Biomechanical characterization of the passive response of the thoracic aorta in chronic hypoxic newborn lambs using an evolutionary strategy

Abstract

The present study involves experiments and modelling aimed at characterizing the passive structuralmechanical behavior of the chronic hypoxic lamb thoracic aorta, whose gestation, birth and postnatalperiod were carried at high altitude (3600 masl). To this end, the mechanical response was studiedvia tensile and pressurization tests. The tensile and pressurization tests measurements wereused simultaneously to calibrate the material parameters of the Gasser–Holzapfel–Ogden (GHO)hyperelasctic anisotropic constitutive model through an analytical-numerical optimization proceduresolved with an evolutionary strategy that guarantees a stable response of the model. The model andprocedure of calibration adequately adjust to the material behavior in a wide deformation rangewith an appropriate physical description. The results of this study predict the mechanical responseof the lamb thoracic aorta under generalized loading states like those that can occur in physiologicalconditions and/or in systemic arterial hypertension. Finally, the novel use of the evolutionary strategy,together with the set of experiments and tools used in this study, provide a robust alternative tovalidate biomechanical characterizations.