In metal fatigue, it is common practice to distinguish between high-cycle fatigue (i.e. failure occurring after 10000-100000 cycles) and low-cycle fatigue. For elastic-plastic materials, there is an established correlation between fatigue and energy dissipation. In particular, high-cycle fatigue occurs when the energy dissipation remains bounded in time. Although the physical mechanisms in shape-memory alloys (SMAs) differ from plasticity, the hysteresis that is commonly observed in the stress-strain response shows that some energy dissipation occurs. It can be reasonably assumed that situations where the energy dissipation remains bounded are the most favorable for fatigue durability. In this communication, we present a direct method for determining if the energy dissipation in a SMA structure (submitted to a prescribed loading history) is bounded or not. That method is simple to use and could be relevant for the design of SMA systems with high durability requirements, such as stents. Some numerical results are presented for the design of Nitinol stents and compared with experimental results from the literature.
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