NESC0682 GNATS/MESH2/GPRINT
GNATS, Nonlinear Stress Analysis of 2-D and Axisymmetric Static Structure by Finite Elements Method
NAME OR DESIGNATION OF PROGRAM, COMPUTER, DESCRIPTION OF PROBLEM OR FUNCTION, METHOD OF SOLUTION, RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM, TYPICAL RUNNING TIME, UNUSUAL FEATURES OF THE PROGRAM, RELATED AND AUXILIARY PROGRAMS, STATUS, REFERENCES, MACHINE REQUIREMENTS, LANGUAGE, OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED, OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS, NAME AND ESTABLISHMENT OF AUTHORS, MATERIAL, CATEGORIES
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| Program name | Package id | Status | Status date |
|---|---|---|---|
| GNATS | NESC0682/01 | Tested | 01-JUN-1978 |
Machines used:
| Package ID | Orig. computer | Test computer |
|---|---|---|
| NESC0682/01 | CDC 7600 | CDC 7600 |
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4. METHOD OF SOLUTION
The GNATS program is based on a total
Lagrangian description of the displaced equilibrium configuration.
The complete strain-displacement equations are used to include the
effects of large displacements and large strains. Elastic-plastic
material behavior, with either isotropic or kinematic hardening,
may be selected. All solution options included in GNATS contain
an equilibrium check which assures that the structure satisfies
equilibrium to a specified tolerance at each stage of loading.
The GNATS program is based on a total
Lagrangian description of the displaced equilibrium configuration.
The complete strain-displacement equations are used to include the
effects of large displacements and large strains. Elastic-plastic
material behavior, with either isotropic or kinematic hardening,
may be selected. All solution options included in GNATS contain
an equilibrium check which assures that the structure satisfies
equilibrium to a specified tolerance at each stage of loading.
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7. UNUSUAL FEATURES OF THE PROGRAM
GNATS is designed for the
general nonlinear analysis of two-dimensional structures. The
MESH2 preprocessor enables the user to generate either a four node
or eight node quadrilateral element and compute several parameters
which are useful in evaluating the mesh. Mesh generation is
accomplished by simultaneously defining the boundary of the domain
in two spaces: the r-z plane which contains the plane to be
analyzed, and an integer i-j plane which controls the density of
the subdivisions. The integer i-j mesh is then mapped onto the r-
z domain using Laplace's equation in second-difference form to
determine the coordinates of interior nodal points. The GPRINT
postprocessor provides users with considerable flexibility in
selecting the most appropriate data to be printed. Variable
FORMAT statements provide additional printing flexibility.
GNATS is designed for the
general nonlinear analysis of two-dimensional structures. The
MESH2 preprocessor enables the user to generate either a four node
or eight node quadrilateral element and compute several parameters
which are useful in evaluating the mesh. Mesh generation is
accomplished by simultaneously defining the boundary of the domain
in two spaces: the r-z plane which contains the plane to be
analyzed, and an integer i-j plane which controls the density of
the subdivisions. The integer i-j mesh is then mapped onto the r-
z domain using Laplace's equation in second-difference form to
determine the coordinates of interior nodal points. The GPRINT
postprocessor provides users with considerable flexibility in
selecting the most appropriate data to be printed. Variable
FORMAT statements provide additional printing flexibility.
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10. REFERENCES
M. L. Callabresi and R. C. Young, GNATS - A Finite
Element Computer Program for the General Nonlinear Analysis of
Two-dimensional Structures, SLL-74-0023, October 1974.
M. L. Callabresi and R. C. Young, Organization of
GNATS - A General Nonlinear Analysis Computer Program for Two-
dimensional Structures, SLL-74-0022, October 1974.
M. L. Callabresi and R. C. Young, GNATS - A Finite
Element Computer Program for the General Nonlinear Analysis of
Two-dimensional Structures, SLL-74-0023, October 1974.
M. L. Callabresi and R. C. Young, Organization of
GNATS - A General Nonlinear Analysis Computer Program for Two-
dimensional Structures, SLL-74-0022, October 1974.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS
Some
plotting and system-dependent utility subroutines must be supplied
by the user, as noted in comments at the beginning of each main
program. Some parallel coding must be removed from the COMPASS
subroutines, depending on whether the FTN or the RUN compiler will
be used. MESH2, GNATS, and GPRINT were compiled by NESC, but they
were not executed because of the missing subroutines.
Some
plotting and system-dependent utility subroutines must be supplied
by the user, as noted in comments at the beginning of each main
program. Some parallel coding must be removed from the COMPASS
subroutines, depending on whether the FTN or the RUN compiler will
be used. MESH2, GNATS, and GPRINT were compiled by NESC, but they
were not executed because of the missing subroutines.
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NESC0682/01
| File name | File description | Records |
|---|---|---|
| NESC0682_01.001 | INFORMATION | 10 |
| NESC0682_01.002 | MESH2 SOURCE PROGRAM (F4) | 1276 |
| NESC0682_01.003 | GNATS SOURCE PROGRAM (F4) | 7741 |
| NESC0682_01.004 | GPRINT SOURCE PROGRAM (F4) | 1821 |
| NESC0682_01.005 | AUXILIARY ROUTINES (COMPASS) | 279 |
| NESC0682_01.006 | AUXILIARY ROUTINES (F4 + COMPASS) | 212 |
| NESC0682_01.007 | MESH2 - SAMPLE PROB. INPUT DATA (CASE1) | 9 |
| NESC0682_01.008 | MESH2 - SAMPLE PROB. PRINTED OUTPUT(CASE1) | 97 |
| NESC0682_01.009 | MESH2 - SAMPLE PROB. INPUT DATA (CASE2) | 25 |
| NESC0682_01.010 | MESH2 - SAMPLE PROB. PRINTED OUTPUT(CASE2) | 1210 |
| NESC0682_01.011 | GNATS - SAMPLE PROB. INPUT DATA (CASE1) | 12 |
| NESC0682_01.012 | GNATS - SAMPLE PROB. PRINTED OUTPUT(CASE1) | 2729 |
| NESC0682_01.013 | GNATS - SAMPLE PROB. INPUT DATA (CASE2) | 15 |
| NESC0682_01.014 | GNATS - SAMPLE PROB. PRINTED OUTPUT(CASE2) | 873 |
| NESC0682_01.015 | GPRINT - SAMPLE PROB. INPUT DATA (CASE1) | 4 |
| NESC0682_01.016 | GPRINT - SAMPLE PROB. PRINTED OUTPUT(CASE1) | 466 |
| NESC0682_01.017 | GPRINT - SAMPLE PROB. INPUT DATA (CASE2) | 7 |
| NESC0682_01.018 | GPRINT - SAMPLE PROB. PRINTED OUTPUT(CASE2) | 301 |
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- I. Deformation and Stress Distributions, Structural Analysis and Engineering Design Studies
Keywords: difference equations, finite element method, mesh generation, nonlinear problems, two-dimensional.