This paper presents an infrared data processing developed to analyse the calori®c manifestations accompanying elastoplastic transformation during tensile tests. The surface temperature images are provided by an experimental set-up essentially made of a testing machine coupled with an infrared camera equipped with a home-made numerizer. The`inverse' passage from temperatures to heat sources is detailed in the case of¯at and thin parallelepipedic samples. The infrared image processing, based on FourierÕs techniques, was checked using spectral solutions of the heat equation in the case of realistic examples close to experiments. Numerical simulations are shown which attest coherence and eciency of the method for several heat source distributions and dierent sets of noisy data. The method is then applied to experimental data ®les coming from tensile tests on mild steels at the room temperature. Sudden dissipative eects due to the propagation of the L uders bands during the plastic plateau can be observed. Then, during the strain hardening, gradual and precocious concentrations of dissipation are shown; they herald the local necking of the sample. Finally, the interest of such experimental results is brie¯y discussed by referring to the specialised literature dealing with localisation phenomena and behaviour identi®cation.

An initially austenitic polycrystalline Ti-50.8 at.% Ni thin-walled tube with small grain sizes has been deformed under tension in air at ambient temperature and moderate nominal axial strain rate. Temperature and strain fields were measured using visible-light and infrared digital cameras. In a first apparently elastic deformation stage, both strain and temperature fields are homogeneous and increase in tandem. This stage is followed by initiation, propagation and growth of localized helical bands inside which strain and temperature increases are markedly higher than in the surrounding regions. During the first apparently elastic stage of the unloading, both strain and temperature fields are homogeneous and decrease. The temperature and strain fields evolutions are then analysed in order to determine the deformation mechanisms (types and extents of phase transformations, variants (de)twinning, macroscopic banding) involved during the homogeneous and heterogeneous stages of deformation throughout the whole tube. The findings have significant implications for the understanding and modelling of superelastic behaviour of NiTi shape memory alloys.

This study deals with an experimental investigation of thermal and calorimetric effects induced by Lü ders band propagation during monotonic and quasi-static tensile tests. One grade of steel is considered. Temperature variations were measured with an infrared camera on the surface of flat samples. Heat sources were deduced from thermal data using the local heat diffusion equation. For elastoplastic materials, when no phase transition occurs, the heat source is essentially due to intrinsic dissipation. The experiments revealed that a dissipation wave accompanied Lü ders band propagation. Some characteristics of the wave, such as its shape, orientation and velocity, were derived from the experimental measurements and compared to previously published results. Finally, comparison of the calorimetric and kinematic data revealed a dissipation function proportional to the absolute value of the longitudinal plastic strain rate.