Power Spectral Density Analysis of Vehicle Vibration Using the NASTRAN Computer Program

Frequency response and power spectral density analyses are implemented on the NASTRAN computer program for the purpose of assessing the vibratory response of automotive vehicles. A review of theoretical concepts related to the frequency domain techniques is presented, followed by a derivation of the equations of vertical motion for a linearly elastic automotive vehicle. Special emphasis is given to the discussion of random loading, and the cross-spectral density matrix for the terrain input to a four-wheel vehicle is derived. Example calculations are performed for a compact-size vehicle exposed to moderately severe road roughness.