Doğrusal olmayan optimizasyon yöntemleriyle kan damarlarının ve cerrahi kondüitlerin malzeme özelliklerinin belirlenmesi

Vascular growth and remodeling during embryonic development is associated with blood flow and pressure induced stress distribution, in which residual strains and stresses play a central role. Residual strains are typically measured by performing in vitro tests on the excised vascular tissue. In this study, we investigated the possibility of estimating residual strains and stresses using physiological pressure-radius data obtained through in vivo noninvasive measurement techniques, such as optical coherence tomography or ultrasound modalities. As an application, vessel buckling occurs due to the mechanical instability in the structure of the material that is used as vascular conduit. Thus it is essential for surgeons to select appropriate buckling resistant materials for reconstructive surgeries. In this study, torsional buckling effect was examined on three different materials such as PTFE, Dacron and porcine pericardium, which are commonly used as vascular conduits, by using linear elastic model. In addition, nonlinear material properties of porcine pericardium and human pericardium were examined. Finally a mechanical perspective for the optimization of living organisms may provide an understanding of the variation in mechanical properties and sizes of biological tissues including cardiovascular vessels, bones and cartilage, subjected to physiological mechanical loading. Thus in this study we proposed two different approaches to reveal the possible optimization scenarios in which either material properties (remodeling) or sizes (growth) of the arterial wall alter in order to make the stress distribution uniform close to homeostatic stresses as much as possible while the blood pressure increases.