不同粒径分布模拟月壤承压特性试验研究

月壤的承压特性决定月面巡视探测器的行驶阻力和沉陷,是影响月面可通过性的主要特征之一。为了得出不同粒径分布的模拟月壤在巡视器地面载荷和月面载荷下的承压特性,通过压板试验获取了3种不同粒径分布模拟月壤的承压性能曲线与参数。分析表明:粒径分布对模拟月壤承压性能影响大,粒径粗且分布均匀的JLU-1模拟月壤承压能力最强,其次为JLU-3模拟月壤,而粒径细且分布窄的JLU-2模拟月壤承压能力最弱;3种模拟月壤的变形指数在其他模拟月壤的范围内,松软状态时接近月壤值,在小载荷作用且松软状态时变形指数小于1;3种模拟月壤的内聚模量在其他模拟月壤的范围内,但大于月壤值;松软状态时3种模拟月壤的摩擦模量在其他模拟月壤的范围内,中密和密实状态下均大于月壤值。研究结果对月面探测器行走机构的仿真和路径规划具有参考意义。     

Multi-state autonomous drilling for lunar exploration

Due to the lack of information of subsurface lunar regolith stratification which varies along depth, the drilling device may encounter lunar soil and lunar rock randomly in the drilling process. To meet the load safety requirements of unmanned sampling mission under limited orbital resources, the control strategy of autonomous drilling should adapt to the indeterminable lunar environments. Based on the analysis of two types of typical drilling media (i.e., lunar soil and lunar rock), this paper proposes a multi-state control strategy for autonomous lunar drilling. To represent the working circumstances in the lunar subsurface and reduce the complexity of the control algo-rithm, lunar drilling process was categorized into three drilling states:the interface detection, initi-ation of drilling parameters for recognition and drilling medium recognition. Support vector machine (SVM) and continuous wavelet transform were employed for the online recognition of dril-ling media and interface, respectively. Finite state machine was utilized to control the transition among different drilling states. To verify the effectiveness of the multi-state control strategy, drilling experiments were implemented with multi-layered drilling media constructed by lunar soil simulant and lunar rock simulant. The results reveal that the multi-state control method is capable of detect-ing drilling state variation and adjusting drilling parameters timely under vibration interferences. The multi-state control method provides a feasible reference for the control of extraterrestrial autonomous drilling.     

Influence of lunar regolith compressibility on sampling performance of thick wall spiral drills

A 2 m class robotic drill was sent to the Moon and successfully collected and returned regolith samples in late 2020 by China. It was a typical thick wall spiral drill (TWSD) with a hollow auger containing a complex coring system to retain subsurface regolith samples. Before the robotic drill was launched, a series of laboratory tests were carried out to investigate and predict the possible drilling loads it may encounter in the lunar environment. This work presents how the sampling performance of the TWSD is affected by the regolith compressibility. Experiments and analysis during the drilling and sampling process in a simulated lunar regolith environment were conducted. The compressibility of a typical lunar regolith simulant (LRS) was measured through uni-directional compression tests to study the relationship between its inner regolith stress and bulk density. A theoretical model was established to elucidate the cutting discharge behavior by auger flights based on the aforementioned relationship. Experiments were conducted with the LRS, and the results show that the sampling performance is greatly affected by the flux of the drilled cuttings into the spiral flight channels. This work helped in scheduling reasonable drilling parameters to promote the sampling performance of the robotic drill in the Chinese Chang'E 5 mission.     

新型含硅芳炔树脂复合材料制备工艺

以含硅芳炔树脂为基体、高强玻璃布为增强材料制备了新型含硅芳炔树脂复合材料,探讨了树脂的固化工艺,研究了树脂含量、成型温度和成型压力对复合材料性能的影响,确定了含硅芳炔树脂复合材料成型的工艺参数:树脂质量分数31%、升温程序170℃/2h+210℃/2h+250℃/4h、成型压力1.0MPa。优化工艺条件下制备的复合材料弯曲强度达278MPa。     

月球风化层钻取采样过程密实度分类研究

钻取采样是月球风化层土壤样品获取的重要方式，密实度是重要的风化层月壤原位特性，对钻进过程中的策略制定有重要影响。本文结合钻取采样过程特点，提出了通过采样机构的力、速度、电流、温度等传感器获取的瞬时信息感知月壤密实度的方法，利用深度学习方法构建一类适应于可变长度序列数据的门控型循环神经网络，实现钻进过程月壤密实度在线分类。研究表明，该分类方法在风化层钻进过程中月壤密实度感知滞后时间约为33 s，对未知序列数据识别正确率大于89.36%，具有较高的分类精度和泛化能力。     

凝胶注模成型多孔Si3 N4 陶瓷及其性能

采用凝胶注模成型工艺制备出了具有低介电常数和高强度特性的多孔Si<,3>N<,4>陶瓷平板和锥形体样件,并对其微观结构、高温介电性能、透波率和弯曲强度等进行了测试与分析.结果表明:该方法获得的多孔Si<,3>N<,4>陶瓷具有低介电常数(2.3-2.8)、高弯曲强度(大于50 MPa)、高温介电性能稳定和透波率良好等优点.     

