Analysis of the Impact of Road Surface Conditions on Vehicle Suspension System Fatigue Life in Nigerian Urban Environments

The premature fatigue failure of automotive suspension components in Nigerian urban environments is a widespread and costly problem for vehicle owners and fleet operators, yet the specific relationship between characterised road surface excitations in Nigerian cities and component fatigue life has not been rigorously established in the literature. This study analyses the impact of road surface roughness conditions on the fatigue life of passenger vehicle suspension system components in Lagos and Abuja, representing South West and North Central urban road environments. Road surface profiles were measured along 15 selected routes in each city using a laser profilometer mounted on a survey vehicle, and International Roughness Index values were computed. Road roughness power spectral density functions were used as inputs to a validated multi-body dynamics simulation model of a passenger vehicle suspension system developed in ADAMS/Car software. Component stress time histories at critical suspension members including the lower control arm, anti-roll bar links, and shock absorber mounting brackets were extracted from simulation outputs. Fatigue life predictions were computed using the rainflow cycle counting method and the Palmgren-Miner linear damage accumulation rule with material S-N data. Results showed that the mean fatigue life of the lower control arm was reduced by a factor of 4.8 in Lagos urban road conditions compared to European road quality benchmarks used in vehicle design standards. Statistical correlation between International Roughness Index and component fatigue life depletion rate was strong (r = 0.89). The findings quantify the premature lifecycle impact of Nigerian road conditions on suspension systems. Keywords: suspension fatigue, road roughness, International Roughness Index, fatigue life prediction, urban roads Nigeria.