闪光对焊机自动控制系统的研究

本文介绍了对焊机的生产工艺过程，并采用８０３１单片机对闪光电流控制，从而使闪光对焊工艺实现了自动化。     

各向异性半平面与一各向同性长条的焊接问题

本文利用平面弹性复变方法和解析函数边值问题的基本理论以及积分方程论，研究了各向异性半平面与一各向同性长条的焊接问题，给出了应力分布封闭形式的解。     

ART-2网络在超声检测信号分析中的应用

本文以焊缝超声检测常见的缺陷（夹渣、气孔、未焊透、未熔合）为对象，选取缺陷时域波形的上升时间、波宽、上升角度和频域特征的波动次数、底宽等特征值组成特征矢量作为ART-2的输入，来实现缺陷性质的识别，并与射线检测结果对比。实验结果表明：采用该方法得到的正确识别率达到81．5％，具有良好的应用前景。     

Modeling of thermal phenomena in single laser beam and laser-arc hybrid welding processes using projection method

This paper concerns mathematical and numerical modeling of thermal phenomena accompanying single laser and laser-arc hybrid butt welding of steel sheets. Coupled heat transfer and fluid flow in the fusion zone were described respectively by transient heat transfer equation and Navier–Stokes equation. Laser beam and electric arc heat sources were modeled using different heat source power distributions. Latent heat associated with the material’s state changes, buoyancy forces and liquid material flow through a porous medium were taken into account in considerations. Differential governing equations were numerically solved using projection method combined with finite volume method. Elaborated solution algorithm was implemented into computer solver used for simulation of heat transfer and fluid flow during welding. The geometry of the weld and heat affected zone as well as cooling rates were estimated on the basis of numerically obtained temperature field.     

Promotion of Neurite Outgrowth and Extension Using Injectable Welded Nanofibers

We report a general strategy to develop injectable welded nanofibers to facilitate the outgrowth and extension of neurites. In this case, nonwoven mats of uniaxially aligned poly(caprolactone)(PCL) nanofibers were firstly cut into several small pieces with fixed fiber lengths of 25, 50 and 100 μm, respectively, using a cryotome. A tissuelyser was employed to homogenize and disperse the short nanofibers to a homogeneous suspension. By tuning treatment duration from 100 s to 400 s, the temperature of the suspension was brought close to the melting point of PCL. As such, the short nanofibers were welded at their cross points while the fibers far away from the cross points remain the original structures. We showed that the viability of neuroblastoma SH-SY5Y cells and their neurite outgrowth and extension were enhanced with the use of such welded short nanofibers. Taken together, this study provides a simple way to generate injectable welded nanofibers, holding potential in affecting neurite outgrowth and extension for nerve repair, in particular, in the central nervous system.     

Finite element modeling of welding processes

This work deals with the simulation of fusion welding by the Finite Element Method. The implemented models include a moving heat source, temperature dependence of thermo-physical properties, elasto-plasticity, non-steady state heat transfer, and mechanical analysis. The thermal problem is assumed to be uncoupled from the mechanical one, so the thermal analysis is performed separately and previously to the mechanical analysis at each time step. The mechanical problem is based on the thermal history. A special treatment is performed on mechanical elements during the liquid/solid and solid/liquid phase changes to account for stress states. The three-dimensional stress state of a butt-welded joint is obtained as an example of an application.     

焊接自动送丝控制系统模糊控制的计算机仿真

利用在数值积分法基础上编制的计算机数字仿真程序,根据系统的动态结构图.针对变速送丝系统PID控制的问题提出了采用模糊控制的改进措施,并进行了计算机的仿真实验研究.     

焊接气溶胶形成机理与焊接发尘量影响因素研究进展

焊接过程中产生的气溶胶影响作业环境和工作人员身体健康。总结了熔化极气体保护焊中焊接气溶胶的形成机理以及影响焊接发尘量的因素,并对每一种影响因素的研究现状和研究结论进行归纳,展望了未来研究焊接气溶胶的形成机理以及影响焊接发尘量的因素的方法和发展趋势。后期需要建立一个基于动态条件下的统一模型研究气溶胶的形成机理和多因素影响的发尘量变化规律,并结合高速摄像和图像处理技术,将研究方法从简单的实验观察提升到规律性的研究。     

拼焊板技术在汽车覆盖件中的应用

拼焊板成形汽车覆盖件具有安全、节能、减重等优点而符合国内外汽车工业发展的方向.对拼焊板的焊接方法、材料应用、冲压成形性能分析、拼焊板成形极限图的建立方法和有限元分析焊缝建模方式进行了综述.针对我国汽车工业拼焊发展现状,提出了当前需要解决的主要问题.     

Influence of parameters on the microstructure of a duplex stainless steel joint welded by a GMAW welding process

Duplex stainless steels (DSSs) are widely used in industry for their desirable properties. Any fusion welding technique modifies the microstructure and, consequently, the properties of the material. This paper presents a parametric study of the variables that determine the energy contribution (current, voltage and welding speed) and the structural modifications produced during gas metal arc welding. The analysis comprises metallographic study, phase balance, dimensioning of the weld beads and tensile and hardness tests. The influence of the variables studied on the thermal cycles obtained (temperatures reached and cooling rate) was determined by using a finite element model. The results showed that, in addition to the indicated parameters, the parameter power transfer per volume (W/m³) and the geometry in the bead must be controlled due to their influence on the heat flow distribution and phase balance.