Thermal strain based Accurate prediction of thermal deformation generated by flame bending and line heating

초록

In this paper, we discuss the thermal-strain based method for accurately predicting the thermal deformation of the plate produced by flame bending (or line heating) in the shipbuilding process. Taking into account the equivalent loads assumed from both inherent strain and thermal strain, thermal deformation is predicted by the finite element analysis using shell elements. Magnitude of equivalent loads were estimated from the magnitude of inherent strain and thermal strain affected by the phase transformation of constitutive equation. The volume expansion of the martensite combined with the phase change of the heated material updated the magnitude of the inherent strain and the thermal strain during the heating process. While applying equivalent loads to elastic and elastic-plastic finite element analysis, this study analyzed the temperature distribution of the heated plate to investigate the inherent strain areas required for ELM (equivalent load method) and SDB (strains directly as boundary) method. It is shown that the finite element model of shell elements accompanied by both ELM and SDB method successfully predicts the thermal deformation within few seconds. In addition, the predicted deformed shape of the SBD method is in good agreement with that of the three-dimensional finite element model of the coupled thermo-structural solid element. The finite element model of shell elements using both ELM and SDB methods shows that thermal deformation can be successfully predicted within a few seconds.