- The LSWRITE command does not capture changes to real constants (R), material properties (MP),
couplings (CP), or constraint equations (CE). - The LSWRITE command automatically transfers solid-model loads to the finite element model, so all
loads are written in the form of finite-element load commands. In particular, surface loads are always
written in terms of SFE (or SFBEAM) commands, regardless of how they were applied. - To modify data on load step file number n, issue the command LSREAD,n to read in the file, make
the desired changes, and then issue LSWRITE,n (which overwrite the old file n). You can also directly
edit the load step file using your system editor, but this is generally not recommended. The GUI
equivalents of the LSREAD command are:
Command(s):LSREAD
GUI: Main Menu> Preprocessor> Loads> Load Step Opts> Read LS File
Main Menu> Solution> Load Step Opts> Read LS File - The LSDELE command allows you to delete load step files from within the program. The GUI equival-
ents of LSDELE are:
Command(s):LSDELE
GUI: Main Menu> Preprocessor> Loads> Define Loads> Operate> Delete LS Files
Main Menu> Solution> Define Loads> Operate> Delete LS Files - Another useful load step related command is LSCLEAR, which allows you to delete all loads and reset
all load step options to their defaults. You can use it, for example, to "clean up" the load step data
before reading in a load step file for modifications.
GUI equivalents for LSCLEAR are:
Command(s):LSCLEAR
GUI: Main Menu> Preprocessor> Loads> Define Loads> Delete> All Load Data> data type
Main Menu> Preprocessor> Loads> Reset Options
Main Menu> Preprocessor> Loads> Define Loads> Settings> Replace vs Add
Main Menu> Solution> Reset Options
Main Menu> Solution> Define Loads> Settings> Replace vs Add> Reset Factors
2.8. Defining Pretension in a Joint Fastener
Pr eloads in bolts and other structural components often have significant effect on deflections and
stresses. Two features, the PRETS179 pretension element and the PSMESH pretension meshing command,
can be used for this type of analysis. If the fastener has been meshed in two separat e pieces, the pre-
tension elements can be inserted between the pieces using the EINTF command.
The pretension load is used to model a pre-assembly load in a joint fastener. The fastener can be made
up of any 2-D or 3-D structural, low- or high-order solid, beam, shell, pipe, or link elements. When using
the PSMESH command, the pretension section, across which the pretension load is applied, must be
defined inside the fastener (shown in Figure 2.21: Pretension Definition (p. 67) for a bolted joint).
2.8.1. Applying Pretension to a Fastener Meshed as a Single Piece
The easiest way to apply pretension elements to a fastener is via the PSMESH command. You can use
the command only if the fastener is not meshed in separat e pieces. The command defines the pretension
section and generat es the pretension elements. It automatically cuts the meshed fastener into two parts
and inserts the pretension elements. If you decide that you want to remove the pretension elements,
they can do so automatically by deleting the pretension section (Main Menu> Preprocessor> Sections>
Delete Section). This feature also allows you to “undo” the cutting operation by merging nodes.
Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationLoading