J. Phys. IV France 112 (2003) 239
Calculation of shape recovery in textured SM materialD.Yu. Makarenkov1, V. Brailovski2 and F. Trochu3
1 Tsiolkovskii Russian State University of Aviation Technology (MATI), Materials Science Department, Ostrovityanova Street 3, Moscow 117321, Russia
2 Université du Québec, ETS, Mechanical Engineering Department, 1100 rue Notre-Dame Ouest, Montréal, Québec H3C 1K3, Canada
3 École Polytechnique de Montréal, Mechanical Engineering Department, P.O. Box 6079, Station Centre-Ville, Montréal, Québec H3C 3A7, Canada
The aim of this work is to create a computer model predicting the strain to be accumulated and then recovered by nitinol superelastic textured sheets upon reversible martensitic transformation. Using an experimental orientation distribution function (ODF), connecting the microscale (grain) and macroscale (semiproduct) levels, the model calculations are realized through the following steps: (1) tensile loading is consecutively applied to the shape memory nitinol sheet in all directions from those rolling to transverse; (2) an external stress is transferred to micro (each grain) level, where the crystallographic strain is obtained by minimizing the total strain energy; (3) then the strains accumulated in each grain are translated backwards to the macrolevel through the ODF: to obtain the macrostrain accumulated by the whole sheet, a weighted summation of grain-accumulated strains is used by assuming the input from each grain orientation to be proportional to the corresponding ODF coefficient. This approach is validated for isotropic (constant ODF) and for normally anisotropic (typical experimental ODF) cases. It is also shown how the sharpening of texture gradually increases the strain anisotropy until the single crystal strain distribution of the unique grain orientation appears in the sheet plane.
© EDP Sciences 2003