Experimental characterisation for micromechanical modelling of CoCr stent fatigue

Abstract Fatigue of CoCr alloy stents has become a major concern in recent times, owing to cases of premature fracture, often driven by microstructural phenomena. This work presents the development of a micromechanical framework for fatigue design, based on experimental characterisation of a biomedi...

Full description

Saved in:
Bibliographic Details
Published in:Biomaterials 2014-01, Vol.35 (1), p.36-48
Main Authors: Sweeney, Caoimhe A, O'Brien, Barry, McHugh, Peter E, Leen, Sean B
Format: Article
Language:English
Subjects:
Advanced Basic Science
Calibration
Chromium Alloys
Cobalt alloy
Dentistry
Fatigue
Finite Element Analysis
Materials Testing
Microstructure
Modelling
Models, Molecular
Stent
Stents
Tensile Strength
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Abstract Fatigue of CoCr alloy stents has become a major concern in recent times, owing to cases of premature fracture, often driven by microstructural phenomena. This work presents the development of a micromechanical framework for fatigue design, based on experimental characterisation of a biomedical grade CoCr alloy, including both microscopy and mechanical testing. Fatigue indicator parameters (FIPs) within the micromechanical framework are calibrated for the prediction of microstructure-sensitive fatigue crack initiation (FCI). A multi-scale CoCr stent model is developed, including a 3D global J2 continuum stent-artery model and a 2D micromechanical sub-model. Several microstructure realizations for the stent sub-model allow assessment of the effect of crystallographic orientations on stent fatigue crack initiation predictions. Predictions of FCI are compared with traditional Basquin-Goodman total life predictions, revealing more realistic scatter of data for the microstructure-based FIP approach. Comparison of stent predictions with performance of a 316L stent for the same generic design exposes the design as over-conservative for the CoCr alloy. In response, the micromechanical framework is used to modify the stent design for the CoCr alloy, improving design efficiency.
ISSN:0142-9612
1878-5905
DOI:10.1016/j.biomaterials.2013.09.087