Finite Element Random-Vibration Analysis of a Vehicle-Mounted Laser Platform Under Three Road Conditions

Road-induced vibration of vehicle-mounted laser platforms is stochastic, and the structural response is influenced by support motion, damping, and connection stiffness. This study combines road measurements with finite element (FE) random-vibration analysis to assess the response of a vehicle-mounted laser platform. Two screw-mounted tri-axial accelerometers measured the excitation at the left-wheel support and the response at the laser-head mount during three repeated runs on each of three roads. The records were sampled at 200 Hz for 33.305 s and processed using 1024-sample Hann-windowed Welch estimates with 50% overlap, corresponding to a frequency resolution of 0.1953125 Hz. A three-level modal mesh study supported the selection of an 8 mm global mesh. The random-vibration solution included 20 modes up to 78.911 Hz, while six selected modes were displayed in post-processing. For the three road conditions, the mean absolute error in the three-axis resultant RMS was approximately 4.85%, and the mean logarithmic PSD correlation coefficient over 0–80 Hz was approximately 0.979. The results support comparative response analysis for the tested configuration. The 2% damping ratio and equivalent support stiffnesses were treated as modeling assumptions, and the single measured input required an equivalent uniform-support excitation model.