钢铝双帽型保险杠横梁多目标优化

为了保证保险杠横梁优良的碰撞性能,并使其质量更小和结构简单,研究了一种钢铝双帽型保险杠横梁.使用LS-DYNA软件对保险杠横梁进行摆锤正面冲击数值模拟,经对比发现,钢铝双材横梁相比相同结构单一材料的横梁在正面碰撞中显示出良好的平衡性和碰撞性能;使用控制变量法研究发现,横梁前后帽的厚度和法兰的位置对其碰撞性能有显著影响;...     

Effects on mechanical properties in electron beam welding of TC4 alloy by laser shock processing

The surface of TC4 titanium alloy welding line by electron beam welding (EBW) was processed by high power Q-switched and repetition-rate Nd: glass laser. Effects of laser power and spot diameter on residual stress and microhardness of the TC4 alloy welding line by laser shock processing (LSP) have been analyzed. Results show that residual stresses almost do not change as laser power is 45.9 J, spot diameter is ϕ9 mm; While laser power is 45.9 J, spot diameter less than ϕ3 mm, the distribution of residual stress in welding line occurs obvious variation, which residual stress increase obviously with spot diameter decrease. When power density is bigger than 1.8 × 10¹⁰ W/cm², residual stresses of electron beam welding line occur change by LSP, which improve obviously residual stress distribution; while laser power is bigger than 1.2 × 10¹⁰ W/cm², the surface micro-hardness of electron beam welding line occurs change by LSP, which improve obviously micro-hardness distribution. Mechanical properties of TC4 titanium alloy welding line will be improved by LSP, which provides experimental foundation for further controlling the distributions of residual stress and micro-hardness during laser shock processing. __________ Translated from Journal of Jiangsu University (Natural Science), 2006, 27(3): 207–210 [译自: 江苏大学学报 (自然科学版)]     

带偏心结构的气体发生器激光焊接工装设计

激光焊接工装在激光焊接生产中是必不可少的,通过比较选取焊接件适宜部位作为定位基准,不但避免了焊接件的偏心结构对焊接工装设计和使用造成的困难,而且巧妙利用焊接件的偏心结构及四方法兰盘,方便地实现了焊接件在焊接工装上的装卡定位,很好地满足了气体发生器大批量生产的焊接质量和焊接工效要求。     

Micro laser welding of polymer microstructures using low power laser diodes

The use of laser welding for joining micro parts has experienced a substantial increase in popularity during recent years. Specifically translucent microfluidic devices are assembled using laser welding; however, a major issue is the laser beam size of commercially available laser-welding equipment and thus the resulting welding seam size, which may be orders of magnitude larger than microfluidic channels and structures. We have successfully achieved extremely small welding seams using focussed low-power laser diodes. Commercial laser welding stations for polymer assembly will typically operate in the power-region 15–50 Watts. The focussed laser beam will have a size of typically 500 μm × 500 μm and may, depending on optical configuration, be up to several mm². The resulting welding-seam will thus be in the area of 300–600 μm depending on beam energy distribution; additionally the melt will spread to unheated areas due to capillary forces. As microfluidic channels are in 20–100 μm regions, even a very limited amount of stray melt may completely fill a part of a channel and thus render it useless. We have used commercially available “single-die” laser-diodes of optical power 200–500 mW. The beam has been focussed and directed using simple optical installations, resulting in a beam-size in the area of 50 μm × 5 μm full width half maximum (FWHM) We have achieved firm welding seams of width <10 μm, with a welding speed of 15 mm/s and with virtually no noticeable spread of melt.     

激光焊接机的优化设计与运动仿真

针对动力电池外壳的激光密封焊接技术,设计了激光焊接机的结构方案,采用X/Y轴直线电动机模组、Z轴线性模组,完成了电池壳四条边及其圆角的一次性焊接。利用UG对整机进行了运动仿真分析,采用ANSYS Workbench软件,完成了立柱和横梁的优化设计。对提高动力电池的焊接质量和效率具有重要作用。     

激光光束质量的评价与应用分析

从M²因子概念出发,分析了M²因子的概念与激光本质参数之间的关系,以及几种典型光束的M²因子,研究了M²因子的局限性,比较了针对不同应用目的的常用激光束质量定义的适用范围,探讨了激光光束质量的影响因素及其控制措施.     

