浅谈高速铁路沉降变形监测技术

本文主要介绍了高速铁路沉降变形观测技术，阐述探讨了沉降变形观测工作在高速铁路施工时的一些技术要求、观测方法及措施，文章系统剖析了高速铁路施工时沉降变形观测的技术要求及措施。     

大口径轻质镜支撑的有限元分析

根据轻质镜的工作状态,分别给出了一种平放时的和两种立放时的支撑方法。用Algor有限元软件对这三种状态进行应力和变形分析,并用Excel对节点变形进行处理,给出了镜面变形曲线,分析结果表明,三种支撑方法能够满足轻质镜的变形精度要求。     

面纸和芯纸相互作用的瓦楞纸板平台应力研究

目的 研究了不同厚度的瓦楞纸板受到纵向压缩时的变形模式,以及对应模式的平台应力理论模型和变化趋势.方法 对不同厚度的瓦楞纸板进行纵向准静态压缩,模拟实际运输中瓦楞纸板受到压缩时的变形情况,建立不同厚度的瓦楞纸板平台应力理论模型,根据试验数据对平台应力进行评估.结果 不同厚度的瓦楞纸板受到静态压缩时,产生了3种不同的变形,包括面纸和芯纸不分离,面纸和芯纸部分分离,面纸和芯纸完全分离.发现对于不同的变形,瓦楞纸板的平台应力变化较为明显,且随着瓦楞纸板厚度的增加,分离情况变多,平台应力的降低较为明显.结论 厚度增大会使瓦楞纸板产生变形使得平台应力下降,因此建立不同厚度的瓦楞纸板平台应力理论模型对瓦楞纸板的力学性能进行评估,这对瓦楞纸板缓冲材料尺寸选择,以及瓦楞纸箱的设计等有一定的指导意义.     

建筑物的沉降及倾斜观测

随着社会的不断进步，施工技术水平的目益成熟完善，高层及超高层建筑物越来越多。建筑物的变形观测也越来越受到人们的重视。各种大型的建筑物在施工和运营过程中，都会不同程度的出现变形。这些总有一个由量变到质变的过程，因而及时的对建筑物进行变形观测，掌握变形规律，及时分析研究和采取相应措施是非常必要的。本文结合某工程实例，浅谈对建筑物的沉降观测及倾斜观测在建筑物的施工中的应用。     

扭矩扳手检定装置受力杆结构优化分析

利用ANSYS Workbench对扭矩扳手检定装置受力杆进行静力学分析,模拟其对扭矩扳手进行扭矩值检定时受到应力、应变及变形的情况,根据得到的数据对其进行结构优化设计、轻量化设计。     

TC4钛合金激光焊接应力变形有限元分析

基于ANSYS有限元分析软件,采用三维移动热源,对TC4钛合金激光焊接残余应力和变形进行了数值模拟和实验研究.结果表明:钛合金激光焊接产生很大的纵向残余应力,而横向残余应力较小.激光焊接线能量增加时,纵向残余应力拉伸区域变宽,峰值应力降低;而横向残余应力随线能量的增加而升高.在临界焊透规范以上焊接时,随焊接线能量的增大,角变形随之而减小,而横向收缩变形增大.焊件被完全穿透时,线能量对角变形的影响作用降低.钛合金激光焊接变形和残余应力实验结果与数值计算结果吻合性较好.通过焊缝金相实验分析了焊接残余应力和变形与线能量的内在关系.     

变形反射镜薄膜应力与元件变形有限元研究

残余应力是变形反射镜面临的一个重要问题。考虑薄膜中残余应力的起源,利用有限元软件建立了变形反射镜有限元模型。基于所建立的有限元模型,计算变形镜各部分受薄膜残余应力作用后的变形与应力分布。与试验测量结果进行对比,计算结果表明,建立的模型是合理的,薄膜产生的残余应力为张应力,氟化物薄膜产生的张应力大于ZnS薄膜产生的压应力,残余应力主要集中在变形反射镜镜面上,基本呈放射状分布,外圈驱动器受到应力较大。     

Cu-Ni-Si-P合金动态再结晶研究及组织转变

在Gleeble-1500D热模拟试验机上,对Cu-2.0Ni-0.5Si-0.03P合金进行高温压缩实验,应变速率为0.01～5s-1、变形温度为600～800℃,对其高温等温压缩流变应力行为进行了研究.研究结果表明:随变形温度升高,合金的流变应力下降,随应变速率提高,流变应力增大.在应变温度为750、800℃时,合金热压缩变形流变应力出现了明显的峰值应力,表现为连续动态再结晶特征.可采用Zener-Hollomon参数的双曲正弦函数来描述Cu-2.0Ni-0.5Si-0.03P合金高温变形时的流变应力行为.从流变应力、应变速率和温度的相关性,得出了该合金高温热压缩变形时的应力指数n,应力参数α,结构因子A,热变形激活能Q和流变应力方程.合金动态再结晶的显微组织强烈受到变形温度的影响.     

