A sample collector for robotic sample return missions III: Impact survivability studies

Laboratory impact tests have been performed on experimental versions of a proposed robotic sample collector for extraterrestrial samples. The collector consists of a retractable aluminum ring containing an impregnable silicone compound that is pressed into the surface of the body to be sampled. As part of a comprehensive program to evaluate this idea, we have performed tests to determine if the samples embedded in the collector medium can survive the impact forces experienced during direct reentry, such as that of the recent Genesis sample return mission. For the present study, samples of sand, rock, glass, and chalk were subjected to decelerations of 1440–2880 g using drop tests. We found that even the most fragile samples, chosen to be representative of a wide range of the types of materials found on the surface of asteroids that have currently been studied, can withstand impacts of the intensity experienced by a sample return capsule during direct reentry.     

Influence of pre-tension on ballistic impact performance of multi-layer Kevlar 49 woven fabrics for gas turbine engine containment systems

In this paper, ballistic impact tests on wrapped multi-layer Kevlar 49 woven fabric systems were carried out with a flat blade projectile to investigate the impact response during a fan blade out event. The influences of the number of Kevlar layers and pre-tension were discussed particularly. Test results were used to analyze failure modes and energy absorption characteristics of multi-ply Kevlar fabrics. Results show that there are two kinds of impact damage for fabrics: global deformation mainly involving stretching of yarns in the impact region and fabric wrinkle from both sides to the impact zone, and local damage characterized by yarn fracture, yarn pull-out, and yarn unraveling. The energy absorption capability of Kevlar 49 woven fabrics improves with the number of fabric layers. The energy absorbed by multi-layer fabrics increases slightly at the beginning and then decreases substantially with pre-tension. The work in this paper can provide guidance for designing light-weight multi-layer fabrics containment systems.     

空间对接中差动式缓冲阻尼机构的建模研究

以美俄在ＡＳＴＰ计划中“联盟号”飞船的对接机构为背景,首先研究了差动式机电缓冲阻尼系统的结构组成和运动原理,并且建立了由捕获环,传动丝杠和固定机架组成的六自由度并联多环机构的运动简化模型。     

柔性航天器的动力学建模问题

首先简单介绍了关于柔性航天器动力学建模的一些综述论文,指出了柔性航天器动力学建模的困难所在。然后,分别对柔性体变形运动的描述模型,浮动参考架的选择、动力学方程的建立和模型降阶等问题进行了探讨。     

小卫星围绕空间站飞行动力学和控制研究

研究微小卫星围绕空间站飞行, 监视空间站运行和外观状态, 减少航天员舱外活动。这是小卫星一种新的应用概念。文章主要研究绕飞轨道动力学和稳定性, 以及在有摄动情况下保持绕飞轨道的控制策略。这种控制策略所消耗燃料非常少, 根据仿真实验结果, 绕飞卫星飞行一个月消耗的燃料可产生速度增量约为３～４ｍ ／ｓ。     

大型星载可展开天线的展开动力学问题

针对大型星载可展开天线所具有的尺寸大、刚性小、展开机构复杂,所处环境恶劣等特点,结合天线的构形特征,着重从可展开天线展开动力学的建模角度,综述了可展开天线的展开动力学问题。对解决途径及办法提出了一些看法。     

着陆缓冲装置特性分析及控制方法研究

着陆缓冲技术在航天器回收系统中的应用日益广泛,文章对着陆缓冲过程所使用的两种发动机推力制度进行了比较;分析了着陆缓冲过程中影响系统最终性能的因素。认为影响最大的因素是初始条件和环境条件的改变,对此提出了一种较为实用的控制方法。应用这一方法,可以最大限度地消除初始条件和环境条件的改变对着陆缓冲装置性能的影响。     

带间隙空间结构的动力学特性分析

研究带间隙空间结构的动力学问题。着重讨论间隙引起的结构非线性特性,从理论上探讨了一维间隙系统的定量及定性求解方法,并通过伸展机构的试验研究,验证了间隙对结构动力学特性的影响。     

High precision and efficiency robotic milling of complex parts:Challenges,approaches and trends

Due to the advantages of large workspace, low cost and the integrated vision/force sensing, robotic milling has become an important way for machining of complex parts. In recent years,many scholars have studied the problems existing in the applications of robotic milling, and lots of results have been made in the dynamics, pose planning, deformation control etc., which provides theoretical guidance for high precision and high efficiency of robotic milling. From the perspective of complex parts r...     

混杂复合材料层合板抗冲击性能研究

为了探究复合材料层合板在实际应用中因承受冲击载荷而造成的结构安全问题,本研究采用实验和仿真相结合的方法,首先探究冲头形状对复合材料层合板损伤机理的影响,然后结合不同冲击能进一步揭示层合板的承载力和能量吸收变化规律。结果表明,相同冲击能下,层合板的损伤范围和承载力随着圆锥头、半球头、平头依次增加;相应的层合板的临界穿透能量随着圆锥头、半球头、平头依次增大;冲头形状和冲击能对层合板的吸能能力有较大的影响。