Linearised Pre-Buckling Solver

The linearised pre-buckling solver is commonly used in stress analysis of slender or thin-walled structures, it allows for the direct solving of 'buckling' problems around an equilibrium position along the non-linear path. The solver is invoked by the MDL command analysis linearised_prebuckling; this command must be specified in the case block.

[Note] Note

When executing B2000++, warnings of the following kind

WARNING:solver.eigenvalue.arpack:12:36:35.234: Maximum number of iterations taken.
All possible eigenvalues (0) have been found.

are indicative that the value for the nmodes option should be increased.

1. MDL Commands

In addition to the MDL command analysis linearised_prebuckling, the following commands may be specified in the case block.

nmodes v

Number of buckling modes v to be computed (default: 1). It is often necessary to set this option to values of 10 or even 20 for the successful solution of the eigenvalue problem.

shift v

The spectral frequency shift value. The computed buckling modes are the ones whose eigenvalues (load factors) are near this value. The default of 0 selects the nmodes lowest buckling modes.