Numerical analysis of NiTi actuators with stress risers: The role of bias load and actuation temperature

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389005%3A_____%2F21%3A00543011" target="_blank" >RIV/61389005:_____/21:00543011 - isvavai.cz</a>

Alternative codes found

RIV/00216305:26210/21:PU140665 RIV/68378271:_____/21:00563598

Result on the web

<a href="https://doi.org/10.1016/j.engfracmech.2021.107551" target="_blank" >https://doi.org/10.1016/j.engfracmech.2021.107551</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.engfracmech.2021.107551" target="_blank" >10.1016/j.engfracmech.2021.107551</a>

Result language

angličtina

Original language name

Numerical analysis of NiTi actuators with stress risers: The role of bias load and actuation temperature

Original language description

NiTi wires and thin ribbons are used in shape memory actuators as active elements undergoing repeated thermal cycles. The NiTi actuators operate either under constant force (CF loading constraint) or they act against a variable force (VF loading constraint) from an elastic bias spring. Any stress riser represents a danger for potential actuator failure upon cycling. Although NiTi actuators always include stress risers either inherently in their design or as material flaws, their effect on actuation performance has, however, not been studied thoroughly yet. This issue is addressed in the present paper through numerical analysis of the effects of actuation load type (CF or VF loading constraint), maximum temperature, and stiffness of the bias springs (in VF loading constraint) on the local evolution of martensitic transformation (MT) and mechanical fields around the notch upon the cyclic thermomechanical loading of a thin NiTi shape memory notched ribbon. The analyses clearly show a strong amplification effect of the transformation strain on the stress concentration factor. The results reveal that the evolution of the forward MT upon cooling causes a sharp stress peak around the notch-tip the magnitude of which depends on the bias spring stiffness while upon heating, the stress at the notch-tip area relaxes due to the reverse MT of the surrounding bulk. Moreover, the simulations indicate that any overheating during the actuation is harmful to the notch-tip as the complete reverse MT at the notch-tip has stress rising effect while incomplete MT at the notch-tip has stress relaxing effect.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

20501 - Materials engineering

Project

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2021

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Engineering Fracture Mechanics

ISSN

0013-7944

e-ISSN

1873-7315

Volume of the periodical

244

Issue of the periodical within the volume

MAR

Country of publishing house

GB - UNITED KINGDOM

Number of pages

11

Pages from-to

107551

UT code for WoS article

000695478000005

EID of the result in the Scopus database

2-s2.0-85100043222