FAST圈梁支承结构性能理论与实验研究

圈梁结构是500 m口径球面射电望远镜(FAST)反射面的主支承结构。承载反射面单元的柔性索网通过150个牵索耳板与圈梁结构相连。建设和观测过程中,基于结构可靠性考虑以及反射面精度要求,主支承结构的刚度必须得到保证。研究发现,如此巨大尺度的结构,温度荷载对圈梁结构的刚度起控制作用。通过科学合理地温度应力释放、结构刚度调整,以及采用预留变形空间的方法,利用有限元模拟并进行实验验证,研究基准面时圈梁刚性变形,为观测时变位抛物面提供输入调整依据。     

浅述惠南庄泵站安全监测的重要性

通过对建筑物在各阶段的监测及数据处理分析，便于检验设计方案是否合理，旌工质量是否满足规范要求。建筑物的施工期监测，可及时反映变形及应力状态和混凝土内部温度，对不断提高和完善施工方法、优化设计方案具有重要意义。     

Silicate glass-to-glass hermetic bonding for encapsulation of next-generation optoelectronics: A review

Many of the new organic–inorganic hybrid materials for next generation optoelectronics have organic components sensitive to oxygen, moisture, and temperature, requiring hermetic encapsulation. Silicate glasses offer the wide optical transmission window needed for the optimal functioning of optoelectronic devices. The low oxygen and moisture permeability required for hermetic encapsulation can be achieved by glass-to-glass bonding with or without an intermediate layer. However, most of the traditional glass bonding techniques require processing at high temperatures not compatible with the new hybrid device materials that are temperature sensitive. In this work, we review the current state of knowledge in low-temperature (<150 °C) silicate glass-to-glass bonding. Hermeticity and bond strength testing methods are described and opportunities for hermetic electrical feedthroughs using silicate glass-to-metal bonding are discussed.     

Light polarization under water near sunrise

Dramatic and rapid changes in the intensity and spectrum of light under water at dusk and dawn are well known, but reports regarding the light's polarization at these periods are sparse. Using a rapid spectropolarimeter, we examined the spatial and spectral characteristics of the underwater polarization patterns from sunrise to midday and compared them with a Rayleigh-based model for e-vector orientation and percent polarization. With the Sun near the horizon, the underwater polarization patterns were distinctive. Unlike the polarization at small solar zenith angles, the underwater polarization at large solar zenith angles cannot be predicted by simple Rayleigh scattering, most likely because of the relatively high contribution of skylight. At sunrise, the underwater polarization pattern outside of Snell's window differed from that found during the day in percent polarization, spatial distribution, and wavelength dependence. These unique polarization characteristics may provide a polarization-sensitive animal with a distinct cue for mediating dial vertical migration performed by plankton or with another timing signal.     

高硼硅玻璃沙拉碗缓冲包装跌落仿真分析

目的 研究高硼硅玻璃沙拉碗跌落冲击时的应力和变形情况,为沙拉碗安全包装提供参考。方法 运用Pro/E软件和Ansys软件建立沙拉碗及其缓冲包装三维有限元模型,对有无缓冲包装以及不同跌落高度和跌落姿态分别进行跌落仿真模拟,获取沙拉碗跌落冲击过程的应力、变形和加速度分布及变化规律。结果 沙拉碗跌落冲击时,最易损坏的部位在上部边缘、底部缓冲包装棱边及角的冲击部位;无缓冲包装时最大应力和脆值分别为76 MPa和1.84×105g,有缓冲包装时的最大应力和脆值分别为0.139 MPa和73.5g。结论 对沙拉碗进行包装设计时,应加强对上部碗口边缘部位和缓冲垫边角的保护;缓冲包装结构对沙拉碗起到了明显的保护作用,该研究为高硼硅沙拉碗缓冲包装的理论研究和结构优化设计提供了参考。     

Thermal stress fracture of solar control window panes caused by shading of incident radiation

The phenomenon of thermal stress fracture in solar control window panes in high-rise buildings due to shading of incident radiation is investigated in this paper. An experimental method, in which a bank of infra-red lamps was used as the simulated solar source, was developed to measure thermal strains and hence thermal stresses built up at the cool edges of the glass pane which was glazed in a480 mm square aluminium frame. Horizontal and diagonal shadows both increased the thermal stresses by approximately10% when compared with the unshaded glass panes. It is shown that fracture mechanics can be used to analyse and predict fracture stresses once the mirror radius and the fracture toughness of the glass pane are known. These predictions agree very well with experimental measurements. Finally, a new glazing technique using a thermal conducting sealant in the rebate is suggested to minimise the incidence and risk of thermal stress fracture. This is achieved by raising the temperature of the cool edges and thus lowering the differential heating effect. Preliminary experiments show that the method is promising.     

Effects of CdCl2 treatment and annealing on CdS/SnO2/glass heterostructures for solar cells

Effects of CdCl₂ post-growth treatments and annealing under different conditions on the surface and interface properties of CdS/SnO₂/glass heterostructure were studied. CdS thin films were grown on SnO₂-coated glass substrates for CdS/CdTe heterojunction solar cells by the solution growth technique. It was found that CdCl₂ post-growth treatments and annealing enhanced the CdS-related XRD peaks, narrowed the CdS characteristic Raman bands, removed or depressed the disorder related Raman features, and improved the CdS film crystalline quality significantly, which are advantageous to the application in solar cells as a window layer material.     

