FINITE-ELEMENT SIMULATIONS OF INTERNAL-STRESSES GENERATED DURING THE FERROELASTIC DEFORMATION OF NITI BODIES

The aim of this paper is to analyse the generation of internal stresse s during the predeformation of NiTi shape memory alloys in tile marten sitic state. This allows to determine the initial stress state in whic h the material will transform during the shape memory effect due to he ating consecutively to this prestrain. In that way a three-dimensional finite element model of the deformation of shape memory alloys has be en developed, the constitutive law being defined using an elastohyster esis tensor model. The influence of behavioural and geometrical factor s are illustrated considering the numerical simulation of different ca ses of practical importance for industrial applications : the study of the bending behaviour of a NiTi cantilever beam as well as the study of the swelling of a pipe connection under both uniform and non unifor m internal displacement fields.