INTEGRATED FINITE-ELEMENT MODEL FOR TRANSIENT FLUID-FLOW AND THERMAL-STRESSES DURING CONTINUOUS-CASTING

A finite element computational methodology is presented for predicting the temperature distribution, fluid flow, and thermal stresses evolvi ng in a solidifying ingot, which itself is growing in length, during t he start-up phase of a continuous casting process, with a particular r eference to aluminum casting. The approach is based on the coupling of a thermal and flow model with a stress model. The thermal flow model is developed using a deforming finite element method with art Eulerian -Lagrangian transformation to account for the fact that the ingot itse lf is also growing at a prescribed casting speed. The stress model is developed also by the finite element method, with mechanical deformati ons in the solidifying materials described by a hypoelastic-viscoplast ic constitutive relation. The integrated model has been applied to stu dy the dynamic development of temperature, flow and stresses in the so lidifying ingot during the start-up phase for continuous casting of al uminum. The results show that the fluid flow and temperature distribut ion experience a rapid change at the initial stage but that the change slows down later in the process as it approaches to the steady state. Computed results compare reasonably well with experimental measuremen ts for temperature distributions in the ingot It is found that the the rmal stresses in general evolve from small to big in magnitude and fro m compressive to tensile in the solidifying ingot. The hoop stress is larger than other stress components, in particular in the outer surfac e region. The air gap formed between the ingot and the bottom block in creases initially and decreases afterward as a result of stress relaxa tion.