数控激光焊接汽车用高强钢焊缝质量的研究

讨论了数控激光焊接高强钢材料焊接质量的影响因素,利用正交法优化设计试验,并对焊接试件进行拉伸力学性能试验,焊缝金相组织和显微硬度试验,焊接接头SEM分析,焊缝盐水腐蚀试验等多种焊缝质量的检测.同时分析了高强钢焊缝质量常见缺陷,并给出了一套可以有效控制焊接高强钢加工质量的优化工艺参数.     

电子束焊接在齿轮加工中的应用

对电子束焊接的特点、工艺要求进行了简述,并通过实例说明这种焊接方法在齿轮加工中的应用场合,采用电子束焊接时各齿轮组件的加工工艺要求及工艺过程。实验结果表明,该工艺扩大了设备的加工能力,提高了设备的利用率。     

Lensed plastic optical fiber with an aspherical fiber end formed by joining an aspherical plastic lens and a plastic optical fiber using laser transmission welding

In optical communication systems which require the coupling of the light source to the fiber, efficient coupling can be practically realized either using a separate lens or by direct formation of the lens at the fiber end. A novel lensed plastic optical fiber (LPOF) is presented with efficient coupling of the plastic optical fibers with a light source. An aspherical plastic lens was bound with a flattened plastic fiber end by laser transmission welding (LTW) to form an aspherical fiber endface which can provide better coupling efficiency than a spherical fiberface. An analysis demonstrates that LTW can offer strong welding with small heat affected zones that are appropriate for commercial use. In this study a useful method for manufacturing lensed-end fibers is developed and demonstrated experimentally.     

基于电压影响下圆偏振激光束的特性

采用狭缝光束分析仪和偏振仪测量了从铝薄膜表面反射的圆偏振光的光斑位置和偏振特性随外界直流电压变化情况,理论拟合激光从铝薄膜反射后的光斑位置与直流电流电压的关系。测量和多项式拟合结果表明,当外部电压值从0变化到2.5V时,圆偏振激光在x轴和y轴上的位置分别是从-45μm移动到-95μm,从35μm移动到75μm,而激光束的光学偏振度基本上不变化。     

高精度激光光束准直系统设计

为了进一步提高激光光束用作直线基准的精度,建立了基于反射镜平动式光束稳定器以及两点式光束漂移分离法的高精度激光光束准直系统。首先,对系统中基于反射镜平动的光束稳定器进行研究,对其光束偏转原理以及影响因素进行分析,并对两点式光束漂移分离方法进行介绍。然后,对光束偏转单元的分辨力以及偏转范围、所使用的压电陶瓷非线性和迟滞特性、以及光束偏转单元的频率响应特性进行实验测试。最后,对该激光准直系统的激光光束准直精度进行测试。实验结果表明本文提出的光束偏转单元在120μrad范围内的光束偏转分辨力可以达到5 nrad,频率响应特性高于2 kHz;最终激光准直系统的准直精度在二维方向上分别达到1.9×10^-8 rad和2.1×10^-8 rad,相对于现有技术约提高了3倍,满足激光光束用作高精度直线基准的需求。     

基于GT-drive的多目标汽车传动系统匹配与优化

利用GT-drive软件建立汽车整车模型,并利用遗传算法与直接搜索工具箱(Genetic Algorithm and Direct Search Toolbox,GADST)和GT-drive软件联合建立多目标汽车传动系统优化模型。结合某款5挡手动变速汽车,以汽车动力性和燃油经济性为指标,对汽车传动系参数进行了优化,得到一组最优的传动系参数,在保持汽车原有动力性能的基础上,达到了降低汽车燃油消耗的目的。该优化结果为车辆的进一步改进设计提供了重要参考依据。     

