Verification of the NIKE3D structural analysis code by comparison against the analytic solution for a spherical cavity under a far-field uniaxial stress
The original scope of this task was to simulate the stresses and displacements of a hard rock tunnel experimental design using a suitable three-dimensional finite element code. NIKE3D was selected as a suitable code for performing these primarily approximate linearly elastic 3D analyses, but it required modifications to include initial stress, shear traction boundary condition and excavation options. During the summer of 1988, such capabilities were installed in a special version of NIKE3D. Subsequently, we verified both the LLNL's commonly used version of NIKE3D and our private modified version against the analytic solution for a spherical cavity in an elastic material deforming under a far-field uniaxial stress. We find the results produced by the unmodified and modified versions of NIKE3D to be in good agreement with the analytic solutions, except near the cavity, where the errors in the stress field are large. As can be expected from a code based on a displacement finite element formulation, the displacements are much more accurate than the stresses calculated from the 8-noded brick elements. To reduce these errors to acceptable levels, the grid must be refined further near the cavity wall. The level of grid refinement required to simulate accurately tunneling problems that do not have spatial symmetry in three dimensions using the current NIKE3D code is likely to exceed the memory capacity of the largest CRAY 1 computers at LLNL. 8 refs., 121 figs.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- DOE/NE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5745682
- Report Number(s):
- UCID-21811; ON: DE90000929; TRN: 89-027901
- Country of Publication:
- United States
- Language:
- English
Similar Records
NIKE3D a nonlinear, implicit, three-dimensional finite element code for solid and structural mechanics user's manual update summary
Numerical integration of structural elements in NIKE3D and DYNA3D
Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
CAVITIES
MATHEMATICAL MODELS
MINE SHAFTS
STRESSES
N CODES
ROCKS
SPHEROIDS
COMPUTER CODES
SHAFT EXCAVATIONS
052002* - Nuclear Fuels- Waste Disposal & Storage
053000 - Nuclear Fuels- Environmental Aspects