exploring the durability limits of Ni-Ti plates under pre-strain conditions for elatocaloric coolling
Jaka Tušek (Author), Andrej Žerovnik (Author), Matjaž Čebron (Author), Miha Brojan (Author), Borut Žužek (Author), Kurt Engelbrecht (Author), Andrea Cadelli (Author)

Abstract

Structural fatigue is the major obstacle that prevents practical applications of the elastocaloric effect (eCE) in cooling or heat-pumping devices. Here, the eCE and fatigue behaviour of Ni-Ti plates are systematically investigated in order to define the fatigue strain limit and the associated eCE. Initially, the eCE was evaluated by measuring adiabatic temperature changes at different strain amplitudes and different mean strains along the loading and unloading transformation plateaus. By comparing the eCE with and without pre-strain conditions, the advantages of cycling an elastocaloric material at the mean strain around the middle of the transformation plateau were demonstrated. In the second part of this work, we evaluated the fatigue life at the mean strain of 2.25% at the loading plateau and at the unloading plateau after initial pre-straining up to 6% and 10%, respectively. It is shown that on polished samples, durable operation of 10 5 cycles can be reached with a strain amplitude of 0.50% at the loading plateau, which corresponds to adiabatic temperature changes of approximately 5 K. At the unloading plateau (after initial pre-strain of 10%), durable operation was reached at a strain amplitude of 1.00%, corresponding to adiabatic temperature changes of approximately 8%K. The functional fatigue was analysed after the cycling and it is shown that once the sample has been stabilized there is no further degradation of the eCE, even after 10 5 cycles. These results present guidelines for the design and operation of efficient and durable elastocaloric devices in the future.

Keywords

elastokalorični učinek;utrujanje;materiali z oblikovnim spominom;elastocaloric effect;fatigue;shape memory materials;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: IMT - Institute of Metals and Technology
UDC: 621.56(045)
COBISS: 15964187 Link will open in a new window
ISSN: 1359-6454
Views: 303
Downloads: 157
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Other data

Secondary language: Slovenian
Secondary keywords: elastokalorični učinek;zlitine z oblikovnim spominom;Ni-Ti;utrujanje;deformacije;
Type (COBISS): Article
Embargo end date (OpenAIRE): 2020-03-22
Pages: str. 295-307
Issue: ǂVol. ǂ150
Chronology: May 2018
DOI: 10.1016/j.actamat.2018.03.032
ID: 13077187
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