Résumé
Due to their superelasticity properties and to their good biocompatibility, NiTi ShapeMemory Alloys (SMA) are being increasingly used for in biomedical applications. Thedesign of these applications is mostly based on modelling obtained on simple tensile tests supposed to be homogeneous [Auricchio and Sacco 2001]. The tension behaviour of an initially austenitic NiTi thin wall tube was investigated at several temperatures by having a fluid circulating inside the tube. Thermal as well as kinematical full-field measurements [Louche et al 2005] have been simultaneously carried out by using respectively infrared camera and image correlation on images captured with a visible camera. These two techniques used simultaneously allow to quantitatively observe the localisation during superelasticity (strain mechanism via martensite transformation) and therefore to characterize the geometric nature of the localisation (type, position, orientation, intensity, kinetic …). They contribute therefore to analyse the physical mechanism origin of these heterogeneities depending on the mode of deformation, velocity of the solicitation, and thermal condition during the tensile test. It has been observed that the strain field which is localised can have different morphologies (band, front…) and that the macroscopic tube’s mechanical behaviour depends on its temperature but also on the localisation morphology types. Link between total displacement of the sample, tension force, propagation speed of the front, and strain jump between each part of the front will be presented. [no pdf]