NESC9923 NIKE2D.

1. NAME OR DESIGNATION OF PROGRAM:  NIKE2D.

3. 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 wih 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.
  
This package is distributed by:
Energy Science and Technology Software Center
P.O. Box 62
1 Science.Gov Way
Oak Ridge, TN 37831
(865) 576-2606 TEL
(865) 576-6436 FAX
E-mail: ESTSC@osti.gov

4. METHOD OF SOLUTION

Four-node isoparametric elements are used for the spatial discretization, and profile (bandwidth) minimization is  optional. An incremental-iteractive 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 iteraction 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 remapped; rezone one or more materials either interactively or automatically with a command file; and initialize remeshed regions by interpolating from nodal point values of the old mesh.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM:

6. TYPICAL RUNNING TIME:

7. UNUSUAL FEATURES OF THE PROGRAM

All material models are stable when used with equilibrium iterations in both static and dynamic problems.

8. RELATED AND AUXILIARY PROGRAMS

FISSILE (Fast Implicit Solver for Systems of Linear Equations), a set of subroutines used by NIKE2D, is included. Similar methods in three dimensions are available in NIKE3D (NESC 9725). The interactive mesh generator MAZE (NESC 9907)  can be used to prepare NIKE2D input, and the ORION (NESC 9906) and TAURUS (NESC 9908) postprocessors produce graphic output from NIKE2D results. Nodal temperatures can be read in from a binary plot file generated by the heat conduction code, TOPAZ2D (NESC 9801). The LLNL-developed DIGLIB graphics software for use on a DEC VAX11 is included.

10. REFERENCES:

11. MACHINE REQUIREMENTS:

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  CTSS (Cray1), VMS (DEC VAX11).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

NIKE2D
uses either the LLNL environment PLOTLIB or DIGLIB graphics devise software; the PLOTLIB software is not included. DIGLIB is designed for the DEC VAX and modification would be required for use on a Cray1.

15. NAME AND ESTABLISHMENT OF AUTHORS

          J.O. Hallquist
          Lawrence Livermore National Laboratory
          P.O. Box 808
          Livermore, California 94550