基于轮地作用参数和PLSDA方法的月壤力学性能评估

为评估在轨月球车周边环境月壤力学性能,以月球车辙信息、轮上载荷和滑转率作为基本参数,提出了16个二元及三元标识量,结合偏最小二乘判别方法(PLSDA)建立评估月壤力学状态模型。根据容重对模拟月壤力学状态进行分级,分别为松软状态、自然状态和紧实状态。应用轮壤相互作用试验台共采集247组试验数据,每种模拟月壤状态的试验数据按照2:1比例随机划分为校正集样本和预测集样本,最终校正集和预测集样本个数分别为166和81个。考虑到原始数据值相差大和所提出部分标识量包含冗余信息的特点,因此在建立PLSDA模型时,应用均值中心化预处理方法对原始数据进行数据预处理,并优选10个标识量建立识别月壤力学状态的PLSDA模型,对应的校正集的准确率和预测集的准确率分别为90.96%和90.12%。结果表明,应用PLSDA方法并结合月球车的车辙信息、轮上载荷和滑转率以及优选标识量所建立的评估月壤力学状态判别模型,其计算快速准确,可用于月球车在轨评估车轮前方月壤的力学特性和通过性能评估。     

固化温度对苎麻纤维增强复合材料性能的影响

研究了固化温度对苎麻纤维增强复合材料力学性能的影响,同时对比研究了平纹苎麻织物、单向苎麻纤维和单向玻璃纤维增强复合材料的力学性能.结果表明:环氧树脂3233分别在120℃,140℃和l80℃固化2h后,其拉伸性能和弯曲性能没有明显的变化;而基于环氧树脂3233的苎麻纤维增强复合材料在120℃和l40℃固化2h后力学性能相当,但是在180℃固化2h后,强度明显减小,模量变化不大;单向苎麻纤维增强复合材料的力学性能要远远大于平纹苎麻织物增强复合材料的力学性能,如单向苎麻复合材料uRamie-3233-120的压缩强度和压缩模量分别为154.0 MPa和35.6 GPa,而苎麻织物增强复合材料fRamie-3233-120分别为95.0 MPa和9.2 GPa;玻璃纤维增强复合材料的强度也会高明显高于苎麻纤维增强复合材料的强度.     

机场道面浅层高早强快速修补砂浆的性能研究

在满足繁忙机场不停航施工要求下,制备出道面浅层高早强快速修补砂浆对保障飞机准点运行及安全起降具有重要意义。采用自制的特种胶凝材料,通过优选砂胶比、水胶比及外加剂复配等技术制备出高早强快速修补砂浆,研究该修补砂浆的力学性能、黏结性能与耐久性能。结果表明:高早强快速修补砂浆2h抗压、抗折强度分别为32.5MPa和4.8MPa,且2h和28d黏结强度可分别达到其抗折强度的75%和84%;与C40混凝土相比,该修补砂浆早期具有微膨胀性,可补偿收缩,减小与旧混凝土间变形差异,120d收缩率降低了60.5%,3d耐磨性可达到C40混凝土28d的耐磨性,且具有优良的抗渗性与抗冲击性。     

Drilling load modeling and validation based on the filling rate of auger flute in planetary sampling

Some type of penetration into a subsurface is required in planetary sampling. Drilling and coring, due to its efficient penetrating and cuttings removal characteristics, has been widely applied in previous sampling missions. Given the complicated mechanical properties of a planetary regolith, suitable drilling parameters should be matched with different drilling formations properly. Otherwise, drilling faults caused by overloads could easily happen. Hence, it is necessary to estab-lish a drilling load model, which is able to reveal the relationships among drilling loads, an auger's structural parameters, soil's mechanical properties, and relevant drilling parameters. A concept for the filling rate of auger flute (FRAF) is proposed to describe drilling conditions. If the FRAF index under one group of drilling parameters is less than 1, this means that the auger flute currently removes cuttings smoothly. Otherwise, the auger will be choked with compressed cuttings. In dril-ling operations, the drilling loads on the auger mainly come from the conveyance action, while the drilling loads on the drill bit primarily come from the cutting action. Experiments in one typical lunar regolith simulant indicate that the estimated drilling loads based on the FRAF coincide with the test results quite well. Based on this drilling load model, drilling parameters have been opti-mized.     

