期性碰摩激励作用下薄壁机匣支撑系统响应机理 总被引:1,自引:1,他引:0
针对发动机薄壁机匣支撑系统在碰摩激励作用下动力学响应复杂,基于机匣振动信号的碰摩故障特征识别难度大的问题,提出了一种用于故障特征机理分析的数值仿真方法。通过建立薄壁机匣系统的等效动力学三维实体模型,将碰摩激励进行等效力学简化,利用瞬态动力学方法对周期性碰摩故障进行了数值仿真。在系统固有特性分析的基础上,对机匣测点在碰摩激励作用下的时域、频域响应特征展开研究,得到了碰摩故障特征的产生机理。机匣位移振动信号主导频率为系统整体低阶固有频率,加速度振动信号主导频率为碰摩脉冲激励频率及其倍频,上述结论可作为碰摩故障发生的依据,为故障早期诊断提供参考。 相似文献