THERMAL-STRESSES IN A FREEZING SPHERE AND ITS APPLICATION TO CRYOBIOLOGY

Thermal stresses in an inwardly solidifying sphere are studied analyti cally. A closed-form solution is given which accounts for thermal expa nsion associated with temperature gradients and volume changes associa ted with phase transition. Consistent with the target application of c ryopreservation of biological solutions and tissues the material is mo deled as elastic-perfectly plastic. Parametric studies using appropria te material properties and typical cryopreservation protocols suggest that strains associated with phase transition lead to far higher stres ses than those associated with thermal expansion, with important impli cations for cryopreservation procedures.