某机身壁板结构环向裂纹扩展分析与试验对比

对于机身加筋壁板结构,获取较为准确的应力强度因子是进行裂纹扩展分析的基础,其核心工作是计算结构的几何因子。本文结合T.Swift提出的机身加筋壁板结构几何因子计算方法,编制了相关分析工具,计算获得某机身壁板结构环向裂纹几何因子,将计算结果与采用有限元法计算获得的几何因子进行对比。最后,将几何因子输入Nasgro软件进行裂纹扩展寿命分析,与试验结果进行对比,吻合较好。该方法计算效率高,可节省大量计算时间,具有较强的工程应用价值。     

基于局部敏感性的平衡场长影响因素分析

平衡场长是民用飞机设计与使用中的重要技术指标之一,其长短对民用飞机的经济性、安全性和通用性均有显著的影响,同时也是确定飞机决策速度的基础,因而,研究平衡场长具有重要意义。介绍平衡场长的概念、计算方法及它与决策速度之间的关系,列举三种敏感性分析理论;以某型民用飞机为例,研究起飞质量、机场高度、风速、温度、跑道坡度等因素对平衡场长的影响,利用上述敏感性分析方法评估不同因素对平衡场长的敏感程度。结果表明:平衡场长和决策速度随着起飞质量、机场高度、顺风风速、温度的增加而增加,随逆风风速的增加而减小;跑道坡度对平衡场长的影响几乎可以忽略;三种敏感性分析方法所得参数的正负相关性一致,五个变量对平衡场长的敏感性排序为:起飞质量风速机场高度温度跑道坡度。     

Downwash modelling for three-lifting-surface aircraft configuration design

This paper introduces a semi-empirical model to predict the downwash gradient at the horizontal tail of a three-lifting-surface aircraft. The superposition principle applied to well established formulations valid for two lifting surfaces is not a reasonable approach to calculate the downwash of a canard-wing-tail layout, and this paper demonstrates that such a basic technique leads to incorrect results. Therefore, an ad hoc prediction model is proposed that considers the combined nonlinear effec...     

铝蜂窝夹层板热管区域平面度控制方法研究

主要研究蜂窝板热管区域局部平面度超差的原因及控制方法。经分析,蜂窝叠块的尺寸精度以及胶膜固化后的厚度不均匀性是导致超差的主要原因,通过提高工装均压板的厚度,利用胶膜厚度的自适应性弥补零部件尺寸累积偏差,提高平面度,并对新方法下产品剥离、剪切强度进行测试,结果表明,该工艺方法可以在不影响产品力学性能的前提下大幅改善产品热管区域平面度。     

基于气凝胶的防隔热一体化材料研究进展北大核心CSCD

新型高速飞行器的快速发展对热防护系统提出了更高要求,基于气凝胶的防隔热一体化材料对提升热防护系统的防隔热性能和结构效率有重要意义。本文基于防热层材料的不同,分类概述了基于气凝胶的防隔热一体化材料的研究进展、结构形式和性能特点,并简要阐述未来防隔热一体化材料发展需要解决的问题。     

Review on residual stress and its effects on manufacturing of aluminium alloy structural panels with typical multi-processes

In the aerospace industry, integrated aluminium alloy plates and stiffened panels with high accuracy and performance attract significant interest. To manufacture these panels as integrity with high accuracy, multiple processes need to be utilised, such as machining, welding and forming. During the whole manufacturing chain, residual stresses can be generated and redistributed in the components among different processes. The residual stress would significantly affect the shapes and properties of the final products. Currently, these great effects are not well considered in the design and manufacturing processes. This paper aims to draw a general understanding of the residual stress generated in the pre-manufacturing processes and its effects on subsequent manufacturing processes. The mechanisms and distributions of residual stresses generated in typical pre-manufacturing processes of structural panels, including machining, welding and additive manufacturing (AM), are firstly summarised. The detailed effects of generated residual stresses on distortion and application properties in subsequent manufacturing processes are then concluded. In addition, current methods developed for the investigation of residual stress effect in multi-processes manufacturing are critically reviewed, including experimental, analytical, finite element (FE) and machine learning methods. Furthermore, the future development trend of methods for residual stress consideration and control in the design of manufacturing processes is summarised, providing comprehensive guidance to achieve the high accurate manufacturing of aluminium alloy structural components.     

民用飞机翼身对接斜撑板结构分析

斜撑板结构可以充分发挥分散载荷和降低区域应力水平的作用。对不同机型的斜撑板结构的传力特性进行分析,总结斜撑板结构的设计要点。并以某机型选用斜撑板结构的设计为例,提出一种斜撑板结构的改进方案(斜撑板侧边和后梁框刚性连接、下边和对接带板充分连接),并与其他两种设计方案进行对比分析。结果表明:改进方案的斜撑板结构翼上区和舱上区的剪应力分别降低了19%和23%,后梁框的集中载荷降低了67%,结构效率更高、稳定性更好。     

Optimum alternate material selection methodology for an aircraft skin

Weight penalty has been a challenge for design engineers of aerospace vehicles. Today’s high-efficiency combat aircraft undergoes intense stress and strain during flying missions, which require stronger and stiffer materials to retain structural integrity. Though metallic materials have been successfully used for the construction of aircraft structures and components, metals still have a low strength-to-weight ratio. This paper aims to develop an alternate optimised material selection methodolog...     

国产高模碳纤维/环氧复合材料的太阳电池板热循环适应性研究

国产CCM40J-6K高模碳纤维基板的空间高低温热循环耐受性是决定其是否可以大规模应用于空间太阳电池板的关键因素，必须解决交变热环境下的面板与电池电路的匹配性和长寿命问题。本文以国产CCM40J-6K高模碳纤维/环氧复合材料的太阳电池板为研究对象，开展了热循环环境适应性试验研究，分别从国产和进口碳纤维基板适应高低温交变能力对比、国产碳纤维基板铺设电池电路后适应热环境能力以及电池板在轨寿命等3个方面进行测试试验。结果表明：国产碳纤维CCM40J-6K所构成的电池板综合性能与进口M40JB-6K相当，CCM40J-6K基板与三结砷化镓电池片匹配性良好，国产碳纤维电池板经疲劳热循环后的开路电压和短路电流的变化率分别为0.55%和0.24%，太阳电池片和玻璃盖片外观完好无损，太阳电池电路与基板聚酰亚胺面保持绝缘，且碳纤维表面无脱粘现象。说明国产碳纤维CCM40J-6K能够应用于太阳电池板研制。     

复合材料整流罩声学等效建模与低频隔声性能研究

运载火箭发射过程中的恶劣噪声环境会导致整流罩内部电子设备失效。开展整流罩的内声场环境预测以及隔声分析,对其降噪研究和优化设计具有重要意义。复合材料整流罩舱壁大量使用蜂窝夹芯板,基于蜂窝夹芯结构精细化模型开展整流罩内声场环境预示计算量大,无法适用。本文建立了复合材料蜂窝夹芯板的力/声学等效模型,并利用精细化模型验证等效模型的精度;进一步基于有限元-边界元方法对某整流罩结构进行低频声振分析;同时,对整流罩的隔声量进行了评价。结果表明:整流罩内声场在频率为160 Hz附近声学环境较为恶劣,整流罩的降噪研究应针对该频段进行。