钢-铝异种合金脉冲激光焊焊缝表征分析

采用Nd:YAG激光焊对304不锈钢和5052铝合金进行异种金属焊接,分别以峰值功率、焊接速度、离焦量和脉冲频率等工艺参数设计24组工艺试验,并对比分析未熔合、熔合和焊穿3种焊缝表面表征。运用激光点位移传感器测量焊缝高度,探索焊缝高度随激光功率等工艺参数的变化趋势,得出钢-铝焊缝3种表面形貌的工艺参数区间。分析结果表明,焊缝的表面形貌是由激光单点能量、离焦量和脉冲频率等因素共同决定,焊缝高度与峰值功率、焊接速度、离焦量和脉冲频率等工艺参数有一定的变化规律。     

多级齿轮传动啮合参数优化研究

传统的多级齿轮传动设计浪费了材料的一部分承载能力,单目标的啮合参数优化方法精确度不够。本文提出用单目标函数进行初步的啮合参数优化,以此为基础再进行一次迭代优化计算。在计算中考虑全部啮合参数对齿轮传动的影响。采用复合形优化方法和智能判别系统可得到更加合理的啮合参数。并用实例论述了这种重复优化的与传统设计和单目标优化的效果对比。     

阀门密封面金属覆层激光焊接的研究

介绍了金属覆层激光焊接技术在阀门密封面上的应用。给出了激光焊接过程的工艺条件和设备参数及其试验鉴定结果。     

CO2激光焊接接头性能的试验分析

采用同轴和侧吹保护气体控制等离子的方法,对车身专用高强度镀锌钢板的CO2激光焊接接头的性能进行了大量的焊接试验研究,并对焊缝进行显微组织分析和相关的机械性能检测.研究激光焊接高强度镀锌钢板的工艺参数对焊接接头的抗拉强度、屈服强度和延伸率等机械性能指标的影响规律,优化了激光焊接的工艺参数.试验表明随着激光焊接过程中输入线能量的增加,焊缝区的硬度值逐渐下降,拉伸试件断裂的区域、断口韧窝大小及分布情况各不同,且焊缝的拉伸裂纹均向母材扩展,说明激光深熔焊接可以有效地避免高强度镀锌钢板焊接接头的软化.     

制造用高功率激光器光束质量的评价与测量

建立了制造用高功率激光器光束质量的评价体系与测量方法,研究了该体系所采用的评价参数、测量原理、测量方法、测量仪器以及测量结果的计算和分析方法.首先,对目前存在的评价激光光束质量的参数进行了比较和判断.接着,以光束传输比(M2)和光束参数积(Kf)为重点,阐述了光束质量评价参数与光束束宽定义之间的关系,提出了工业应用背景...     

Process modeling and parameter optimization using neural network and genetic algorithms for aluminum laser welding automation

In the automotive industry, applying aluminum alloys to car chassis have become an important concern in order to reduce car weight. In aluminum laser welding, the strength of weld is typically reduced by porosity, underfill, and magnesium loss. In order to overcome these problems, laser welded with filler wire was suggested. In this study, experiments on the laser welding AA5182 of aluminum alloy with AA5356 filler wire were performed with respect to laser power, welding speed, and wire feed rate. The experiments showed that the tensile strength of the weld was higher than that of the base material under certain conditions. Using the experimental results, a neural network model was proposed to predict the tensile strength. To optimize the process parameters, a fitness function was formulated, taking into account weldability and productivity. A genetic algorithm was used to optimize the laser power, welding speed, and wire feed rate. The optimal value of these parameters was considered to be the proper process conditions in terms of weldability and productivity.     

半导体激光阵列光束整形技术研究进展

光束整形作为提高半导体激光阵列光束质量的有效手段,近年来得到了人们越来越多的关注。综述了几种典型的半导体激光阵列整形技术,详细介绍了近年来半导体激光光束整形的最新进展,分析了各种整形方法的技术特点,总结了半导体激光阵列整形技术的发展趋势。