Guest
GT STRUDL Guidelines for GTSTRUDL Nonlinear Analysis
V 3 2.5.8 - 1 Rev P
2.5.8 Guidelines for GTSTRUDL Nonlinear Analysis
The computational resources and the cost required for a nonlinear analysis may be
significantly greater than the cost for a LINEAR STIFFNESS ANALYSIS depending on the
degree of nonlinearity in the problem. In many instances, the degree of nonlinearity is difficult to
predict before the analysis is performed making it very important to be able to exercise control
over the analysis. The following list provides several guidelines for controlling the use of the
nonlinear analysis features:
1. Start with a small model with similar nonlinear characteristics (i.e. geometric,
material, or boundary nonlinearity) to the "real" structure.
2. Limit the number of cycles of equilibrium iterations using the MAXIMUM
NUMBER OF CYCLES command described in Section 2.5.4.1. As a rule of
thumb, the larger the problem, the lower the number of cycles that should be
used for the initial set of iterations.
3. Use the SAVE/RESTORE features (Section 2.1.2.4 and as described in the
"GTSTRUDL Installation and Operation Guide" specific to your computer) in
conjunction with the MAXIMUM NUMBER OF CYCLES as described
above to save and possibly later restart a suspended nonlinear analysis. If a
nonlinear analysis is restored, use the NONLINEAR ANALYSIS
CONTINUE (Section 2.5.5) command to restart the analysis.
4. Use of the FORM LOAD Command as illustrated in Section 2.5.5 is an
effective way to increment a loading for nonlinear analysis.
5. Any number of independent loading conditions may be active for a nonlinear
analysis execution. If it is desirable to see the combined effect of several
independent loadings, the FORM LOAD command (Section 2.1.11.3.2)
should be used to form the combined independent load prior to the
NONLINEAR ANALYSIS command. If dependent loadings (LOAD
COMBINATION) are active for a nonlinear analysis, an error message is
output, the SCAN mode is entered, and the nonlinear analysis is terminated.
6. For each active independent loading, the nonlinear equilibrium iteration process
shown in Figure 2.5.1.2-1 is performed. Therefore, the number of active
V 3 2.5.8 - 1 Rev P
2.5.8 Guidelines for GTSTRUDL Nonlinear Analysis
The computational resources and the cost required for a nonlinear analysis may be
significantly greater than the cost for a LINEAR STIFFNESS ANALYSIS depending on the
degree of nonlinearity in the problem. In many instances, the degree of nonlinearity is difficult to
predict before the analysis is performed making it very important to be able to exercise control
over the analysis. The following list provides several guidelines for controlling the use of the
nonlinear analysis features:
1. Start with a small model with similar nonlinear characteristics (i.e. geometric,
material, or boundary nonlinearity) to the "real" structure.
2. Limit the number of cycles of equilibrium iterations using the MAXIMUM
NUMBER OF CYCLES command described in Section 2.5.4.1. As a rule of
thumb, the larger the problem, the lower the number of cycles that should be
used for the initial set of iterations.
3. Use the SAVE/RESTORE features (Section 2.1.2.4 and as described in the
"GTSTRUDL Installation and Operation Guide" specific to your computer) in
conjunction with the MAXIMUM NUMBER OF CYCLES as described
above to save and possibly later restart a suspended nonlinear analysis. If a
nonlinear analysis is restored, use the NONLINEAR ANALYSIS
CONTINUE (Section 2.5.5) command to restart the analysis.
4. Use of the FORM LOAD Command as illustrated in Section 2.5.5 is an
effective way to increment a loading for nonlinear analysis.
5. Any number of independent loading conditions may be active for a nonlinear
analysis execution. If it is desirable to see the combined effect of several
independent loadings, the FORM LOAD command (Section 2.1.11.3.2)
should be used to form the combined independent load prior to the
NONLINEAR ANALYSIS command. If dependent loadings (LOAD
COMBINATION) are active for a nonlinear analysis, an error message is
output, the SCAN mode is entered, and the nonlinear analysis is terminated.
6. For each active independent loading, the nonlinear equilibrium iteration process
shown in Figure 2.5.1.2-1 is performed. Therefore, the number of active
