探测器安全着陆风险评估与敏感性分析

探测器安全着陆是行星探测的关键环节,而目前着陆成功率偏低,进行安全着陆风险研究有着非常现实的工程需求.为此,首先分析探测器结构与着陆方式,梳理行星表面影响安全着陆的主要因素,明确着陆安全判据,然后基于蒙特卡罗思想,模拟行星表面地貌和探测器着陆方式,给出了探测器在盲降下安全着陆概率估计的仿真方法.在此基础上,考虑探测器尺寸和着陆区域面积,对探测器安全着陆概率进行敏感性分析,结果表明探测器的尺寸对安全着陆概率有显著影响.      

气象因素对飞行安全高度的影响

通过分析气象因素对气压式高度表测量高度的影响,求出了高度误差极值。说明了我国安全高度按高于航线两侧25km范围内的最大标高400m或600m存在一定误差,提出了一些预防措施。     

大范围轨道机动的燃料消耗优化方法

针对航天器大范围轨道交会提出了二冲量燃料最省机动方案的数值寻优算法及多冲量机动方案的啸声境遗传算法.利用共面圆\椭圆轨道间的转移实例对两种算法正确小生境遗传算法.利用共面圆\椭圆轨道间的转移实例对两种算法正确性进行了验证,通过仿真实验,比较了大范围交会轨道机动中不同冲量次数对总燃料消耗的影响,分析得出了非共面轨道交会机动时燃料最省的指导性方案.     

基于代理模型的结构外形优化

提出了一种将代理模型用于机翼结构外形优化的方法。重点介绍了建立结构分析代理模型的过程,包括确定设计变量及取值范围、生成试验设计点、建立参数化结构模型、有限元结构优化设计、提取结构特性并构造代理模型。最后通过一个简单的机翼结构优化算例验证了这种方法的可行性和有效性。     

基于细观刚度模型的缠绕复合材料结构有限元分析方法

 缠绕复合材料结构分析是缠绕复合材料力学性能研究及应用的重要基础。发展了一种缠绕复合材料结构分析有限元方法,该方法基于缠绕复合材料细观刚度模型,通过建立细观刚度场与整体结构的映射关系,将缠绕复合材料细观刚度模型引入缠绕复合材料结构有限元分析中。采用各向异性单元,几何模型与网格划分等过程不需要进行复杂的处理,单元材料属性采用细观刚度模型计算,并通过已建立的细观刚度场和整体结构的映射关系输入。建立了缠绕复合材料结构有限元分析的流程,采用MATLAB程序编写了细观刚度场计算程序,采用ANSYS提供的APDL语言开发了几何建模、分网、读入刚度矩阵等相应分析程序,最后进行了算例分析。算例结果表明,缠绕复合材料内部各层应力应变呈周期性分布,应力应变在纤维交叉和波动区域有所变化,纤维波动对局部应力具有放大作用;纤维走向的交替造成内部剪切应力的正负交替;纤维弯曲引起的局部刚度下降造成局部的应变较大。与传统的经典层合板理论或有限元方法相比,在缠绕复合材料有限元分析中,采用基于傅里叶级数的细观刚度模型,可以反映材料内部细观结构对应力应变分布的影响;同时,方法简单,便于程序实现。     

Power plant selection in a carbon constrained world the TERA(technoeconomic environmental risk analysis)

There is an increasing concern that current trends of consumption of natural resources cannot continue.It is imperative that major targeted investments are made into economical and reliable environment friendly propulsion and power solutions.Many novel and promising concepts are being proposed.The selection of the best candidates to pursue for investment becomes a very difficult choice.A detailed TERA(techno-economic environmental risk analysis) framework is described here to quantify risks and to compare and rank competing schemes on a formal and consistent basis.This technique is based on detailed and rigorous thermodynamic representations of power plants.A layer of environment,economic,weather and other models to describe the appropriate local conditions is superimposed to this.The outcome is a techno-economic environmental risk analysis framework with appropriate detail of each power plant as applied to the appropriate conditions.The results for each concept can then be compared and contrasted to make appropriate selections.      

高温高压下的燃气／空气热管换热方案

以高温高压燃气加热高压纯空气为研究背景,用平均温差法对气-气热管换热器设计计算,进行结构方案设计,采用有效度-传热单元数法对换热器传热进行校核计算。设计换热器为圆柱形筒壁结构,出口为渐缩型喷管结构,采用半轴比为2／1的椭圆形热管。     

深空辐射环境对航天活动的危害及对策

深空辐射环境是影响深空探测任务的一个主要因素,它主要包括太阳粒子事件、银河宇宙射线、俘获辐射带和黑体表面辐射。文章分析了它对航天活动的危害,并探讨了相应的对策。     

航天器局部系统动力特性的频率匹配设计

对航天器结构进行频率匹配设计,是降低耦合响应,控制其在发射阶段动力响应水平的有效方法,文章进行了局部系统动力特性的频率匹配技术研究。用基于响应谱分析的频率匹配技术优化配置局部系统的固有频率,使其与整星动力学特性和动态激励特性更加匹配,并结合结构动力特性优化使局部系统频率满足设计值。通过工程实例,验证了该方法用于控制航天器动力响应的有效性,优化后设备加速度响应幅值相对于优化前降低了20％～40％。     

Integrated batteries layout and structural topology optimization for a solar-powered drone

The purpose of this paper is to demonstrate an integrated optimization scheme for a solar-powered drone structure. Consider a primary beam in the wing of large aspect ratio, where 100 lithium batteries are assembled. In the proposed integrated optimization, the batteries are considered here as parts of the load-carrying structure. The corresponding mechanical behaviors are simulated in the structural design and described with super-elements. The batteries layout and the structural topology are then introduced as mixed design variables and optimized simultaneously to achieve an accordant load-carrying path. Geometrical nonlinearity is considered due to the large deformation. Different periodic structural configurations are tested in the optimization in order to meet the structural manufacturing and assembly convenience. The optimized designs are rebuilt and tested in different load cases. Maintaining the same structural weight, the global mechanical performances are improved greatly compared with the initial design.