Stelios Kyriakides, Research
Abstract
Tension induced phase transformation in pseudoelastic NiTi leads to inhomogeneous deformation with the austenitic and martensitic phases coexisting. Deformation of nearly 7% is recovered on unloading during which the deformation is again inhomogeneous. By contrast, under compression the transformation stress is significantly higher, the strain is lower and is essentially homogeneous. In pure bending experiments on pseudoelastic NiTi tubes, this asymmetry manifests as coexistence of two curvature regimes with diamond-shaped patterns of martensite developing on the tensioned side. The analysis reproduces the major features of the experimental results and provides insight into how the nonlinearities of the NiTi material interact with geometric nonlinearities.
Experiment
Simulation
