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Spectrum Synthesis

Spectrum Synthesis combines one or more Fatigue Damage Spectrum (FDS) curves into a damage-equivalent acceleration PSD.

Input and output

  • Input: one HistogramData packet with matrix_1d representation. Each curve is treated as one Mission Profile FDS.
  • Output: one acceleration PSD curve with matrix_1d representation. Histogram Output can export it as .hm1.h5.

Mission Profile

The Mission Profile tab lists the FDS curves discovered during the latest execution. Each profile has an editable positive floating-point Repeats value with a default of 1.

The target damage is the sum of every resampled FDS multiplied by its repeat count. The common frequency range is the union of all input FDS ranges; values outside each profile's original range are not extrapolated.

Advanced properties

The Advanced tab follows the same GroupBox organization used by SRS & FDS:

  • Frequency Resampling: bin mode, bin count, and interpolation.
  • Dynamic Parameters: quality factor Q.
  • FDS Parameters: Rayleigh or Lalanne damage model, K, m, and C.
  • Synthesis Parameters: equivalent PSD test duration.
  • Solver Parameters: synthesis method and iterative convergence controls.
  • Others: output PSD unit and output name.

Solvers

Direct Formula is the default. It applies the closed-form Halfpenny inverse independently at every common frequency point.

Iterative FDS Match uses the direct result as its initial PSD, recomputes FDS through the full SDOF response transfer function, and applies a relaxed multiplicative damage-ratio correction until the relative-error target or maximum iteration count is reached.