TY - JOUR

T1 - Recovery stress behavior of Fe-SMA under fatigue and thermal loading

AU - Chen, Zhen Yu

AU - Gu, Xiang Lin

AU - Vollmer, Malte

AU - Niendorf, Thomas

AU - Ghafoori, Elyas

AU - Yu, Qian Qian

N1 - Funding Information: This study was supported by the National Natural Science Foundation of China (Project Nos. 52222803 , 51938013 and 51878485 ) and National Key R&D Program of China ( 2022YFC3803000 ). We also thank re-fer AG in Switzerland for providing Fe-SMA materials.

PY - 2023/7

Y1 - 2023/7

N2 - The present paper investigates mechanical properties and recovery stress behavior of an iron-based shape memory alloy (Fe-SMA) with a special focus on the effect of fatigue and thermal loading. Change in recovery stress of activated Fe-SMAs subjected to fatigue at RT, −20 °C, 60 °C, and −20 to 60 °C was monitored. A second activation after fatigue was performed to investigate the retrievability of the lost recovery stress owing to fatigue. Coefficients of thermal expansion (CTEs) of the samples with different activation histories were also calculated. Results showed that the maximum reduction in recovery stress after two million cyclic loads of Δɛ=0.070% was approximately 20% under RT and −20 °C. A high temperature (60 °C) weakened such detrimental effect owing to higher critical stresses for martensitic transformation at higher temperatures, leading to only 10% reduction in recovery stress. Loss in the recovery stress due to fatigue was pronouncedly retrieved by a reactivation regardless of the temperature scenarios. This study extends understanding of recovery stress behavior of Fe-SMAs subjected to fatigue and thermal loading, and explores the retrievability of relaxed recovery stress by a second activation.

AB - The present paper investigates mechanical properties and recovery stress behavior of an iron-based shape memory alloy (Fe-SMA) with a special focus on the effect of fatigue and thermal loading. Change in recovery stress of activated Fe-SMAs subjected to fatigue at RT, −20 °C, 60 °C, and −20 to 60 °C was monitored. A second activation after fatigue was performed to investigate the retrievability of the lost recovery stress owing to fatigue. Coefficients of thermal expansion (CTEs) of the samples with different activation histories were also calculated. Results showed that the maximum reduction in recovery stress after two million cyclic loads of Δɛ=0.070% was approximately 20% under RT and −20 °C. A high temperature (60 °C) weakened such detrimental effect owing to higher critical stresses for martensitic transformation at higher temperatures, leading to only 10% reduction in recovery stress. Loss in the recovery stress due to fatigue was pronouncedly retrieved by a reactivation regardless of the temperature scenarios. This study extends understanding of recovery stress behavior of Fe-SMAs subjected to fatigue and thermal loading, and explores the retrievability of relaxed recovery stress by a second activation.

KW - Fatigue

KW - Iron-based shape memory alloy

KW - Reactivation

KW - Recovery stress

KW - Thermal loading

UR - http://www.scopus.com/inward/record.url?scp=85158894584&partnerID=8YFLogxK

U2 - 10.1016/j.tws.2023.110799

DO - 10.1016/j.tws.2023.110799

M3 - Article

AN - SCOPUS:85158894584

VL - 188

JO - Thin-walled structures

JF - Thin-walled structures

SN - 0263-8231

M1 - 110799

ER -