Analysis of Chang’e-5 lunar core drilling process

Chang’e-5 explorer successfully acquired lunar regolith core samples from depths of greater than 1 m of lunar surface. This study analyzed the lunar core drilling process based on the telemetry data, image information, and returned samples to optimize the sampling device design and enhance the understanding of the lunar regolith. In particular, a prediction method for the projected drilling path and local terrain fitting of drilling dip angle was proposed based on the flight events recorded during the core drilling process and the image information acquired before, during, and after sampling. The results revealed that the drilling dip angle of Chang’e-5 was approximately 2.3°, and the deviation of the drilling length and depth was less than 2 mm. For continuous drilling, a fusion method based on telemetry data and image information was applied to determine the demarcation point of drilling with and without the lunar soil. The position of the demarcation point implied that the drilling point remained at approximately 6 mm loose soil, thereby lagging the action of the force response. Additionally, a characteristic parameter comparison method was proposed for the lunar and ground drilling to analyze the status of the lunar soil. Furthermore, the analysis results revealed that the majority of the Chang’e-5 drilling samples were derived from 0–73.8 cm below the lunar surface and few samples were extracted below 73.8 cm, as the drilling encountered several rocky regions. Moreover, the drilling point exhibited two prominent stratification variations at ～28.7 cm and ～70 cm below the lunar surface. Ultimately, the preliminary relationship between sample dissected position in soft tube and drilling displacement was analyzed. The segmented estimation results can support research on subsurface lunar soil.     

双酚A型环氧树脂紫外光固化工艺及其力学性能

为了推进紫外光固化技术在环氧树脂及其复合材料制备中的应用,以双酚A型环氧树脂E51为基体,采用自行研制的紫外光设备固化,利用红外光谱法测定固化后树脂的固化度,研究了树脂体系中光引发剂和稀释剂含量对树脂固化速率的影响以及环氧树脂的紫外光固化特性,获得的树脂体系的最优配方为：双酚A型环氧树脂E51:活性稀释剂660A:光引发剂1176=100:10:5（质量比）,并对紫外光固化树脂浇铸体的力学性能进行了测试,其拉伸强度和模量分别可达到32.34 MPa和1.80 GPa,弯曲强度和模量分别为60.64 MPa和1.73 GPa。结果表明,紫外光固化速率随树脂体系中光引发剂含量的增加而上升,随活性稀释剂含量的增加先上升后下降;与传统热固化相比,紫外光固化不仅可以大幅度缩短树脂体系的固化时间,同时,制得的树脂浇铸体具有良好的综合力学性能。研究结果对紫外光固化技术在实际生产中的应用具有重要意义。     

硫化压力对橡胶／金属热硫化粘接剥离强度的影响

研究 NR1155天然橡胶在不同硫化压力下热硫化后的物理力学性能。基于90°粘合剥离强度测试方法分别测量了不同硫化压力下制备的橡胶／金属复合结构试样的粘合剥离强度,并采用低场 NMR 橡胶交联密度测定仪分析试样中橡胶部分的交联密度,同时采用冷场发射电子扫描显微镜（SEM）研究剥离破坏表面。结果表明：NR1155天然橡胶胶料与 Chemlok205／Chemlok220热硫化胶粘体系具有很好的相容性和协同硫化作用。随着硫化压力的提高,橡胶／金属的粘合剥离强度呈现先降低后增加的规律,且最大剥离力呈现对硫化压力的函数依赖关系,而硫化胶的交联密度则呈现相反的趋势。     

空间光学结构用改性氰酸酯树脂及其复合材料性能

以空间光学结构应用为背景,对新研制改性氰酸酯树脂低温固化体系开展评价研究,包括树脂体系的固化特性、力学性能、耐湿热性以及工艺性能等;与HS40高模量碳纤维复合制备了复合材料,对其主要力学性能进行了研究。结果表明,改性氰酸酯树脂催化体系具有优异的固化反应特性,起始固化温度为101.2℃,较未催化的氰酸酯树脂降低了97.4℃;拉伸性能以及弯曲性能均有提高,同时其沸水饱和吸水率仅1.3%左右,明显低于双马（4%）和环氧树脂（5.8%）;树脂的工艺性良好,适合热熔法制备预浸料;应用热熔浸渍法制备的HS40碳纤维/氰酸酯树脂预浸料经层合固化后力学性能优异：纵向拉伸强度和模量分别为2 244.5 MPa和248.0 GPa。     

