竹棉涤包芯纱的纺制

介绍了竹纤维的基本性能特征.从工艺配置、操作方面介绍了竹纤维与棉纤维混纺,包覆涤纶长丝包芯纱的纺纱工艺.竹纤维与棉纤维混纺,纺制涤纶长丝包芯纱技术的关键在细纱工序,其中细纱机改造为重点,同时优选工艺参数对提高成纱质量效果显著.     

产业用摩擦纺包芯纱及其织物性能分析

在DREF-Ⅲ型摩擦纺纱机上生产涤纶短纤维包覆玻璃长丝的包芯纱,用于二维机织平纹织物及增强复合材料.通过对摩擦纺包芯纱线、织物及其复合材料与未经过包覆的玻璃长丝、织物、复合材料加工、拉伸、弯曲等性能的数据对比,认为摩擦纺包芯纱织物用于生产产业用增强复合材料是可行的,可改善复合材料生产的工作条件,保护工人身体健康.     

涤纶纱与涤纶长丝交织物的生产

探讨在ZAX9100型喷气织机上生产涤纶纱与涤纶低弹网络丝交织物的技术要点。提高整经质量,整经速度控制在500 m/min;针对涤纶纱的特点,优化浆料配方和浆纱工艺参数;合理穿综穿筘;优选喷气织机工艺,包括后梁和停经架位置、综平时间、开口时间、上机张力和主辅喷嘴定时等,合理设定筒纱与导纱器间距离;选择合适的边撑,保证布边质量。最终成功生产了涤纶纱与涤纶长丝交织物,织机效率达93%以上。认为:针对经纬纱特性和设备工艺优选工艺参数,可以保证产品的顺利生产。     

镀银长丝嵌织方式对织物屏蔽效能的影响

研究织物中镀银长丝嵌织方式对其屏蔽效能的影响。将镀银长丝缠绕在自制的纱线架上,通过模拟镀银长丝在织物中的不同排列方式,构建了镀银长丝仿真织物模型,进行了镀银长丝不同嵌织间距、不同排列方式以及不同辐射频率下几种镀银长丝织物的仿真模拟试验。采用平面材料电磁波屏蔽效能标准测试方法对仿真模型的屏蔽效能进行了测试。结果表明:不同的镀银长丝排列方式、镀银长丝嵌织间距及网络格对角线长度对织物的屏蔽效能都有影响。方差分析可证实:以上三种因素对织物的屏蔽效能均有显著性影响。     

微型X射线管灯丝电源的研制

根据微型X射线管的特点,设计了基于推挽电路和闭环反馈电路的灯丝驱动电源。采用了UCC3808脉宽调制(Pulse Width Modulation,PWM)控制芯片产生两路相位相反的PWM信号,并经由UCC37324金属氧化物半导体(Metal-Oxide-Semiconductor,MOS)管大电流驱动器提高驱动效率,实现推挽结构的后端驱动电路。闭环反馈电路的设计采用精密电阻将管电流的信号转换为等比例的电压信号引入到反馈环节,通过系统自身的闭环控制实现管电流的恒定,并保持高效率和低功耗。实验首先通过外接1.5?的功率电阻测量系统功率,测得输入功率为11 W,效率超过80%,符合灯丝电源的功耗指标要求;然后连接实际的X光管灯丝,经测试可正常工作,管流稳定度为0.227%。     

纤维缠绕弯管的线型设计与仿真

提出了一种弯管缠绕线型的设计方法.首先,建立了弯管的纤维缠绕数学模型,在对缠绕线型规律进行分析的基础上,再采用测地线辅助以定位销的纤维缠绕设计方法进行纤维缠绕,实现了弯管纤维缠绕的系统仿真,这种方法克服了传统纤维缠绕模式在缠绕弯管端部时要采用非测地线线型,而只采用测地线再辅助以定位销即可实现弯管的纤维缠绕.仿真结果表明,该纤维缠绕线型设计方案精确可靠,满足纤维缠绕的基本要求,对实际生产有很重要的作用,并为弯管纤维缠绕的应用奠定了理论基础.     

Peptide-based nanomaterials: Building back better & beyond

The exquisite structure–function correlations observed for native protein filaments have prompted research into the design of simpler peptide-based analogues that can be tailored for specific applications as synthetic filamentous nanomaterials. Sequence-structure correlations that have been established from analysis of native proteins have been previously adapted to create a supramolecular folding code based on simple design principles. While successful, the supramolecular folding code has not been critically examined in terms of the relationship between the proposed models and experimentally determined structures. Recent cryo-EM analyses of peptide-based filaments at near-atomic resolution offers the opportunity to compare the predictions of the supramolecular folding code to the resultant atomic models. The results provide insight into the limitations of the folding code and suggest an approach to refine the design of peptide-based filaments.     

Effects of geodesic dome trajectories on the specific strength of composite overwrapped pressure vessels: FE modelling

In this study, it was aimed to find out geodesic dome trajectories of composite overwrapped pressure vessels, and investigate the effect of dome profiles on the structural performances. In this context, geodesic paths for 0.2, 0.3, 0.4, 0.5 and 0.6 dimensionless polar opening radii were determined by solving elliptical integrals and filament winding angles were calculated throughout the dome and cylindrical portions. Afterward, finite element analysis was performed to obtain mechanical properties by using the Ansys ACP module. As a result of the current study, it has been concluded that dome profile and filament winding angle are highly dependent on the polar opening radii. When the performance factor was considered, it has been determined that the optimum pressure vessel has 0.6 dimensionless polar opening radii. Moreover, it was observed that minimum equivalent stress, strain, deformation and inverse reverse factors have occurred in the pressure vessel with 0.6 dimensionless polar opening radii. Furthermore, it was showed that effective parameters in the mechanical performance of pressure vessels can be optimized to obtain strengthened and lighter structures.     

Non-oxide CMC fabricated by Fused Filament Fabrication (FFF)

The present study introduces an approach to additively manufacture non-oxidic Ceramic Matrix Composites (CMCs) by the Material Extrusion (MEX)-based Fused Filament Fabrication. Therefore, highly SiC particle filled thermoplastic filaments were developed containing short fibers and/or long fibers to maintain shape during the thermal treatment and exhibiting flaw tolerant behavior. Polymer Infiltration and Pyrolysis (PIP) was applied to densify the microstructure. It is shown that a low content of long fibers of about 5 % can already exhibit damage tolerance comparable to steel reinforced concrete. Thus, the mechanical behavior is different to conventional fiber composites with significant higher fiber volume content. Nevertheless, these results enable new opportunities for producing advanced complex CMC components by means of Additive Manufacturing (AM).