Prediction of thermal buckling in sheet metal structures based on finite element modeling and its experimental verification

Abstract

This paper introduces a methodology to model the thermal buckling based on a finite element method and to predict the critical temperature of the sheet metal structures. For the modeling, the spot-welded column that consists of a hat-shaped thin panel and a flat thick plate was considered. When thermal strain is constrained, compressive stress is generated in the column and buckling occurs when the stress exceeds its critical value. The commercial software (ABAQUS/Standard) was used to conduct finite element analysis. To simulate the thermomechanical process, heat transfer analysis and mechanical analysis were sequentially coupled. The transient nodal temperature output was imported to the nonlinear buckling analysis. Unlike mechanical buckling, an explicit axial shortening of the structures cannot be measured in thermal buckling. Therefore, it is difficult to investigate the relationship between force and displacement and to predict the critical temperature. Instead, out-of-plane displacement of the surface was observed to determine its relationship with the reaction force and temperature. Also, determination methods of onset of buckling were also investigated to obtain the accurate critical temperature of structures. To validate the predictions, the column specimens were fabricated and experimental verification was conducted with the universal testing machine and the Infrared (IR) heater. In addition, imperfections in the testing system were added to the finite element model. Reaction force, transient temperature, and out-of-plane displacement were compared and the differences between the simulation and the experiment were discussed.