Drop tower is an important ground based facility for microgravity science experiment.The technical performances of the drop tower NMLC are advanced compared with similar facilities in the US,Germany and Japan.The main...Drop tower is an important ground based facility for microgravity science experiment.The technical performances of the drop tower NMLC are advanced compared with similar facilities in the US,Germany and Japan.The main components such as drop capsule,deceleration devices,release mechanism present its advantages and creativities.展开更多
Despite numerous research investigations to understand the influences of various structural parameters,to the authors'knowledge,no research has been the effect of different angles of incidence on stab response and...Despite numerous research investigations to understand the influences of various structural parameters,to the authors'knowledge,no research has been the effect of different angles of incidence on stab response and performance of different types of protective textiles.Three distinct structures of 3D woven textiles and 2D plain weave fabric made with similar high-performance fiber and areal density were designed and manufactured to be tested.Two samples,one composed of a single and the other of 4-panel layers,from each fabric type structure,were prepared,and tested against stabbing at[0○],[22.5○],and[45○]angle of incidence.A new stabbing experimental setup that entertained testing of the specimens at various angles of incidence was engineered and utilized.The stabbing bench is also equipped with magnetic sensors and a UK Home Office Scientific Development Branch(HOSDB)/P1/B sharpness engineered knives to measure the impact velocity and exerted impact energy respectively.A silicon compound was utilized to imprint the Back Face Signature(BFS)on the backing material after every specimen test.Each silicon print was then scanned,digitized,and precisely measured to evaluate the stab response and performance of the specimen based on different performance variables,including Depth of Trauma(DOT),Depth of Penetration(DOP),and Length of Penetration(LOP).Besides,the post-impact surface failure modes of the fabrics were also measured using Image software and analyzed at the microscale level.The results show stab angle of incidence greatly influences the stab response and performance of protective textiles.The outcome of the study could provide not only valuable insights into understanding the stab response and capabilities of protective textiles under different angle of incidence,but also provide valuable information for protective textile manufacturer,armor developer and stab testing and standardizing organizations to consider the angle of incidence while developing,testing,optimizing,and using protective textiles in various applications.展开更多
大叶片板式贮箱是当前最为先进的一种新型贮箱,大叶片板式结构是该贮箱推进剂管理的核心部件.对微重力条件下大叶片板式贮箱内流体行为进行了数值仿真和微重力试验验证.采用液体体积分数法(VOF,volume of fluid)两相流动模型数值模拟板...大叶片板式贮箱是当前最为先进的一种新型贮箱,大叶片板式结构是该贮箱推进剂管理的核心部件.对微重力条件下大叶片板式贮箱内流体行为进行了数值仿真和微重力试验验证.采用液体体积分数法(VOF,volume of fluid)两相流动模型数值模拟板式贮箱内流体流动特性,得到了流体分布规律.搭建了大叶片板式贮箱缩比模型试验系统,对板式贮箱内流体行为进行微重力落塔试验,得到微重力环境下流体特性.数值仿真和试验结果表明,大叶片板式贮箱在微重力环境下管理流体性能良好,大叶片板式结构为空间流体(包括低温流体)管理提供一种良好的途径.同时本文仿真和试验为国内板式贮箱设计提供了必要的支撑数据.展开更多
文摘Drop tower is an important ground based facility for microgravity science experiment.The technical performances of the drop tower NMLC are advanced compared with similar facilities in the US,Germany and Japan.The main components such as drop capsule,deceleration devices,release mechanism present its advantages and creativities.
文摘Despite numerous research investigations to understand the influences of various structural parameters,to the authors'knowledge,no research has been the effect of different angles of incidence on stab response and performance of different types of protective textiles.Three distinct structures of 3D woven textiles and 2D plain weave fabric made with similar high-performance fiber and areal density were designed and manufactured to be tested.Two samples,one composed of a single and the other of 4-panel layers,from each fabric type structure,were prepared,and tested against stabbing at[0○],[22.5○],and[45○]angle of incidence.A new stabbing experimental setup that entertained testing of the specimens at various angles of incidence was engineered and utilized.The stabbing bench is also equipped with magnetic sensors and a UK Home Office Scientific Development Branch(HOSDB)/P1/B sharpness engineered knives to measure the impact velocity and exerted impact energy respectively.A silicon compound was utilized to imprint the Back Face Signature(BFS)on the backing material after every specimen test.Each silicon print was then scanned,digitized,and precisely measured to evaluate the stab response and performance of the specimen based on different performance variables,including Depth of Trauma(DOT),Depth of Penetration(DOP),and Length of Penetration(LOP).Besides,the post-impact surface failure modes of the fabrics were also measured using Image software and analyzed at the microscale level.The results show stab angle of incidence greatly influences the stab response and performance of protective textiles.The outcome of the study could provide not only valuable insights into understanding the stab response and capabilities of protective textiles under different angle of incidence,but also provide valuable information for protective textile manufacturer,armor developer and stab testing and standardizing organizations to consider the angle of incidence while developing,testing,optimizing,and using protective textiles in various applications.
文摘大叶片板式贮箱是当前最为先进的一种新型贮箱,大叶片板式结构是该贮箱推进剂管理的核心部件.对微重力条件下大叶片板式贮箱内流体行为进行了数值仿真和微重力试验验证.采用液体体积分数法(VOF,volume of fluid)两相流动模型数值模拟板式贮箱内流体流动特性,得到了流体分布规律.搭建了大叶片板式贮箱缩比模型试验系统,对板式贮箱内流体行为进行微重力落塔试验,得到微重力环境下流体特性.数值仿真和试验结果表明,大叶片板式贮箱在微重力环境下管理流体性能良好,大叶片板式结构为空间流体(包括低温流体)管理提供一种良好的途径.同时本文仿真和试验为国内板式贮箱设计提供了必要的支撑数据.
