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Optimal trailer design for tractor-trailer transportation depends on accurate and reliable estimates of typical lifetime loading duty cycles. On-the-road testing was done to measure the vertical acceleration response of three different trailers in forest logging conditions. The test conditions included various trailer axle and load configurations, weight transported, and road surfaces including both gravel and paved roads. It was concluded that the rigid trailer body bounce and pitch, the non-rigid body trailer bending, and the wheel hop are the primary components of the vertical response. These results establish approximately what types of operational amplitudes are to be expected for these operations and will provide the basis for the development of a more general trailer frame load prediction model.

The directional dynamics of partially filled articulated tank vehicles is investigated via computer simulation assuming constant forward velocity. The directional response characteristics of an articulated tank vehicle is investigated for various steering manoeuvres and compared to that of an equivalent rigid cargo vehicle to demonstrate the destabilizing effects of liquid load shift. It is concluded that during a steady steer input, the distribution of cornering forces caused by the liquid load shift yields considerable deviation of the path followed by the tank vehicle. The lateral load shift encountered in a partially filled tank vehicle during lane change and evasive type of highway manoeuvres gives rise to roll and lateral instabilities.

General purpose tank vehicles often carry partial loads in view of variations in the weight density of the liquid cargo and are thus subject to slosh loads during highway manoeuvres. The magnitude of destabilizing forces and moments due to liquid slosh is strongly related to a number of vehicle and tank design factors, such as tires, suspension, articulation mechanism, weights and dimensions, tank geometry and fill level. The rollover threshold of the tank vehicle is compared to that of an equivalent rigid cargo vehicle to demonstrate the destabilizing effects of liquid slosh. The rollover threshold of the tank vehicle is evaluated for a number of tank design factors. Influence of tank size and cross-section on the rollover threshold of the tank vehicles is investigated. The study concludes that the lateral load shift and thus the rollover threshold is strongly related to the tank cross-section geometry.