Mechanical APDL Structural Analysis Guide

Com- GUI Path

mand

Option

Main Menu> Solution> Analysis Type> Analysis

Options

Mode-extraction Method MODOPT

Main Menu> Solution> Analysis Type> Analysis

Options

Number of Modes to Extract MODOPT

Main Menu> Solution> Analysis Type> Analysis

Options

Number of Modes to Expand (see MXPAND

Note below)

Main Menu> Solution> Analysis Type> Analysis

Options

Mass Matrix Formulation LUMPM

Main Menu> Solution> Analysis Type> Analysis

Options

Prestress Effects Calculation PSTRES

Main Menu> Solution> Load Step Opts > Out-

put Ctrls > DB/Results Files

Control Output to the Results File OUTRES

This command cannot be accessed from a

menu.

Residual Vector Calculation RESVEC

When you specify a modal analysis, a Solution menu that is appropriate for modal analyses appears.
The Solution menu is either “abridged” or “unabridged,” depending on the actions you took prior to
this step in the current session.The abridged menu contains only those solution options that are valid
and/or recommended for modal analyses. If you are on the abridged Solution menu and you want to
access other solution options (that is, solution options that are valid for you to use, but their use may
not be encouraged for this type of analysis), select the Unabridged Menu option. For details, see Using
Abridged Solution Menus in the Basic Analysis Guide.

3.4.2.1. Option: New Analysis (ANTYPE)

Select New Analysis. If you wish to compute additional load vectors, residual vectors, or enforced motion
terms subsequent to a prior modal analysis, select Restart.

3.4.2.2. Option: Analysis Type: Modal (ANTYPE)

Use this option to specify a modal analysis.

3.4.2.3. Option: Mode-Extraction Method (MODOPT)

Select one of the following mode-extraction methods:

Mode-Extraction Comments

Method

Used for large symmetric eigenvalue problems. This method

uses the sparse matrix solver, overriding any solver specified

via the EQSLV command.

Block Lanczos

Used for very large symmetric eigenvalue problems (500,000+

degrees of freedom), and is especially useful to obtain a solu-

PCG Lanczos

tion for the lowest modes to learn how the model will behave.

This method uses the PCG iterative solver and therefore has

the same limitations (that is, it does not support superele-

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Applying Loads and Obtaining the Solution