Mechanical behaviour of architectured NiTi materials in complex loading

International audienceThe aim of the study is to create architectured materials constituted of NiTi tubes combining the intrinsic and novel properties of Nickel-Titanium shape memory alloys with purposely engineered topologies. By joining thin-wall tubes by means of electrical resistance welding, we create regular cellular materials. The superelastic behaviour of two architectured materials based on identical tubes but with two topologies are modelled using finite element approaches. Large transformations are taken into account or neglected and two constitutive equations are considered; predicted behaviours are compared by simulating complex loading with superelastic loops and subloops. The parameters of the constitutive equations are identified on tensile tests performed on small dog-bone shaped specimens machined from the tubes by spark cutting. The results of the modelling are at last compared with experiments performed on one given architectured NiTi material