frqscl

Mapdl.frqscl(scaling='', **kwargs)

Turns on automatic scaling of the entire mass matrix and frequency

APDL Command: FRQSCL range for modal analyses using the Block Lanczos, PCG Lanczos, or Supernode mode extraction method.

Parameters
scaling

Off - Do not use automatic scaling of the mass matrix and frequency range.

On - Use automatic scaling of the mass matrix and frequency range.

Notes

Use this command to deactivate or force activation of automatic scaling of the entire mass matrix and frequency range for modal analyses where the entire mass matrix is significantly different (i.e., orders of magnitude difference) than the entire stiffness matrix (for example, due to the particular unit system being used). Where the mass matrix is significantly smaller compared to the stiffness matrix, the eigenvalues will tend to approach very large numbers (>10e12), making the Block Lanczos, PCG Lanczos, or Supernode mode extraction method less efficient and more likely to miss modes.

ANSYS uses scaling (if appropriate) by default. However, you can issue FRQSCL,ON to force the entire mass matrix and frequency range to be scaled to bring the stiffness and mass matrices closer together in terms of orders of magnitude, improving efficiency and reducing the likelihood of missed modes. The resulting eigenvalues are then automatically scaled back to the original system. If you are using micro MKS units, where the density is typically very small compared to the stiffness, you may want to issue FRQSCL,ON to force scaling on.

If the stiffness and mass are on the same scale, FRQSCL,ON has no effect.

This command is available only for modal analyses using the Block Lanczos, PCG Lanczos, or Supernode mode extraction method (MODOPT,LANB, LANPCG, or SNODE).

This command is not valid and has no effect when used in conjunction with the MSAVE,ON command in a modal analysis with the PCG Lanczos mode extraction method.