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Thirtieth Annual Robert J. Melosh Competition - "Recent Advances in Computational Fracture Mechanics"
Friday, April 26, 2019
10:00 am - 11:00 am
Haim Waisman, Associate Professor, Columbia University
The modelling of cracks and shearbands, arising from brittle and ductile response of materials, poses significant computational challenges. In this talk I will present our recent developments in modelling of fracture phenomena that address some of these challenges. The first part of the talk, devoted to brittle and quasi-brittle fracture, will focus on a new formulation based on a high order extended finite element method (XFEM) and Irwin's integral. XFEM provide an attractive alternative to standard finite elements in that they do not require fine spatial resolution in the vicinity of discontinuities nor do they require repeated re-meshing to properly address propagation of cracks. The second part of the talk will focus on dynamic fracture of metals which may result in brittle and/or ductile fracture depending on factors such as material properties, loading rate and specimen geometry. At high strain rates, a thermo-plastic instability known as shear banding may occur, which typically precedes fracture, while at lower rates brittle fracture is observed. I will present a novel unified finite element formulations for shear bands and cracks, in which cracks are modelled by a modified phase field method. The main modelling aspects along with some numerical examples to illustrate the performance of the model will be presented.
Carpenter, Ruby Nell