The Development of In-Process Monitoring and Control Techniques for Aerospace Applications of Friction Stir Welding

Abstract

Research presented in this dissertation focuses on the utilization of Friction Stir Welding (FSW) as a primary joining technology for the manufacture of lightweight structures in the aerospace industry. While FSW is beginning to be utilized for production aircraft assemblies, it remains in its relative infancy as a rivet replacement technology. Significant progress has been required regarding a number of technical issues. Here, advancements are presented in the areas of in-process quality evaluation of faying surface sealants, wherein the welding process itself becomes a diagnostic tool to determine sealant condition, automatic joint tracking, in which sealant force signature is exploited to enable simplified path planning, process variant utilization, which is explored by way of joining an advanced, candidate alloy for aerospace with non-traditional tools and parameters, and tool wear, which is proposed to be monitored by an adaptive torque controller featuring the capability to estimate an ever changing tool profile.