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Modeling of Size Dependent Failure in Cardiovascular Stent Struts under Tension and Bending

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Abstract

Cardiovascular stents are cylindrical mesh-like metallic structures that are used to treat atherosclerosis. The thickness of stent struts are typically in the range of 50–150 μm. At this microscopic size scale, the tensile failure strain has been shown to be size dependent. Micromechanically representative computational models have captured this size effect in tension. In this paper polycrystalline models incorporating material fracture are used to investigate size effects for realistic stent strut geometries and loading modes. The specific loading a stent undergoes during deployment is uniquely captured and the implications for stent design are considered. Fracture analysis is also performed, identifying trends in terms of strut thickness and loading type. The results show, in addition to the size effect in tension, further size effects in different loading conditions. The results of the loading analyses are combined to produce a tension and bending failure graph. This design safety diagram is presented as a tool to predict failure of stent struts. This study is particularly significant given the current interest in producing smaller stents.

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Acknowledgments

The authors wish to acknowledge funding from Embark, Irish Research Council for Science, Engineering and Technology: Funded by the National Development Plan and the SFI/HEA Irish Centre for High-End Computing (ICHEC) for the provision of computational facilities and support. The authors wish to thank Mr. P. Savage and Dr. J. P. McGarry for input and assistance. The simulations in this work were performed on the SGI Altix 3700 high performance computer at NUI, Galway and the Bull NovaScale 6320 at ICHEC.

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  1. Department of Mechanical and Biomedical Engineering, National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Ireland

    F. J. Harewood & P. E. McHugh

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Correspondence to P. E. McHugh.

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Harewood, F., McHugh, P. Modeling of Size Dependent Failure in Cardiovascular Stent Struts under Tension and Bending. Ann Biomed Eng 35, 1539–1553 (2007). https://doi.org/10.1007/s10439-007-9326-6

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