纤维缠绕复合材料环形容器设计优化(英文)

纤维缠绕环形容器可充分利用空间,节省结构质量和消除系统质心漂移,目前在很多工业领域中发挥着日益重要的作用。本文基于复合材料层合理论和测地线缠绕原理,提出了纤维缠绕环形压力容器的线型优化设计方法。应用微分几何,导出了圆环面上测地缠绕轨迹和纤维不架空判据。以初始缠绕角和缠绕层厚度为变量,对结构重量进行最小化设计,得到了对应于不同管径比的优化缠绕线型。对优化线型进行了计算机缠绕仿真,并给出了缠绕铺层的各向正轴应力分布。结果表明,优化设计的缠绕线型模式精确可靠,满足纤维缠绕的基本要求。纤维缠绕角度大小更趋于合理,从而能充分发挥缠绕结构的力学性能,减经系统重量,使优化得到的环形容器结构性能比传统测地线缠绕环形容器有很大提高。本文的设计计算方法可直接用于复合材料环形气瓶的初步设计。     

Degradation and silicidation of Ta- and W-filaments for different filament temperatures

Using typical conditions for hot wire chemical vapour deposition (HWCVD) of high quality thin silicon films in a UHV deposition chamber, we studied the silicidation of different filaments mainly varying the filament temperatures between 1700 °C and 2130 °C. The experiments were done with constant current, running the filament for 5 to 8 h and even longer. The changes of filament resistance and filament temperature with time will be shown and discussed. We investigated the material changes over the whole filament by Scanning Electron microscopy (SEM), especially the thickness of the formed silicide layers. The change of filament resistance depending on the filament temperature was also monitored, pointing out the different behaviour of tungsten and tantalum filaments. As a result, optimum temperature regimes for tantalum and tungsten filaments could be derived with respect to the filament degradation reducing the filament lifetime. Using a specially developed protection for the cold ends, a tungsten filament could be run for more than 139 h under silane with a filament temperature of T_fil ≈ 2000 °C.     

Investigation of the mechanic behaviours in hollow composite shafts having different fiber reinforcement and orientation angles

This study experimentally investigates the mechanical properties and behaviors of the hollow circular composite shafts, which are widely used in the industry and operated under a variety of environmental influences. Within the context of this study, glass, carbon and kevlar fibers were utilized as fiber materials and epoxy resins were preferred as the matrix material for hollow circular composite shafts. Composite shafts having 80 mm, 200 mm, 250 mm length and different internal diameters were used for three‐point bending tests. Composite hollow shafts were manufactured by utilizing filament winding method at different orientation angles (θ = 45°, 60°, 75°, 80°, 88°). The bending behaviors of the hollow circular composite shafts manufactured were repeated separately for each sample in three‐point bending tests. The results obtained were evaluated inter se, displayed in graphics and necessary considerations were addressed.     

The effects of repeated transverse impact load on the burst pressure of composite pressure vessel

The present experimental study deals with the repeated transverse impact effect on the burst pressure of composite pressure vessels. Filament winding method is used to produce the vessels. Glass fiber reinforced (GFR) vessels are manufactured by using E-glass and epoxy resin. Composite pressure vessel was manufactured from fibers oriented [+55°/−55°/+55°/−55]_2s and the impact energies were chosen as 10, 15, 20, 25, 30 J for empty vessel during the impact tests. In addition, 10, 15, 20, 25 J for water filled conditions at 25 and 70 °C. The transverse impact load was applied in single and three times repeated form. The results show that when the impact load and water temperature increases, the burst pressure decreases.     

芳纶帘子线的浸胶工艺对其与橡胶粘合性能的影响

芳纶帘子线与橡胶的粘合强度除了与帘子线的表面处理有关外 ,芳纶帘子线的浸胶工艺对其粘合性能也有较大的影响。本文重点讨论了芳纶帘子线浸胶时间、烘干方式、焙烘时间的变化对其粘合性能的影响。     

Visualization of liquid bridge rupture due to flow induced by corner effects

A high-speed visualization of the phenomenon of rupture of liquid bridges placed in a square cross-section capillary tube was done for three different hydrocarbons (n-Decane, iso-Octane and Decyl-alcohol). The process of rupture could be visualized from side and front views. This technique permitted to observe that the break-up of the bridge was caused by the draining of the liquid through the liquid filaments that were formed at the corners. The rupture of the interface occurred smoothly without any appreciable perturbation on the free surface, starting with a small hole that grows up until the interface splits in four parts. This rupture is strongly determined by geometric and surface properties, such as contact and geometrical angles.     

Reversibility of silicidation of Ta filaments in HWCVD of thin film silicon

If tantalum filaments are used for the hot wire chemical vapour deposition (HWCVD) of thin film silicon, various types of tantalum silicides are formed, depending on the filament temperature.Under deposition conditions employed for device quality amorphous and microcrystalline silicon (T_wire ≈ 1750 °C) a Ta₅Si₃ (as determined by XRD) shell is formed around the Ta core. After 8 h of accumulated deposition time this shell has a thickness of around 20 μm. Upon annealing of the filament in vacuum at 2100-2200 °C the tantalum silicide shell becomes thinner, while a Ta layer is reappearing at the surface of the wire. After 4 h of annealing the silicide is completely removed, whereas the total diameter of the wire has not significantly changed. The resistance of the filament has been monitored and after the annealing procedure, it completely recovered to that of a fresh wire. This regeneration procedure greatly helps to avoid frequent replacement of the filaments.     

弹性联轴节的特点及其应用

介绍大工字轮收线机上一种弹性软输在交变扭矩下的特点和应用情况。     

冷轧可逆式大张力卷取机研制

介绍了冷轧可逆式大张力卷取机的结构及功能,详细阐述了设备研制的主要内容和方法。到目前为止,已相继研制出卷筒工作直径为Φ510mm、Φ610mm等,可适应不同卷径、不同板宽及不同卷取张力的系列化产品,能满足冷轧生产的各种要求。     

The embedment of fiber Bragg grating sensors into filament wound pressure tanks considering multiplexing

Filament wound pressure tanks are under high internal pressure during the operation and it has the complexity in damage mechanism and failure modes. For this reason, it is necessary to monitor the tank through its operation as well as during the whole fabrication process. A large number of sensors must be embedded into multiple positions of the tank from its fabrication step for monitoring the whole tank. Fiber optic sensors, especially fiber Bragg grating (FBG) sensors are widely used for various applications because of good multiplexing capabilities. However, we need to develop the embedding technique of FBG sensors into harsh inner environment of the tank for the successful embedment. In this paper, we studied the embedding technique of a number of FBG sensors into filament wound pressure tanks considering multiplexing and conducted in situ structural health monitoring of filament wound pressure tanks during water-pressurizing test using embedded FBG sensor arrays. From the experimental results, it was demonstrated that FBG sensors can be successfully adapted to filament wound pressure tanks for their structural health monitoring by embedding.