爆炸焊接边界效应的力学能量原理

在爆炸焊接工艺中,存在一种称为边界效应的物理现象。即在一般情况下,在爆炸焊接后的复合材料中,会出现雷管区不复、其余周边被打伤、打裂和变形严重等问题。这些问题严重地影响着这类材料的质量。该文从传统的和经典的力学及能量原理出发,探讨了边界效应产生的力学 能量原理,并且提出了预防的措施。     

浸入式水口MgAlON质内衬材料的抗Al2O3附着性研究

浸入式水口在连铸过程中，特别是多炉连铸铝镇静钢时，由于Al2O3在水口内壁附着引起堵塞问题。研究了无碳无二氧化硅的MgAlON质耐火材料，考察了MgAlON—Al2TiO5、MgAlON—BN、Al2O3-C、CaO-ZrO2-C材料的抗Al2O3附着性。结果表明，MgAlON-AT复合材料的抗舢203附着性和抗钢水侵蚀性均优于其它材料．     

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.     

半金属摩阻材料中铜纤维摩擦磨损行为的研究

用扫描电子显微镜(SME)和X-射线能谱分析法(EDX)对铜纤维增强的半金属摩阻材料与灰铸铁对偶滑摩后的摩擦表面进行了分析,研究了摩阻材料中铜纤维的摩擦磨损行为.结果表明,在摩擦磨损过程中,摩阻材料摩擦表面上铜的分布更加弥散化,并且铜纤维具有集铁作用,因而摩阻材料摩擦表面上形成了富铁贫铜表面工作层;铜能从摩阻材料摩擦表面转移到对偶摩擦表面,故对偶摩擦面上分布一定量铜,这是摩擦副具有稳定摩擦系数和良好耐磨性的关键因素;铜纤维取向对摩阻材料摩擦磨损行为有显着影响.     

主动约束层阻尼板结构动力学建模研究

将有限元法和GHM法相结合，给出了建立主动约束层阻尼（ACLD）板结构动力学模型的新方法。建模时，考虑到粘弹材料（VEM）的纵向位移影响，采用GHM方法描述VEM的本构关系，解决了VEM的力学特性随温度和频率变化的难点，避免因VEM的复杂本构关系而产生的微分积分方程。算例表明本文给出的建模方法是准确的，ACLD结构能够有效控制结构振动。     

Bi3+对纳米MnO2水热合成的影响研究

在中性和酸性条件下，以MnO2作为锰源，通过水热合成了纳米MnO2，通过XRD和TEM对产物进行的观察表明，在酸性条件下，向溶液中添加一定量的Bi^3 ，产物的晶型由α型向γ型转化，产物形貌由针状、丝状向颗粒状转变。     

On integral equation approaches to the mechanics of fibre-crack interaction

The paper examines the problem of a penny-shaped crack which is formed by the development of a crack in both the fibre and the matrix of a composite consisting of an isolated elastic fibre located in an elastic matrix of infinite extent. The composite region is subjected to a uniform strain field in the direction of the fibre. The paper presents two integral-equation based approaches for the analysis of the problem. The first approach considers the formulation of the complete integral equations governing the associated elasticity problem for a two material region. The second approach considers the boundary integral equation formulation of the problem. Both methods entail the numerical solution of the governing integral equations. The solutions to these integral equations are used to evaluate the stress intensity factor at the boundary of the penny-shaped crack.     

离心式永磁直流发电机的设计研究

离心式永磁直流发电机把皮带轮与离心式转子设计为一体,磁场得到了充分利用,降低了成本。本文介绍了电子稳压器通过移相、削波输出电压稳定的直流电,解决了小型农用车的低速照明问题和用电设施需用直流电的问题。     

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本文根据物质平衡原理,对于定容和水驱凝析气藏提出了预测采收率的方法,并提出了凝析气藏的总采收率与干气和凝析油采收率的关系式。     

全耗尽CMOS／SOI技术的研究进展

ＳＯＩ材料技术的成熟，为功耗低，抗干扰能力强，集成度高，速度快的ＣＭＯＳ／ＳＯＩ器件的研制提供了条件，分析比较了ＣＭＯＳ／ＳＯＩ器件与体硅器件的差异，介绍了国外薄膜全耗尽ＳＯＩ技术的发展和北京大学微电子所的研究成果。