The common commercial charge coupled device (CCD) camera is combined with a composite light filter to form a vision sensing system of low cost. It can capture the whole image of a weld pool clearly during constant-current gas tungsten arc welding (GTAW). Based on the imageprocessing algorithm, the edges of the weld pool under different welding conditions can be extracted. Calibration is made to...

Weld residual stresses often approach, or exceed, the yield strength of the material, with serious implications for the integrity of engineering structures. It is not always feasible to measure residual stresses, so integrity assessments often rely heavily on numerical models. In ferritic steels, the credibility of such models depends on their ability to account for solid-state phase transforma...

Observing the weld pool and measuring its geometrical parameters are important issues for automated and robotic welding, wherein the visual detection and localization of weld pool are critical steps. Previous methods of visual measurement of weld pool usually assume that the weld pool exists in a predefined area, and its contour should be a specific geometric shape and size. Furthermore, previo...

A substantially successful technology that has emerged is the use of electro-optics, which has been expanded into the realm of ‘machine vision’ with the rapid advance in optical sensor technology and computer processing power. The basic principle of the optical sensor has remained unchanged over the years. Charge-Coupled Devices (CCDs), laser diodes and microprocessors form the basis of this ty...

An innovative laser-vision-based sensing method is proposed to measure weld pool oscillation frequency in pulsed gas tungsten arc welding (GTAW-P). A low-power five-line laser pattern is projected onto the entire weld pool surface as well as its reflection is intercepted by an imaging plane and captured by a high-speed camera. By observing and analyzing the change of the captured laser images d...

The authors of this experimental research work have made an attempt to experimentally investigate the ultimate flexural load of ferrocement slabs of size 700mm. X 200mm. X 15mm. (thickness) reinforced with PVC coated steel weld mesh, and compare the results with slabs using GI-coated steel weld mesh, by varying the number of layers from 1-3. Ordinary Portland Cement, locally available river san...

Evaluation of residual stress in the weld toe region is of critical importance. In this paper, the residual stress distribution both near the surface and in depth around the weld toe was investigated using neutron diffraction, complemented with X-ray diffraction. Measurements were done on a 1300 MPa yield strength steel welded using a Low Transformation Temperature (LTT) consumable. Near surfac...

-S 169 WELDING JOURNAL ABSTRACT. A 3-D transient numerical model was developed for simulation of gas metal arc (GMA) weld pools with free surface and droplet impact effects. This effort predicted a moving GMA weld pool by considering not only the heat transfer and fluid flow driven by surface tension gradient, electromagnetic force, buoyancy, and arc pressure, but also detailed information abou...

Girth weld cracking is one of the main failure modes in oil and gas pipelines; girth weld cracking inspection has great economic and social significance for the intrinsic safety of pipelines. This paper introduces the typical girth weld defects of oil and gas pipelines and the common nondestructive testing methods, and systematically generalizes the progress in the studies on technical principl...

Laser-based ultrasonic (LBU) measurement shows great promise for on-line monitoring of weld quality in tailor-welded blanks. Tailor-welded blanks are steel blanks made from plates of differing thickness and/or properties butt-welded together; they are used in automobile manufacturing to produce body, frame, and closure panels. LBU uses a pulsed laser to generate the ultrasound and a continuous ...