Events Calendar

AME Department Seminar

Speaker: Panos Papadopoulos, Professor. Department of Mechanical Engineering. University of California, Berkeley Berkeley, CA 94720-1740.

Talk Title: Multiscale Modeling of Phase Transition in Superelastic Nitinol Polycrystals

Abstract: Nitinol is a Ni-Ti alloy used widely in biomedical devices, such as endovascular stents, angioplasty guidewires, vena-cava filters, etc. One of the major attractions of Nitinol as a biomedical material is its superelastic behavior. This is due to a stress-induced solid- solid phase transformation which accommodates large deformations that may be completely reversed upon removal of the stress. Most constitutive models of phase transformation in superelastic Nitinol account for the austenite-martensite transformation only, and disregard the formation of an intermediate rhombohedral phase (R-phase). However, the presence of R-phase influences the formation of martensitic variants, thus rendering the transformation process path-dependent. In this seminar, a path-dependent micromechanics-based model that incorporates all possible transformations is presented first for the stress-induced phase transformation of Nitinol single crystals. This is subsequently extended to a multiscale thermomechanical model which accounts for the presence of polycrystalline texture. An efficient numerical strategy for solving the resulting constitutive equations is also proposed within a finite element setting.

Host: Prof. Geoff Spedding

More Info: http://ae-www.usc.edu/seminars/index.shtml#upcoming

Location: Seaver Science Library (SSL) - 150

Audiences: Everyone Is Invited

Contact: April Mundy

Event Link: http://ae-www.usc.edu/seminars/index.shtml#upcoming