Power Requirements for Traversing Uneven Roadways

Vehicles which travel on uneven roadways or rough surfaces require power beyond that associated with air drag, rolling resistance or other sources of friction even though kinetic and potential energy may be conserved on the average. This is true because damped relative motions within the vehicle dissipate energy, and, even for nearly rigid vehicles, energy is lost at impact with the ground whenever the vehicle loses contact with the ground surface due to the finite downward acceleration of gravity.

Using elementary vehicle models, the nature and magnitude of the component of propulsive force associated with these energy loss mechanisms is estimated. In certain speed ranges, this force is found to vary dramatically with speed for several types of periodic roadway profiles studied. While the force due to unevennesss may be small compared to other forces for high-speed vehicles operating on smooth surfaces, it can be the major source of required power for off-road vehicles operating on very rough terrain.