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De Novo Hierarchical Simulations of Stress Corrosion Cracking in Materials P. Vashishta, R.K. Kalia, & A. Nakano ( Univ. of Southern California ), W.A. Goddard & M. Ortiz (Caltech), A. Grama (Purdue), T. Cagin (Texas A&M) NSF ITR Grant Number: DMR 0427188.

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  1. De Novo Hierarchical Simulations of Stress Corrosion Cracking in MaterialsP. Vashishta, R.K. Kalia, & A. Nakano (Univ. of Southern California), W.A. Goddard & M. Ortiz (Caltech), A. Grama (Purdue), T. Cagin (Texas A&M)NSF ITR Grant Number: DMR 0427188 MD simulation by Kalia, Nakano & Vashishta reveals atomistic mechanisms of the initiation, growth & healing of wing cracks under dynamic compression in leterally confined silica glass. Frictional sliding of pre-crack surfaces nucleates nanovoids, which evolve into nanocrack columns at the pre-crack tip. Nanocrack columns merge to form a wing crack, which grows via coalescence with nanovoids in the direction of maximum compression. Lateral confinement arrests the growth and partially heals the wing crack. Cagin & Goddard developed reliable interatomic potentials to perform predictive molecular dynamics simulations. Grama & Nakano designed scalable parallel simulation algorithms.

  2. De Novo Hierarchical Simulations of Stress Corrosion Cracking in MaterialsP. Vashishta, R.K. Kalia, & A. Nakano (Univ. of Southern California), W.A. Goddard & M. Ortiz (Caltech), A. Grama (Purdue), T. Cagin (Texas A&M)NSF ITR Grant Number: DMR 0427188 Kinetic Monte Carlo simulation of hydrogen diffusion near a dislocation loop in iron shows the segregation of H atoms in the core region of both edge & screw dislocations, which play an important role in hydrogen embrittlement. To reach macroscopic length & time scales in the study of environmentally assisted cracking, Ortiz is developing a scheme to couple molecular dynamics interatomic potentials, discrete dislocation framework, & kinetic Monte Carlo methods. Effect of the stress field of a dislocation loop in Fe on the energies of Hydrogen interstitial sites and redistribution of H.

  3. De Novo Hierarchical Simulations of Stress Corrosion Cracking in MaterialsP. Vashishta, R.K. Kalia, & A. Nakano (Univ. of Southern California), W.A. Goddard & M. Ortiz (Caltech), A. Grama (Purdue), T. Cagin (Texas A&M)NSF ITR Grant Number: DMR 0427188 The USC-Caltech-Purdue-TA&M team co-organized the 5th Computational Science Workshop for Underrepresented Groups, which provided 24 undergraduates & 12 faculty mentors from 20 HBCUs & MSIs with hands-on experience in parallel computing, including the assembly of PC nodes from off-the-shelf components, loading them with scientific & simulation software, and connecting them to a Gigabit switch. This parallel computer was used for algorithmic & simulation exercises in a tutorial setting.

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