pyyeti.frclim.sefl

pyyeti.frclim.sefl(c, f, f0, n=1)[source]

Semi-empirical normalized force limit.

Parameters:

  • c (scalar) – Constant based on experience, typically around 1.5

  • f (scalar) – Frequency of interest, typically lower end of band.

  • f0 (scalar) – Fundamental frequency in direction of interest.

  • n (scalar; optional) – The exponent n of the rolloff factor (f0/f)^n is included in the equations to reflect the decrease in the residual mass of the component with frequency.

Returns:

nfl (scalar) – The normalized force limit:

nfl = c                   f <= f0
nfl = c / (f/f0)^n        f > f0

Notes

See reference [1] for more information on force limiting.

References

See also

ntfl(), ctdfs(), stdfs()

Examples

Compute force limit for a s/c attached to a launch vehicle, where the interface acceleration specification level is 1.75 g, and:

  • frequency of interest starts at 75 Hz

  • fundamental axial mode of s/c is 40 Hz

>>> from pyyeti import frclim
>>> m = 6961    # s/c mass
>>> faf = 40    # fundamental axial frequency of s/c
>>> spec = 1.75
>>> m*spec*frclim.sefl(1.5, 75, faf)
9745.4