Irradiation of large area Mylar membrane and characterization of nuclear track filter

Ion irradiation of Si⁸⁺ ion beam of 100 MeV was scattered by a gold foil on a Mylar membrane of 25 Μm thickness in the form of film roll (width, 12.5 cm and length, 400 cm) at the Nuclear Science Centre, New Delhi. The characterization of etched nuclear tracks was carried out by gas permeation measurements. The samples cut from the film roll of required size for permeability measurements were etched in a controlled manner in a constant temperature bath of 6N NaOH solution. The opening of the conical etched tracks was characterized by hydrogen gas permeation.     

The wheel–rail interface—some recent accidents

The importance of the wheel–rail interface to the safe operation of railways is discussed. Some aspects of the history of rails and wheels are introduced. Several recent accidents involving the wheel–rail interface are described. The great importance of operating both vehicles and track as a system is emphasized, together with the necessity of maintaining both in good condition.     

银铜复合电触点复合强度检测方法的讨论

贵金属及其合金铆钉型复合电触点除了应考核其冷态复合强度之外，还必须增加在热态下复合强度的考核，只有这样才能满足用户在产际运行时对复合触点复合强度的要求。     

Possibilities and extension of XRD material response analysis in failure research for the advanced evaluation of the damage level of Hertzian loaded components

Due to clearly distinguishable damage symptoms, it is differentiated between the surface and sub‐surface failure mode of rolling bearings. Material states red out by X‐ray diffraction (XRD) residual stress measurements point to a variety of loading conditions especially at raceway surfaces that are associated with several competing failure mechanisms. The corresponding lifetime reduction can range from the lower fatigue strength region to material ratcheting in extreme cases. Relevant position of the microstructural changes and nature of the failure mechanisms are characterized. The time alteration of the XRD material parameters measured at or near the surface and at the depth of the maximum equivalent stress correlates, in a different manner, with the statistical parameter of the 10 % bearing life. Both failure modes are illustrated by concrete examples. Contaminated lubricant and boundary lubrication, which represent practically important surface‐induced failures, are discussed in more detail. Gray staining, i.e. shallow pitting, often occurs without distinct indication of global material aging by means of XRD characteristics. Here, scanning electron microscopy observations and electron microprobe analyses point to corrosion fatigue as acting surface failure mechanism. The interaction between material and lubricant under complex loading regimes particularly of mixed friction and corrosion opens further failure research areas in the field of tribology.     

Finite elements in the analysis of pressure vessels and piping-a bibliography (1976–1996)

The paper gives a bibliographical review of the finite element methods (FEMs) applied for the analysis of pressure vessel structures/components and piping from the theoretical as well as practical points of view. The range of applications of FEMs in this area is wide and cannot be presented in a single paper; therefore the aim of this review is to give the reader an encyclopaedic view of the differnt possibilities that exist today for the finite element analysis in the fields of pressure vessels and piping. The bibliography at the end of the paper contains approximately 1900 references to papers, conference proceedings and theses/dissertations on the subject that were published in 1976–1996. These are classified in the following categories: linear and non-linear, static and dynamic, stress and deflection analysis; stability problems; thermal problems; fracture mechanics problems; contact problems; fluid-structure interaction problems; manufacturing of pipes and tubes; welded pipes and pressure vessel components; development of special finite elements for pressure vessels and pipes; finite element software; and other topics. Also finite element software, general purpose and special purpose codes, used for the analysis of pressure vessels and pipes are briefly discussed and presented.     

Ge/Pd/n-GaAs低阻欧姆接触的SIMS分析

采用Ge／Pd／GaAs结构和快速热退火在n－GaAs上形成了低阻欧姆接触。利用H次离子质谱（SIMS）技术揭示和讨论了低欧姆接触形成的机理。比较了采用X 和CsX 信号检测的Ge，Pd，Ga和As的深度分布。结果表明采用CSX 可以提供更准确的结果和成分信息。     

用发展的Sachs法研究模拟轧辊中的残余应力

对不同辊型，尺寸，材料与加工处理方法的模拟冷轧辊进行了内剥层试验研究，求出了原辊和打中心孔或扩孔后辊内残余应力分布曲线，提出了虚拟打孔法和虚拟剥层法，解决了实心辊中心和空心辊内表层的残余应力的精确测量问题，丰富了Ｓａｃｈｓ内剥层法的内容，机械法打中心孔，热处理前打中心孔，空心辊表淬前改变温度场的方法可降低残余应力值，后者降低残余应力的效果尤为显著。     

The effect of pre-wetting on dynamic contact angles

A roll-coating experimental system is used to study the effect of pre-wetting on dynamic contact angles, the interfacial displacement depth, and the associated phenomenon of air entrainment. The system consists of a roll, which is horizontally rotating in a liquid pool. The dynamic contact angle is recorded by a macrophotography system. The test liquids are glycerol solutions with viscosities in the range 104 < μ < 748 mPa · s. The value of (μV/ρg)^0.5 is taken as the characteristic length to be used in the dimensionless relationships which correlate experimental measurements. The effect of base layer entry angle into the liquid pool on the dynamic contact angles and other flow parameters is studied. Comparison is made with measurements in dry tape-coating and other pre-wet roll–coating systems.     

On an invariance principle for unilateral contact at a bimaterial elastic interface

This paper examines the axisymmetric elastostatic problem related to the unilateral receding contact at a pre-compressed smooth bimaterial elastic interface. The separation at the interface is caused by the action of axisymmetric stress fields of unequal magnitude, which are applied at any location of the separate halfspace regions. The analysis of the problem focuses on the determination of the zone of separation as a function of the pre-compression, the magnitudes and locations of the axisymmetric stress fields inducing the separation, and the elasticity characteristics of the halfspace regions. It is found that the radius of the separation zone can be evaluated in explicit form. In the particular instance when the loadings applied at the surface of the halfspace regions are equal in magnitude and distribution, the analysis reveals that the radius of the separation zone is independent of the elasticity properties of the halfspace regions and can be evaluated in exact closed form.     

接触传热表面粗糙度曲线的统计特征

测量了一般机械加工表面的轮廓曲线，基于小波变换提取了粗糙度曲线，分析了轮廓高度和接触峰高度的统计分布特征。研究结果表明，轮廓高度不服从严格的正态分布，但具有一定的正态性，而接触峰高度的统计特征与其评定标准有直接的关系。因此，对于接触热阻的计算模型来说，接触点数的计算应以合理选取接触峰的评定标准为前提。