Neutron Stress Measurement of W‐Fiber Reinforced Cu Composite

Stress measurement methods using neutron and X‐ray diffraction were examined by comparing the surface stresses with internal stresses in the continuous tungsten‐fiber reinforced copper‐matrix composite. Surface stresses were measured by X‐ray stress measurement with the sin²ψ method. Furthermore, the sin²ψ method and the most common triaxal measurement method using Hooke's equation were employed for internal stress measurement by neutron diffraction. On the other hand, microstress distributions developed by the difference in the thermal expansion coefficients between these two phases were calculated by FEM. The weighted average strains and stresses were compared with the experimental results. The FEM results agreed with the experimental results qualitatively and confirmed the importance of the triaxial stress analysis in the neutron stress measurement.     

Service Load Effective Compression Flange Width in Fiber Reinforced Polymer Deck Systems Acting Compositely with Steel Stringers

This paper reports on the field study of a steel stringer-fiber reinforced polymer (FRP) deck composite bridge in Pennsylvania. The objective of the study is to assess the effective compression flange width in the FRP deck and floor systems when they act compositely with underlying steel girders at service conditions. The research results reported herein support the notion of employing a design approach, for both interior and exterior girders of a composite floor system, that is philosophically consistent with current practice related to steel girders acting compositely with concrete decking. It appears from the results presented herein that FRP decks and floors acting compositely with underlying steel girders exhibit an effective width that is close to the actual girder spacing for interior beams, and approximately one-half this value for exterior beams.     

Bond of GFRP Bars in Concrete: Experimental Study and Analytical Interpretation

The local bond mechanics of glass-fiber reinforced polymer (GFRP) bars in normal strength concrete was investigated through experimental testing and analytical modeling. The experimental program was comprised of 30 direct tension pullout specimens with short anchorages. A novel test setup, specially designed so as to minimize the spurious influence of testing conditions on measured bond properties was adopted in the study. Parameters considered were the bar roughness and diameter, the size effect expressed by the constant cover to bar diameter ratio, and the external confining pressure exerted over the anchorage length by transverse externally bonded FRP sheets. Results of the study were summarized in the form of local bond-slip curves, whereby performance limit states were quantified by the amount of loaded end slip and bond strength. An analytical model of the bond stress-slip response of a GFRP bar was derived from first principles and calibrated against the test data of the present investigation. Using the calibrated model, design values for bond and slip were estimated with reference to the code limit state model for bond.     

国外复合材料用高级增强纤维的发展现状

本文综述了国外碳纤维、陶瓷、聚芳酰胺、超高分子量聚乙烯、液晶聚合物纤维的发展现状,包括它们的生产能力、消费情况、性能特点,主要生产国和生产公司、产品牌号以及应用领域等,并指出了其生产进展和发展动向。     

Comparative Study of Models on Confinement of Concrete Cylinders with Fiber-Reinforced Polymer Composites

The use of fiber-reinforced polymer (FRP) composites for strengthening and/or rehabilitation of concrete structures is gaining increasing popularity in the civil engineering community. One of the most attractive applications of FRP materials is their use as confining devices for concrete columns, which may result in remarkable increases of strength and ductility as indicated by numerous published experimental results. Despite a large research effort, a proper analytical tool to predict the behavior of FRP-confined concrete has not yet been established. Most of the available models are empirical in nature and have been calibrated against their own sets of experimental data. On the other hand, the experimental results available in the literature encompass a wide range of values of the significant variables. The objective of this work is a systematic assessment of the performance of the existing models on confinement of concrete columns with FRP materials. The study is conducted in the following steps: the experimental data on confinement of concrete cylinders with FRP available in the technical literature are classified according to the values of the significant variables; the existing empirical and analytical models are reviewed, pointing out their distinct features; the whole set of available experimental results is compared with the whole set of analytical models; and strengths and weaknesses of the various models are analyzed. Finally, a new equation is proposed to evaluate the axial strain at peak stress of FRP-confined concrete cylinders.     

Flexural and Shear Rigidity of Composite Sheet Piles

The flexural and shear rigidity of pultruded composite sheet pile panels consisting of E-glass fiber-reinforced polyester are studied in this paper. The analysis consists of an experimental investigation and an analytical modeling to determine the resistance of the sheet pile panels to the deflections for design of composite sheet pile walls. Timoshenko’s beam theory was used to experimentally determine the flexural rigidity (EI) and shear rigidity (kAG) of the panel. Three- and four-point bending tests were performed on six different span lengths and the results were self-compared from the two independent tests. Analytical expressions for the flexural and shear rigidities were derived to allow the prediction based on the layered structure of pultruded shapes. The values computed from the analytical expressions were examined with the experimental results.     

光孤子源的研制

报道了利用增益开关分布反馈半导体激光器，Ｆ－Ｐ光学滤波器及掺饵光纤放大顺研制成光孤子源的研究工作。光孤子源性能稳定，输出的超短光脉冲重复频率为２．５ＧＨｚ脉宽２４，谱宽０．１４ｎｍ，时间带宽积０．４１９，平均输出光功率２．４ｍＷ。     

用纤维TiO2作光催化剂降解饮用水中腐殖质

用纤维状ＴｉＯ２作为光催化剂，采用间歇和连续两种操作方式，在Ｏ３／ＴｉＯ２／ＵＶ体系中处理含腐殖质的饮用水，使腐殖质去除率在９７％，纤维ＴｉＯ２可过滤回收，易于实际应用。     

利用光纤数字同步传送网2.048 Mbit/s支路传送高精度标准时间信号

首次提出一种利用光同步数字传送网的2.048Mbit/s信号传送高精度时间编码信号的方法和实验结果。它可以使整个通信网的交换机、计费系统、网管系统、基站控制器等设备实现与UTC的时间同步。目前的实验证明,时间同步的不确定度优于±5μs。     

PAN／Ni－P纤维和碳黑填充的HIPS复合材料的导电性

研究经化学镀镍的聚丙烯腈（ＰＡＮ）导电纤维（ＰＡＮ／Ｎｉ－Ｐ）填充的高抗冲聚苯乙烯（ＨＩＰＳ）复合材料的导电性与导电填料浓度的关系及加入有机钛酸酯偶联剂的影响、为了进一步提高复合材料的导电性，在ＰＡＮ／Ｎｉ－Ｐ纤维填充的复合材料中又加入不同量的碳黑，由于碳黑粒子的加入改善了纤维间的接触状态，更有利于导电网络的形成，从而大大提高了复合材料的导电能力。