Effects of laser beam energy and incident angle on the pulse laser welding of stainless steel thin sheet

This paper reports an experimental study of laser spot welding on stainless steel sheets. A pulsed Nd:YAG laser was used to weld the stainless steel specimen in the range of laser energy 0.6–1.2 J and incident angle 30–75° (the angle of the laser beam incident direction to the sheet surface). Metallography was applied to measure the cross-sectional size and shape of the welded spot. From the experimental results, it is found that as the laser energy increases, the penetration depth, bead length, and bead width of the welded spot increase. As the laser incident angle increases, the penetration depth and the bead width increase while the bead length decreases. The results illustrate that the shape and size of the welded spot depend not only on the laser energy, but also on the incident angle of laser beam.     

高钒高速钢碳化钒形态的数值化分析

针对碳化钒的不同形态,设计出定量分析软件,并利用形状因子K,实现了高钒高速钢不同碳化物形态数值化处理,当K介于0.785～1.000之间碳化钒形态为团球状;K≤0.223,碳化钒呈开花状.高钒高速钢当碳含量达到4.2%时,K为0.86和当量直径D为0.78μm,碳化物呈团球状均匀分布.     

Optimum design of long-span suspension bridges considering aeroelastic and kinematic constraints

Cable supported bridges are wind prone structures. Therefore, their aerodynamic behaviour must be studied in depth in order to guarantee their safe performance. In the last decades important achievements have been reached in the study of bridges under wind-induced actions. On the other hand, non-conventional design techniques such as sensitivity analysis or optimum design have not been applied although they have proved their feasibility in the automobile or aeronautic industries. The aim of this research work is to demonstrate how non-conventional design techniques can help designers when dealing with long span bridges considering their aeroelastic behaviour. In that respect, the comprehensive analytical optimum design problem formulation is presented. In the application example the optimum design of the challenging Messina Strait Bridge is carried out. The chosen initial design has been the year 2002 design proposal. Up to a 33% deck material saving has been obtained after finishing the optimization process.     

Adjustable speed surface subdivision

We introduce a non-uniform subdivision algorithm that partitions the neighborhood of an extraordinary point in the ratio σ:1−σ, where σ(0,1). We call σ the speed of the non-uniform subdivision and verify C¹ continuity of the limit surface. For σ=1/2, the Catmull–Clark limit surface is recovered. Other speeds are useful to vary the relative width of the polynomial spline rings generated from extraordinary nodes.     

HALT技术在变频器中的应用初探

HALT技术可在产品设计阶段快速消除设计缺陷,缩短研发时间和成本,迅速提高产品的质量和固有可靠性。本文从HALT试验的背景出发,介绍了HALT试验的基本原理和意义。在对HALT箱各方面性能验证的基础上,针对我司11kW变频器,详细讲述了HALT试验的具体操作过程。     

基于龙虎山水电站水轮机选型设计

根据龙虎山水电站的工程概况,对该电站的设计参数进行选择分析,综合考虑各种因素,对比国内能量指标较优的转轮,从各个方面对各型号进行了比较,确定了“4大+1小”为最优方案,选择了最适合于本电站的水轮机的机型.     

稀土永磁低速同步电动机制造技术

介绍了稀土永磁低速同步电动机原理结构特点，着重论述该电机在制造中的关键技术和研究。     

永磁式双转子电机的理论与实践

根据电机学的基本理论,分析了永磁式双转子电机的原理和结构特点,结合其特点,指出这类电机生产和使用中存在的关键问题,为进一步的工程应用做好准备。     

基于80C196MC的交流牵引变频调速控制系统

本文介绍了一种以新型智能功率模块IPM，SPWM专用控制芯片80C196MC为基础构成的交流牵引变频调速控制系统，介绍了系统的控制原理及软硬件的设计方案。     

灯泡贯流式水轮发电机组轴系振动及静挠度计算分析

灯泡贯流式水轮发电机组一般采用卧轴结构，本通过对大轴可能存在的载荷工况进行了全面分析，得出了影响卧式轴系的主要运行工况，为设计和安装提供了技术支持。