Sasan Khalaj

Grade:  Ph.D.

Ph.D. Thesis:

Numerical and Experimental Investigation of Biodegradable Polymeric stents

Year: Sept. 2013 -Feb. 2021.

Abstract:

Biodegradable endovascular stents have been claimed to be reliable candidates for implantation devices used in treating cardiovascular diseases. In this study, an experimental investigation is conducted on mechanical characteristics of poly (lactic acid) (PLA), before and during degradation for stent application. A bioreactor is designed and fabricated to mimic in-vivo environment of the body for studying degradation behavior of PLA fibers. Moreover, it is aimed in this study to investigate the effect of geometrical parameters on the degradation behavior of PLA stents in terms of strut fracture and fragment separation. In this regard, various structural geometry of the PLA stents was simulated in a stenosed artery using finite element method. For predicting the PLA degradation, a computational model was prepared by which the influence of stents design on their radial strength and fracture was investigated. The decreasing trend of Young's modulus, variations in residual stress value after relaxation and pattern of stress relaxation are found during degradation. The simulation results indicated that the smooth design leads to uniform degradation in the whole stent and decreases the danger of stent fragments separation. This study provides useful information on PLA properties during degradation to assess the material in context of degradable stents.

Keywords: Biodegradable stent, Poly (lactic acid), Structural geometry, Degradation.