! The structure must be unconstrained in the initial load step, or
! else the initial acceleration specification will have no effect.
DDELE, ...! Remove displacement constraints (if appropriate)
LSWRITE! Write load data to load step file (Jobname.S01)
! Transient solution
TIME, ...! Realistic time interval
NSUBST, ...! Use appropriate time step
KBC,0! Ramped loads (if appropriate)
D, ...! Constrain structure as desired
! Continue with normal transient solution procedures
LSWRITE! Write load data to load step file (Jobname.S02)See the Command Reference for discussions of the ACEL,TIME,NSUBST,KBC,LSWRITE,DDELE, and
KBC commands.
5.3.3. Set Solution Controls
This step for a transient dynamic analysis is the same as for a basic structural analysis (see Set Solution
Controls (p. 10) in Structural Static Analysis (p. 9)) with the following additions:
If you need to establish initial conditions for the full transient dynamic analysis (as described in Establish
Initial Conditions (p. 110)), you must do so for the first load step of the analysis. You can then cycle
through the Solution Controls dialog box additional times to set individual load step options for the
second and subsequent load steps (as described in Repeat Steps 3-6 for Each Load Step (p. 117)).
5.3.3.1. Access the Solution Controls Dialog Box
To access the Solution Controls dialog box, choose menu path Main Menu> Solution> Analysis Type>
Sol'n Control. The following sections provide brief descriptions of the options that appear on each tab
of the dialog box.For details about how to set these options, select the tab that you are interested in and
then click theHelpbutton.Nonlinear Structural Analysis (p. 193) also contains details about the nonlinear
options introduced in this chapter.
5.3.3.2. Using the Basic Tab
The Basic tab is active when you access the dialog box.
The controls that appear on the Basic tab provide the minimum amount of data needed for the analysis.
Once you are satisfied with the settings on the Basic tab, you do not need to progress through the
remaining tabs unless you want to adjust the default settings for the more advanced controls. As soon
as you click OK on any tab of the dialog box, the settings are applied to the database and the dialog
box closes.
You can use the Basic tab to set the options listed in Table 2.1: Basic Tab Options (p. 11). For specific
information about using the Solution Controls dialog box to set these options, access the dialog box,
select the Basic tab, and click the Help button.
Special considerations for setting these options in a full transient analysis include:
- When setting ANTYPE and NLGEOM, choose Small Displacement Transient if you are performing a new
analysis and you want to ignore large deformation effects such as large deflection, large rotation, and
large strain. Choose Large Displacement Transient if you expect large deflections (as in the case of a
long, slender bar under bending) or large strains (as in a metal-forming problem). Choose Restart Current
Analysis if you want to restart a failed nonlinear analysis, if you have previously completed a static prestress
or a full transient dynamic analysis and you want to ext end the time-history, or if you wish to use the
Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationPerforming a Full Transient Dynamic Analysis