两种气相法白炭黑水分测定方法的比较

使用卡尔·菲休库仑法和重量法分别测定了两种气相法白炭黑微粉中的水分质量分数,为白炭黑水分测定提供了技术途径,并对两种测定方法进行了比较。研究结果表明卡尔·菲休库仑法与重量法皆可用于固体物质的水分测定,且库仑法精度较高,更适用于微量水的测定,而重量法适用于较高水分质量分数的测定。     

Hypersonic properties of nano- and microstructured CVD diamond

Basic information related to the acoustic dispersion, local sound velocity distribution and influence of the grain size on the elastic properties of white plasma-assisted chemical vapour-deposited diamond has been obtained by a new Brillouin scattering technique. The obtained results show no acoustic dipersion and the existence of internal stresses that influence the elastic properties of the diamond sample.     

Multipoint cure monitoring of CFRP laminates using a flexible matrix sensor

Since a carbon fiber reinforced plastic (CFRP) structure is complicated in the adoption of integral molding, local molding faults such as under curing and dry spots are liable to occur. To solve this problem, the distribution of the degree of curing for the entire composite structure must be measured. In the present study, we propose a patch-type flexible matrix sensor based on permittivity measurements. Multiple electrodes and wirings are readily fabricated simultaneously using a photolithographic process. Moreover, the sensor has only m + n wirings for m × n sensors, and is thereby suitable for multipoint cure monitoring. We also constructed a method for estimating the degree of curing considering the effect of frequency dependence of the permittivity of resin and viscosity variation due to temperature change. Experiments of multipoint cure monitoring are carried out using a CFRP plate and an actual aircraft structure. As a result, we confirmed the effectiveness of this method by comparing with results using a conventional differential scanning calorimeter.     

Fatigue design of complex welded structures

This paper is concerned with the design of complex welded structures subjected to fatigue loadings. In the last years it has been developed a new approach for predicting the high cycle fatigue behaviour of welded joints, based on the Notch-Stress Intensity Factors of the uncracked geometries, which have been successfully applied to welded joints of different geometries using an analytical frame in combination with stress data obtained from Finite Element Analyses. The approach is based on the observation that the very small weld toe radius obtained by using traditional welding technologies is consistent with the assumption of a sharp V-notch geometry, characterised by an exponential stress field, which the fatigue strength depends on. Recently published Eurocodes suggest the use of a hot spot approach, both for steel and aluminium structures. Nevertheless the evaluation of fatigue strength of engineering complex structures remains a difficult and, in some way, controversial subject. We hope that this synthetic presentation of the N-SIF and hot spot approaches as compared to the European Standards could help to clarify the subject and to design better and more reliable structures.     

A case study on ground treatment for a rock tunnel with high groundwater ingression in Taiwan

This paper presents a case study on the collapse caused by sudden groundwater ingression in the Pinglin pilot tunnel, and the treatments developed for the adverse ground conditions encountered. The ideas for the ground treatment are to reduce groundwater pressure as well as to consolidate the fractured zone in rock formations. The paper highlights the importance of paying particular attention to the ground treatment process and grouting quality control. Ongoing adjustments of grouting mixture and pressure may be necessary with the changing ground conditions.     

竖向加速度设计反应谱研究

鉴于我国《建筑抗震设计规范》（GB 50011-2010）未给出竖向加速度反应谱表达式这一现状,本文收集292组美国地区的强震记录,研究了各种地震环境下不同结构阻尼比对谱比取值（V/H）的影响,针对场地等单一影响因素统计得出谱比平均值并采用遗传算法进行最优拟合。以场地因素上的拟合谱比为基准谱比,考虑震中距、阻尼等因素取修正以建立各地震环境下的谱比建议式。应用我国10抗震规范中水平加速度反应谱表达式和本文的谱比建议式,本文列举了一个示例地震环境,并推导出竖向加速度设计反应谱建议式,研究成果可供我国抗震规范参考。     

爆炸冲击下水底隧道的动态响应及毁伤模式研究

考虑炸药起爆、冲击波传播、冲击波与结构的相互作用以及结构的动态响应等复杂过程,基于Lagrange-Euler耦合算法,建立了水底隧道水下爆炸的全耦合数值仿真模型。通过与爆炸试验结果进行对比,验证了数值模型的可靠性;研究了水下爆炸冲击荷载作用下的水底隧道的毁伤破坏过程、空间分布规律及破坏模式。结果表明:水底隧道的破坏模式不仅与隧道自身的动力特性有关,还取决于起爆距离及炸药当量等;隧道的破坏模式为局部冲切或剥落破坏、弯曲破坏伴随着局部剥落破坏以及整体弯曲破坏。     

受边缘非线性分布荷载作用矩形薄板的面内应力分析

矩形薄板边缘受非线性分布面内载荷作用的情况在工程中经常遇到,精确的应力分析也是薄板稳定性分析的基础,由于问题的复杂性目前还没有精确解.该文根据弹性力学理论,采用里兹法求解矩形薄板边缘受非线性分布载荷作用的面内应力,应力函数采用切比雪夫多项式并满足所有应力边界条件.结合数学计算软件Mathematica,分析了不同长宽比...