Biography
Liguo Zhao
Loughborough University, UK
Modelling of Time-Dependent Mechanical Behaviour of Poly (lactic-acid) and Poly (butylene succinate) Blends for Stent Application
Abstract:
The preparation of Poly (lactic-acid) (PLA) and Poly (butylene succinate) (PBS) blends, with various PLA/PBS weight ratios, was achieved by melting and mixing technique at high temperature. Small dog-bone specimens, produced by compression moulding, were used to test mechanical properties under uniaxial tension. The elongation of PLA/PBS blends increased with the increase of PBS content, but with a compromise of tensile modulus and strength. An increase of strain rate led to enhanced stress response, demonstrating the time-dependent deformation nature of the material. Moreover, an advanced viscoplastic model with nonlinear hardening variables was applied to simulate rate-dependent deformation of PLA/PBS blends, with model parameters calibrated simultaneously against the tensile test data. Model simulations compared well with experimental results.The viscoplastic model was further applied to simulate crimping and deployment ofscaffold in a diseased artery using the finite element method, focusing on the time-dependent deformation behaviour of the scaffold. Stress relaxation over time was particularly investigated for the whole scaffold-artery system following scaffold implantation.
Biography:
Zhao is currently a Professor in Solid Mechanics at Wolfson School of Mechanical, Electrical and Manufacturing Engineering of Loughborough University (UK, since 2012). Prior to this, he had been working as a senior lecturer at University of Portsmouth (UK, 2005~2012) and postdoctoral research associate/fellow in some of the top UK universities (Cambridge, Imperial College and Nottingham, 1997~2005). He holds a PhD in Solid Mechanics (1996) and a BEng in applied mechanics (1992), awarded by Xi’an Jiaotong University, one of the top and prestigious universities of China. Since 1999, Dr Zhao has been continuously working on Structural Integrity of gas turbine engines, focusing on deformation, facture, fatigue, creep, crack initiation and growth in nickel-based superalloys. In this high-impact area, he has secured, as lead/principal investigators, three large multi-institutional EPSRC grants, totalling 2.2 million pounds.In particular, Dr Zhao has been successful in developing new research in the area of Biomechanics, out of a PhD research program in 2012 and with recent publications in Materials Science and Engineering C and Journal of Biomechanics.The development opened up an opportunity for him to collaborate with Abbott Vascular, a world-leading stent-manufacturing company in USA, via research projects funded by the company. Also recently, he has been awarded a three-year new grant in this area by the British Heart Foundation, in collaboration with both Abbott USA and Lucideon UK.