Vehicle Axle Accelerations Due to Road Roughness for Accelerated Life Testing

In order to develop an accurate and realistic accelerated life test, vehicle axle acceleration must be correlated to actual road profiles. This paper describes analytical and empirical methods used to correlate vehicle acceleration to road roughness. A quarter-car model was developed to simulate the vertical response of a vehicle. The quarter-car model uses a tire footprint to average the road profile. Pennsylvania Transportation Institute's (PTI) inertial profilometer was used to record road profiles of city streets through out Pennsylvania. Peak axle accelerations from actual accelerometer data were correlated with the profile's International Roughness Index (IRI). Additional road profiles were input to the quarter-car simulation model. The resulting accelerations from the simulation model fit the above correlation constructed with experimental data. Thus, a quarter-car simulation model can be used with road profile data to develop accelerated life tests.