一种潜伏性无卤阻燃中温固化环氧树脂体系

选用双氰胺和UR500为固化体系,自制阻燃剂M,制备一种预浸料用潜伏性无卤阻燃中温固化环氧树脂体系。结果表明,该树脂体系室温下储存期超过30 d,固化后力学性能优良,拉伸性能可达66. 5MPa,弯曲强度可达133 MPa,冲击强度可达10. 7 kJ/m2,阻燃防火性能优异,氧指数高达33. 1%,垂直燃烧满足UL-V0级,且可离火自熄。扫描电镜和热分析的结果表明,该体系优异的阻燃性能主要源于其燃烧后所成碳层的隔热隔氧作用。     

氮化硅陶瓷的增韧研究

研究了加入ZrO_2和SiC晶须对热压烧结Si_3N_4的增强增韧作用。加入ZrO_2和SiC晶须能提高复合材料的断裂韧性K_(IC),但降低了抗弯强度。分别加入10vol％纯ZrO_2和含有钇的Y-ZrO_2,使Si_3N_4陶瓷的室温K_(IC)从原来的6.3MPa·m~(1/2)分别提高到7.3MPa·m~(1/2)和7.6MPa·m~(1/2)。加入10wt％SiC晶须,使Si_3N_4陶瓷的室温K_(IC)从6.3MPa·m~(1/2)提高到7.1MPa·m~(1/2)。     

酚醛树脂炭的合成及力学性能研究

为了表征多孔炭泡沫材料基体的结构与力学性能,采用碱催化法制备热固性酚醛树脂,经固化、高温炭化处理合成多孔炭泡沫材料的基体——酚醛树脂炭。研究酚醛树脂炭的微观结构、压缩强度及压缩断裂韧性。结果表明:酚醛树脂炭结构以树脂炭基体、微孔和微裂纹为主,其碳元素以sp3杂化的非晶炭形式存在;压缩强度为8.58 MPa,压缩断裂特征为脆性断裂模式;酚醛树脂炭的压缩断裂韧性较差,断裂过程中吸收的总能量为0.135 MJ/m3。     

高性能M40J/BADCy复合材料的研究

对E51环氧树脂改性双酚A型氰酸酯(BADCy)体系的力学性能及热性能进行了研究,发现当E51环氧树脂的质量含量为5%时,改性体系的弯曲强度和冲击强度分别由原来的95.6MPa和9.24kJ/m²提高到了117.8MPa和12.6kJ/m²,而热变形温度仅下降8℃。以该改性体系为基体制作的M40J复合材料,其弯曲强度、模量和剪切强度分别高达:1270MPa,172GPa,68 9MPa。消泡剂BYK141能提高M40J/BADCy复合材料的力学性能,层间剪切强度可提高到77.1MPa。M40J/BADCy复合材料还具有良好的耐环境能力,是一种理想的航空航天结构材料。     

黏结剂含量对碳基材料性能和结构的影响

以沥青焦、炭黑、人造石墨粉为骨料,以硫改性沥青为黏结剂,通过浆涂混合冷压炭化工艺,制备了一系列碳基体材料.考察了黏结剂含量对碳材料的物理性能和微观结构的影响.结果表明,碳材料的物理性能和微观结构与黏结剂含量有重要的关系;随黏结剂含量的增加,材料的密度和强度呈增大的趋势,而开孔率则逐渐下降;当黏结剂质量分数为44%时,材料的弯曲强度和压缩强度分别达到42.6 MPa和187 MPa;当黏结剂质量分数超过44%时,材料在炭化过程中破裂.这些变化可归因于黏结剂与骨料颗粒在热混捏和炭化过程中的相互作用机理.     

Lunar Exploration Neutron Detector for the NASA Lunar Reconnaissance Orbiter

The design of the Lunar Exploration Neutron Detector (LEND) experiment is presented, which was optimized to address several of the primary measurement requirements of NASA’s Lunar Reconnaissance Orbiter (LRO): high spatial resolution hydrogen mapping of the Moon’s upper-most surface, identification of putative deposits of appreciable near-surface water ice in the Moon’s polar cold traps, and characterization of the human-relevant space radiation environment in lunar orbit. A comprehensive program of LEND instrument physical calibrations is discussed and the baseline scenario of LEND observations from the primary LRO lunar orbit is presented. LEND data products will be useful for determining the next stages of the emerging global lunar exploration program, and they will facilitate the study of the physics of hydrogen implantation and diffusion in the regolith, test the presence of water ice deposits in lunar cold polar traps, and investigate the role of neutrons within the radiation environment of the shallow lunar surface.