Finite Element Calculation about Stress Concentration Coefficient of Welded Butt Joints of Magnesium Alloy

Geometrical parameters of welded joint affect the stress concentration coefficient seriously. In order to increase the fatigue property of welded structure, it has great significance to reduce stress concentration coefficient of welded structures by researching and improving the geometry of welded joints. In this paper, the effects of weld toe inclination angle θ and weld edge transition arc radius r on the stress concentration coefficient of welded butt joints of magnesium alloy were analyzed by using ABAQUS finite element program, and the change rule of stress concentration coefficient with the variation of the two parameters was also researched. The calculation results indicate that reducing weld toe inclination angle or increasing transition arc radius can effectively decrease the stress concentration coefficient of welded butt joints, so as to improve the fatigue property of welded structures. For the safe use of welded structures, the true weld edge transition arc radius r should be greater than 3mm, and weld toe inclination angle θ should be smaller than 30°.

Finite Element Calculation about Stress Concentration Coefficient of Welded Butt Joints Based on the ABAQUS

Stress concentration coefficient of welded joints has a crucial influence on mechanical properties of welded structures. Geometrical parameters of welded joints seriously affect the stress concentration coefficient. In order to increase the mechanical properties and using safety of welded structures, it has great significance for reducing stress concentration coefficient and improving the mechanical properties of welded structures by researching and improving the geometry of welded joints . In this paper, the effect of weld toe inclination angle θ and weld edge transition arc radius r on the stress concentration coefficient of welded butt joints were analyzed by using ABAQUS finite element program, and the change rule of stress concentration coefficient with the variation of the two parameters was also researched. The calculation results indicate that reducing weld toe inclination angle or increasing transition arc radius can effectively decrease the stress concentration coefficient of welded butt joints, so as to improve the mechanical properties of welded structures. For the safe use of welded structures, the true weld edge transition arc radius r should be greater than 3mm, and weld toe inclination angle θ should be smaller than 30°.

Visual Technique for Detecting Weld Position Based on Hough Transformation

Detecting the weld position is the precondition of seam tracking during an arc welding process, and is crucial to achieve high-quality welds. Visual sensing is one of the most attractive approaches to detect the weld position, which provides valuable information to control the arc following the expected path. The weld edge is main characteristics of the weld position image, here the visual technique for detecting the weld position based on Hough transformation is proposed. The weld position can be detected and recognized through Hough transformation, while the weld edge image is detected using the Canny operators. And Hough transformation is modified based on the actual weld situation. Therefore, the precision of the weld detection can be improved. From the analysis of experiments, it has been proved that the proposed method can detect the width and the center of the weld, and is suitable for the seam tracking system based on the computer vision.

Linear Friction Welding of Ti-6Al-4V Alloy: Microstructure Characterization

Ti-6Al-4V was successfully jointed by linear friction welding (LFW). A sound weld of thickness of 65-115 $m was obtained under the present conditions. The weld consisted of the superfine α+β structure, which is associated with the rapid heating and cooling processes involved in LFW. The thermomechanically affected zone (TMAZ) was limited and comprised of the severely deformed α and β grains. In the flash, a gradual microstructure was formed from the weld edge to the flash edge. A martensite structure (α’) was formed besides the acicular α+β in the flash edge owing to the fast cooling rate.