To this point we have derived the Shock Response Spectrum (SRS) from a time signal of acceleration input.
For random vibration data it is usually more efficient to represent the acceleration loading by means of a PSD. In 1953, Miles [7] presented an equation similar in nature to the SRS. Using the simple formula expressed in Eqn. 1, he derived a spectrum of the RMS (Root Mean Square) acceleration response to a random PSD applied to a SDOF system of natural frequency fn. The corresponding displacement spectrum can also be determined using the author’s modification given in Eqn. 2.