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Background: Shape memory alloys (SMAs) are phase transforming materials featuring strong thermomechanical couplings. Infrared thermography and heat source reconstruction (HSR) enable to track the calorific signature of deformation processes. Objective: The objective was to characterize the transformation processes in a superelastic nickel-titanium SMA wire subjected to a force-controlled superelastic tensile cycle. Methods: In-situ recorded thermographs were converted into spatiotemporal maps of heat sources using an inhouse developed post-processing method based on the heat diffusion equation resolved numerically for unknown heat sources. Results: Sequentially appearing patterns of localized transformation events of four types were identified and associated with martensite bands nucleations and their subsequent merging upon tensile loading. Analogically, the events associated with austenite bands nucleations and their subsequent merging were identified upon unloading. In addition, weak heat sources observed before and after the localized transformation events were associated with the homogeneous martensitic transformation. Conclusions:The intrinsic dissipation heat associated with the nucleation and merging events is estimated to be ~25% of the released/absorbed latent heat.

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Full-field measurement techniques are now mature. As such, they have profoundly impacted the experimental mechanics community in recent years. The way that shape memory alloys (SMAs) are now tested is not spare from this deep-rooted trend, as reflected by the increasing number of papers published in the SMA literature. In this context, the aim of this contribution is to give an overview of the use of full-field measuring techniques for SMA characterization purposes. We recall first the basic principle of one volume and four surface techniques employed in this community. Several typical papers where such techniques are employed are then presented, by highlighting in each case the extent to which the thermomechanical response of SMAs could be better understood and modeled thanks to these techniques. A classification by several criteria of about 300 references is finally offered and discussed. The main criteria are the type of SMA, the type of technique employed to perform the measurements, and the type of test.