Chapter 13 Joining Sheets to Tubular Profiles by Tube Forming .......................................................................... 319 Luis M. M. Alves, Instituto Superior Tecnico, Technical University of Lisbon, Portugal Paulo A. F. Martins, Instituto Superior Tecnico, Technical University of Lisbon, Portugal This chapter presents an innovative forming process for joining sheet panels to tubular profiles at room temperature. Finite element analysis and experimentation are utilized to understand the deformation mechanics of the process, to identify the operational feasibility window, and to discuss the capabilities across the useful range of working conditions. The feasibility of the proposed joining process is demon- strated by presenting conceptual applications and industrial prototypes comprising a seat-back bottom frame and an automotive hand-brake system. Results show that joining sheets to tubular profiles by means of tube forming can successfully replace conventional joining technologies based on mechanical fixing with fasteners, welding, or structural adhesive bonding. Chapter 14 Modeling and Optimization of Gas Metal Arc Welding (GMAW) Process ....................................... 339 R. Venkata Rao, Sardar Vallabhbhai National Institute of Technology (SV NIT), India Weld quality is greatly affected by the operating process parameters in the gas metal arc welding (GMAW) process. The quality of the welded material can be evaluated by many characteristics, such as bead geometric parameters, deposition efficiency, weld strength, weld distortion, et cetera. These characteristics are controlled by a number of welding process parameters, and it is important to set up proper process parameters to attain good quality. Various optimization methods can be applied to define the desired process output parameters through developing mathematical models to specify the relation- ship between the input parameters and output parameters. The method capable of accurate prediction of welding process output parameters would be valuable for rapid development of welding procedures and for developing control algorithms in automated welding applications. This chapter presents the