NIKE2D, Analysis of Static and Dynamic Response of 3-D Solids

1 - Description of program or function: NIKE2D is a vectorized, implicit, finite-deformation, large strain, finite-element code for analyzing the response of two-dimensional axisymmetric, plane stress solids. A variety of loading conditions can be handled including traction boundary conditions, displacement boundary conditions, concentrated nodal point loads, body force loads due to base accelerations, and body force loads due to base accelerations, and body force loads due to spinning. Slide-lines with interface friction are available. Elastic, orthotropic-elastic, elastic-plastic, soil and crushable foam, thermo-elastic-plastic, linear viscoelastic thermo-orthotropic elastic, elastic-creep, and strain rate dependent material models are implemented. Nearly incompressible behavior that arises in plasticity problems and elasticity problems with Poisson's ratio approaching 0.5 is accounted for in the element formulation to preclude mesh lock-ups and the associated anomalous stress states. 2 - Method of solution: Four-node iso-parametric elements are used for the spatial discretization, and profile (bandwidth) minimization is optional. An incremental-interactive numerical algorithm, based on the Green-Naghdi stress rate formulation is implemented in NIKE2D. Arc length methods are used to solve problems that involve snap through buckling, plastic instabilities, and related problems where equilibrium is difficult to achieve. Forces due to surface tractions (pressure and shear) and spinning are calculated based on the current configuration and are recalculated for each equilibrium interaction using the current estimate of the configuration. No limit exists on the number of load-time histories that can be defined, and any loading function may reference any time history. Body force loads may be applied in static and dynamic analyses. The automatic rezoning in NIKE2D consists of three phases: generate nodal values on the old mesh for all variables to be re-mapped; rezone one or more materials either interactively or automatically with a command file; and initialize re-meshed regions by interpolating from nodal point values of the old mesh