Distortion of welded structures using a simple method for prediction of weld induced shrinkage volume method

Abstract

Post-weld distortion is an inherent dilemma associated with all welded structures. Past industrial control has relied significantly on the knowledge attained through experience within similar structures, along with simple empirical formulae. Most welded structures are too complex for the simple empirical formulae to be applicable, and therefore, post-weld rectification is often uncontrolled, with great cost. The use of computer simulative Finite Element Analysis has the potential to significantly decrease the cost of manufacturing of welded structures, with relative distortion known in advance of actual welding commencement. This research presents a simple affordable method for the prediction of weld-induced distortion called the “Shrinkage Volume Method.” The Shrinkage Volume Method presumes that the overall distortion is created through the driving force produced by the thermal contraction of a simple shrinkage volume within the weld zone. This simplified approach drastically reduces the computational time required to produce an accurate solution, and hence increases its ability to be adopted within industry, as solutions can be developed within industrial timeframes with minimal cost. Low-cost Finite Element Analysis software named Strand7 ™ is used in this investigation. The introduction of a new prediction tool requires validation and verification through experimental investigation, and accordingly, an experimental test rig has been constructed that can test specimens identical to those being modeled. Calibration of the numerical method for a continuous butt-weld demonstrates that apart from some small, however steady inconsistencies, this method generates reasonably accurate solutions for the required, restraining force with a minimum of computational resources. This investigation shows that reasonably accurate predictions can be made within industrial budgets and timeframes for the distortion of welded structures. After understanding the methodology behind the modeling of the structure, new investigations can be completed within minimal time constraints.