DIRECT SIMULATION OF SUBGRAIN DISLOCATION STRUCTURES Srinivasan M. Sivakumar and Michael Ortiz

1. Reinsertion X2 Die Entry x2 INCREMENTAL VARIATIONAL SCHEME ELASTIC PLASTIC WORK OF DEFORMATION x1 RADOVITZKY & ORTIZ, 1999  REGIONS OF SINGLE SLIP Shear Plane X1 & with INFINITE LATENT HARDENING AUBRY & ORTIZ, 2003 Die Exit CRITERION FOR BRANCHING: DIRECT SIMULATION OF SUBGRAIN DISLOCATION STRUCTURES Srinivasan M. Sivakumar and Michael Ortiz Graduate Aeronautical Laboratories CALIFORNIA INSTITUTE OF TECHNOLOGY AN APPLICATION EQUAL CHANNEL ANGULAR EXTRUSION • LARGE DEFORMATION SINGLE CRYSTAL PLASTICITY • STRONG LATENT HARDENING – SINGLE SLIP PLASTICITY • SEQUENTIAL LAMINATION CONSTRUCTION MIMICS THE LAMELLAR DISLOCATION STRUCTURES OBSERVED • RANK-ONE CONVEXIFICATION ALGORITHM • NON-LOCAL EFFECTS USING DISLOCATION DENSITY TENSOR • KEY APPLICATIONS: • ALL SEVERE PLASTIC DEFORMN. PROCESSES (SPD) • EXAMPLE: ECAE (ECAE) PATCHY SLIP Asaro (1983) LAMELLAR STRUCTURES (Cu) (Lee, et al. 2002) MULTIPLE LENGTH SCALE SEPARATIONS SEQUENTIAL LAMINATION - RANK-1 CONVEXIFICATION SEQUENTIAL LAMINATES CALCULATIONS FOR  = 900 ECAE - SINGLE PASS Shear strain=200% FCC – AL-CU ALLOY KOHN, 1991 SINGLE CRYSTAL RESULTS (for a particular random orientation) COMPATIBILITY EQUILIBRIUM EQUATIONS CONFIGURATIONAL EQUILIBRIUM ESTIMATED: CALCULATED: (AN A POSTERIORI ESTIMATON OF SIZES) INTERFACES POLYCRYSTAL RESULTS • Thanks to: • Caltech’s ASCI ASAP Center • C.Tome and I. Beyerlein (LANL) • Matt Fago (Caltech) • Lydia Suarez (Caltech) and • Marta Kahl (Caltech) EXPERIMENTAL EVOLUTION OF CALCULATED POLE FIGURES