Simulation of solid cargo-vehicle interaction during braking of a heavy vehicle with ABS

The effect of cargo shifting on the braking efficiency of a freight truck is investigated thorough development and analysis of an analytical model of the cargo-vehicle system together with the tie-down system. Braking efficiency is characterized in terms of the stopping distance, as a function of the cargo securement method (direct and indirect) and deck vibration caused by varying levels of road roughness. The relative movement of the cargo with respect to the deck causes decoupling of the cargo and the vehicle masses. The effective braking forces are thus applied to a reduced total mass. An important phenomenon that influences the cargo-vehicle interaction derives from the decoupling of the cargo and vehicle masses during the shifting of the cargo, leading to a situation in which the braking forces are applied to a reduced mass. The vehicle performance with a rigidly fixed cargo is also evaluated for comparison purposes. Results show that the indirectly restrained cargo produces the minimum stopping distances, irrespective of the road roughness, while the maximum stopping distances are attained for the directly restrained cargo.