PARAM, ODS

Bulk Data Entry An Operating Deformed Shape (ODS) run requires the output for all the elements or all the grids for limited loading frequencies of interest.

Parameter Values Description
ODS <YES, NO> Typically, an Operating Deformed Shape (ODS) run requires the output for all the elements or all the grids for limited loading frequencies of interest. The specific frequencies may come from peak responses. Even though the recovery is needed for the limited number of frequencies, the full eigenvectors are needed to recover the displacement for all degree of freedom inside modal FRF solution. Usually the number of limited loading frequencies is much less than the number of eigenvectors. The recovery of eigenvectors takes significant amount of time for AMSES/AMLS eigensolvers. Furthermore, there is a need for huge disk space requirement to keep the full eigenvectors.
YES
Reduces both computational time and disk space utilization to recover the displacements for all degree of freedom. In this process, OptiStruct would keep some of the AMSES/AMLS scratch space in disk. After the modal FRF solution, this tree structure would be used to recover operating deformed shape at limited frequencies and the scratch space from AMLS/AMSES would be deleted soon after.
NO (Default)
Eigen vectors from AMLS/AMSES would be directly recovered for the required degree of freedom. Also, the scratch space of AMSES/AMLS would not be stored in the disk.

Comments

  1. For this feature to work with AMLS, the job needs to be run with FastFRS (PARAM,FFRS,YES). ODS_FastFRs binary is also required with the versions mentioned below:
    • AMLS version 5.0.278 or newer
    • ODS_FastFRS 2.0.0323 or newer.
    • A new environment variable FASTFRS_ODS_EXE should point to the new ODS_FastFRS binary.
  2. ODS is supported only with a single modal space. This means it only allows single set of SPC, MPC and single set of METHOD(STRUCTURE)/METHOD(FLUID). ODS supports fluid-structure interaction so that you can have one METHOD for structure and the other METHOD for fluid. ODS currently supports single set of FREQ also.
  3. Frequency-dependent materials/bushing are not currently supported with PARAM,ODS,YES; while AMLS is used as an eigensolver. However, this facility is available with AMSES eigensolver.
  4. With PEAKOUT present, the maximum benefit with PARAM,ODS,YES will be achieved for ESE/EKE/EDE and DISP/VELO/ACCE.