/IMPL/BUCKL/1

Engine Keyword Euler buckling modes will be computed.

Format

/IMPL/BUCKL/1

V1 V2 Nbuck MSGLVL MAXSET SHFCL

Definition

Field Contents SI Unit Example
V1, V2 Eigenvalue range of interest. 2

(Real)

  
Nbuck Number of modes to be computed.

(Integer > 0)

  
MSGLVL Diagnostic (printout) level.

(Integer Range: [0;4])

  
MAXSET Number of vectors in a block or set.
= 0
Set to 8

(Integer Range: [0;16])

  
SHFCL Shift in buckling modes pencil.
= 0
Set to 1.e-2
  

Comments

  1. Computation of Euler buckling modes follows a linear implicit computation. /IMPL/LINEAR must be defined.
  2. The units of V1 and V2 are eigenvalues. Each buckling eigenvalue is the factor by which the pre-buckling state of stress is multiplied to the produce buckling in the shape defined by the corresponding eigenvector. Negative eigenvalue means the critical loading is in the opposite direction.
  3. Eigenvalues are found in order of increasing magnitude; that is, those closest to zero are found first. Different V1 and V2 inputs show the ranges in the following table:
    V1 V2 [V1,V2] (V1 < V2)
    0. V2 Lowest Nbuck roots below V2
    V1 0. [V1,+∞]
    0. 0. [-∞,+∞]
  4. MSGLVL controls the amount of diagnostic output during the eigenvalue extraction. The default value of zero suppresses all diagnostic output. A value of one prints eigenvalues accepted at each shift. High values result in increasing levels of diagnostic output.
  5. MAXSET is used to limit the maximum block size in the Lanczos solver. It may be reduced if there is insufficient memory available. The default value is recommended.
  6. A specification of SHFCL near the first factor of critical loading may improve the performance, especially when the applied load differs from the first buckling load by orders of magnitude.