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排序方式: 共有154条查询结果,搜索用时 31 毫秒
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将视景仿真技术应用于飞机的飞行复现仿真分析,为飞行员提供了飞行训练时的真实世界景象和场景的渲染效果,对于提高飞行训练效果具有重要的作用。文章基于Vega Prime开展飞行训练视景仿真系统研究,对视景仿真系统中的关键技术开展了研究,实现了飞行过程的复现、作战轰炸过程的再现,并对对地攻击结果给出评估。 相似文献
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Wenli Zhang Xiaolei Li Yan Zhang Yu Dong Weigang Yao Lei Liang Xiaowen Qi 《应用聚合物科学杂志》2021,138(32):50803
Polytetrafluoroethylene (PTFE) owns an excellent self-lubricating performance, but its wear rate is very high due to the large-scale spalling of the matrix in the friction. In this paper, A new kind of PTFE composites with sandwich structure was prepared by layer-press technology, whose middle layer is filled with metal mesh. The influence of the mesh structure and mesh density of middle metal layer on tribological properties of composites were researched in detail. The results revealled that the metal mesh located in the composites can efficiently prevent the large-scale spalling of PTFE, which induces the sample of PTFE/500# plain woven dutch metal mesh (PTFE-500#PWD) to have a lower wear rate (9 × 10−5 mm3/Nm) and COF (0.106) under the fixed experimental condition. The prepared PTFE/metal mesh composites reveal excellent anti-friction and anti-wear performance, which can be used to fabricate a new kind of self-lubricating materials. 相似文献
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由于故障预测与健康管理系统(PHM)是涉及多层次、多领域、耦合度高的复杂系统,很难从整体对PHM系统进行设计和验证,所以始终没有成熟的工具和方法;从数据驱动的视角,研究了飞机PHM系统设计及验证;以数据为主线,采用了4种方法实现PHM系统设计及验证:1)采用系统建模语言(SysML)进行PHM系统的架构设计;2)采用基于事件的方法将被观测系统的行为状态化,实现PHM系统中资源的充分利用,降低局部的资源压力;3)采用基于模型的推理方法,实现了系统状态模型的应用;4)采用多线程、异构能量耦合等方法定义了一个PHM仿真框架,并在该框架指导下开发了一个仿真环境,并针对机载配电系统设置了几种测试用例进行诊断推理,对提到的各种方法进行了验证;研究结果表明,上述方法是合理有效的,可以构建描述完整、资源均衡的PHM系统架构。 相似文献
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为提高小型无人机飞行控制系统的可靠性,利用GPS提供的高度信息设计了气压高度传感器的余度备份.运用飞机运动学方程对低频率GPS高度信号进行补偿,提高了信号的实时性与可用性,设计的气压高度传感器故障处置流程将高度信号的切换与模态管理结合起来,减小了高度信号切换产生的不良瞬态.仿真结果表明,飞行控制系统在气压高度传感器出现故障时可及时切换到高度备份传感器并能有效隔离故障源,GPS高度信号经补偿后可满足飞行安全要求,余度设计提高了整个飞行控制系统的可靠性. 相似文献
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The paper presents a study about the glass transition of commercially available epoxy resins used for structural strengthening of concrete members for instance by means of Carbon Fiber Reinforced Polymer (CFRP) strips. Prior to an experimental investigation with a dynamic mechanical analysis (DMA), an overview on differences between definitions for the glass transition temperature Tg is given. Several testing recommendations are listed in this respect. Subsequently, DMA tests on three commercially available products are presented. A first focus is put on the different evaluation methods for one specific test result. It is visible that considerable differences in the finally adapted glass transition temperature might arise if one or the other procedure is followed. Additional parameters, such as curing procedure, specimen age, temperature history, and ultimate temperature during heating are considered, too. In all the above mentioned cases, differences in the glass transition can be found. Higher specimen age, higher ultimate temperature during testing, accelerated curing, as well as a lower heating rate implicate higher glass transition temperatures, showing that the glass transition temperature is not a fixed material characteristic. In a final step, the relevance for Tg for civil engineering applications is described. The various design code provisions for defining the service temperature in structures related to Tg are presented. The overall aim of the investigation is to show that structural engineers and end users have to be aware of the different influential parameters on the final results regarding the glass transition temperature, which also highlights the need of a potential deeper product investigation in case technical data sheets lack detailed information. 相似文献
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Scatter of fatigue life of a fleet is mainly caused by the variability in structures and load spectra. To ensure the safety in service, the probabilistic characterization of load spectrum variability should be researched in durability analysis and testing work. This paper investigates the variability of load damage rate of a fleet. Based on the flight historical parameters measured by individual aircraft tracking (IAT) from hundreds of aircrafts for a certain type of fighter in China, SWT formula and linear damage rule are used to evaluate the load damage, and then, one average and four other individual load spectra are selected corresponding to different damage severities. Fatigue tests are conducted with the Aluminum alloy 7B04-T74 specimens under five spectra and the Titanium alloy TA15M specimens under three of them. The engineering crack initiation lives are measured and the mean lives are estimated assuming the fatigue life following a log-normal distribution. An obvious difference of at least 2.4 times in the load damage rates is found in the fleet. The fatigue lives of a fleet of aircrafts are calculated by Neuber’s approach, and the probabilities refer to damage severities of those 5 load spectra in a fleet are evaluated. The statistical analysis of the fatigue lives and the probabilities shows that a lognormal distribution can be used to describe the variability of load damage rate of a fleet. The variation of the load damage rate is in the same order of magnitude with that in structural properties. 相似文献
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复合材料-金属机械连接性能研究 总被引:1,自引:0,他引:1
对不同类型的连接件进行了试验研究,得到了破坏模式和破坏载荷,使用超声波损伤检测的方法,观察了孔边的挤压破坏情况。基于ABAQUS有限元软件,建立了有限元模型,分析了钉头形式(凸头、埋头),有无补偿垫片和连接形式对机械连接性能的影响。研究表明,使用凸头钉比埋头钉,能使破坏载荷能提高30%左右;使用补偿垫片能够提高连接件的承载能力;使用双钉连接较单钉连接,破坏载荷能提高一倍左右。 相似文献
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