Numerical simulation of thermo-mechanical problems by coupling ABAQUS® and FLUENT®

Abstract

The type of thermo-mechanical problem studied in this article is such that the thermal evolution of the problem affects the stress response, but the temperature field does not depend on the stress field. Consequently, the temperature history can be calculated in an uncoupled thermal analysis and, afterwards, introduced as a predefined field in the stress/displacement analysis. The software ABAQUS® has this capability but is quite limited when pretending to define a realistic thermal model. FLUENT® is used worldwide for robust simulation, visualization and analysis of fluid flow and heat transfer, with a wide capability for defining the thermodynamic characteristics of the processes. As a result more realistic thermal models can be accomplished using FLUENT®. The problem studied here was the cooling of a grooved rail (Ri60) in a cooling bed. These rails have constant cross-sectional geometries but different parts of the cross-sections have different thickness. Such asymmetry leads to non-uniform cooling and development of thermal stresses, which may be higher than the yield stress of the material at high temperatures. The situation leads to bending of the rail and development of residual stresses. Through the development of a Finite Element (FE) thermal-model in FLUENT® we could obtain more accurate temperature history of each rail’s nodes. Subsequently, these results were introduced into the FE-stressmodel created in ABAQUS®, to calculate the rail’s stresses and deformations. This procedure is called sequentially coupled thermal-stress analysis. Nevertheless, in doing so, we faced the need of communication between FLUENT® and ABAQUS®. To make it possible we developed a results-conversion-program (named ‘conv_flu_abq’), using Linux shell programming (using scripts awk); R® (GNU software) and C programming. Using these tools, the conversion code had time and memory efficient execution. The development and structure of the code is presented. The code was tested successfully and the results are also provided.