PARAM, ENFMETH

Bulk Data Entry Used to control the calculation of enforced displacement vectors in a Modal Frequency Response (MFREQ) analysis.

Parameter Values Description
ENFMETH <REL, ABS, or TOTAL>
REL (Default)
Activates the relative method.
The modal frequency response solution is obtained by using both SPCD static displacement vectors and eigen vectors. SPCD static displacement vector is used to calculate the contribution of modal dynamic loads.
ABS, TOTAL
Activates the absolute or total method.
The calculation of SPCD static displacement is not needed. The contribution of modal dynamic load would directly come from applied displacement/velocity/acceleration at the SPCD degrees of freedom.

Comments

  1. ABS/TOTAL and REL should provide almost similar results when the dynamic matrices are symmetric.
  2. However, ABS/TOTAL is computationally efficient because it avoids calculation of static displacement vectors from SPCD degrees of freedom. ABS/TOTAL is very effective in dealing with asymmetric matrices (K2PP, M2PP, B2PP).
  3. For more details, refer to Frequency Response Analysis in the User Guide.