Sensitivity Analysis

The coding for sensitivity analysis is concentrated within the sensi_coor.c (coordinates as design variables) and sensi_orien.c (orientation as design variables) subroutines. The design responses and the parameters describing them are stored in a character*81 field objectset(5,nobject), where nobject is the number of design responses.

The structure of the field objectset is as follows:

• objectset(1,*)
  • 1-18: design response (e.g. ALL-DISP)
  • 19-20: LE or GE (for constraints)
  • 21-40: boundary weighting distance
  • 41-60: relative constraint value
  • 61-80: absolute constraint value
  • 81-81: R for reading the sensitivities from file jobname.sen, W for writing the sensitivities to file jobname.sen (only stored in objectset(1,1))
• objectset(2,*)
  • 1-5: filter type
  • 6-8: BOU if boundary weighting is active, else empty
  • 10-12: EDG if edge conservation is active, else empty
  • 14-16: DIR if direction weighting is active, else empty
  • 17-19: MIN for minimization, MAX for maximization
  • 21-40: filter radius
  • 41-60: $\rho$ of the Kreisselmeier-Steinhauser function
  • 61-80: $\bar{\sigma}$ of the Kreisselmeier-Steinhauser function
• objectset(3,*)
  • 1-81: node or element set to which the design response applies
• objectset(4,*)
  • set of opposite nodes (only for MAXMEMBERSIZE AND MINMEMBERSIZE geometric constraints)
• objectset(5,*)
  • 1-80: name of the design response
  • 81-81: C for Constraint, G for Geometric constraint and O for Objective

The structure of subroutines sensi_coor.c and sensi_orien.c is made up of a preprocessing part, a processing part and a postprocessing part. The preprocessing part is executed only once, for frequency sensitivities the processing and postprocessing part is executed as many times as there are eigenvalues, else they are executed only once.