Fatigue damage study of cold metal transition fusion-brazed aluminium/steel dissimilar joints

ABSTRACT

An aluminium/steel CMT-welded joint is mainly composed of fusion zone (FZ), interfacial intermetallic compound (IMC) zone, and heat-affected zone (HAZ). IMC and FZ are the weakest link in the welded joint. The fatigue fracture indicates that the lattice distortion caused by the lattice mismatch of Fe₂Al₅ and Fe is more likely to engender dislocation slipping and cracks easily nucleate during the fatigue testing. The hysteresis loop is shifted to the right, which indicating that the specimen experiences a ratcheting effect. In the high-stress condition, the cyclic hardening induced by the ratcheting strain is much stronger than that in the lower stress condition, which improves the fatigue life of the materials.     

铝合金薄板CMT焊缝的超声波检测

采用超声波探伤技术对厚度小于 5mm的铝合金薄板 CMT搭接、对接两种焊缝进行检测,并且通过金相解剖进行验证：超声波探伤技术可以应用于铝合金薄板焊缝的检测,且缺陷检出率较高;在 CMT工艺下,铝合金薄板对接焊缝的焊接质量高于搭接焊缝的焊接质量。     

Business Continuity Management: A Standards-Based Approach

ABSTRACT

Business enterprises are increasingly realizing the importance of business continuity management (BCM). Availability BS 25999 Standard has facilitated a consistent methodology that organizations can follow in designing their BCM System. This paper intends to provide a conceptual understanding of BCM right from BCM Policy to BCM maturity by describing the steps involved in the implementation of BCM Standard – BS 25999 – to ensure business continuity in the event of an outage. The key BCM tasks have been categorized into three phases of business continuity – Pre-event Preparation, Event Management, and Post-event Continuity. This paper also highlights some of the challenges experienced by the author in carrying out Risk Assessment and Business Impact Analysis. The Business Continuity Maturity Model® of Virtual Corporation is provided (with their permission) as a tool to strengthen business continuity maturity or organizations.     

基于SJA1000的CAN总线智能节点设计

本文介绍了利用89C52、SJA1000、CTM1050实现CAN总线智能节点的设计,包括电路设计和软件设计。在电路设计中使用CTM1050实现带隔离的CAN收发电路,简化了电路设计,降低了硬件电路成本。     

Effectiveness of cold metal transfer process for welding 7075 aluminium alloys

Abstract

Cold metal transfer (CMT) welding is a promising process to improve the mechanical characteristics of the hard to weld 7075-T6 aluminium alloy owing to its unique advantages in contrast to conventional metal inert gas welding process. The welded joints, using ER5356, were identified and characterised by means of optical microscopy, scanning electron microscopy and energy dispersive spectroscopy. Mechanical properties were measured by tensile and hardness tests. Results indicate that CMT provides better joint tensile strength and ductility compared to metal inert gas welding. The softness in the heat affected zone was very low, but a big hardness gap was recognised in the welded metal compared to base metal. The joint had mechanical property coefficients of 77%, 60% and 69% for yield strength, ultimate tensile strength and elongation respectively.     

Stiffness of particulate reinforced metal matrix composites with damaged reinforcements

Abstract

During tensile plastic deformation particulate reinforced metal matrix composites (MMCs) undergo reinforcement damage and a parallel reduction in stiffness. An analytical model is developed to calculate this stiffness reduction using the equivalent inclusion technique proposed by Eshelby. The model considers both damaged and undamaged reinforcement particles as ellipsoidal inclusions but with different stiffness tensors. The effect of the aspect ratio of the reinforcing particles has been accounted for in the model. The model is very flexible and can meet different specific damage situations by designing a suitable stiffness tensor for the damaged reinforcements. Finite element analysis is used to modify a numerical stiffness tensor for cracked reinforcement particles. The model is compared with an earlier model of modulus reduction in MMC materials and with a few experimental measurements made on a 15 vol.-%SiC particulate reinforced aluminium alloy 2618 MMC.     

AP1000核电厂SGTR事故工况下CMT水位分析

本文使用LOFTTR2AP-1.6程序分析了AP1000核电厂在蒸汽发生器传热管破裂（SGTR）事故工况下堆芯补水箱（CMT）的水位变化情况.分析结果表明,即使在极端的情况下,SGTR工况也不会导致CMT的水位下降到触发自动卸压系统（ADS）动作的整定值,不会导致更为严重的瞬态,符合压水堆用户要求文件（URD）的规定.     

碲镉汞晶片表面加工损伤的电化学腐蚀观察方法

本文报道一种新的观察碲镉汞（ＣＭＴ）晶片表面加工损伤的方法──电化学腐蚀法。文中讨论了电化学腐蚀法的原理，给出了实验结果。实验表明：机械磨抛的ＣＭＴ晶片表面的加工损伤可用电化学腐蚀法清楚地揭示出来；磨抛产生的机械划痕在电化学腐蚀前后一一对应，而且腐蚀后可清晰、直观地看到腐蚀前看不见的机械划痕；结合化学腐蚀的方法测量了一定磨抛条件下Ｗ３．５磨料在ＣＭＴ晶片表面产生的最大加工损伤深度约３２～４０ｐｍ；机械磨抛产生的划痕和其在表面留下的应力沟道区是ＣＭＴ晶片表面在磨抛加工中受到损伤的主要机构。分析认为平均损伤深度主要影响磨抛ＣＭＴ晶片的表面复合速度，而最大加工损伤深度则对ＣＭＴ器件、特别是多元器件性能参数的均匀性影响比较大；故控制好ＣＭＴ晶片表面加工的最大损伤深度也是制备性能均匀的ＣＭＴ多元探测器的一个重要环节。     

Surface modification of nanodiamond in aqueous medium

1　INTRODUCTIONTheresearchandpracticeofnanodiamond (dia mondofnano scale ,insomearticlesultrafinedia mond (UFD )orultradisperseddiamond (UDD )iscalled)synthesishasstartedbothintheUnitedStatesandtheformerUSSRinearlier 1980s[1,2 ] .Afterthat,reportsabouttheresearchandsynthesisofthisnano scalematerialpresentthemselvescontinuously .TheproductsofthiskindcomeforthinJapan ,Ger many ,GreatBritainandFranceaswell[3,4 ] .Scien tistsinlandhavealsoshowntheirinterestandinten sivestudieshavealsob…