Deformation infrared calorimetry for materials characterization applied to study cyclic superelasticity in NiTi wires

Abstract

In this article, we introduce the Deformation Infrared Calorimetry (DIRC) technique for resolving spatial distributions of heat and work in samples subjected to uniaxial loading under isothermal conditions. Heat and work distributions are computed from synchronized temperature and strain fields obtained by infrared thermography (IRT) and digital image correlation (DIC). The DIRC data acquisition and processing are described in the first part of the article. Then, we show the relevance and usage of DIRC by employing it to characterize the cyclic evolution of the thermomechanical response of a superelastic NiTi wire termed functional fatigue. Particularly, we evaluated the evolution of the heat, work, and internal energy changes upon the repeated propagation of stress-induced martensitic transformations (SIMTs) shear-bands, producing a highly heterogeneous deformation scenario. Further postprocessing of DIRC allowed us to associate the functional fatigue of the material with the evolution of the production/recovery of martensite and the energy storage and dissipation during the propagation of SIMT shear-bands.

Keywords

• Heat Sources
• Deformation calorimetry
• NiTi wires
• Strain Localization
• Superelasticity
• Functional Fatigue