Wednesday  |  Phipps  |  09:00 AM–09:20 AM

#13893, Exploring the Thermo-Mechanical Path Dependence of Structural and Functional Fatigue of NiTi Shape Memory Alloys

The thermo-mechanical behavior of NiTi shape memory alloys (SMAs) is path dependent, and this influences multiple applications that utilize the shape memory effect and superelasticity, including lightweight aerospace actuators and minimally invasive cardiovascular implants. The goal of this work is gaining a deeper understanding of the mechanisms by which various thermo-mechanical loadings influence the structural and functional fatigue of NiTi-based SMAs. In terms of structural fatigue, there is a lack of information about the fatigue cracking behavior with respect to temperature—to date, crack growth rates have been measured at only five temperatures with respect to the transformations among austenite, martensite, and R-phase. This work will share crack growth rates during isothermal cycling for a wider continuum of temperatures. Furthermore, in terms of functional fatigue, this work will probe a peculiar non-monotonic relationship of the residual strain accumulation with respect to cooling stress for thermal cycling with various loading paths.

Eathan Devine   University of Tulsa
Perry McCollum   University of Tulsa
William LePage   University of Tulsa