Jitai NIU
,
Zhonghong LAI
,
MuZhen WANG
,
Liming LIU
,
Lin WU
材料科学技术（英）
The effects of laser welding parameter on strength of welded joints were studied. The mechanism for loss of joint strength was analyzed. It was pointed out that an important factor affecting joint strength is the reaction between matrix and reinforced phase. On the basis of this, the concept of critical Si activity alpha ([si]min) was proposed. Using appropriate welding parameters and Si activity, high quality laser welded joints in an aluminum matrix composite SiCW/6061A1 can be successfully obtained.
关键词:
Chenming XU
,
Hongming GAO
,
Guangjun ZHANG
,
Lin WU
材料科学技术（英）
An arc light radiation phenomenon in TIG welding process was studied through experiments and theoretical analysis. The arc spectra were acquired under a variety of welding parameters from 200 nm to 1000 nm wavelength range in TIG. The influence of welding parameters on the arc radiation was discussed. The radiation energy from lines emission mechanisms was calculated and the comparison was made with the one from the continuum emission mechanisms. The result shows that the radiation energy from the line emission mechanisms is equal to the one from the background. Based on the experiments and analysis, a physical model of arc light radiation has been developed. In this model, the arc plasma was presumed to be in local thermal equilibrium (LTE) with light thinness property. The Bolzmann distribution and Saha equation were applied to establish the arc light radiation model. This helps lay the foundation for further mathematical modeling of the arc light radiation.
关键词:
Spectral diagnosis
,
null
,
null
,
null
Chunli YANG
,
Sanbao LIN
,
Fengyao LIU
,
Lin WU
,
Qingtao ZHANG
材料科学技术（英）
The mechanism of penetration depth increased by activating flux in activating tungsten inert gas (A-TIG) welding was studied by measuring the distribution of trace element Bi in the weld and monitoring the change of arc voltage during A-TIG welding of stainless steel 0Cr18Ni9 with fluxes SiO2 and TiO2. The results show that the mechanism of penetration depth in A-TIG welding depends on the sort of flux used. The weld pool convection after coating the flux SiO2 and flux TiO2 is changed inversely compared with convectional TIG welding without flux. The arc voltage is increased by flux SiO2 whilst flux TiO2 does not have effect on the arc voltage. The reason of penetration depth increase for SiO2 is due to the constriction of arc plasma and the change of surface tension gradient. The increase of weld penetration depth with TiO2 only ascribes to the change of surface tension gradient.
关键词:
TIG welding
,
null
,
null
,
null
Jinsong TIAN
,
Lin WU
,
Ming DAI
,
Yu KONG
材料科学技术（英）
Off-line programming provides an essential link between CAD and CAM, whose development should result in greater use of robotic are welding. An are welding system with a robot and a rotating/tilting positioner is a major application area, where manual programming is a very tedious job. Off-line programming is a constructive way to solve the problem. The inverse kinematics algorithm of robot and positioner is the foundation of the off-line programming system. Although previously there were some researchers who studied the positioner inverse kinematics algorithm, they only focused on a special solution of the positioner inverse kinematics, which is the solution at down-hand welding position. However, in welding production, welding position other than down-hand position is also needed. A method for representing welding position was introduced. Then a general algorithm of rotating/tilting positioner inverse kinematics is presented.
关键词:
Tao QIU
,
Shanben CHEN
,
Yuntao WANG
,
Lin WU
材料科学技术（英）
A new welding flexible manufacturing cell (WFMC) with intelligent welding sensors was investigated. Based on the analysis of information flow in WFMC, automation Petri net control model has been studied, which can be extended to complex welding flexible manufacturing system in the future.
关键词:
Tong LIU
,
Jinsong TIAN
,
Lin WU
,
Ming DAI
材料科学技术（英）
Feature modeler of welded structure provides both 3D-geographical and non-geographical features for the off-line programming of are welded robot. Welded structure is regarded as an assembly, the design of welded structure consists of three aspects: plane, joint, and groove design. Each aspect corresponds to a category of features. The plane features are defined by interactive feature definition. A method analogous to the "mating feature" is introduced to represent the joint features. Based on AutoCAD 2000, a B-rep solid modeler, a prototype system is implemented.
关键词:
Hongming GAO
,
Lin WU
,
Honggang DONG
材料科学技术（英）
Up till now, most of the researchers believe that there are four kinds of forces in the weld pool convection, they are surface tension, electromagnetic force, buoyancy and gas shear stress. So electromagnetic force is very important, especially when large current is applied. In most of previous models, the electromagnetic force is calculated analytically, in which only the axial component of current is considered. Actually the radial component of current has the same effect, and may be advanced in some locations. In double-sided arc welding process, instead of the earth clamp, another torch is placed on the opposite side, the current will go from one torch, through the weld zone, to another torch. In this case, the current is more concentrated in the weld zone, the electromagnetic force will have significant effect compared with conventional welding process. In this paper, a new method of numerical calculation for electromagnetic force is developed, in which both axial and radial components are considered. And as an example, the distribution of electromagnetic force in double-sided arc welding is calculated. It demonstrates that this new method could give more accurate simulation of electromagnetic force, and is close to the actual process.
关键词:
Electromagnetic force
,
null
,
null
Hongming GAO
,
Lin WU
,
Honggang DONG
材料科学技术（英）
A three dimensional current density distribution in double-sided gas tungsten are welding (GTAW) proces is performed. The current density distribution field is evaluated by numerically solving Maxwell equations in the domain of the workpiece. In the boundary condition, the current density on the workpiece surface is assumed as Gaussian distribution. Results show that the current distribution in DSAW is different from single side are welding, it is more concentrated and the relative location of the two torches influence the current distribution greatly.
关键词:
李铂
,
周建江
,
夏伟杰
,
吴连慧
液晶与显示
doi:10.3788/YJYXS20142904.0605
直线是机载座舱显示画面中最基本的图元,其显示质量对于整个画面的显示效果影响较大,尤其是小角度下直线显示的“麻花”现象一直是影响显示效果的关键问题之一.为了提高小角度下直线的显示效果,本文提出了一种基于Wu算法的亮度渐变改进算法.该算法通过渐进地展现直线从轴方向上的亮度变化过程,减少亮度畸变,有效地改进了显示效果.通过Matlab仿真和FPGA实现,验证了该算法反走样后的小角度直线显示效果明显优于其他算法,而且结合中点画线法后,绘制时间与Wu算法相当.同时该算法还可改善大角度直线和圆弧的显示效果,消除了大角度直线的边缘锯齿,解决了圆弧在小角度部分的虚化问题.因此本文算法可用于对实时性和显示效果要求高的机载座舱显示系统,以缓解飞行员的视觉疲劳.
关键词:
座舱显示
,
反走样
,
改进Wu算法
,
小角度
,
FPGA实现
吴连慧
,
周建江
,
夏伟杰
,
陈雅雯
液晶与显示
doi:10.3788/YJYXS20153001.0163
对于光栅化的三角形,其边缘存在明显的锯齿现象,因此需要进行反走样处理.基于Wu直线反走样算法的思想,考虑了水平直线外侧直接添加插值点的算法和三角形三边外侧反走样的算法.综合两者的优点,在绘制光栅化的三角形的同时,边缘叠加Wu反走样直线,并考虑背景像素灰度值的作用.结果表明,改进的三角形光栅化的边缘反走样算法有效提高了三角形光栅化后边缘的显示效果,该算法计算量小,便于FPGA实现,可用于对图形显示质量要求很高的机载显示系统.
关键词:
反走样
,
Wu算法
,
光栅化
,
FPGA
