scholarly journals Influence of Strain Ratio on Bending Fatigue Life and Fatigue Crack Growth in TiNi Shape-Memory Alloy Thin Wires

2006 ◽  
Vol 47 (3) ◽  
pp. 759-765 ◽  
Author(s):  
Ryosuke Matsui ◽  
Yoshiyasu Makino ◽  
Hisaaki Tobushi ◽  
Yuji Furuichi ◽  
Fusahito Yoshida
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Crack Growth ◽  
Strain Ratio ◽  
Bending Fatigue ◽  
Thin Wires

scholarly journals Influence of Strain Ratio on Bending Fatigue Life in TiNi Shape Memory Thin Wire

2007 ◽  
Vol 340-341 ◽  
pp. 1193-1198 ◽  
Author(s):  
Ryosuke Matsui ◽  
Hisaaki Tobushi ◽  
Yoshiyasu Makino
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Shape Memory ◽  
Low Cycle Fatigue ◽  
Fatigue Cracks ◽  
Strain Ratio ◽  
Thin Wire ◽  
Bending Fatigue ◽  
Rotating Bending ◽  
Plane Bending

In this study, we performed the bending fatigue test and investigated the influence of strain ratio on fatigue life in TiNi shape memory thin wire. The pulsating plane bending, alternating plane bending and rotating bending fatigue tests were carried. Additionally, we carried out the observation of the fatigue fracture surface by a scanning electron microscope. The behavior of fatigue crack was investigated. The results obtained are summarized as follows. (1) The martensitic transformation (MT) stress of the superelastic thin wire (SE-NT) is higher than that of the SMA thin wire (SME-NT) and the fatigue life of SE-NT is shorter than that of SME-NT. Maximum bending strain at the fatigue limit is the MT starting strain. (2) The low-cycle fatigue life curve in plane bending for SE-NT is expressed by a power function of maximum strain εmax and the number of cycles to failure Nf. The smaller the strain ratio for the same εmax, the shorter the fatigue life. (3) In both the rotating bending and the plane bending, fatigue cracks nucleate on the surface of the wire and one fatigue crack grows preferentially. The region in which fatigue crack propagated is fan-shaped.

Grain size effects on NiTi shape memory alloy fatigue crack growth

2017 ◽  
Vol 33 (2) ◽  
pp. 91-107 ◽  
Author(s):  
William S. LePage ◽  
Aslan Ahadi ◽  
William C. Lenthe ◽  
Qing-Ping Sun ◽  
Tresa M. Pollock ◽  
...  
Keyword(s):  
Grain Size ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Crack Growth ◽  
Size Effects ◽  
Niti Shape Memory Alloy ◽  
Image Position ◽  
Grain Size Effects

Abstract

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