拉伸速度及其他参数变化对束纤维细化过程的影响

羊毛拉伸细化中，拉伸的速率对分子的构象和滑移影响重大，不仅会造成拉伸力过大形成冲击和损伤，而且会导致能耗大，结构不稳定。利用自行设计的拉伸细化过程测量装置，实时测量了羊毛纤维条拉伸的力学行为，并在此基础上讨论和分析了拉伸速度、毛条捻度、握持距离等不同拉伸工艺条件对纤维细化过程的影响，验证了控制拉伸速度的重要性。     

Hydrogen embrittlement of a bimaterial

Commonly, within the energy industry, the corrosion resistance of pressure vessel steels is increased by the addition of an overlay coating comprising a nickel-based alloy or a stainless steel. However, the interface between the two alloys is prone to hydrogen-assisted cracking, due to for example carbide precipitation near the interface. In the present study, the sensitivity of the tensile strength of the interface to hydrogen concentration is measured for both notched and un-notched specimens made from the overlay welding of 690 nickel alloy on a low alloy steel A533B. An elastic–plastic finite element analysis is used to determine the stress and strain state near the notch root, and thereby to calculate the local distribution of hydrogen within the lattice and at traps. The observed strength of the notched specimens is best rationalised by assuming that the local cohesive strength of the interface is a function of the lattice hydrogen concentration, with a negligible influence of the trapped hydrogen. The scatter in specimen strength, and the relative strength of the notched and un-notched specimens, are adequately described by Weibull statistics, with a low value of Weibull modulus equal to 3.4.     

低温和频率对橡胶弹性元件刚度性能的影响

介绍橡胶弹性元件静刚度和动刚度的测试原理,设计一种新型低温刚度试验工装以对橡胶弹性元件进行静态和模态试验,研究温度对橡胶弹性元件静刚度和动刚度的影响,以及频率对橡胶弹性元件动刚度的影响。结果表明:本试验工装结构合理,满足试验要求,随着温度的降低,橡胶弹性元件静刚度和动刚度增大;随着频率的增大,橡胶弹性元件的动刚度在低频段增大,在一定频率后变小,最后趋于稳定;温度低于-40℃时橡胶弹性元件的动刚度-频率曲线的变化拐点前移。     

中心销板式牵引装置的试验设计与研究

介绍中心销板式牵引装置的结构和原理,设计新型系统加载试验方案,研究牵引装置的纵向刚度、垂向刚度、横向刚度和耐疲劳性能,并与传统牵引橡胶堆组对试验进行分析对比。试验结果表明:试验设计与实际工况一致,系统加载试验能准确反映出牵引装置的力学性能;牵引装置的刚度小于牵引橡胶堆组对,且各项性能满足要求;试验研究成果可为牵引装置类产品的设计和试验提供参考。     

灌注桩内壁图像探测及处理设备的研制

目前在建筑行业中,若能够直观客观地观察到地下几十米深的圆形灌注桩基是否有裂纹等影像对工程人员来说是十分有意义的。本课题配合相关行业室外作业需求,研发相应的设备及配套软件,通过防水摄像头把地下深处桩基内壁的图像传送到地面上的笔记本电脑显示屏幕上,可依据不同桩基的口径尺寸大小自动调整比例标尺,在屏幕右侧及下方显示标尺刻度,可观察并通过标尺测算出内壁裂纹等大小尺寸,同时标注出准确深度位置。当摄像头到达桩基底部时能给出标识,并将所得到的图像及其他信息压缩保存以便分析。     

基于单片机的棉纤维成熟度仪系统

 开发基于单片机的棉纤维成熟度仪。利用单片机集成度高,功能强,可靠性高,结构简单,应用灵活和价格低等特点,以偏振光成熟度检测原理为基础,运用单片机实现检测的自动化和智能化。通过光学电路将棉纤维成熟度以光电信号形式输出,A/D转换通道进行模数转换,完成对成熟度各个参数的计算,与标准值比较并输出相对偏差。根据部分棉花品种的实测结果和经验,给出透射光强与成熟度系数的关系以及相对光强与纤维数量修正系数的关系。     

应用于橡胶与金属粘合的单涂胶粘剂性能研究

应用于橡胶和金属粘合的单涂体系胶粘剂具有周期短、效率高等优点。就CILBOND单涂胶粘剂性能进行了全面的研究,结果显示,CILBOND单涂胶粘剂对橡胶与金属间的粘合性能,以及胶粘剂膜层的耐盐雾、耐疲劳等性能均有良好的效果。     

风电聚氨酯齿型同步带性能试验设计及应用

针对风电聚氨酯齿型同步带进行性能试验。设计了同步带破断力、齿体剪切力和屈挠疲劳试验新方案,并对同步带的窄带破断力和齿体剪切力进行了测试。结果表明：试验设计新方案的装置结构合理、操作方便、满足试验要求,能准确地测试同步带的性能,可为同步带类产品性能试验以及同步带用骨架材料的研发和试验提供参考。     

Intersonic delamination in curved thick composite laminates under quasi-static loading

Dynamic delamination in curved composite laminates is investigated experimentally and numerically. The laminate is 12-ply graphite/epoxy woven fabric L-shaped laminate subject to quasi-static loading perpendicular to one arm. Delamination initiation and propagation are observed using high speed camera and load–displacement data is recorded. The quasi-static shear loading initiates delamination at the curved region which propagates faster than the shear wave speed of the material, leading to intersonic delamination in the arms. In the numerical part, the experiments are simulated with finite element analysis and a bilinear cohesive zone model. Cohesive interface elements are used between all plies with the interface properties obtained from tests. The simulations predict a single delamination initiating at the corner under pure mode-I stress field propagating to the arms under pure mode-II stress field. The crack tip speeds transition from sub-Rayleigh to intersonic in conjunction with mode change. In addition to intersonic mode-II delamination, shear Mach waves emanating from the crack tips in the arms are observed. The simulations and experiments are found to be in good agreement at the macro-scale, in terms of load-displacement behavior and failure load, and at the meso-scale, in terms of delamination initiation location and crack propagation speeds. Finally, a mode dependent crack tip definition is proposed and observation of vibrations during delamination is presented. This paper presents the first conclusive evidence of intersonic delamination in composite laminates triggered under quasi-static loading.