Owing to the uneveness of the ground the crew of a vehicle is exposed to mechanical vibrations which represent a significant strain to the human body. This strain can result in impairment of comfort, in nausea, inability to operate the vehicle and in severe health disorders.
Recommendations and standards are based on the fact that acceleration magnitude is perceived to a greater extent within the range of low frequencies and that therefore is only practical to study frequencies up to 100 Hz. The assessment criteria contained in recommendations are based on sinusoidal vibrations, in fact, the vibrations of vehicle are irregularly distributed. For that reason it is necessary to carry a frequency-analysis while the vehicle is in operation.
Furthermore, the attempt is made to establish correlations between road surface-condition, speed, inflation pressure, tyre-type and load, by varying the a/m influences.