title: Micro-scale testing and micromechanical modelling for high cycle fatigue of CoCr stent material.
abstract: This paper presents a framework of experimental testing and crystal plasticity micromechanics for high cycle fatigue (HCF) of micro-scale L605 CoCr stent material. Micro-scale specimens, representative of stent struts, are manufactured via laser micro-machining and electro-polishing from biomedical grade CoCr alloy foil. Crystal plasticity models of the micro-specimens are developed using a length scale-dependent, strain-gradient constitutive model and a phenomenological (power-law) constitutive model, calibrated from monotonic and cyclic plasticity test data. Experimental microstructural characterisation of the grain morphology and precipitate distributions is used as input for the polycrystalline finite element (FE) morphologies. Two microstructure-sensitive fatigue indicator parameters are applied, using local and non-local (grain-averaged) implementations, for the phenomenological and length scale-dependent models, respectively, to predict fatigue crack initiation (FCI) in the HCF experiments.
authors: Mechanical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Ireland.
authors: C A
authors: CA
authors: Sweeney
authors: Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Ireland.
authors: B
authors: B
authors: O'Brien
authors: Department of Materials, Imperial College London, UK.
authors: F P E
authors: FP
authors: Dunne
authors: Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Ireland.
authors: P E
authors: PE
authors: McHugh
authors: Mechanical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Ireland. Electronic address: sean.leen@nuigalway.ie.
authors: S B
authors: SB
authors: Leen
mesh_terms: D000497:Alloys; D002857:Chromium / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D020342:Finite Element Analysis; D008422:Materials Testing; D055595:Mechanical Phenomena; D015607:Stents; D013314:Stress, Mechanical
chemical_list: D000497:Alloys; D002857:Chromium; D003035:Cobalt
keywords: CoCr alloy; Crystal plasticity; Finite element; High cycle fatigue