Beigpr,  Readme file for beigpa.v707, alter for buckling in SOL 106

M. A. Gockel, April 11, 2000

1. BACKGROUND

The capability for buckling analysis without restart in SOL 106 was introduced in Version 
70.7.  See the discussion of param, buckle, 2 in the release notes.  This alter provides 
the correct answers for both the case of follower forces, and the case where the force 
directions are constant.  It corrects error 38785.  It is also more efficient in 
converging on the first mode. 

2. INPUT

Put 

include 'beigpa.v707'

before the CEND entry.  Put a METHOD entry in Case Control, along with param,buckle,2.  
Put an eigrl entry in bulk data, although it will not be read.  The alter will use the 
READ module (symmetric eigensolver) if there are no follower forces, and the CEAD 
module (general eigensolver) when there are.  The few lowest modes will be calculated.

3. OUTPUT 

The eigenvalues and eigenvectors are output.  If the CEAD module is used, the solution 
will be complex in form, although the imaginary part should be zero.  If the root has 
a significant imaginary part that root and its eigenvector should be ignored.

4. SAMPLE PROBLEM

File beigp1.dat is a 10-cell beam with an end load aligned along the local element 
axis after deformation (FORCE1 entry).  It requires the CEAD module for its solution, 
which results in complex output with zero imaginary part.