Modeling and simulation in strain-induced phase transformations in a diamond anvil cell
Biao Feng (Iowa state university), Valery Levitas (Iowa State University), Oleg Zarechnyy (Iowa state university)
Mechanics of Phase Transforming and Multifunctional Materials
Tue 2:40 - 4:00
CIT 219
The main processes in a quai-static high pressure physics and mechanics are compression of a thin sample in a diamond anvil cell (DAC) to high pressure and producing high pressure phases in it. Plastic strain-induced phase transformations (PTs) in a sample under compression in DAC are investigated in detail, by applying finite element approach. A large-strain model for coupled PTs and plastic flow is developed, which includes micromechanically based strain-controlled kinetics. Finite element algorithm and procedure is developed and implemented in the ABAQUS. Cases without and with deformable gasket are considered. An extended version of the Coulomb and plastic friction model for multiphase material with evolving concentration of phases is developed and implemented in ABAQUS to model contact interaction between diamond anvils, gasket, and sample. It includes large contact sliding and variable contact surface with and without gaps. Detailed analyses of the coupled plastic flow and PTs are studied during loading, unloading, and reloading for various ratios of the yield strengths of the low and high pressure phases, kinetic parameters, and friction parameters. For the lower yield strength of high pressure phases, coupled strain and phase localization is revealed. Various experimentally observed effects are reproduced and interpreted. Obtained results revealed difficulties in experimental characterization of strain-induced PTs and suggested some ways to overcome them. 1 V. I. Levitas and O. M. Zarechnyy, Phys. Rev. B 82, 174123 (2010). 2 V. I. Levitas and O. M. Zarechnyy, Phys. Rev. B 82, 174124 (2010).