Mechanical APDL Structural Analysis Guide

Figure 9.3: Flowchart of Linear Perturbation Eigenvalue Buckling Analysis

1st Phase of Linear Perturbation (SOLVE, ELFORM)

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

(2) Regenerate [K ].

(3) Delete most of the loads inherited from

base analysis.

Base Analysis

Static or Full Transient

(4) Perform coordinate update (program

automatically executes UPCOORD) if

base analysis includes NLGEOM,ON.

T i

2nd Phase of Linear Perturbation (SOLVE)

(1) Allow modifications of perturbation loads

to generate {F }.perturbed

(2) Solve for {U } from [K ]{U } = {F }

(3) Generate linear stress stiffening matrix [K ] using

{U }.

perturbed

T i perturbed perturbed L S perturbed

(5) Perform buckling analysis to solve

[K ]{Ti φ }-j λ [K ]{j SL φ }=0.j

Linear Perturbation Analysis