On the consistency of finite element models in thermoelastic analysis Original Research Article

In thermoelastic analysis, compatible finite elements may predict oscillating stresses if the temperature distribution is not coherent with the element strain coming from the assumed displacement approximation. Modelling the stress field as an independent variable could be a viable alternative to avoid these spurious outcomes. To this purpose, the behavior of mixed, hybrid stress and equilibrium finite element models in the presence of initial strains due to temperature is investigated and compared with the usually employed displacement approach. The consistency requirement for each model is established and the spurious outcomes due to inconsistent temperature fields are discussed, examining also the effects of element geometry distortions. The analysis, illustrated through some numerical tests, shows that a direct approximation for the stress field can eliminate, or at least reduce, the generation of spurious stress modes, although this is not a priori guaranteed by a mixed approach.