PRESENTATION BY
Dr Patrick McGarry
National University of Ireland, Galway

PRESENTATION TITLE
Understanding the Mechanical Behaviour of Biological Materials – From Single Cells to Bone Biomechanics

ABSTRACT
This presentation will focus primarily on the areas of cell biomechanics and orthopaedic biomechanics and will also include a brief overview of Dr McGarry’s research in the area of cardiovascular biomechanics.
 
Cell Biomechanics:  Numerous in-vitro studies have established that biological cells react to their physical environment and to externally applied mechanical loading. However, the mechanisms underlying such phenomena are poorly understood. Previous models consider the cell as a passive homogenous material, requiring an artificial increase in the stiffness of spread cells to replicate experimental measurement. In this presentation the development and implementation of an active constitutive formulation that predicts the distribution, remodelling and contractile behaviour of the cytoskeleton is described. The modelling framework is used to investigate:  (i) the role of substrate elasticity on the spreading and adhesion of cells; (ii) the contractile response of cells to cyclic stretching; (iii) the response of contractile cells to externally applied compression and shear.

Orthopaedic Biomechanics:  The multi-axial inelastic behaviour of trabecular bone is investigated at a micro-scale and macro-scale level.  It is demonstrated that trabecular bone deforms plastically under uniaxial, confined and hydrostatic compression. Vertebral device subsidence experiments are also performed, providing measurements of the trabecular plastic zone. It is demonstrated that a pressure-dependent plasticity formulation must be used for continuum level macro-scale models of trabecular bone in order to replicate the experimental observations. In addition to the study of bone plasticity, an anisotropic damage initiation criterion is developed for extended finite element method (XFEM) prediction of crack initiation and propagation in cortical bone. This anisotropic damage model is shown to accurately predict the dependence of crack propagation patterns and fracture toughness on mode mixity and on osteon orientation.

ABOUT THE PRESENTER
Patrick McGarry has been a Lecturer in Biomedical Engineering at the College of Engineering and Informatics at the National University of Ireland, Galway since 2006.  Prior to his current appointment Dr McGarry worked as a postdoctoral researcher at the University of California Santa Barbara and at the National Centre for Biomedical Engineering Science, National University of Ireland, Galway. He has published 35 journal papers in the fields of solid mechanics and biomechanics. He has supervised seven PhD students to completion. His research group has received several prestigious international and national awards in the field of biomedical engineering.

REFRESHMENTS WILL BE PROVIDED AT 11h45
For further information, please contact:
Professor Noel O’Dowd, Tel. No: (061) 202545 or Email: noel.odowd@ul.ie