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Shape recovery behaviour of NiTi strips in bending: experiments and modelling


We present a theoretical and experimental investigation of the bending recovery performances for a commercial NiTi shape memory alloy strip. We evaluate the mechanical properties and the shape setting parameters and estimate the evolution of the curvature during heating in an Ethylene Glycol-based water solution. To model the strip bending response, we use a one-dimensional phenomenological constitutive equation for the shape memory material, based on the introduction of (twinned and detwinned) martensite and austenite volume fractions as internal variables. Under the assumption of uniform bending, we calculate a quasi-closed-form solution for the stress and martensite fraction distributions in a shape memory beam during bending and subsequent shape recovery. Using our characterisation data as input parameters of the model, we find that the theoretical curvature evolution is in good agreement with experimental data.

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Correspondence to Raffaella Rizzoni.

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Communicated by Francesco dell'Isola and Samuel Forest.

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Rizzoni, R., Merlin, M. & Casari, D. Shape recovery behaviour of NiTi strips in bending: experiments and modelling. Continuum Mech. Thermodyn. 25, 207–227 (2013).

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  • Shape memory effect
  • Bending
  • Heat treatment