In the present paper, the fatigue behaviour of a near-equiatomic pseudo-elastic NiTi SMA (Shape Memory Alloy) is experimentally examined by means of tensile cyclic loading tests. In situ X-ray Diffraction (XRD) analyses are also performed in order to measure the contents of both austenite and martensite phase during testing. The experimental campaign highlights a stress–strain diagram defined through five different stress–strain functions. Such a diagram is here proposed to be analytically described by a model in two steps: (i) firstly, the domain for each of the above functions is determined by exploiting the experimental measurements of both austenite and martensite phase content; (ii) then, the equations defining each function are deduced by assuming that the fatigued material behaves as a single-spring system or a two-spring system (working in parallel or in series).
Fatigue analysis of a near-equiatomic pseudo-elastic NiTi SMA / Vantadori, Sabrina; Carpinteri, Andrea; DI COCCO, Vittorio; Iacoviello, Francesco; Natali, Stefano. - In: THEORETICAL AND APPLIED FRACTURE MECHANICS. - ISSN 0167-8442. - 94:(2018), pp. 110-119. [10.1016/j.tafmec.2018.01.012]