An improved numerical model of the tube-tubesheet joint rolling process

The focus of this paper is the numerical modeling of the mechanical tube expansion process, called roller expansion, used in tube to tubesheet joints in heat exchangers. The paper compares a novel finite element based model with previously used models. The numerical models are compared with an experiment where optical measurement techniques are used to measure the actual wall thinning of the tube after roller expansion. In addition to the geometrical comparison the evolution of the grain structure of the tube before and after expansion is used to validate the hardening distribution in the numerical models. These methods provide enough information about the expanded joint to come to the conclusion that the novel method is superior to the existing models at describing the mechanical rolling process