Comparison of Measures of Vibration Affecting Occupants of Military Vehicles

The work reported herein was undertaken as an initial step in clarifying a clouded issue between two vibration measures for describing vehicle ride performance. It focused on the vertical component of human vibration in a vehicle ride dynamics setting and made experimental measurements of both vibration measures. Using test facilities in the Federal Republic of Germany and the United States, numerous vehicles in common use by NATO forces were studied under proving-ground conditions to assemble a data base of recorded driver-seat accelerations. These were analyzed to infer their corresponding Absorbed Power and International Organization for Standardization (ISO) acceleration measures. The two vibration measures were found to be essentially the same in terms of their ability to express vehicle ride performance and differences in subjective vibratory roughness. The confounding effects of psychological factors, potential for injury, and time of exposure were indentified as common problems needing further investigation. These factors are discussed in terms of accumulated experience with both measures. Recommendations are made for a more thorough testing involving all components of vibration. Future tests should include medically trained individuals accustomed to dealing with human test subjects. It is also recommended that both measures continue to be used while experience accumulates with ISO acceleration with the eventual aim of incorporating the best features of both measures into a refined ISO measure to be used exclusively. Keywords: Ride criteria, Ride dynamics, Ride meter, Ride quality, Vehicle dynamics.