The National Centre for Prosthetics and Orthotics, University of Strathclyde, 131 St. James Road, Glasgow, G4 0LS, UK.
J Mech Behav Biomed Mater. 2011 Apr;4(3):261-8. doi: 10.1016/j.jmbbm.2010.10.004. Epub 2010 Oct 17.
Nitinol, a nickel titanium alloy, is widely used as a biocompatible metal with applications in high strain medical devices. The alloy exhibits both superelasticity and thermal shape memory behaviour. Basic mechanical properties can be established and are provided by suppliers; however the true stress-strain response under repeated load is not fully understood. It is essential to know this behaviour in order to design devices where failure by fatigue may be possible. The present work develops an approach for characterising the time varying mechanical properties of fine Nitinol wire and investigates processing factors, asymmetric stress-strain behaviour, temperature dependency, strain rate dependency and the material response to thermal and repeated mechanical loading. Physically realistic and accurately determined mechanical properties are provided in a format suitable for use in finite element analysis for the design of medical devices. Guidance is also given as to the most appropriate experimental set up procedures for gripping and testing thin Nitinol wire.
镍钛诺是一种镍钛合金，作为一种具有生物相容性的金属被广泛应用于高应变医疗器械中。该合金具有超弹性和热形状记忆性能。基本的机械性能可以由供应商确定，但在重复负载下的真实应力-应变响应还不完全清楚。为了设计可能发生疲劳失效的器件，了解这种行为是至关重要的。本工作开发了一种用于表征细镍钛诺丝材时变力学性能的方法，并研究了加工因素、不对称应力-应变行为、温度依赖性、应变率依赖性以及材料对热和重复机械加载的响应。以适合医疗器械设计有限元分析使用的格式提供了物理上合理且准确确定的力学性能。还给出了夹持和测试细镍钛诺丝的最合适的实验设置程序的指导。
