Welding Literature Review

Literature review

A number of researchers have tried theoretically or experimentally the ways to predict the welding distortions and welding residual stresses. Some of them have also tried to predict the thermal and mechanical responses of welding structure in practice industrial production.

Two dimensional non linear transient welding simulations with three dimensional structural analyses in a decoupled approach. Using two dimensional thermo mechanical welding process simulations for determining the temperature loading for a three dimensional structural model determine buckling distortion after welding in large and complex structures. The simplified FEM to simulate out of plane distortion caused by fusion butt welding; he replaced the thermal

Weld quality is dependent on arc stability and minimizing the effects of disturbances or changes in the operating condition commonly occurring during the welding process. In order to minimize these effects, a controller can be used. Fuzzy controller was used in order to stabilize the arc during CO2 welding. The control rules of the fuzzy controller were formed using the authors’ experience and knowledge of the welding process. The control parameters to be tuned were the membership functions. Therefore, the controller’s performance depended on the membership functions. The Taguchi parameter design, which makes the control performance insensitive to the operating condition changes and noise, was used to determine the membership functions. He found smaller the mita index value the more stable the arc became, the welding voltage which minimized the Mita index should be determined to find the welding voltage value online, which maintained the stable arc state or minimized the Mita index, the fuzzy controller was used. The L9 (34) orthogonal array was used in Fuzzy

Murugan et.al[1]studied the effects of the process parameters on the angular distortion, he states that ‘α’ decreases with the increase in‘t’ where ‘α’ is angular distortion and‘t’ is time between the successive passes. The angular distortion is more when t is shorter, because more bead width provides more contraction in the top of the bead. When t is longer, a larger amount of heat is lost by the plate and the temperature is lower compared to when t is shorter, so the amount of angular distortion is less. The angular distortion α increases with the increase in N. Generally, in an unrestrained joint, the degree of angular distortion is approximately proportional to the number of passes. The slope of the curve decreases with the increase in N. In multipass welds, previously deposited weld metal provides restraint, so the angular distortion per pass decreases as the weld is built up. Similarly the angular distortion a decreases with the increase in wire feed rate F.As the wire feed rate increases the welding speed has also to be increased to maintain the volume of material in the v groove of welded