Analysis of weld-induced residual stresses and distortions in thin-walled cylinders

Circumferential weld specifically in thin-walled structures is a common joint type in the fabrication of structural members in aerospace, aeronautical and pressure vessel industries. This type of weld joint suffers various types of weld-induced residual stress fields (hoop and axial) and deformation patterns (axial shrinkage, radial shrinkage). These imperfections have negative effects on fabrication accuracies and result in low strength welded structures that can lead to premature failures. To precisely capture the distortions and residual stresses, computational methodology based on three-dimensional finite element model for the simulation of gas tungsten arc welding in thin-walled cylinders is presented. Butt-weld geometry with single “V” for a 300 mm outer diameter cylinder of 3 mm thick is used. The complex phenomenon of arc welding is numerically solved by sequentially coupled transient, non-linear thermo-mechanical analysis. The accuracy of both the thermal and structural models is validated through experiments for temperature distribution, residual stresses and distortion. The simulated result shows close correlation with the experimental measurements. This paper was recommended for publication in revised form by Associate Editor Dae-Eun Kim Naeem Ullah Dar received the B.Sc. and M.S. degrees in mechanical engineering from the Univer-sity of Engineering & Technology, Taxila, in 1989 and 2004 respectively. Presently, he is PhD scholar in mechanical engineering at UET, Taxila. His publications are over 25 in different Int. journals and conferences. His research includes manufacturing process (GTAW welding process, HSM process, abrasive waterjet process, incremental forming etc), welding simulations, optimization, and expert system. He spent more than 16 years in different mechanical manufacturing fields. He also received MBA degree in project management and six sigma black belt from SQII in 2005. Ejaz M. Qureshi is currently a graduate student working for his PhD in computational weld mechanics at National University of Sciences and Technology (Pakistan). After receiving his B.S. degree in Mechanical Engineering in 1997, he worked for five years in an industrial manufacturing setup producing hi-tech welded structures. Qureshi has published numerous technical papers in professional refereed journals and conferences of international repute. He has also been an active referee for several conferences and journals. His current research interests include: manufacturing processes simulation, structural integrity of welded structures and computational plasticity of cylinders/pressure vessels. M.M.I. Hammouda received the B.Sc. and M.Sc. degrees in mechanical engineering from Al Azhar University, Cairo, Egypt in 1970 and 1975 respectively. He received his PhD degree in mechanical engineering from Cambridge University, England in 1978. His has more than 35 publications in different International journals and conferences. The research includes mechanical behavior of engineering materials, linear elastic and elastic-plastic fracture mechanics, manufacturing process modeling and simulations. Presently being a foreign faculty professor in mechanical engineering department of UET, Taxila, Pakistan, he spent more than 25 years in academic and teaching. He is a member of the Editorial Board of the International Journal of Fatigue and Fracture of Engineering Materials and Structures. www.blackwell-science.com].