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Dynamic behavior of a partly-filled liquid cargo vehicle subject to simultaneous application of cornering and braking maneuvers is investigated through computer simulation. A three-dimensional quasi-dynamic model of a partly-filled tank of circular cross-section is developed and integrated into a comprehensive three-dimensional model of an articulated vehicle to study its directional response under varying steering and braking inputs, fill volumes and road surface friction. The liquid load movement encountered under combined steering and braking is expressed in terms of variations in the instantaneous c.g. coordinates and mass moments of inertia of the liquid bulk, assuming negligible influence of fundamental slosh frequency and viscous effects.

This paper summarizes the methodology and findings of an investigation to determine friction coefficients between typical loads and trailer deck materials in static, sinusoidal, and field measured random vibration environments. To conduct the tests in a controlled laboratory environment, a special sled-deck fixture was designed. Provisions were made to allow a change in sled-deck contact materials and to vary the load on the sled. For dynamic testing, the deck was subjected to sinusoidal and field based random signals obtained from tractor-trailer traversing paved and gravel roads. The results reveal that under vertical vibration, these friction coefficients can be as low as 25% of their corresponding static values. The random vibration tests revealed that friction coefficients can fall below 75% of the mean value for up to 35% of the total test duration. Thus, loads that rely on static friction for security may be highly prone to load shifts in a dynamic environment.