Multiscale dislocation dynamics simulations of shock-induced plasticity in small volumes

• Published in: Philosophical magazine (Abingdon, England) Vol. 92; no. 10; pp. 1173 - 1197
• Main Author: Shehadeh, Mutasem A.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis Group 01.04.2012; Taylor & Francis
• Subjects: boundary condition; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Defects and impurities in crystals; microstructure; Deformation, plasticity, and creep; dislocation dynamics; dislocation structure; Exact sciences and technology; homogeneous nucleation; Interaction between different crystal defects; gettering effect; lattice rotation; Linear defects: dislocations, disclinations; Materials science; multiscale simulation; Physics; shock wave; slip band; Structure of solids and liquids; crystallography; Treatment of materials and its effects on microstructure and properties; Dislocation interactions; High strain; Deformation; Dislocation glide; Iron; Continuum; Finite element method; Uniaxial compression; Edge effect; Plasticity; Copper; Strain rate; Dislocation motion; Digital simulation; Mechanical properties; Boundary conditions; Slip planes; Dislocations; Shock waves; Monocrystals; Multiscale method; Slip system; Homogeneous nucleation; Microstructure; Formation mechanism; Defect formation
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786435.2011.637988

Multiscale dislocation dynamics plasticity (MDDP) was used to investigate shock-induced deformation in monocrystalline copper. In order to enhance the numerical simulations, a periodic boundary condition was implemented in the continuum finite element (FE) scale so that the uniaxial compression of shocks could be attained. Additionally, lattice rotation was accounted for by modifying the dislocation dynamics (DD) code to update the dislocations' slip systems. The dislocation microstructures were examined in detail and a mechanism of microband formation is proposed for single- and multiple-slip deformation. The simulation results show that lattice rotation enhances microband formation in single slip by locally reorienting the slip plane. It is also illustrated that both confined and periodic boundary conditions can be used to achieve uniaxial compression; however, a periodic boundary condition yields a disturbed wave profile due to edge effects. Moreover, the boundary conditions and the loading rise time show no significant effects on shock-dislocations interaction and the resulting microstructures. MDDP results of high strain rate calculations are also compared with the predictions of the Armstrong-Zerilli model of dislocation generation and movement. This work confirms that the effect of resident dislocations on the strain rate can be neglected when a homogeneous nucleation mechanism is included.