Double curvature shells in ship building industries are primarily formed through line heating technique. Line heating, also known as flame bending involves heating of steel plates using heat sources like oxy-acetylene gas torch, laser, induction heating, etc. The differential expansion and contraction across the plate thickness causes plastic deformation and bending of plates. Line heating is a complex forming technique as the plastic deformation and bending depends on many factors such as peak temperature, heating and cooling rate, depth of heated zone and many other secondary factors. In the present study, a finite element model is developed for the thermo-mechanical analysis of line heating. A regression analysis is performed to study the effect of various parameters affecting the process. Temperature dependent properties are used in the analysis. A free-free boundary condition is modeled for structural analysis using spring elements in FEM code that helps in identifying the resultant shapes of various line heating patterns. The effect of cooling in line heating is studied by including distributed convective boundary condition in the FE model developed.
Keywords: plate forming, flame bending, ship building, FEM, numerical techniques, regression analysis, transient thermal analysis.