Temperature full-field measurement and heat sources estimation during superelastic tests of NiTi samples

Intensive experimental investigations have been carried out to characterise and understand the deformation mechanisms associated with the superelasticity of SMAs. In that respect, thermal and kinematical full-field measurement are increasingly performed during mechanical tests of NiTi samples [1-4]. They have allowed to bring new information to analyse the mechanical behaviour of this alloy, including localisation phenomena.

In order to obtain a quantitative energy information and a better recognition of the deformation mechanisms involved, an estimation of the local heat sources based on an image processing of the heat balance equation has been achieved. In the poster, we will present first the theoretical equations and the hypotheses used to estimate the heat sources from the measured thermal fields. The software and the validation of the method will be presented in the second part. Finally, typical results showing the heat sources (local latent heat) distribution during mechanical tests will be given.

[1] S. Daly, G. Ravichandran, K. Bhattacharya, Acta Mater., 55 3593–3600, (2007).

[2] E.A. Pieczyska, S.P. Gadaj, W.K. Nowacki, H. Tobushi, Exp Mech., 46, pp 531–542, (2006).

[3] D. Favier , H. Louche, P. Schlosser, L. Orgéas, P. Vacher and L. Debove, Acta Mater., Vol. 55, 16, pp 5310-5322, (2007).

[4] P. Schlosser, H. Louche, D. Favier and L. Orgéas, Strain, Vol 43, 3, pp 260-271, (2007).