Space Qualification — Tool

Random vibration g_RMS

A random vibration spec is a set of PSD breakpoints — frequency against g²/Hz. The overall severity is the square root of the area under that curve, integrated properly on log–log axes where the segments are straight lines, not the flat trapezoids a spreadsheet would give you.

Slopes between breakpoints are treated as constant dB/octave, the standard convention. The 3σ figure is the usual planning shorthand for peak demand; the underlying Gaussian process exceeds it about 0.3 % of the time.