钢纤维混凝土桥面铺装试验研究与工程应用

针对桥面铺装层的受力状况和破坏原因 ,重点对钢纤维砼材料进行了抗弯强度试验和耐磨损试验 ,并进行了钢纤维砼弯曲性能分析 ,闸述了钢纤维砼的耐磨机理 ;结合 130 76m2 的实际工程应用 ,进行了钢纤维砼桥面铺装施工技术总结 ,分析了采用钢纤维砼作为桥面铺装层所带来的效益 ,可供类似工程参考应用     

A numerical and experimental investigation of the interactions between a non‐uniform planar array of incompressible free jets

The interaction between multiple incompressible air jets has been studied numerically and experimentally. The numerical predictions have been first validated using experimental data for a single jet configuration. The spreading features of five unequal jets in the configuration of one larger central jet surrounded by four smaller equi‐distant jets, have been studied, for different lateral spacing ratios of 1.5, 2.0 and 2.5 and a central jet Reynolds number of 1.24×105 (corresponding to a Mach number of 0.16). Flow of five equal jets has also been simulated, for the sake of comparison. The jet interactions commence at an axial distance of about 3–4 diameters and complete by an axial distance of about 10 diameters for the lowest spacing ratio of 1.5. For larger spacing ratios, the length required for the start and completion of jet interaction increase. Peripheral jets bend more towards the central jet and merge at a smaller distance, when their sizes are smaller than that of the central jet. The entrainment ratio for multiple jets is higher than that for a single jet. Excellent agreement is observed between the experimental data and theoretical predictions for both mean flow field and turbulent quantities, at regions away from the jet inlet. The potential core length and initial jet development, however, are not predicted very accurately due to differences in the assumed and actual velocity profiles at the jet inlet. Copyright © 2004 John Wiley & Sons, Ltd.     

Load-Carrying Capacity of Circular Plates Made of a Fiber-Reinforced Composite

The load-carrying capacity of circular plates made of a fiber-reinforced composite and loaded with axisymmetric transverse forces under axisymmetric boundary conditions is investigated. The plates can be freely supported or clamped along their contour. To the known yield condition used, in the plane of main bending moments, there correspond irregular hexagons, which depend on the mechanical properties of composite constituents and some characteristic geometrical parameters. It is shown that, depending on the ratio of ultimate radial and circumferential bending moments, in the plastic state, the circular plates (the central part of the clamped plates) take the form of a cone or a frustum of cone. For each of the cases, the limit load is found, which is a function of the above-mentioned mechanical parameters. The statically allowable fields of bending moments and the corresponding allowable fields of deflection rates are determined. The solutions found are exact. Special cases for the freely supported plates are analyzed, and the results obtained are presented in the form of graphs.__________Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 2, pp. 177–192, March–April, 2005.     

三种测应变线路的比较

介绍了三种测应变的线路,通过实验证实,在测扭矩时,用4片电阻应变片构成的线路,可以排除弯矩的影响。     

功能梯度材料弯曲断裂模型分析

讨论功能梯度材料裂纹板受纯弯、纯扭、弯扭载荷作用下的弯曲断裂问题。根据弹性力学基本方程、断裂力学有关理论，分别将弹性常数：杨氏模量、泊松比、剪切模量设为任意函数、指数函数或幂函数，建立了各向同性、正交异性功能梯度材料板的弯曲断裂模型，即一系列相关的偏微分方程边值问题。对于功能梯度材料弯曲断裂问题的研究具有一定的参考价值。     

Bending loss measurement using a fiber cavity ringdown scheme

A novel sensitive technique for the determination of losses in fiber cavities is presented. The method is based on the cavity ringdown scheme implemented in silica-based single-mode fibers. Bending losses of fiber cavities of different lengths have been measured showing all an oscillating behavior with respect to the curvature radius of the fiber as predicted by a theoretical model. The best minimum detectable absorbance per cavity pass achieved by this new method is 1.72×10⁻³ dB within a 10 m-long cavity. This limit suffices well for an accurate determination of optical bending losses even in bend-insensitive fibers. Furthermore, the comparison of the measured bending losses with a theoretical model allows the extraction of different fiber parameters. Good agreement has been found between the experimentally derived parameters and literature data.     

简支阶梯轴弯曲变形的傅里叶级数近似计算

利用广义函数和傅里叶正弦级数来求解简支阶梯轴的挠曲线四阶近似微分方程，推得简支阶梯轴的挠曲线近似方程，进而可以近似计算出其任一截面处的弯曲变形。     

SMA智能复合材料结构的力学分析与建模

介绍了SMA智能复合材料结构力学建模在弯曲变形及振动控制方面的研究现状,论述了连续型和有限元建模方法,分析了SMA智能复合材料结构大变形问题及温度影响问题,并就SMA智能复合材料结构的力学建模提出几点建议。     

解平行四边形板弯曲问题的二元B样条有限元法

将文献［１］以二元二次Ｂ样条函数为基底,求解矩形薄板弯曲问题的二元Ｂ样条有限元的方法推广到用于求解平行四边形板弯曲问题．结果表明：该方法系数矩阵每行的非零元仅２１个,相对于朱明权和ＣｈｕｉＣ．Ｋ．等的张量积型样条有限元方法,计算量与存贮量都大大节约．     

Preferential Uniplanar Orientation of Cellulose Microfibrils Reinvestigated by the FTIR Technique

A simple detection method to observe the uniplanar orientation behavior of native cellulose microfibrils to the cell wall surface by using Fourier transform infrared (FTIR) spectroscopy in the transmission mode is reported. Four bands at 1372, 1355, 1337, and 1317 cm⁻¹ (the latter two have been mentioned previously by Liang and Marchessault (1960, J. Polym. Sci. 43: 85–100)) were found to be sensitive to such orientation: the two middle bands at 1355 and 1337 cm⁻¹ increase remarkably when the 0.60–61 nm lattice planes lie parallel to the cell wall surfaces. The reverse was true when the 0.53–54 nm lattice planes oriented preferentially. Polarization of the two bands at 1372 and 1355 cm⁻¹ was parallel, while that of the other two bands at lower wavenumbers, i.e., at 1337 and 1317 cm⁻¹, was perpendicular to the molecular axis of cellulose. These bands were assigned to OH-related motion, probably to in-plane OH bending, as reported by Maréchal and Chanzy (2000, J. Mol. Spectrosc. 523: 183–196).