The availability of engineering strength data on shape memory alloys (SMAs) under cyclic thermal activation (functional fatigue) is central to the rational design of smart actuators based on these materials. Test results on SMAs under functional fatigue are scarce in the technical literature and the few data available are mainly limited to constant-stress loading. Since the SMA elements used within actuators are normally biased by elastic springs or by another SMA element, their stress state is far from constant in operation. The mismatch between actual working conditions and laboratory arrangements leads to suboptimal designs and undermines the prediction of the actuator lifetime. This paper aims at bridging the gap between experiment and reality. Four test procedures are planned, covering most of the typical situations occurring in practice: constant-stress, constant-strain, constant-stress with limited maximum strain and linear stress-strain variation with limited maximum strain. The paper describes the experimental apparatus specifically designed to implement the four loading conditions and presents fatigue results obtained from commercial NiTi wires tested under all those protocols.

Functional fatigue of NiTi Shape Memory wires for a range of end loadings and constraints / SCIRE' MAMMANO, Giovanni; Dragoni, Eugenio. - In: FRATTURA E INTEGRITÀ STRUTTURALE. - ISSN 1971-8993. - ELETTRONICO. - 23:(2013), pp. 25-33. [10.3221/IGF-ESIS.23.03]

Functional fatigue of NiTi Shape Memory wires for a range of end loadings and constraints

SCIRE' MAMMANO, Giovanni;DRAGONI, Eugenio
2013

Abstract

The availability of engineering strength data on shape memory alloys (SMAs) under cyclic thermal activation (functional fatigue) is central to the rational design of smart actuators based on these materials. Test results on SMAs under functional fatigue are scarce in the technical literature and the few data available are mainly limited to constant-stress loading. Since the SMA elements used within actuators are normally biased by elastic springs or by another SMA element, their stress state is far from constant in operation. The mismatch between actual working conditions and laboratory arrangements leads to suboptimal designs and undermines the prediction of the actuator lifetime. This paper aims at bridging the gap between experiment and reality. Four test procedures are planned, covering most of the typical situations occurring in practice: constant-stress, constant-strain, constant-stress with limited maximum strain and linear stress-strain variation with limited maximum strain. The paper describes the experimental apparatus specifically designed to implement the four loading conditions and presents fatigue results obtained from commercial NiTi wires tested under all those protocols.
2013
28-dic-2012
23
25
33
Functional fatigue of NiTi Shape Memory wires for a range of end loadings and constraints / SCIRE' MAMMANO, Giovanni; Dragoni, Eugenio. - In: FRATTURA E INTEGRITÀ STRUTTURALE. - ISSN 1971-8993. - ELETTRONICO. - 23:(2013), pp. 25-33. [10.3221/IGF-ESIS.23.03]
SCIRE' MAMMANO, Giovanni; Dragoni, Eugenio
File in questo prodotto:
File Dimensione Formato  
159-Article Text (.docx, max 100 Mb)-592-1-10-20121228.pdf

Open access

Tipologia: Versione pubblicata dall'editore
Dimensione 710.27 kB
Formato Adobe PDF
710.27 kB Adobe PDF Visualizza/Apri
Pubblicazioni consigliate

Licenza Creative Commons
I metadati presenti in IRIS UNIMORE sono rilasciati con licenza Creative Commons CC0 1.0 Universal, mentre i file delle pubblicazioni sono rilasciati con licenza Attribuzione 4.0 Internazionale (CC BY 4.0), salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/887289
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 12
  • ???jsp.display-item.citation.isi??? ND
social impact