Peer-Reviewed Journal Details
Mandatory Fields
Sweeney, C.A., O'Brien, B., McHugh, P.E., Leen, S.B.
Experimental characterisation for micromechanical modelling of CoCr stent fatigue.
Optional Fields
Fatigue Cobalt alloy Stent Microstructure Modelling
Fatigue of CoCr alloy stents has become a major concern in recent times, owing to cases of prematurefracture, often driven by microstructural phenomena. This work presents the development of a micro- mechanical 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. Com- parison 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.
Grant Details
EMBARK and New Foundations Schemes
Publication Themes