点焊机器人焊接系统

本文介绍用于点焊机器人的焊接系统的基本硬件结构,工作原理及系统的主要功能和特点。     

B 炸药中绝热剪切带形成机理的细观研究

通过对快速加载后Ｃｏｍｐ．药柱剖面的扫描电镜和光学显微镜观察分析，对Ｃｏｍｐ．Ｂ炸药在快速加载下剪切带形成机理的微观机制有了初步的认识。文中采用形变试样的剖面观察分析方法，针对固体药柱这种比较软的材料，如何进行磨样、抛光、浸蚀，作了一些尝试和探索，总结出一套有效的实施办法。对不同加载速率条件下受压缩的药柱中细观组织进行了观察、分析、比较，首次给出国产Ｃｏｍｐ．Ｂ炸药装药的原始细观组织形貌，以及快速加载后药柱中细观组织形貌。经过分析，得到冲击载荷下炸药装药中绝热剪切带形成、发展的定性认识，为分析Ｃｏｍｐ．Ｂ炸药装药受冲击载荷时热点形成机理提供了一些有益的实验依据。     

一种改进的激光光斑中心检测算法在路基沉降测量中的实现

通过检测激光光斑中心位置偏移的方法来监测路基沉降,是一种便携易布设的方法。而激光光斑中心的检测可以使用重心法、圆拟合、椭圆拟合、高斯曲面拟合。采用重心法运算简单精度低,而采用拟合法精度更高,由于光轴与靶面间存在夹角,光斑更近似看作一椭圆,应用椭圆拟合,辅之以亚像素精度分割,Canny边缘提取后获得了较为理想的沉降监测精度。     

多程序点焊控制器的研制

本文主要介绍了多程序点焊控制箱的程序过程以及主控制器及调制器的工作原理，并采用了一种新型的触发电路代替传统的脉冲变压器，具有触发可靠、大功率、高精度、电路简单等特点。     

Sub-wavelength resolution in air-coupled ultrasound images of spot welds

Resistance spot welds joining steel sheets were examined using air-coupled ultrasound at 1 MHz. Transmission C-scan images were obtained using two axially aligned transducers, with each focused on its adjacent surface of the specimen. Because of the enormous impedance mismatch between air and steel, the transmitted signal was exceedingly weak, requiring several hours to collect an image. Although the air-coupled images resembled the weld shapes as determined by an independent technique, surface topography introduced considerable image distortion. The smearing of the images was substantially less than the 5.9-mm wavelength in steel, with the steepness of the transition between welded and unwelded areas indicating a transverse resolution about 1 mm. Similarities to near-field imaging are mentioned as a possible explanation for the observed sub-wavelength resolution.     

Inventory models for multi-warehouse systems under fixed and flexible space leasing contracts

In this paper, we analyze a practical situation in which an inventory manager is faced with several options to store excess stocks whenever the storage capacity of his/her warehouse is insufficient. The manager can choose from either storage space providers through fixed long term or flexible leasing contracts, or the manager can acquire the extra required space from the spot market. We formulate this inventory problem with multiple storage facilities as a nonlinear program and show that it has a global optimal solution. We then provide closed-form solutions for the optimal ordering quantity and leased spot market space depending on the value of the unconstrained economic order quantity. In addition, we develop some structural properties for the optimal ordering policy and include several examples to illustrate the formulated models.     

Modeling of failure near spot welds in lap-shear specimens based on a plane stress rigid inclusion analysis

In this paper, the failure mechanism of resistance spot welds in dual-phase steel lap-shear specimens is investigated based on experimental observations, two-dimensional elasticity theories and two-dimensional finite element analyses. Optical micrographs of the cross sections of spot welds in lap-shear specimens of a dual-phase steel before and after failure are first examined to understand the failure mechanism. The experimental results suggest that under lap-shear loading conditions, a necking failure is initiated near the middle of the nugget circumference in the base metal and then the failure propagates along the nugget circumference in the sheet to final fracture. Based on the stress function approach of the elasticity theory, an analytic solution for an infinite plate containing a rigid inclusion subjected to a resultant shear force is developed and used to investigate the stress and strain distributions near the nugget in lap-shear specimens. The results of the elastic analytic solution and those of a two-dimensional elastic finite element analysis indicate that the initial yielding starts on the two side edges of the inclusion in the sheet. However, the results of a two-dimensional elastic-plastic finite element analysis indicate that as the applied displacement increases, the maximum equivalent plastic strain shifts from the two side edges of the inclusion to the middle of the inclusion along the inclusion circumference in the sheet. The computational results suggest that the location of the initial necking failure should occur near the middle of the nugget circumference in the sheet as observed in experiments based on the forming limit diagram (FLD) for ductile sheet metals.     

高合金不锈钢在降膜板式蒸发器上的应用

外流降膜板式蒸发器作为替代列管式蒸发器的新设备应用于氧化铝行业,其板片材质处于一个摸索选择的过程。本文就高合金不锈钢板片的失败事例进行分析,通过试验、试用,最终找到较为理想的材质。     

BFe30-1-1白铜管早期腐蚀失效原因分析

某电厂凝汽器BFe30-1-1白铜管投运后几年内出现较为严重的局部腐蚀和点腐蚀，为此，对材质、水质等诸多因素进行了分析研究，通过宏观、微观检查和电化学试验，认为是微生物及生物粘泥的附着引起了铜管的早期腐蚀失效。