The Fractography and Crack Patterns of Broken Glass

The topographical features which appear on the fracture surfaces of broken glass objects and the resulting crack patterns which develop are Nature’s documentation of the fracture event. They are considered after a brief discussion of glass strength. Strength is central to the fracture surface features for it determines the strain energy release rate and the dynamics of crack extension. The surface features known as the mirror, the mist, and the hackle are illustrated and addressed through the principles of fracture mechanics and associated energy criteria. Quantitative aspects of the fracture process such as the stress level at fracture for a glass object are directly related to the size of the fracture mirror. The concept of a fracture mirror constant is related to the strength. Formation of the mist and hackle surface regions are also fundamentally addressed, as is crack branching. Distinctive crack patterns that evolve during fracture, that is the traces of the cracks intersecting the glass free surfaces, are described. Dicing fragmentation of high-strength tempered glass and the long sword-like shards of low-strength annealed glass fracture are contrasted through their strain energies. Characteristic cracking patterns are reviewed for several common glass fractures including those for pressure breaks, both bottle explosions and flat glass window failures from wind pressure whose basic similarities are described. The patterns of crack branching or forking, the branching angles and the crack length prior to forking, are also discussed. Other glass crack patterns such as those from impact and thermal stress are also considered.     

Energy absorbing mechanisms in short-glass-fibre-reinforced polypropylene

The tensile load elongation curves to failure of samples cut along different directions from a extruded sheet of short-glass-fibre-reinforced polypropylene having good fibre alignment along the extrusion direction, were obtained at a strain rate of 0·01 min⁻¹. The work of rupture was calculated from the area under the stress extension curves. The contribution made by some of the energy absorbing mechanisms like plastic deformation of the matrix, debonding, and fibre pull-out to the total work have been considered in some detail. In the extrusion direction, and at angles up to 30° to this direction, the interfacial shear stress and load transfer are high. Consequently, the plastic deformation of the matrix througout the specimen volume, and particularly around fibre ends, makes a dominant contribution to the work of rupture, with a small but significant contribution from debonding and also from fibre pullout at the fracture surfaces. At larger angles, the interfacial shear stress and load transfer are relatively lower, and the work of rupture is considerably less. Supporting evidence for these observations from acoustic emission studies and electron micrographs of raptured surfaces is also presented.     

Nano-structured morphological features of pulsed direct current magnetron sputtered Mo films for photovoltaic applications

Historically, molybdenum thin films have been used as the back contact for Cu(In,Ga)Se₂ based solar cells and as such the properties of these layers play an important role in the overall cell structure. This paper describes the production of molybdenum films using pulsed d.c. magnetron sputtering from compressed molybdenum powder targets. The films were deposited at different substrate temperatures under constant power and constant current modes, and analysed using X-ray diffraction, scanning electron microscopy, atomic force microscopy and four point resistance probe. Mechanical strain and resistivity were found to decrease with substrate temperature together with a shift in the (110) crystallographic plane towards higher diffraction angles. All films were well adhered to the glass substrates irrespective of their high tensile strain. Surface morphology analysis revealed the presence of nano-structured stress relief patterns which can enhance the nucleation sites for subsequent CuInSe₂ deposition. A high-resolution cross sectional image showed the columnar growth of the films. Surface roughness analysis revealed that roughness increased with increase in substrate temperature.     

Strain-sensitive Raman spectroscopy and electrical resistance of carbon nanotube-coated glass fibre sensors

This paper presents the development of glass fibres coated with nanocomposites consisting of carbon nanotubes (CNTs) and epoxy. Single glass fibres with different CNT content coating are embedded in a polymer matrix as a strain sensor for composite structures. Raman spectroscopy and electrical response of glass fibres under mechanical load are coupled for in situ sensing of deformation in composites. The results show that the fibres with nanocomposite coating exhibit efficient stress transfer across the fibre/matrix interface, and these with a higher CNT content are more prone to fibre fragmentation at the same matrix strain. A relationship between the fibre stress and the change in electrical resistance against the fibre strain is established. The major finding of this study has a practical implication in that the fibres with nanocomposite coating can serve as a sensor to monitor the deformation and damage process in composites.     

冲击载荷作用下平板玻璃穿孔机理

玻璃作为采光材料、广泛应用于建筑物、车船、家具等，但玻璃是典型的脆性材料，极易破坏。在冲击载荷作用下，玻璃板破坏形式常常与动载荷的作用类型有直接关系，可分为简单破碎、混合破碎和穿孔。本文利用弹击实验在附有PVC复合材料背板的玻璃面板成孔，记录在冲击载荷作用下玻璃面板的穿孔情况，利用Hertz理论，给出了冲击载荷作用下玻璃面板中的应力分布，分析了玻璃破碎锥角的形成机理；给出了在同等实验条件下，不同厚度玻璃／PVC板构成的层合靶板，玻璃面板厚度与破碎锥角的关系。