B.S. (University of La Plata), M.Sc., Ph.D. (University of Seville), Postdoctoral Fellowship (Caltech)
Current Research Work
Spallation in Metals: Ductile failure of metals during spallation is driven by cavitation, growth, and coalescence of voids. These micro-mechanical mechanisms underlying the crack growth in metals are important in order to understand ductile failure. Molecular dynamics (MD) has been extensively used for the study of dislocation emission from nano-sized voids and their subsequent plastic growth. However, the limitation in the time step of the integration scheme places severe limitations on the time scales that are accessible to MD. In order to overcome these issues, my group have implemented, extended and applied a novel method to study coupled thermo-mechanical problems driven by complex plasticity processes.
Sub-linear scaling methods for calculating crystal defects using DFT: Density Functional Theory (DFT) is a widely used ab-initio method for electronic-structure calculations. However, a major drawback of traditional DFT is that it requires the calculation of individual orbitals subject to an orthogonality condition. The orthogonalization of the orbitals is an expensive O(M3) operation, where M denotes the number of atoms in the system, which makes calculations of large samples prohibitively expensive. To tackle these challenges, a number of linear scaling DFT formulations have been proposed. However, an additional challenge is encountered in the study of crystalline defects since they are present in part per million atoms and linear scaling does not suffice this issue. In order to tackle some of these challenges, my group have developed and implemented a sublinear scaling method for the study of crystalline defects using ab-initio Density Functional Theory. The key attribute of the approach is that DFT is the sole input with no ad hoc assumptions, spurious physics or uncontrolled approximations. Our computational platform, MacroDFT, is capable of simulating systems with billion atoms using DFT and has shown a good parallel performance in the most modern supercomputers (i.e, DoE-MIRA up to 65% on 262, 144 processors).
- M. Ponga, A.A. Ramabathiran, K. Bhattacharya and M. Ortiz. (2016). Mechanisms of ductile failure in Magnesium under spallation. Accepted for publication in Modelling and Simulation in Materials Science and Engineering.
- M. Ponga, K. Bhattacharya and M. Ortiz. (2015). A sublinear scaling density functional theory method for crystalline defects. Accepted for publication in The Journal of the Mechanics and Physics of Solids.
- M. Ponga, M. P. Ariza and M. Ortiz. (2015). Finite-temperature non-equilibrium quasi-continuum analysis of nanovoid growth in copper at low and high strain rates. Mechanics of Materials. 90(1): 253-267.
- M. Ponga, M. P. Ariza, M. Ortiz and K. Bhattacharya. (2014). Linear Scaling DFT for Defects in Metals. TMS Supplemental Proceedings. 1(1): 265-272.
- M. Ponga, M. P. Ariza I. Romero, M. Ortiz. (2012). Finite Temperature Nanovoids Evolution in FCC Metals Using Quasicontinuum Method. Advances in Fracture and Damage Mechanics X. 488-499(1): 387-390.
- M.P. Ariza, M. Ponga, I. Romero and M. Ortiz. (2012). HotQC simulation of nanovoid growth under tension in copper. International Journal of Fracture. 174(1): 75-85.