Arc welding process is widely used for fabricated thin structures in aerospace, shipyard, etc. Welding deformation is undesirable owing to the decrease in buckling strength and injures the beautiful appearance of structures. In addition, it causes errors during the assembly which result in more rework and productivity restriction. Welding deformation is complicated in real structure and is difficult to control. In the present study, numerical simulation by applying finite element has been performed using ANSYS to predict residual stress and cambering distortion in welded titanium alloy sheet. Furthermore, attempt was made to eliminate this distortion by applying dynamic spot cooling source technique behind the welding torch. The computed result revealed that the cambering could be eliminated under proper control of the parameters of this technique, such as the distance between the two sources. Transient residual stress through the thickness exhibit different behaviour and magnitude from that in conventional welding, and its cost is minimised by such technique. Explanation of this minimising mechanism was discussed.

No abstract

Many techniques were developed to control residual stress and distortion during welding process to minimizes their magnitude in the affected area. Due to complicity to find qualitative analysis for welding residual stress and distortion in real experiment work, the numerical simulation of welding process give a good solution to helpful the process and evaluated extensive analysis. In the present paper two different residual stress mitigation techniques moving cooling spot and moving heating spot were investigated in thin welded sheet structure using FEA. Thermo mechanical analysis and simulation of the processes were performed by ANSYS. The obtained results show different residual stresses behaviour developed during welding, the residual stress magnitude were minimized in both used techniques especially in trailing heat sink welding process. The out of plane distortion results show successfully eliminating of cambering distortion, it is also found that the effective elimination are based on the proper position parameters with respect to the welding heat source.

No abstract

The trend in automotive, aircraft, and marine industries is the increasing use of sheet materials to reduce weight in components and optimize materials performance. Welding is the main fabrication and assembly process in many of these industrial applications. However, in using thin-shell structures in such applications, welding may results in significant residual stresses and out-of-plane distortion. Transient thermal stresses, residual stresses, and distortion sometimes cause cracking and mismatching of joints. High tensile residual stresses are undesirable since they can contribute to fatigue failure. The analysis and measurement of temperature and stresses in component are often too complex to conduct in practise, and thus finite element models provide feasible approach to examine these matters. In this paper, finite element analysis has been performed using the ANSYS package to study the behaviour of longitudinal residual stress and strain in a welded thin aluminium-manganese alloy. The model presented simulates conventional welding and welding with the introduction of welding mitigation technique for enhancement of heat transfer, in which a trailing heat sink was applied. The thermal profiles obtained using the mitigation technique is completely different from those obtained in the conventional cooling. The localized transient residual stress and through-thickness strain after applying a cooling sink are discussed. The transient residual stress behaviour was highly affected by the modified temperature distribution and magnitude due to introducing the heat transfer enhancement.