Fatigue relevant road surface statistics

Road roughness is a major source of vehicle fatigue. To improve the understanding of vehicle durability, statistical methods are applied to characterise measured road profiles. Different statistical road models are used to generate corresponding synthetic road profiles. Vehicle fatigue is assessed utilising a simple quarter-vehicle model in combination with the Palmgren-Miner damage hypothesis, Basquin’s relation and Rainflow counting. Several road realisations (Monte-Carlo simulation) provide an estimate of the expected fatigue damage. The results suggest that actual roads cause more damage than synthetic Gaussian roads, possibly due to occasional road transients (bumps and holes), causing large loads on the vehicle. Thus, a road model being the sum of Gaussian ‘noise’ and transient events is suggested.