Mechanical APDL Structural Analysis Guide

Figure 9.2: Flowchart of Linear Perturbation Modal Analysis

1st Phase of Linear Perturbation (SOLVE, ELFORM)

(1) Restart from base analysis (multiframe restart).

(2) Regenerate [K ] and material data.

(3) Delete most of the loads inherited from

base analysis.

Base Analysis

Static or Full Transient

2nd Phase of Linear Perturbation (SOLVE)

(1) Allow modifications of perturbation loads to

generate {F }.

(2) Perform coordinate update (program

automatically executes UPCOORD) if

base analysis includes NLGEOM,ON.

(3) Generate [M] and [C] matrices.

(4) Perform modal analysis.

T

Downstream Analysis performed using .MODE

and .FULL files (MSUP or PSD analysis).

i

perturbed

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General Procedure for Linear Perturbation Analysis